Systems and processes for waste plastic valorization

Abstract

Embodiments described herein generally relate to new systems and processes for waste plastic valorization. In an embodiment is provided an integrated process for converting waste plastic. The integrated process includes pyrolyzing a waste plastic feed to produce a pyrolysis product comprising intermediate products and solids. The process further includes reforming the intermediate products to produce a gas fraction and an oil fraction. The process further includes polymerizing at least a portion of ethylene and propylene present in the gas fraction to form an ethylene-propylene copolymer. The process further includes fabricating carbon nanofibers from at least a portion of the oil fraction. The process further includes producing carbon quantum dots from at least a portion of the solids. Electrodes incorporating the carbon nanofibers and dye-sensitized solar cells incorporating the carbon quantum dots are also described herein.

Description

UWYO / 0121PC(UW 24-030)Systems and Processes for Waste Plastic ValorizationGOVERNMENT RIGHTS

[0001] The invention was made with government support under Grant No. DE-FE0031997 awarded by the Department of Energy. The government has certain rights in the invention.FIELD

[0002] Embodiments of the present disclosure generally relate to new systems and processes for waste plastic valorization.BACKGROUND

[0003] The amount of waste plastic generated worldwide is estimated at over 350 million tons. Of this waste plastic, 49% and 19% are used as landfill or incinerated, respectively, 23% are mismanaged, and only 16% are collected for recycling. These disposal methods are unsustainable. Landfilled and mismanaged plastics accumulate in the ecosystem, and plastic particles, additives, and pathogens enter the food chain, while incineration releases carbon dioxide and other pollutants. Conventional waste plastic recycling mainly involves mechanical reprocessing into products, yet it suffers from sorting limitations, contamination, and deterioration of the plastic.

[0004] To address these problems, valorization has emerged as a promising method for converting waste plastics into value-added products and mitigating pollution. For example, some conventional technologies utilize photoelectrochemical technology to valorize polyethylene terephthalate to form formate and hydrogen. Other conventional technologies dehydrogenate plastics to produce carbon nanotubes by using microwaves and metallic catalysts. Another conventional technology uses thermo-electrochemical (elecATT) treatment, which integrates alkaline thermal treatment with electrochemical processing. ElecATT converts a mixture of low density polyethylene and seaweed into value added products: hydrogen (H2), waxy polymeric condensates, and carbon nanotubes. Application of nickel supported by zirconia and zeolite further enhanced production of H2 in elecATT processing. An alternative conventional technology utilizes hydrochloric acid (HC1) from polyvinyl chloride (PVC) dehydrochlorination to attack PET and convert PVC and PET into terephthalic acid and 1,2-di chloroethane. Other conventional technologies carbonize vehicleUWYO / 0121PC(UW 24-030)waste plastic into graphene via fast discharge. Overall, conventional approaches decompose plastic molecules and obtain gases, liquids, or solids as products. However, these products are feedstocks of the next phase, and few studies have explored their applications.

[0005] There is a need for new systems and processes for waste plastic valorization.SUMMARY

[0006] Embodiments described herein generally relate to new systems and processes for waste plastic valorization. In contrast to conventional technologies, the inventors found an integrated process for valorizing waste plastic to simultaneously utilize gas, liquid (for example, oil and / or wax), and solid products. As described herein, the full spectrum of products (for example, gas, liquid, and solid products) resulting from the pyrolysisreforming of waste plastic may be utilized as precursors of value-added products. Such value-added products may include ethylene-propylene copolymers, carbon nanofibers (CNFs), and carbon quantum dots (CQDs). The CNFs may be subsequently utilized as electrodes, such as supercapacitor electrodes. The CQDs may be utilized as co-sensitizers for a primary sensitizer, such as an N3 dye, in dye-sensitized solar cells.

[0007] In an embodiment, an integrated process for converting waste plastic is provided. The process includes pyrolyzing a waste plastic feed comprising a polyolefin to produce a pyrolysis product comprising an intermediate product and solids. The process further includes reforming the intermediate products to produce: a gas fraction and an oil fraction. The process further includes polymerizing at least a portion of ethylene and propylene present in the gas fraction to form an ethylene-propylene copolymer. The process further includes fabricating carbon nanofibers from at least a portion of the oil fraction. The process further includes producing carbon quantum dots from at least a portion of the solids.

[0008] In another embodiment, a dye-sensitized solar cell is provided. The dye sensitized solar cell includes carbon quantum dots described herein.

[0009] In another embodiment, an electrode is provided. The electrode includes carbon nanofibers described herein.

[0010] In another embodiment, a system for converting waste plastic is provided. The system includes a pyrolysis reactor; a reforming reactor downstream from, and in fluid communication with, the pyrolysis reactor; a polymerization reactor downstream from, andUWYO / 0121PC(UW 24-030)in fluid communication with, the reforming reactor; and a controller coupled to the pyrolysis reactor, the reforming reactor, the polymerization reactor, or combinations thereof.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the above recited features of the present disclosure may be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

[0012] FIG. 1A is a schematic overview of an integrated process for waste plastic valorization according to at least one embodiment of the present disclosure.

[0013] FIG. IB is a generalized schematic flow diagram showing various implementations of processes described herein corresponding to operational areas or units in a waste plastic valorization system.

[0014] FIG. 2 is a schematic diagram of a catalytic two-section plastic pyrolysis system on laboratory scale according to at least one embodiment of the present disclosure.

[0015] FIGS. 3A-3D show analysis data from products made at different reforming temperatures. (FIG. 3 A) Yields of gas products, oil products, wax products, solid products, and HC1. (FIG. 3B) Yields of C2H4 and C3H6 and C2H4 to C3H6 (EP) molar ratio. (FIG. 3C) Carbon number distribution of oil products and peak area percentages of aliphatics at different reforming temperatures. (FIG. 3D) X-ray diffraction (XRD) of solid products. Conditions: under 50.83 seem N2, the pyrolysis section was ramped from room temperature (approximately 25°C) to 500°C at a ramp rate of 10°C / min and held at 500°C for 80 min; and the reforming section temperatures were constant at 500°C, 550°C, 600°C, 650°C, or 700°C.

[0016] FIG. 4A shows photographs of EP copolymers formed — EP-500 (upper left), EP-600 (upper right), and EP-700 (lower) — according to embodiments of the present disclosure.

[0017] FIG. 4B shows an overlay of carbon- 13 nuclear magnetic resonance (13C NMR) spectra of the EP copolymers: EP-500, EP-600, and EP-700. 6 refers to chemical shift (PPm).UWYO / 0121PC(UW 24-030)

[0018] FIGS. 5A-5D show scanning electron microscope (SEM) images of carbon nanofibers (CNFs) produced according to embodiments of the present disclosure. The precursors for forming the CNFs shown in the SEM images were polyacrylonitrile (PAN) (FIG. 5A), and 25% PAN replaced by oil reformed at 500°C (FIG. 5B), 600°C (FIG. 5C), and 700°C (FIG. 5D). The corresponding CNFs were denoted as CNF-100PAN, CNF-250H-500, CNF-250H-600 and CNF-250H-700, respectively.

[0019] FIGS. 6A-6D show electrochemical data measured on the CNFs: (FIG. 6A) cyclic voltammetry (CV) curves; (FIG. 6B) galvanostatic charge-discharge (GCD) curves; (FIG. 6C) Nyquist plot; and (FIG. 6D) cycling performance. “1 OOP AN” denotes 100% PAN; “250H-500” indicates that 25% of PAN was replaced by oil reformed at 500°C; “250H-600” indicates that 25% of PAN was replaced by oil reformed at 600°C; “250il-700” indicates that 25% of PAN was replaced by oil reformed at 700°C.

[0020] FIG. 7A shows images of deionized water (left) and a solution of carbon quantum dots (CQDs) produced from solids made from plastic pyrolysis (right) and irradiated by ultraviolet light, 365 nm.

[0021] FIG. 7B is a transmission electron microscope (TEM) image of CQDs formed by embodiments of the present disclosure.

[0022] FIG. 7C is a fluorescent light (FL) map of CQDs formed by embodiments of the present disclosure.

[0023] FIG. 7D is an overlay of ultraviolet-visible (UV-vis) spectra of a CQD solution in DI water and an N3 dye solution in ethanol. Region from 320 to 350 nm (excitation band); region from 369 to 513 nm (emission band).

[0024] FIGS. 8A-8D show performance data of solar cells formed using CQDs according to embodiments described herein. The performance data was measured under air mass 1.5 Global (AMI.5 G) immediately after assembly (at t=0 hours). FIG. 8A: Currentvoltage (J-V) curves. FIG. 8B: External quantum efficiency (EQE) spectra and integrated current densities of dye-sensitized solar cells (DSSCs). Note that the responses of SC-TiCh and SC-CQD were all 0, and overlapped with wavelength axis. FIG. 8C: Nyquist plot and the equivalent circuit (R: resistor, C: capacitor, Q: constant phase element). FIG. 8D: Bode plot. In FIGS. 8A-8D, SC-TiCh, SC-CQD, SC-N3, and SC-CQD-N3, denote solar cells withUWYO / 0121PC(UW 24-030)TiCh paste only, treated by CQDs, dyed by N3 dye, and treated by CQDs then N3 dye, respectively.

[0025] FIG. 9A shows a cyclic voltammetry (CV) curve of CQDs on platinum-coated (Pt-coated) fluorine-doped tin oxide (FTO) glass. Counter electrode: 1 mm thick Pt foil. Reference electrode: Ag / AgCl. The scan rate was 50 mV / s, from -1.5 V to 1.5 V.

[0026] FIG. 9B shows a diagram of the energy level and charge transfer path between components of a solar cell according to embodiments of the present disclosure. CB and VB refer to conduction band and valance band, respectively.

[0027] FIG. 10 shows thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) data of an example plastic mixture (waste plastic feed). Conditions: under N2 atmosphere, ramped from room temperature to 700°C at 10°C / min and held at 700°C for 2 h.

[0028] FIG. 11 shows the yield distributions of H2 and hydrocarbons (HC) Ci to C5+ at different reforming temperatures according to embodiments described herein. Conditions: under 50.83 seem N2, the pyrolysis section was ramped from room temperature to 500°C at a ramp rate of 10°C / min and held at 500°C for 80 min; and the reforming section temperatures were constant at 500°C, 550°C, 600°C, 650°C, or 700°C.

[0029] FIG. 12 shows aliphatic versus aromatic area percentage of the oil formed at different reforming temperatures according to embodiments described herein. Conditions: under 50.83 seem N2, the pyrolysis section was ramped from room temperature to 500°C at a ramp rate of 10°C / min and held at 500°C for 80 min; and the reforming section temperatures were constant at 500°C, 550°C, 600°C, 650°C, or 700°C.

[0030] FIGS. 13 A and 13B show attenuated total reflection (ATR) data of oil (FIG.13 A) and ATR data of wax (FIG. 13B) formed according to embodiments described herein. Conditions: under 50.83 seem N2, the pyrolysis section was ramped from room temperature to 500°C at a ramp rate of 10°C / min and held at 500°C for 80 min; and the reforming section temperatures were constant at 500°C, 550°C, 600°C, 650°C, or 700°C.

[0031] FIG. 14 is an SEM image of a solid formed from pyrolysis of a waste plastic feed according to embodiments described herein. Conditions: under 50.83 seem N2, the pyrolysis section was ramped from room temperature to 500°C at a ramp rate of 10°C / min and held at 500°C for 80 min.UWYO / 0121PC(UW 24-030)

[0032] FIG. 15A is an elemental spectrum of a comparative example carbon nanofiber (CNF-100PAN). “C” in the figure refers to carbon.

[0033] FIGS. 15B-15D show elemental spectra of example carbon nanofibers produced according to embodiments of the present disclosure: CNF-250il-500 (FIG. 15B); CNF-250H-600 (FIG. 15C); and CNF-250il-700 (FIG. 15D).

[0034] FIGS. 16A-16D show N2 isothermal adsorption / desorption curves of CNF-1 OOP AN (FIG. 16A), CNF-250il-500 (FIG. 16B), CNF-250il-600 (FIG. 16C), and CNF-250H-700 (FIG. 16D).

[0035] FIGS. 17A-17D show pore size distribution data of CNF-100PAN (FIG. 17A), CNF-250H-500 (FIG. 17B), CNF-250il-600 (FIG. 17C), and CNF-250il-700 (FIG. 17D). CPV refers to cumulative pore volume.

[0036] FIGS. 18A-18C shows ATR spectra of fresh CNFs (FIG. 18 A), stabilized CNFs (FIG. 18B), and carbonized CNFs (FIG. 18C). Conditions: during stabilization, the temperature was ramped at l°C / min to 300°C and kept at 300°C for 1 h under 70 seem air; carbonization was followed by ramping at 10°C / min to 800°C and kept for 3 h under 70 seem N2. CNF- 100P AN refers to the 100% PAN sample (comparative examples), CNF-250H-500 refers to the sample where 25% of PAN was replaced by oil reformed at 500°C, CNF-250H-600 refers to the sample where 25% of PAN was replaced by oil reformed at 600°C, and CNF-250H-700 refers to the sample where 25% of PAN was replaced by oil reformed at 700°C.

[0037] FIGS. 19A-19D show possible mechanisms of stabilization and carbonization of CNFs. FIGS. 19A and 19C: stabilization and carbonization of PAN. FIG. 19B and 19D: stabilization and carbonization of oil produced according to embodiments of the present disclosure.

[0038] FIG. 20 shows size distribution data of carbon quantum dots produced according to embodiments of the present disclosure.

[0039] FIGS. 21 A and 21B are SEM images of the FTO glass coated by a TiCh substrate (SC-TiCh) indicating the transparent layer, FTO layer, and the diffusive layer: scale bar of 100 pm (FIG. 21 A); scale bar of 10 pm (FIG. 21B).

[0040] FIG. 22 shows a schematic of an example dye-sensitized solar cell according to embodiments described herein.UWYO / 0121PC(UW 24-030)

[0041] FIGS. 23 A-23D show long-term stability data of dye-sensitized solar cells under AMI. 5 G solar light: photo-conversion efficiency (FIG. 23 A); FIG. 23B: short-circuit current density (FIG. 23B); open-circuit voltage (FIG. 23 C); and fill factor (FIG. 23D). SC-N3 is a control example dye-sensitized solar cell, SC-CQD-N3 is an example dye-sensitized solar cell of the present disclosure.

[0042] Figures included herein illustrate various embodiments of the disclosure. To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0043] Embodiments of the present disclosure generally relate to new systems and processes for waste plastic valorization. For the first time, gas, oil and solid residue derived from waste plastics may be valorized simultaneously according to embodiments of the present disclosure. For example, embodiments described herein may be utilized to convert low-value waste plastic materials to high-value products, such as ethylene-propylene (EP) copolymers, carbon nanofibers (CNFs), and carbon quantum dots (CQDs). Unlike conventional technologies, all or substantially all of the waste plastic (or all or substantially all of the polyolefin present in the waste plastic) may be converted into high-value products by use of embodiments described herein. For example, greater than 90%, such as greater than 94%, such as greater than 96%, such as greater than 98%, such as greater than 99%, such as 100% of the carbon atoms present in the waste plastic may be converted into polymers, CNFs, and / or CQDs. In further contrast to conventional technologies, embodiments of the present disclosure are atom-economical. Embodiments of the present disclosure may allow for the polymer, CNFs, and / or CQDs to be formed from the same waste plastic feed.

[0044] As described herein, conventional waste plastic recycling mainly involves mechanical reprocessing into products, yet it suffers from sorting limitations, contamination, and deterioration of the plastic. To address these problems, valorization has emerged as a promising method for converting waste plastics into value-added products and mitigating pollution. Valorization decomposes plastic molecules and obtain gases, liquids,UWYO / 0121PC(UW 24-030)or solids as products. However, these products are feedstocks of the next phase, i.e., intermediate products, and few studies have explored their applications.

[0045] Embodiments of the present disclosure, in contrast, exploring the intermediate products during plastic valorization. No studies have explored using gas, liquid and solid products from plastic pyrolysis-reforming to fabricate ethylene-propylene copolymers, carbon nanofibers (CNFs), and carbon quantum dots (CQDs). Embodiments described herein are the first to carry out each of these three applications, and the first to simultaneously realize all three.

[0046] A schematic of an integrated process for valorizing waste plastic into high-value-added products according to at least one embodiment is shown in FIG. 1 A, further described below. First, C2H4 and C3H6 present in the gas products from the pyrolysis-reforming may be used to synthesize ethylene-propylene (EP) copolymers. CNFs described herein possess good physical and chemical properties, such as electrical conductivity and chemical stability. These features may enable various engineering applications such as adsorption, sensors, and catalysts. Second, the liquid products from pyrolysis-reforming may be added as precursors of CNFs. These liquid products (for example, oil) may serve as porogens that vaporize and create pore spaces during heat treatment. Meanwhile, the aromatics in the oil become graphite or graphitic, which supplies carbon materials and increases conductivity of the CNFs. Such CNFs may be used as electrodes of supercapacitors. Third, quantum dots are a series of nanosized crystalline semiconductors. CQDs are a class of quantum dots made mostly of carbon and exhibit biocompatibility, low toxicity, and excellent fluorescent properties. The high carbon content of the solid products of waste plastic pyrolysisreforming makes it a possible precursor of CQDs. The optical properties of CQDs described herein may allow them to be co-sensitizers of dye-sensitized solar cells (DSSCs).

[0047] Embodiments of the present disclosure provide an integrated process for valorizing waste plastic. In some embodiments, which may be combined with other embodiments, waste plastic may be first decomposed by pyrolysis-reforming; the products from the pyrolysis-reforming may serve as precursors for EP copolymers, CNFs, and CQDs (EP-CNF-CQDs). The CNFs may be subsequently used as supercapacitor electrodes, and the CQDs may be utilized as co-sensitizers of DSSCs. By using pyrolysis-reformingUWYO / 0121PC(UW 24-030)products, the performances of both applications were improved, and the possible mechanisms are presented. This process may be utilized to valorize real-life waste plastics.

[0048] FIG. 1A shows a schematic overview of an integrated process 100 for valorization of waste plastic and application of the products according to at least one embodiment of the present disclosure. Conventional disposal of waste plastic includes incineration or disposal in a landfill, as well as mismanagement of waste plastic. Such disposal methods are detrimental to the environment and to humans and are cost-ineffective.

[0049] In contrast, embodiments of the present disclosure enable upgrading of low-value waste plastic materials to high value products such as ethylene-propylene (EP) copolymers, carbon nanofibers (CNFs), and carbon quantum dots (CQDs). To the inventors’ knowledge, the present disclosure provides, for the first time, gas, oil, and solid residue derived from waste plastics to be valorized simultaneously. Waste plastic valorization generally refers to the process of converting waste plastic into valuable products such as new polymers, chemicals, and advanced materials such as nanofibers and quantum dots. For example, according to 2024 estimates, waste plastic is typically about USD $0.22-1.54 per kilogram, while the upgraded products such as EP copolymers, CNFs, and CQDs are typically about USD $3-4 per kilogram, USD $1,620 per kilogram, and about USD $4,000 per kilogram, respectively. Waste plastic valorization is a more useful alternative to landfilling and incineration and a way to create new materials, chemicals, fuels, and building materials, which reduces reliance on virgin plastic and mitigates pollution.

[0050] The integrated process 100 generally includes pyrolysis-reforming 101a and valorization 101b. The products from valorization 101b may be used in a wide variety of applications 101c. During pyrolysis-reforming, waste plastic 102 (made up of polymers 103) may be generally converted to gas products 105a, oil products 105b, and solid products 105c (also referred to herein as solid residue). These gas, oil, and solid products may be valorized (upgraded). For example, gas products 105a may be converted to polymers 109 (such as ethylene-propylene copolymers) via polymerization 106. As another example, the oil products 105b may be converted to carbon nanofibers (CNFs) 110 by, for example, electrospinning 107 the oil products 105b with a nanofiber precursor such as polyacrylonitrile (PAN). As another example, the solid products 105c may be converted toUWYO / 0121PC(UW 24-030)carbon quantum dots (CQDs) by, for example, oxidation 108. CQDs may be used in, for example, solar cells. For the CQDs, FIG. 1 A shows a CQD solution 111.

[0051] These products after valorization may then be utilized for a variety of applications 101c. For example, polymers 109 made from the gas products 105a may be used in, for example, a variety of uses 112 such as automobile parts, membranes, tires, o-rings, containers, and / or films, among other uses. As another example, the CNFs 110 made from oil products 105b may be used for supercapacitors 113. As shown in inset 114, specific capacity and Warburg coefficient may be adjusted by use of the nanofiber precursor, for example, the oil products 105b. As another example, the CQDs made from solid products 105c may be utilized in solar cells, such as dye-sensitized solar cells (DSSCs) 115. As shown in inset 116, current density and efficiency of the DSSC 115 may be adjusted by use of any suitable primary sensitizer, such as N3 dye as described herein.

[0052] Embodiments of the present disclosure generally relate to new systems for waste plastic valorization. Waste plastic valorization may also be referred to herein as waste plastic conversion. FIG. IB shows a generalized schematic flow diagram showing various implementations of processes described herein corresponding to operational areas or units in a waste plastic valorization system 150. Embodiments and implementations of the waste plastic valorization system may be combined with other embodiments and implementations described herein, such as embodiments and implementations of processes for waste plastic conversion. Generally, systems described herein allow for the conversion of low-value waste plastic materials to high-value products such as ethylene-propylene copolymers, carbon nanofibers, and carbon quantum dots.

[0053] The system 150 may include a pyrolysis reactor 151 in which a waste plastic feed is pyrolyzed. The waste plastic feed may generally include polymers such as olefin polymers (polyolefins). Suitable polyolefins may include polyolefins made from an alpha olefin. Suitable polyolefins present in the waste plastic feed may include polyethylene (PE), polypropylene (PP), other polyolefins, or combinations thereof. The polyolefins present in the waste plastic feed may include a polyolefin homopolymer, a polyolefin copolymer, a polyolefin block copolymer, a polyolefin random block copolymer, or combinations thereof. The polyolefins present in the waste plastic feed may include an isotactic polyolefin, an atactic polyolefin, a syndiotactic polyolefin, or combinations thereof. Suitable polyethyleneUWYO / 0121PC(UW 24-030)grades present in the waste plastic feed may include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, or combinations thereof. Polyolefin copolymers and terpolymers are contemplated.

[0054] An ethylene polymer having a density in a range from 0.910 to 0.940 g / cm3is referred to as a “low density polyethylene” (LDPE). An ethylene polymer having a density of more than 0.940 g / cm3, such as in a range from 0.940 to 0.970 g / cm3is referred to as a “high density polyethylene” (HDPE). An ethylene polymer having a density in a range from 0.926 to 0.940 g / cm3is referred to as a “medium density polyethylene” (MDPE). Polyethylene having a density in a range from 0.890 to 0.930 g / cm3, typically in a range from 0.915 to 0.930 g / cm3, that is linear and does not contain long-chain branching is referred to as “linear low density polyethylene” (LLDPE). “Linear” means that the polyethylene has no or only a few long-chain branches, typically having a branching index (g'vis) of 0.97 or above, such as 0.98 or above.

[0055] An amount of polyolefin present in the waste plastic feed may be about 10 wt% or more, such as in a range from about 10 to about 99 wt%, such as from about 20 to about 98 wt%, such as from about 40 to about 95 wt%, such as from about 50 to about 90 wt%, such as from about 70 to about 85 wt% based on a total wt% the waste plastic feed. Alternatively, an amount of polyolefin present in the waste plastic feed may be about 10 wt% or more, such as in a range from about 50 to about 99 wt%, such as from about 55 to about 98 wt%, such as from about 60 to about 95 wt%, such as from about 70 to about 90 wt%, such as from about 75 to about 90 wt% based on a total wt% of the waste plastic feed. Alternatively, an amount of polyolefin present in the waste plastic feed may be from about 80 wt% to about 95 wt%, such as from about 82 wt% to about 92 wt%, such as from about 85 wt% to about 90 wt% based on a total wt% of the waste plastic feed. The total wt% of the waste plastic feed is 100 wt%.

[0056] The waste plastic feed may include any suitable amount of polyethylene, such as about 40 wt% or more, such as from about 40 wt% to 100 wt%, such as from about 45 wt% to about 85 wt%, such as from about 55 wt% to about 75 wt%, such as from about 60 wt% to about 70 wt% based on the total wt% of the waste plastic feed. Alternatively, the waste plastic feed may include an amount of polyethylene in a range from 0 wt% to about 40 wt%, such as from about 5 wt% to about 30 wt%, such as from about 10 wt% to about 25 wt%,UWYO / 0121PC(UW 24-030)such as from about 15 wt% to about 20 wt% based on the total wt% of the waste plastic feed.

[0057] The waste plastic feed may include any suitable amount of polypropylene, such as about 40 wt% or more, such as from about 40 wt% to 100 wt%, such as from about 45 wt% to about 85 wt%, such as from about 55 wt% to about 75 wt%, such as from about 60 wt% to about 70 wt% based on a total wt% of the waste plastic feed. Alternatively, the waste plastic feed may include an amount of polypropylene in a range from 0 wt% to about 40 wt%, such as from about 5 wt% to about 30 wt%, such as from about 10 wt% to about 25 wt%, such as from about 15 wt% to about 20 wt% based on the total wt% of the waste plastic feed. Alternatively, the waste plastic feed may include an amount of polypropylene in a range from 0 wt% to about 10 wt%, such as from about 1 wt% to about 8 wt%, such as from about 2 wt% to about 6 wt%, such as about 4 wt% based on the total wt% of the waste plastic feed.

[0058] The waste plastic feed may include a polyolefin waste without additional waste plastics or other components or compositions being present in the waste plastic feed. Alternatively, the waste plastic feed may include polyolefin and other types of waste plastic which are different from the polyolefin. That is, the waste plastic feed may include waste plastic other than the polyolefin. For example, in addition to the polyolefin, the waste plastic feed may include an oxygen-containing polymer, a halogen-containing polymer, or combinations thereof. Illustrative, but non-limiting, examples of oxygen-containing polymers that may be present in the waste plastic feed may include: a polyester such as polyethylene terephthalate (PET), polybutylene terephthalate, or a combination thereof; a polyamide; a polyurethane; a polyphenol; a polycarbonate; a polylactic acid; a polyacrylic acid; a polyacrylate; a polyacetal; a halogen-containing polymer; or combinations thereof. Illustrative, but non-limiting, examples of halogen-containing polymers that may be present in the waste plastic feed may include: a chlorinated polymer such as chlorinated polyethylene; polyvinylchloride (PVC), polyvinylidene chloride (PVDC); a fluorinated polymer such as fluorinated polyethylene, such as polytetrafluoroethylene; or combinations thereof.

[0059] When the waste plastic feed includes waste plastic other than the polyolefin, an amount of the waste plastic other than the polyolefin may be about 45 wt% or less, such asUWYO / 0121PC(UW 24-030)about 35 wt% or less, such as about 25 wt% or less, such as about 20 wt% or less, such as about 15 wt% or less, such as about 10 wt% or less, such as about 5 wt% or less, such as about 2 wt% or less, or in a range from greater than 0 wt% to about 20 wt%, such as from about 0.5 to about 15 wt%, such as from about 1 to about 10 wt%, such as from about 2 to about 5 wt%, or in a range from about 5 wt% to about 20 wt%, such as from about 8 wt% to about 18 wt%, such as from about 10 wt% to about 15 wt% based on the total wt% of the waste plastic feed.

[0060] PET and PVC are prevalent in waste plastics. In various embodiments, which may be combined with other embodiments, the waste plastic feed may include a polyolefin, and optionally one or more additional waste plastics other than polyolefin such as PVC, PET, or a combination thereof.

[0061] The polyester, if present, in the waste plastic feed, may include PET, polybutylene terephthalate, or a combination thereof, among other polyesters. When the waste plastic feed includes a polyester, the polyester may be present in the waste plastic feed in an amount of about 10 wt% or less, such as about 5 wt% or less, such as about 2 wt% or less, such as about 1 wt% or less, such as about 0.5 wt% or less based on the total wt% of the waste plastic feed.

[0062] When the waste plastic feed includes a chlorinated polymer (for example, PVC), the chlorinated polymer may be present in the waste plastic feed in an amount of about 20 wt% or less, such as about 15 wt% or less, such as about 10 wt% or less, such as about 5 wt% or less, such as about 2 wt% or less, or in a range from greater than 0 wt% to about 20 wt%, such as from about 0.5 to about 15 wt%, such as from about 1 to about 10 wt%, such as from about 2 to about 5 wt%, or in a range from about 2 to about 7.5 wt%, such as from about 3.5 to about 6 wt%, or in a range from about 5 wt% to about 20 wt%, such as from about 8 wt% to about 18 wt%, such as from about 10 wt% to about 15 wt% based on the total wt% of the waste plastic feed.

[0063] The waste plastic other than the polyolefin may include, for example, polystyrene (PS). The waste plastic feed may include any suitable amount of polystyrene, for example, in a range from 0 wt% to about 40 wt%, such as from about 5 wt% to about 30 wt%, such as from about 10 wt% to about 25 wt%, such as from about 15 wt% to about 20 wt% based on the total wt% of the waste plastic feed. Alternatively, the waste plastic feedUWYO / 0121PC(UW 24-030)may include an amount of polystyrene in a range from 10 wt% to about 50 wt%, such as from about 12 wt% to about 35 wt%, such as from about 15 wt% to about 30 wt%, such as about 19 wt% to about 25 wt%, such as about 21 wt% based on the total wt% of the waste plastic feed.

[0064] The waste plastic feed may be characterized as having a certain halogen content. The waste plastic feed may include a halogen content, if present, in an amount of about 100,000 ppm (about 10 wt%) or less, such as about 36,000 ppm (about 3.6 wt%) or less, such as about 10,000 ppm (about 1 wt%) or less, or in a range from greater than 0 wt% to about 10 wt%, such as from greater than 0 wt% to about 3.6 wt%, such as from greater than 0 to about 1 wt% based on the total wt% of the waste plastic feed.

[0065] The waste plastic feed may further include a virgin plastic. Virgin plastic refers to a new unused plastic material and is not manufactured from reprocessed materials. Virgin plastics have not been previously blended with scrap, waste, or previously used material. The virgin plastic may serve to aid in processing the waste plastic feed. When the waste plastic feed includes virgin plastic, the virgin plastic may be present in the waste plastic feed in an amount of about 10 wt% or less, such as about 5 wt% or less, such as about 2 wt% or less, such as about 1 wt% or less, such as about 0.5 wt% or less based on the total wt% of the waste plastic feed.

[0066] The waste plastic feed may be solid at 25°C. The waste plastic feed may include a solid characterized by an average particle size of about 10 centimeters (cm) or less, such as about 1 cm or less, such as about 100 millimeters (mm) or less, such as about 10 mm or less, such as about 5 mm or less, such as about 3 mm or less, such as about 1 mm or less, such as about 500 microns (pm) or less, such as about 10 pm or less. The waste plastic feed may be in any suitable form such as a pellet, a flake, a fluff, a particle, or combinations thereof. The waste plastic feed may include a solid in pellet form. The solid in pellet form may be characterized by an average particle size in a range from about 0.01 to about 10 mm, such as from about 0.1 to about 1 mm. The waste plastic feed may include a solid in fluff form. The solid in fluff form may be characterized by an average particle size of about 1,500 pm or less, such as about 1,000 pm or less, such as about 500 pm or less, such as about 400 pm or less, such as about 300 pm or less, such as about 100 pm or less, such as about 50 pm or less, such as about 10 pm or less.UWYO / 0121PC(UW 24-030)

[0067] If desired, mechanical treatment of the waste plastic feed, such as comminution of the waste plastic feed, may be performed on the waste plastic feed prior to entering the pyrolysis reactor 151. In general, comminution allows the waste plastic to be broken into pieces of various sizes by, for crushing, grinding, cutting, vibrating, shredding, pelletizing, granulating, hammering, other comminution processes, or combinations thereof. The waste plastic feed may be comminuted with a crusher, a grinder, a cutter, a vibrator, a shredder, a pelletizer, a granulator, a hammer mill, or combinations thereof. The waste plastic feed may be comminuted into, for example, a pellet, a flake, a fluff, a particle, or combinations thereof.

[0068] Referring back to FIG. IB, various elements described with respect to the system 150 may be coupled to a controller 157, as shown by the dashed lines in FIG. IB. The controller 157 may be utilized to control, for example, one or more operating parameters of the one or more elements illustrated in the system 150, one or more operations of processes described herein, or combinations thereof. The controller 157 may include a processor, memory, and support circuits. The processor of the controller 157 may be one of any form of general purpose microprocessor, or a general purpose central processing unit (CPU), each of which may be used in an industrial setting, such as a programmable logic controller (PLC), supervisory control and data acquisition (SCADA) systems, or other suitable industrial controller.

[0069] The memory of the controller 157 may be non-transitory and may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), or any other form of digital storage, local or remote. The memory of the controller 157 may contain instructions, that when executed by the processor of the controller 157, may facilitate the operation of one or more elements illustrated in FIG. IB, one or more operations of processes described herein, or combinations thereof. The instructions in the memory of the controller 157 are in the form of a program product such as a program that may implement a process of the present disclosure. The program code of the program product may conform to any one of a number of different programming languages. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (for example, read-only memory devices within a computer such as CD-ROM disks readable by a CDROM drive, flash memory, ROM chips, or any type of solid-stateUWYO / 0121PC(UW 24-030)non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (for example, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information may be stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of processes described herein, are non-limiting examples of the present disclosure. The disclosure may be, for example, implemented as the program product stored on a computer-readable storage media (for example, memory) for use with a computer system (not shown). The program(s) of the program product may define functions of the disclosure described herein. In general, the controller 157 may be configured to implement any suitable operation of any suitable process described herein.

[0070] The controller 157 may be coupled to the pyrolysis reactor 151. The controller 157 may be configured to cause the pyrolysis reactor 151 to receive a waste plastic feed comprising a polyolefin. The controller 157 may be further configured to cause the pyrolysis reactor 151 to decompose and / or pyrolyze the polyolefin present in the waste plastic feed into a pyrolysis product under pyrolysis conditions. The pyrolysis product may include, for example, solids (also referred to herein as solid residue, for example, solid products 105c) and intermediate products. The intermediate products may include large and medium sized hydrocarbons condensed into wax and oil (also referred to as oil products, for example, oil products 105b), respectively, and small, non-condensable hydrocarbons that are gases (also referred to herein as gas products, for example, gas products 105a). The waste plastic feed, polyolefins present in waste plastic feed, and pyrolysis product are further described herein. The controller may be further configured to cause the pyrolysis reactor 151 to discharge the intermediate products and / or the solids. The intermediate products may be discharged from the pyrolysis reactor 151 through line 159. The solids may be discharged from the pyrolysis reactor 151 through line 158.

[0071] The system 150 may further include a carbon quantum dot synthesis unit 155. The carbon quantum dot synthesis unit 155 may be located downstream from, and coupled to, the pyrolysis reactor 151 via line 158. The controller 157 may be coupled to the carbon quantum dot synthesis unit 155. The controller 157 may be configured to cause the carbon quantum dot synthesis unit 155 to receive the solids from the pyrolysis reactor 151. TheUWYO / 0121PC(UW 24-030)controller 157 may be configured to cause the carbon quantum dot synthesis unit 155 to convert the solids into a carbon quantum dot product under any suitable conditions, such as oxidation conditions. The carbon quantum dot product may be in the form of carbon quantum dot particles, such as carbon quantum dot nanoparticles. The controller 157 may be configured to cause the carbon quantum dot synthesis unit 155 to discharge the carbon quantum dot product via a line (not shown). Such carbon quantum dot products, also referred to herein as carbon quantum dots, are value-added products. After the valorization, or upgrading, of the waste plastic to form carbon quantum dots, as value-added products, the carbon quantum dots may then be utilized in a variety of applications such as solar cells, such as DSSCs 115.

[0072] The system 150 may further include a reforming reactor 152. The reforming reactor 152 may be located downstream from, and in fluid communication with, the pyrolysis reactor 151 via line 159. The controller 157 may be coupled to the reforming reactor 152. The controller 157 may be configured to cause the reforming reactor 152 to receive the intermediate products from the pyrolysis reactor 151 traveling through line 159. The controller 157 may be configured to cause the reforming reactor 152 to convert at least a portion of the intermediate products into a hydrocarbon wax, a hydrocarbon oil, and a hydrocarbon gas under any suitable reforming conditions. As described herein, the intermediate products formed by pyrolysis may include hydrocarbons in the form of waxes, oils, and / or gases. Reforming in reforming reactor 152 may decompose, or convert, large hydrocarbon molecules present in the intermediate products into medium sized hydrocarbon molecules, and medium sized hydrocarbon molecules into smaller-sized hydrocarbon molecules. For example, the inventors found that, when the system 150 does not include reforming reactor 152, the yields of hydrocarbon waxes were significantly higher than the yields of hydrocarbon waxes when the system 150 included a reforming reactor 152. Moreover, the inventors found that the yields of hydrocarbon gases and hydrocarbon oils were higher when the system 150 includes reforming reactor 152, indicating that reforming may be used to increase the yield of hydrocarbon gases and oils (via decomposing large and medium sized hydrocarbon molecules) while reducing the yield of hydrocarbon waxes. Further, the inventors found that the yield of hydrocarbon gases significantly increased as the reforming temperature was increased. The reforming temperature may be selected toUWYO / 0121PC(UW 24-030)increase a yield of the gas fraction and to simultaneously decrease the yield of the wax fraction, the oil fraction, or both the wax and oil fractions.

[0073] The controller 157 may be configured to cause the reforming reactor 152 to discharge the hydrocarbon wax, the hydrocarbon gas, the hydrocarbon oil, or combinations thereof. The hydrocarbon wax, gas, and oil may be discharged from the reforming reactor 152 in a single stream, or separate streams. In some embodiments, which may be combined with other embodiments, the hydrocarbon wax may be discharged from the reforming reactor 152 through line 160. In some embodiments, which may be combined with other embodiments, the hydrocarbon gas and hydrocarbon oil may be discharged as a hydrocarbon mixture from the reforming reactor 152 through line 161. Additionally, or alternatively, the hydrocarbon gas and the hydrocarbon oil may be discharged from the reforming reactor 152 as separate streams.

[0074] The system 150 may further include an optional separation unit 153. The optional separation unit 153 may be located downstream from, and in fluid communication with, the reforming reactor via line 161. The optional separation unit 153 may be utilized to separate, for example, the hydrocarbon gas and hydrocarbon oil into separate fractions. When the reforming reactor product from the reforming reactor 152 contains the hydrocarbon gas, oil, and / or wax, the optional separation unit 153 may be utilized to separate the mixture into a hydrocarbon gas fraction, a hydrocarbon oil fraction, and / or a hydrocarbon wax fraction. The controller 157 may be coupled to the optional separation unit 153. The controller 157 may be configured to cause the optional separation unit 153 to receive a hydrocarbon mixture comprising one or more of the hydrocarbon gas, hydrocarbon oil, and / or the hydrocarbon wax from the reforming reactor 152. The controller 157 may be configured to cause the optional separation unit 153 to separate a hydrocarbon gas from the hydrocarbon mixture. The controller 157 may be configured to cause the optional separation unit 153 to separate a hydrocarbon oil from the hydrocarbon mixture. The controller 157 may be configured to cause the optional separation unit 153 to separate a hydrocarbon wax from the hydrocarbon mixture. The controller 157 may be configured to discharge the hydrocarbon gas (for example, as a hydrocarbon gas fraction) via line 163. The controller 157 may be configured to discharge the hydrocarbon oil (for example, as a hydrocarbon oil fraction) via line 162. Although not shown, the controller 157 may be configured toUWYO / 0121PC(UW 24-030)discharge the hydrocarbon wax (for example, as a hydrocarbon wax fraction) via a separate line. Separation at the optional separation unit 153 may include any suitable separation technique such as gas-liquid separation, liquid-liquid separation, or combination thereof, such as distillation, fractional distillation, vacuum distillation, flash evaporation, fractionation, extraction, decantation, coalescence, or combinations thereof.

[0075] The system 150 may further include a polymerization reactor 154. The polymerization reactor 154 may be located downstream from, and in fluid communication with, the optional separation unit 153 via line 163. As described herein, the hydrocarbon gas fraction may travel through line 163. The controller 157 may be configured to cause the polymerization reactor 154 to receive hydrocarbon gas fraction from the optional separation unit 153. In some embodiments, which may be combined with other embodiments, the system 150 may be free of optional separation unit 153. In these and other embodiments, hydrocarbon gas may be flown directly to the polymerization reactor 154 from the reforming reactor 152. For example, the controller 157 may be configured to cause the polymerization reactor 154 to receive hydrocarbon gas from the reforming reactor 152.

[0076] The hydrocarbon gas fraction may include C1-C5 hydrocarbon gases, such as C1-C4 hydrocarbon gases, such as C1-C3 hydrocarbon gases, such as ethylene, propylene, or combinations thereof. The controller 157 may be further configured to cause the polymerization reactor 154 to convert ethylene and propylene present in the hydrocarbon gas fraction into an ethylene-propylene (EP) copolymer. Additionally, or alternatively, the controller 157 may be configured to cause the polymerization reactor 154 to convert ethylene into polyethylene. Additionally, or alternatively, the controller 157 may be configured to cause the polymerization reactor 154 to convert propylene to polypropylene (PP). The controller 157 may be configured to cause the polymerization reactor 154 to discharge one or more of an EP copolymer, PE, and / or PP via line 164. Such polymers are value-added products. After the valorization, or upgrading, of the waste plastic to form polymers, as value-added products, the polymers may then be utilized in a variety of applications such as automobile parts, membranes, tires, o-rings, containers, and films, among other applications.

[0077] Besides hydrocarbon gases, the hydrocarbon gas fraction may further include carbon monoxide (CO) and EE. Mixtures of CO and EE are referred to as syngas. SyngasUWYO / 0121PC(UW 24-030)may be converted to C2 and C3 olefin hydrocarbons (i.e., ethylene and propylene). In some embodiments, which may be combined with other embodiments, the system 150 may further include a syngas conversion unit (not shown) downstream from, and in fluid communication with the reforming reactor 152, the optional separation unit 153, or both. The controller 157 may be configured to cause the syngas conversion unit to receive syngas, convert the syngas into ethylene, propylene, or combinations thereof. For example, the controller 157 may be configured to cause the syngas conversion unit to perform Fischer-Tropsch reaction on the syngas to form the ethylene, propylene, or combinations thereof.

[0078] The controller 157 may be configured to cause the syngas conversion unit to discharge the ethylene, propylene, or combinations thereof. The ethylene, propylene, or combinations thereof discharged from the syngas conversion unit may be fed by a line (not shown) to the polymerization reactor 154. At the polymerization reactor 154, EP copolymer, PE, and / or PP may be formed from this ethylene, propylene, or combinations thereof made from the syngas.

[0079] The system 150 may further include a carbon nanofiber fabrication unit 156. The carbon nanofiber fabrication unit 156 may be located downstream from, and in fluid communication with, the separation unit 153 via line 162. Additionally, or alternatively, the carbon nanofiber fabrication unit 156 may be located downstream from, and in fluid communication with, the reforming reactor 152 via a line (not shown). The controller 157 may be coupled to the carbon nanofiber fabrication unit 156. The controller 157 may be configured to cause the carbon nanofiber fabrication unit 156 to receive a hydrocarbon oil from the optional separation unit 153, the reforming reactor 152, or combinations thereof. The controller 157 may be configured to cause the carbon nanofiber fabrication unit 156 to convert the hydrocarbon oil fraction to a carbon nanofiber under conditions sufficient to form a carbon nanofiber.

[0080] The carbon nanofiber fabrication unit 156 may be any suitable unit for forming carbon nanofibers such as a unit that may be utilized for performing electrospinning, heat treatment, carbonization, and / or stabilization (for example, oxidation and / or crosslinking). The controller 157 may be configured to cause the carbon nanofiber fabrication unit 156 to receive polyacrylonitrile (PAN), polyvinyl acetate (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), poly(diaryloxyphosphazene) (PDPP). or combinationsUWYO / 0121PC(UW 24-030)thereof. Mixtures of the hydrocarbon oil with one or more of PAN, PVA, PVB, PVP, PDPP, or combinations thereof may be electrospun into fibers and the resultant electrospun fibers may be converted to carbon nanofibers via heat treatment, stabilization, and / or carbonization. The controller 157 may be configured to cause the carbon nanofiber fabrication unit 156 to discharge a carbon nanofiber via a line (not shown). Such carbon nanofibers are value-added products. After the valorization, or upgrading, of the waste plastic to form carbon quantum dots, as value-added products, the carbon quantum dots may then be utilized in a variety of applications such as electrodes, for example, electrodes useful in supercapacitors 113.

[0081] The system 150 may further include a neutralization unit (not shown). The neutralization unit may be downstream from, and in fluid communication with, the reforming reactor, the pyrolysis reactor, or both. For example, the neutralization unit may be positioned along line 159, along line 161, and / or along line 163. The controller 157 may be coupled to the neutralization unit. The controller 157 may be configured to cause the neutralization unit to receive HC1 during processing of the waste plastic feed. The controller 157 may be configured to cause the neutralization unit to neutralize or trap byproducts of the pyrolysis, the reforming, or combinations thereof. Byproducts of pyrolysis, reforming, or both may include hydrochloric acid (HC1) from, for example, PVC dehydrochlorination. To neutralize HC1, the neutralization unit may include an alkali material. An alkali is a basic salt of an alkali metal or an alkaline earth metal. Suitable alkali materials may include NaOH, KOH, or combinations thereof. The alkali material may be in the form of an aqueous alkali material. Neutralization of HC1 serves to prevent corrosion of equipment and / or unwanted side reactions. Here, HC1 released during pyrolysis and / or reforming may undesirably combine with decomposed polyolefins and contaminate entire batches of polymers. Accordingly, the neutralization unit may be used to reduce the concentration of, or remove, HC1.

[0082] Although not shown in FIG. IB, it should be understood that suitable equipment for controlling, for example, temperature, pressure, and flow control of various feeds, effluents, and output streams may be used with the system 150. For example, heat exchangers may be used to cool or heat a liquid or a gas along one or more lines or within various units or reactors of the system 150. Pumps and motors may be utilized to control theUWYO / 0121PC(UW 24-030)rate of flow of the materials traveling or flowing through the lines and the operating pressures of various components of the system 150. In addition, individual units and / or reactors of system 150 may include mixers, impellers, and the like to ensure sufficient mixing of materials present in the reactors and / or units. Further, the system 150 may include valves or other release mechanisms for, e.g., purging gases or liquids from the system 150. Various process controls may be used. Such process controls may include probes and sensors such as pressure indicators, differential pressure cells, temperature indicators, thermocouples, temperature switches, resistance temperature detectors, solenoids, flowmeters, flow regulators and valves, gas analyzers, humidity sensors, radar sensors, ammeters, current meters, liquid level detectors, feed level probes, electrical drives, and combinations thereof.

[0083] Embodiments of the present disclosure also generally relate to processes for waste plastic valorization. Processes described herein may be utilized to convert any suitable waste plastic feed. Embodiments and implementations of processes described herein may be combined with other embodiments and implementations described herein. For example, embodiments and implementations of processes described herein may be performed with embodiments and implementations of system 150 (FIG. IB) or other systems. In general, processes of the present disclosure enable conversion of waste plastic to various value-added hydrocarbon-containing products. As further described herein, each of the gas, the oil, and the solid from pyrolysis-reforming may be converted into distinct value-added materials within an integrated process.

[0084] Processes described herein may generally include (a) pyrolysis-reforming of a waste plastic feed to form solids, a gas fraction, an oil fraction, a wax fraction, or combinations thereof; (b) optionally polymerizing components (for example, ethylene and / or propylene) present in the gas fraction produced from the pyrolysis-reforming; (c) optionally fabricating carbon nanofibers from at least a portion of the oil fraction produced from the pyrolysis-reforming; and (d) optionally producing carbon quantum dots from at least a portion of the solids produced from the pyrolysis-reforming. The process may be an integrated process where, for example, pyrolysis-reforming may be integrated with a downstream upgrading of the pyrolysis-reforming products to polymers, carbon nanofibers, carbon quantum dots, or combinations thereof. That is, the gas, oil, and solid residue derived1UWYO / 0121PC(UW 24-030)from pyrolysis-reforming of a waste plastic feed may be valorized simultaneously according to embodiments of the present disclosure.

[0085] The pyrolysis-reforming process of operation (a) may be performed in the pyrolysis reactor 151 and the reforming reactor 152 of system 150. The pyrolysis-reforming process of operation (a) may include pyrolyzing a waste plastic feed to produce a pyrolysis product. Pyrolysis may be performed in the presence of a catalyst. The pyrolysis product may include an intermediate product and solids. The intermediate product may include one or more molecules having any suitable number of carbon atoms, such as from 1 to 50 carbon atoms. The intermediate products may include C1-C50 hydrocarbons. The intermediate products may include hydrocarbon gases (e.g., C1-C6 hydrocarbons), hydrocarbon oils (e.g., C6-C20 hydrocarbons), hydrocarbon waxes (e.g., C20-C50 hydrocarbons), or combinations thereof. The solids produced from the pyrolysis may include one or more molecules comprising any suitable number of carbon atoms such as 40 to thousands of carbon atoms.

[0086] Pyrolysis of the waste plastic feed may be performed in the pyrolysis reactor 151 under pyrolysis conditions. Pyrolysis conditions may include operating the pyrolysis reactor 151 at a pyrolysis temperature in a range from about 400 to about 600°C, such as from about 450 to about 550°C, such as about 500°C. Pyrolysis conditions may include operating the pyrolysis reactor 151 at a pyrolysis pressure (absolute pressure) in a range from about 70 to about 500 kPa, such as from about 70 to about 100 kPa. Pyrolysis conditions may include a pyrolysis temperature ramping rate from room temperature (about 25°C) to the pyrolysis temperature in a range from about 1 to about 50°C / min, such as from about 5 to about 20°C / min, such as about 10°C / min. For example, the pyrolysis process may include increasing the temperature of the pyrolysis reactor 151 from 25°C to the pyrolysis temperature (for example, about 500°C) at a pyrolysis temperature ramping rate of about 10°C / min. The pyrolysis reaction in which the waste plastic feed is decomposed to solids and intermediate products may be held at this pyrolysis temperature (held isothermal) for any suitable period. The pyrolysis process may be performed under an atmosphere of a non-reactive gas, such as nitrogen (N2) gas, argon (Ar), or combinations thereof. For example, the non-reactive gas may be flowed into the pyrolysis reactor 151 during pyrolysis. For example, a flow rate of the non-reactive gas into the pyrolysis reactor 151 before and / orUWYO / 0121PC(UW 24-030)during pyrolysis may be in a range from about 20 to about 100 standard cubic centimeters per minute (seem), such as from about 40 to about 60 seem, such as about 50 seem.

[0087] The solids produced from the pyrolysis is the pyrolysis residue and may be collected by any suitable means. The intermediate products may be volatilized and / or collected as liquids (oil and / or wax) and / or gases. These products may depend on the composition of the plastic mixture. For example, pyrolysis of polyethylene and polypropylene may lead to ethylene (C2H4), propylene (CsHe), and / or other aliphatics. Pyrolysis of polyvinylchloride and polystyrene may lead to aromatics.

[0088] The pyrolysis-reforming process of operation (a) may further include reforming the intermediate products. Reforming after the pyrolysis may be used to adjust the gas and liquid products (oil and / or wax) by, for example, controlling the reforming temperature. Reforming may be performed by heating and / or by use of steam. Catalysts may be used to aid in reforming. Reforming of the intermediate products may serve to break bonds (scission) of molecules in the intermediate products and / or aromatize molecules present in intermediate products. For example, larger molecules (molecules having a relatively higher number of carbon atoms) in the intermediate products may be converted to smaller molecules (molecules having a relatively lower number of carbon atoms). For example, reforming may decompose, or convert, large hydrocarbon molecules present in the intermediate products into medium sized hydrocarbon molecules, and medium sized hydrocarbon molecules into smaller-sized hydrocarbon molecules. The inventors found that, when reforming is not performed, the yields of hydrocarbon waxes were significantly higher than the yields of hydrocarbon waxes when reforming is performed. Moreover, the inventors found that the yields of hydrocarbon gases and hydrocarbon oils were higher when the process includes reforming, indicating that reforming may be used to increase the yield of hydrocarbon gases and oils (via decomposing large and medium sized hydrocarbon molecules) while reducing the yield of hydrocarbon waxes. Further, the inventors found that the yield of hydrocarbon gases significantly increased as the reforming temperature was increased. In addition, the yield of the hydrocarbon waxes, hydrocarbon oils, or combinations thereof may decrease. Hydrocarbon gases may be formed by beta-scission (P-scission) during pyrolysis and / or reforming. Various possible mechanisms of pyrolysisreforming are described in the Examples section. Hydrocarbon gases may include, forUWYO / 0121PC(UW 24-030)example, a C1-C5 hydrocarbon, such as a C1-C4 hydrocarbon, such as C2-C4 olefins, such as ethylene, propylene, or combinations thereof.

[0089] Reforming of the intermediate products may be performed in the reforming reactor 152 under reforming conditions. Reforming conditions may include operating the reforming reactor 152 at a reforming temperature range from about 400 to about 800°C, such as from about 450 to about 750°C, such as from about 500 to about 700°C, such as from about 550 to about 650°C. Reforming conditions may include operating the reforming reactor 152 at a reforming pressure in a range from, in absolute pressure, 70 to about 500 kPa, such as from about 70 to about 100 kPa. Reforming conditions may include a reforming temperature ramping rate from room temperature (about 25°C) to the reforming temperature (or from the pyrolysis temperature to the reforming temperature) in a range from about 1 to about 50°C / min, such as from about 5 to about 20°C / min, such as about 10°C / min. For example, the reforming process may include increasing the temperature of the reforming reactor 152 from 25°C (or from the pyrolysis temperature, for example, about 500°C) to the reforming temperature (for example, about 600°C) at a reforming temperature ramping rate of about 10°C / min. The reforming reaction in which the intermediate products are decomposed to smaller hydrocarbon molecules may be held at this reforming temperature (held isothermal) for any suitable period. The inventors found that the reforming temperature may be selected to tune a molar ratio of the ethylene to propylene in the gas product, for example, in a range from about 1:1 to about 2.4:1, such as from about 1.05:1 to about 2.2:1, such as from about 1.1:1 to about 2.1:1 (ethylene:propylene). For example, yields of ethylene relative to propylene increased as the reforming temperature increased from 500 to 700°C. This may be due to more C3+ being decomposed to ethylene (C2H4) at higher reforming temperatures.

[0090] The reforming process may be performed under an atmosphere of a non-reactive gas, such as nitrogen (N2) gas, argon (Ar), or combinations thereof. For example, the non-reactive gas may be flowed into the reforming reactor 152 during reforming. For example, a flow rate of the non-reactive gas into the reforming reactor 152 before and / or during reforming may be in a range from about 20 to about 100 standard cubic centimeters per minute (seem), such as from about 40 to about 60 seem, such as about 50 seem.UWYO / 0121PC(UW 24-030)

[0091] After the pyrolysis-reforming process of operation (a), the process may further include an optional separation operation. The optional separation may be performed in the optional separation unit 153. The optional separation process may include separating one or more of the hydrocarbon gas, hydrocarbon oil, and / or hydrocarbon wax into separate fractions. In some embodiments, which may be combined with other embodiments, the optional separation may include separating a hydrocarbon gas fraction and a hydrocarbon oil fraction from a hydrocarbon mixture exiting the reforming reactor 152. The optional separation may include performing any suitable gas-liquid separation process, liquid-liquid separation process, or combination thereof, such as distillation, fractional distillation, vacuum distillation, flash evaporation, fractionation, extraction, decantation, coalescence, or combinations thereof.

[0092] Pyrolysis of the waste plastic feed, reforming of the intermediate products, or combinations thereof may produce HC1 when the waste plastic feed includes a chlorinated polymer (for example, chlorinated polyethylene), polyvinylchloride, polyvinylidene chloride, or combinations thereof. For example, polyvinylchloride may undergo dehydrochlorination to produce HC1. In some embodiments, which may be combined with other embodiments, the process may optionally include neutralizing the hydrogen chloride, for example, with an alkali material (for example, NaOH, KOH, or combinations thereof). The optional neutralization operation may be performed in the neutralization unit described above.

[0093] An alkali is a basic salt of an alkali metal or an alkaline earth metal. Suitable alkali materials may include NaOH, KOH, or combinations thereof. The alkali material may be in the form of an aqueous alkali material. Neutralization of HC1 serves to prevent corrosion of equipment and / or unwanted side reactions. Here, HC1 released during pyrolysis and / or reforming may undesirably combine with decomposed polyolefins and contaminate entire batches of polymers. Accordingly, the neutralization unit may be used to reduce the concentration of, or remove, HC1.

[0094] The polymerization at optional operation (b) may be performed in the polymerization reactor 154. Here, a feed gas (for example, hydrocarbon gas or hydrocarbon gas fraction obtained from pyrolysis-reforming) comprising ethylene, propylene, or combinations thereof may be fed to the polymerization reactor 154. At the polymerizationUWYO / 0121PC(UW 24-030)reactor 154, the feed gas may be contacted with any suitable catalyst system under polymerization conditions to form a polymer such as PE, PP, and / or EP copolymer. The catalyst system may include a catalyst such as a metallocene catalyst or a vanadium based catalyst, for example, vanadium oxychloride or vanadium tetrachloride. The catalyst system may further include any suitable co-catalyst, such as an aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, organoaluminum compounds, organozinc compounds, organomagnesium compounds, organolithium compounds, and the like. Suitable co-catalysts may include ethylaluminum sesquichloride. The catalyst system may further include a promoter. Promoters may serve to increase activity of the “vanadium” catalyst severalfold and / or to enhance propylene reactivity in its copolymerization with ethylene. Suitable promoters may include chlorinated ester promoters, for example, ethyl tri chloroacetate.

[0095] Polymerization may be performed in the presence of a hydrocarbon fluid, for example, pentane, hexane, octane, or combinations thereof. Polymerization may be performed under any suitable polymerization conditions to form the desired polymer. Polymerization conditions may include operating the polymerization reactor 154 at a polymerization temperature in a range from about -5 to about 200°C, such as from about 0 to about 150°C, such as from about 10 to about 90°C, such as from about 15 to about 60°C, such as about 20 to about 25°C. Polymerization conditions may include operating the polymerization reactor 154 at a polymerization pressure in a range from about 100 kPa to about 1000 kPa (absolute pressure), such as from about 100 to about 300 kPa. Polymerization conditions may include operation of a mixer or stirrer, such as an impeller, configured to mix the catalyst system with monomers (for example, ethylene, propylene, or combinations thereof) and to help ensure sufficient contact between the components of the mixture. For example, the mixer or stirrer may be operated at any suitable mixing speed such as in a range from about 100 to about 1,000 revolutions per minute (rpm), such as from about 500 rpm to about 1,000 rpm. Polymerization conditions may include injecting the feed gas (for example, ethylene, propylene, or both) into the polymerization reactor 154 at any suitable rate such as in a range from about 100 to about 1,000 seem, such as from about 200 to about 700 seem, such as from about 300 to about 500 seem, such as about 400 seem.UWYO / 0121PC(UW 24-030)

[0096] In some embodiments, which may be combined with other embodiments, the polymerization operation includes obtaining or recovering an EP copolymer. The EP copolymer may have any suitable molar ratio of ethylene to propylene incorporation. For example, a molar ratio of ethylene to propylene in the EP copolymer may be within ±20%, such as within ±15%, such as within ±10%, such as within ±5% of a molar ratio of ethylene to propylene in the feed gas used for the polymerization. The EP copolymer may have a molar ratio of ethylene to propylene in a range from about 1:1 to about 2.4:1, such as from about 1.05:1 to about 2.2:1, such as from about 1.1:1 to about 2.1:1 (ethylene: propylene).

[0097] EP copolymers made according to embodiments described herein may have any suitable number-average molecular weight (Mn), such as an Mn in a range from about 15,000 to about 75,000 g / mol, such as from about 25,000 to about 65,000 g / mol, such as from about 35,000 to about 55,000 g / mol, such as from about 40,000 to about 50,000 g / mol. EP copolymers made according to embodiments described herein may have any suitable weight-average molecular weight (Mw), such as an Mw in a range from aboutl 00,000 to about 160,000 g / mol, such as from about 110,000 to about 150,000 g / mol, such as from about 120,000 to about 140,000 g / mol, such as from about 125,000 to about 135,000 g / mol. Mn and Mw are determined as described in the Examples section. EP copolymers made according to embodiments described herein may have any suitable poly dispersity index (Mw / Mn), such as an Mw / Mn in a range from about 1.9 to about 3.9, such as from about 2.4 to about 3.4, such as from about 2.6 to about 3.2.

[0098] Besides ethylene and propylene, the gas fraction produced from pyrolysisreforming may include CO and EE. In these and other embodiments, and when the gas fraction includes CO and EE, the process may further optionally include converting the CO and EE (syngas) in the gas fraction to a C2-C4 olefin, such as ethylene, propylene, or combinations thereof. This ethylene, propylene, or combinations thereof formed from the syngas may then be subjected to polymerization conditions to form PE, PP, and / or an EP copolymer. Various suitable methods to convert syngas to olefins are known in the art. A suitable method for the conversion of syngas to olefins may include Fischer-Tropsch processing.UWYO / 0121PC(UW 24-030)

[0099] As described herein, EP copolymers have broad application. For example, EP copolymers may be utilized for EP elastomers, EP impact modifiers, rubber precursors, or combinations thereof.

[0100] The fabrication of carbon nanofibers at optional operation (c) may be performed in carbon nanofiber fabrication unit 156. Here, an oil (for example, hydrocarbon oil or hydrocarbon oil fraction obtained from pyrolysis-reforming) may be fed to the carbon nanofiber fabrication unit 156. The hydrocarbon oil may include aliphatics (such as Cll-C15 aliphatics and / or Cl 6+ aliphatics); aromatics (such as monoaromatic hydrocarbons, Cl 6+ monoaromatic hydrocarbons or polyaromatic hydrocarbons), or combinations thereof. Monoaromatic hydrocarbons may include C5-C24 monoaromatic hydrocarbons, such as C5-C20 monoaromatic hydrocarbons, such as C6-C16 monoaromatic hydrocarbons, such as C6-C10 monoaromatic hydrocarbons or C11-C15 monoaromatic hydrocarbons. Illustrative, but non-limiting, examples of monoaromatic hydrocarbons may include benzene, ethylbenzene, and indene. Polyaromatic hydrocarbons may include C5-C24 polyaromatic hydrocarbons, such as C5-C16 polyaromatic hydrocarbons, such as C6-C10 polyaromatic hydrocarbons. Illustrative, but non-limiting, examples of polyaromatic hydrocarbons may include naphthalene and methylnaphthalene.

[0101] At the carbon nanofiber fabrication unit 156, the carbon nanofibers may be converted to carbon nanofibers under conditions sufficient to form the carbon nanofibers. Conversion of the hydrocarbon oil to the carbon nanofibers at optional operation (c) may include: (1) preparing a precursor mixture that includes the hydrocarbon oil and a polymer; (2) electrospinning the precursor mixture to form nanofibers; (3) stabilizing (for example, oxidizing and / or crosslinking) the nanofibers; (4) carbonizing the nanofibers.

[0102] The precursor mixture may be prepared by mixing appropriate amounts of a polymer and the hydrocarbon oil (oil fraction). Polymers may include polyacrylonitrile PAN, PVA, PVB, PVP, PDPP, or combinations thereof. The precursor mixture may include an amount of the polymer (for example, PAN, PVA, PVB, PVP, and / or PDPP) in a range from about 50 to about 99 wt%, such as from about 55 to about 95 wt%, such as from about 60 to about 90 wt%, such as from about 65 to about 85 wt%, such as from about 70 to about 80 wt%, such as about 75 wt% based on a total wt% of polymer and the hydrocarbon oil. The precursor mixture may further include an amount of the hydrocarbon oil in a range fromUWYO / 0121PC(UW 24-030)about 1 to about 50 wt%, such as from about 5 to about 45 wt%, such as from about 10 to about 40 wt%, such as from about 15 to about 35 wt%, such as from about 20 to about 30 wt%, such as about 25 wt% based on a total wt% of polymer and the hydrocarbon oil. The total wt% of the polymer and the hydrocarbon oil is 100 wt%. The precursor mixture may further include an appropriate solvent to help dissolve the polymer such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or combinations thereof.

[0103] The precursor mixture may then be electrospun utilizing voltage to draw threads from the precursor mixture. Any suitable method of electrospinning may be utilized. For example, a voltage may be applied to the precursor mixture, charging the liquid precursor mixture causing it to deform into a conical shape (a Taylor cone). A charged jet erupts from the cone, elongating and thinning as it travels. The solvent evaporates, solidifying the charged jet into a nanofiber. The solid fibers are deposited onto a ground collector, for example, as a nonwoven mat, with alignment controlled by a rotating collector.

[0104] Following electrospinning, the nanofibers may be stabilized under any suitable stabilization conditions. Stabilization conditions may include heating the nanofibers at a stabilization temperature in a range from about 200 to about 400°C, such as from about 250°C to about 350°C, such as about 300°C. Stabilization conditions may include flowing air into an oven (or other suitable vessel) in which the nanofibers being stabilized are disposed. A flow rate of air into the oven may be in a range from about 20 to about 500 seem, such as from about 40 to about 200 seem, such as from about 60 to about 120 seem, such as about 70 seem. Stabilization conditions may include a stabilization temperature ramping rate from room temperature (about 25°C) to the stabilization temperature in a range from about 0.5 to about 20°C / min, such as from about 1 to about 10°C / min. For example, the stabilization may include increasing the temperature of the oven from 25°C to the stabilization temperature (for example, about 300°C) at a stabilization temperature ramping rate of about l°C / min. The nanofibers may be stabilized under the stabilization conditions for any suitable period.

[0105] Following stabilization, the stabilized nanofibers may be subjected to carbonization. Prior to carbonization, and after stabilization, the stabilized nanofibers may be allowed to cool to room temperature. Carbonization of the nanofibers may be performed under any suitable carbonization conditions. Carbonization conditions may include aUWYO / 0121PC(UW 24-030)carbonization temperature in a range from about 500 to about l,000°C, such as from about 700 to about 900°C, such as about 800°C. Carbonization conditions may include flowing a non-reactive gas, such as N2, Ar, or combinations thereof, into an oven (or other suitable vessel) in which the nanofibers being carbonized are disposed. A flow rate of N2, Ar, or combinations thereof into the oven may be in a range from about 20 to about 500 seem, such as from about 40 to about 200 seem, such as from about 60 to about 120 seem, such as about 70 seem.

[0106] Carbonization conditions may include a stabilization temperature ramping rate from room temperature (about 25°C) to the carbonization temperature in a range from about 1 to about 50°C / min, such as from about 5 to about 20°C / min, such as about 10°C / min. For example, the carbonization may include increasing the temperature of the oven from 25°C to the carbonization temperature (for example, about 800°C) at a carbonization temperature ramping rate of about 10°C / min. The nanofibers may be carbonized under the carbonization conditions for any suitable period to form the carbon nanofibers.

[0107] Carbon nanofibers described herein may be characterized as having a pore structure dominated by micropores and a Langmuir-type adsorption isotherm.

[0108] The carbon nanofibers may have any suitable total pore volume (Vtp), such as a VtPof greater than 0.15 cm3 / g, such as about 0.16 cm3 / g or more, such as about 0.18 cm3 / g or more, such as about 0.20 cm3 / g or more, such as about 0.22 cm3 / g or more (and optionally up to about 0.45 cm3 / g), or in a range from greater than 0.15 cm3 / g to about 0.45 cm3 / g, such as from about 0.16 to about 0.40 m3 / g, such as from about 0.18 to about 0.30 cm3 / g, such as from about 0.20 to about 0.25 cm3 / g, or from about 0.18 to about 0.23 cm3 / g. The carbon nanofibers may have an Vtp greater than that of carbon nanofibers formed from polyacrylonitrile alone.

[0109] The carbon nanofibers may have any suitable specific surface area (SSA), such as an SSA of greater than 365 m2 / g, such as about 400 m2 / g or more, such as about 450 m2 / g or more, such as about 500 m2 / g or more, such as about 550 m2 / g or more (and optionally up to about 900 m2 / g), or in a range from greater than 365 m2 / g to 900 m2 / g, such as from about 370 to about 850 m2 / g, such as from about 400 to about 800 m2 / g, such as from about 450 to about 750 m2 / g, such as from about 500 to about 700 m2 / g, such as from about 550 to about 650 m2 / g, such as from about 550 to about 600 m2 / g, or in a range from about 450UWYO / 0121PC(UW 24-030)to about 600 m2 / g, such as from about 458 to about 567 m2 / g. The carbon nanofibers may have an SSA greater than that of carbon nanofibers formed from polyacrylonitrile alone.

[0110] Carbon nanofibers described herein may achieve a specific capacitance increase of at least 5%, such as at least 10%, such as at least 15%, such as at least 20%, such as at least 30%, such as at least 40%, such as least 50% (and optionally up to about 90% increase) relative to the carbon nanofibers fabricated from polyacrylonitrile alone under galvanostatic charge-discharge at 1 A / g. The carbon nanofibers may have a higher specific capacitance when used as an electrode in a supercapacitor relative to that of carbon nanofibers formed from polyacrylonitrile alone.[OHl] The carbon nanofibers may have a higher specific capacitance calculated from a galvanostatic charge-discharge curve (CGCD) at 1 A / g than PAN-only carbon nanofibers. The carbon nanofibers may have a specific capacitance calculated from a galvanostatic charge-discharge curve (CGCD) at 1 A / g of about 160 F / g or more, such as about 180 F / g or more, such as about 200 F / g or more, such as about 220 F / g or more (and optionally up to about 300 F / g), or in a range from about 160 to about 300 F / g, such as from about 175 to about 275 F / g, such as from about 180 to about 260 F / g, such as from about 200 to about 250 F / g, such as from about 210 to about 240 F / g, such as about 226 F / g.

[0112] The carbon nanofibers may have a higher capacitance retention than PAN-only carbon nanofibers. The carbon nanofibers may have a capacitance retention of greater than 92%, such as greater than 94%, such as greater than 96%, such as greater than 98% (and optionally up to 100%) after at least 450 charge-discharge cycles.

[0113] The carbon nanofibers may have a lower charge-transfer resistance (Ret) than PAN-only carbon nanofibers. While not wishing to be bound by any theory, it is believed that aromatic species in the oil graphitize during carbonization to reduce charge-transfer resistance relative to PAN-only carbon nanofibers. The carbon nanofibers may have an Ret of about 4 Q or less, such as about 3 or less, such as about 2.76 or less, such as about 2.5 or less, such as about 2.23 or less, such as about 2.06 or less, such as about 1.97 or less, such as about 1.30 or less, such as about 1.01 or less (and optionally down to about 1 ).

[0114] The carbon nanofibers may have a lower Warburg coefficient (G) than PAN-only carbon nanofibers. A low Warburg coefficient (G) suggests facile mass transport of chargeUWYO / 0121PC(UW 24-030)from electrolyte to electrode surface. While not wishing to be bound by any theory, the lower o may be due to carbon nanofibers described herein having a more porous structure relative to PAN-only carbon nanofibers. The carbon nanofibers may have a Warburg coefficient of 2.75 / s0 5or less, such as about 2.65 or less, such as about 2.2 / s05or less, such as about 2.0 / s05or less (and optionally down to about 0.5 Q / s05), or in a range from about 1.0 to about 2.75 Q / s05, such as from about 1.5 to about 2.7 Q / s05, such as from about 1.9 to about 2.65 Q / s05.

[0115] An electrode of the present disclosure may include carbon nanofibers formed according to embodiments described herein. In some embodiments, which may be combined with other embodiments, a working electrode may include carbon nanofibers of the present disclosure. Such a working electrode may be utilized in, for example, a supercapacitor.

[0116] The production of carbon quantum dots at optional operation (d) may be performed in carbon quantum dot synthesis unit 155. Here, the solids produced during pyrolysis-reforming may be fed to the carbon quantum dot synthesis unit 155. The solids produced during pyrolysis may include any suitable amount of carbon and / or hydrogen. For example, the solids may include an amount of carbon in a range from about 90 to about 100 wt%, such as from about 95 to less than 100 wt% based on a total wt% of carbon and hydrogen in the solids. The total wt% of carbon and hydrogen in the solids is equal to 100 wt%. The solids may include an amount of hydrogen in a range from 0 wt% to 10 wt%, such as from greater than 0 to about 5 wt% based on the total wt% of carbon and hydrogen in the solids.

[0117] The solids may include, for example, turbostratic carbon black. Turbostratic carbon black is a form of carbon with graphitic-like layers (sp2) that are randomly oriented or rotated relative to each other, rather than perfectly stacked as in graphite, creating curved sheets with disordered stacking (turbostratic structure) within grape-like particle aggregates. An x-ray diffraction pattern of the solids may include three peaks at diffraction angles (29) of about 25.00°, about 43.25°, and about 79.89° corresponding to the 002, 100, and 112 planes of turbostratic carbon black.

[0118] At the carbon quantum dot synthesis unit 155, carbon quantum dots may be produced from the solids. Producing carbon quantum dots from the solids may include contacting the solids with an oxidizing agent at a temperature greater than 150°C, such asUWYO / 0121PC(UW 24-030)in a range from about 150°C to about 250°C, such as about 170°C to about 200°C, such as about 180°C. A suitable oxidizing agent may include hydrogen peroxide. Producing the carbon quantum dots may be performed in an oven, autoclave, or other suitable vessel. Following the treatment with the oxidizing agent, the resulting solution or suspension may be filtered and washed with an appropriate liquid such as deionized water.

[0119] Carbon quantum dots of the present disclosure may have any suitable average particle size, for example, an average particle size in a range from about 1 to about 10 nm, such as from about 2 to about 8 nm, such as from about 3 to about 7 nm, such as about 5 nm. The carbon quantum dots may have an excitation-dependent emission in a range from about 370 to about 510 nm when excited by an excitation wavelength in a range from 290 to 465 nm.

[0120] Carbon quantum dots of the present disclosure have a unique ultraviolet spectrum. The ultraviolet spectrum of the carbon quantum dots may include a Tt—>Tt* transition at a wavelength in a range from about 250 to about 290 nm, such as from about 260 to about 265 nm, such as about 262 nm. Tt—>Tt* transitions may involve exciting a TI (bonding) electron to a TI* (antibonding) orbital. The ultraviolet spectrum of the carbon quantum dots may include one or more n— >7i:* transitions in a range from about 280 to about 320 nm, such as from about 290 and 311 nm. n— >7i:* transitions may involve exciting an electron from a non-bonding (n) orbital to an antibonding pi (K*) orbital. The ultraviolet spectrum of the carbon quantum dots may include a broad tail that extends into the visible range.

[0121] The carbon quantum dots may function as co-sensitizers in a dye-sensitized solar cell (DSSC). DSSCs are generally solar cells such as thin film solar cells. DSSCs are based on a semiconductor formed between a photo-sensitized anode and an electrolyte. A nonlimiting schematic of a DSSC incorporating carbon quantum dots is shown in FIG. 22, further described below. The carbon quantum dots, when used as co-sensitizers with a ruthenium-based dye (such as N3 dye) in a DSSC, may increase short-circuit current density, photo-conversion efficiency, and / or photocurrent relative to an otherwise identical dye-sensitized solar cell lacking carbon quantum dots.

[0122] A DSSC of the present disclosure may include a photoanode. The photoanode may include titanium dioxide. The DSSC may further include a dye sensitizer and carbonUWYO / 0121PC(UW 24-030)quantum dots described herein. The dye sensitizer and carbon quantum dots may form at least a portion of a transparent layer and / or a diffusive layer of the DSSC as shown in FIG.22. The dye sensitizer may include a ruthenium-containing dye, for example, N3 dye. N3 dye has the chemical name cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-di carb oxy lato)ruthenium (II) and may be represented by the following chemical structure:

[0123] The arrows between the nitrogen atoms and ruthenium (Ru) represent dative bonds. The “NCS” ligands bonded to the ruthenium metal refer to nitrogen-carbon-sulfur.

[0124] The DSSC may further include an I / I3 redox electrolyte, a platinum-coated cathode. Table 8 shows an example electrolyte of DSSCs that may be used with embodiments of the present disclosure.

[0125] DSSCs described herein outperform DSSCs without carbon quantum dots. For example, the inclusion of the carbon quantum dots may increase a short-circuit current density (Jsc) by about 5% or more, such as about 10% or more, such as about 15% or more, such as about 20% or more, such as about 25% or more (and optionally up to about 100%) relative to the DSSC without the carbon quantum dots. Additionally, or alternatively, the inclusion of the carbon quantum dots may increase a photoconversion efficiency (PCE) by about 5% or more, such as about 10% or more, such as about 15% or more, such as about 20% or more, such as about 25% or more (and optionally up to about 100%) relative to the DSSC without the carbon quantum dots. Additionally, or alternatively, inclusion of the carbon quantum dots may reduce a charge-transfer resistance at the TiCh / electrolyte interface relative to the DSSC without the carbon quantum dots. Additionally, orUWYO / 0121PC(UW 24-030)alternatively, inclusion of the carbon quantum dots may increase electron lifetime relative to the DSSC without the carbon quantum dots.

[0126] The DSSC may be characterized as having any suitable short-circuit current density, for example, a short-circuit current density of about 8.9 mA / cm2or more, such as about 9.5 mA / cm2or more, such as about 10 mA / cm2or more, such as about 10.5 mA / cm2or more (and optionally up to about 20 mA / cm2), or in a range from about 8.9 to about 15 mA / cm2, such as from about 9.5 to about 14 mA / cm2, such as from about 10 to about 13 mA / cm2, such as from about 10.5 to about 12 mA / cm2, such as about 10.9 mA / cm2. The DSSC may be characterized as having any suitable photo-conversion efficiency, such as a photo-conversion efficiency of about 3.7% or more, such as about 3.9% or more, such as about 4.2% or more (and optionally up to 10%), or in a range from about 3.7% to about 10%, such as from about 3.9% to about 8%, such as from about 4% to about 6%, such as from about 4.2% to about 5%, such as about 4.25%.

[0127] The carbon quantum dots may increase electron lifetime by about 50% or more, such as about 75% or more, such as about 78% or more (up to about 100%), or in a range from about 50% to about 100%, such as from about 60% to about 90%, such as from about 70% to about 80% relative to the DSSC without the carbon quantum dots. In some embodiments, which may be combined with other embodiments, an electron lifetime of the DSSC may be about 11 milliseconds (ms) or more, such as about 15 ms or more, such as about 19 ms or more (optionally up to about 100 ms), or in a range from about 11 to about 100 ms, such as from about 13 to about 50 ms, such as from about 15 to about 30 ms, such as about 18 to about 25 ms, such as from about 19 to about 23 ms, such as about 19.3 ms.

[0128] The carbon quantum dots may be characterized as having a highest occupied molecular orbital (HOMO) in a range from about a highest occupied molecular orbital (HOMO) in a range from about -7.50 to about -4.90 eV, such as from about -5.52 to about -5.36 eV, such as about -5.44 eV. Additionally, or alternatively, the carbon quantum dots may be characterized as having a lowest unoccupied molecular orbital (LUMO) in a range from about -4.2 to about 0 eV, such as from about -3.09 to about -2.95 eV, such as about -3.02 eV. These values for HOMO and LUMO may help facilitate energy level alignment between the ruthenium-based dye and the TiO2 conduction band.UWYO / 0121PC(UW 24-030)

[0129] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use embodiments of the present disclosure, and are not intended to limit the scope of embodiments of the present disclosure. Efforts have been made to ensure accuracy with respect to numbers used (for example, amounts, dimensions, etc.) but some experimental errors and deviations should be accounted for.Examples

[0130] The Examples demonstrate embodiments of the present disclosure, including the transformative and sustainable approach to waste plastic valorization described herein. In the Examples, the full spectrum of products (gas, liquid, and solid products) resulting from the pyrolysis-reforming of a plastic mixture functioned as precursors of value-added products: (1) ethyl ene-propylene copolymers, (2) polyacrylonitrile (PAN)-based carbon nanofibers (CNFs), and (3) carbon quantum dots (CQDs). The CNFs were subsequently applied as supercapacitor electrodes, and the CQDs acted as co-sensitizers for the primary sensitizer, N3, in dye-sensitized solar cells (DSSCs). Adding oil to PAN was found to increase the specific capacitance of the CNFs, compared with that of pure PAN CNFs. With the aid of CQDs, the short-circuit current density and photo-conversion efficiency of DSSCs was found to increase.

[0131] The study presented herein is the first work showing decomposition of plastics into gas, oil, wax and solid, and is the first one to explore the applications of gas, oil and solid simultaneously. This work is also the first one to valorize gas, oil, and solid into EP copolymer, carbon nanofibers and carbon quantum dots, respectively.1. Introduction2, Materials and methods2.1. Pyrolysis-reforming2.1.1. Plastic Mixture

[0132] The composition of the plastic mixture was adapted from statistics based on a document from the Department of Energy (DE-FOA-0002376), which provides a typical plastic mixture recipe for studying waste recycling. The plastic mixture included virgin plastics purchased from Sigma Aldrich: 32 wt% high-density polyethylene (HDPE), 32 wt%UWYO / 0121PC(UW 24-030)low-density polyethylene (LDPE), 11 wt% polyvinyl chloride (PVC), 4 wt% polypropylene (PP), and 21 wt% polystyrene (PS).2,1.2. Procedures

[0133] FIG. 2 shows a lab-scale pyrolysis-reforming setup 200 utilized for the experiments. The setup 200 included a pyrolysis section 201 and a reforming section 202. The pyrolysis-reforming reaction occurred in a quartz tube 204 (110 cm long, 25 mm outer diameter and 2.5 mm wall thickness), under 50.83 seem ultra-high-purity N2 gas. The quartz tube 204 was loaded into two identical tube furnaces (Carbolite Gero) connected in series. The first tube furnace functioned as the pyrolysis section 201, and the second tube furnace served as the reforming section 202. Plugs 220 are placed on both ends of the quartz tube 204. An alumina boat 203 and quartz wool 206 are placed in the quartz tube 204. A gas cylinder 214 containing N2 gas was fluidically coupled to the quartz tube 204 via line 210. Along the line 210 were ball valves 216 and a mass flow controller 218 to adjust the rate of N2 gas flowing into the quartz tube 204. On the other end of the quartz tube 204, line 210 couples the interior of the quartz tube 204 with 500 mL condensing bottles 222, a buffer test tube 224, a neutralization bottle 226 having a neutralization agent therein, and a desiccant test tube 228 having a desiccant therein. The neutralization bottle 226 removed hydrogen chloride (HC1) by use of 200 mL 1 M sodium hydroxide (NaOH). The desiccant was anhydrous Copper (II) sulfate (CuSCU). The buffer test tube 224 was used to prevent the mixing of the condensed products and NaOH solution.

[0134] The setup 200 also shows the various products obtainable from pyrolysisreforming: a solid residue (or solids) in the alumina boat 203; a wax fraction located near the outlet of the quartz tube 204; liquid (oil) fractions condensed in the condensing bottles 222; and a gas fraction flowing out of the desiccant test tube 228 via line 212.

[0135] Before the experiment, 3 g of the plastic mixture was placed in an alumina boat 203 that was in the middle of the pyrolysis section 201, the air in the quartz tube 204 was purged by N2, and the reforming section 202 was preheated at one of the reforming temperatures (500°C, 550°C, 600°C, 650°C, and 700°C). During the experiment, the pyrolysis section 201 was ramped from room temperature to 500°C at 10°C / min and held at 500°C for 80 min. Due to the variation of room temperature, the gas cylinder 214 was not connected until the pyrolysis section 201 reached 100°C, making one experiment 120 min.UWYO / 0121PC(UW 24-030)

[0136] The liquid product condensed at an outlet of the quartz tube and collection bottles. The solid product remained in the alumina boat. Gas products were studied on a gas chromatography system (GC), liquid product was studied on a GC-mass spectroscopy and an attenuated total reflection (ATR) spectrometer, and solid product was studied by using an elemental analyzer, X-ray diffraction (XRD) diffractometer, and scanning electron microscopy (SEM). HC1 was quantified by performing ion chromatography.

[0137] During the experiment, the non-condensable entered a Restek Multi-Layer Foil 12 L bag (not shown) after passing through the neutralization bottle 226 and desiccant test tube 228. After the experiment, quartz tubes, tubings, and condensing bottles were washed with GCMS-grade acetone (Sigma Aldrich). The solution was filtered by filter paper (Whatman 25 mm diameter paper, with 11 pm pore size). The filtrate was placed on a hot plate at 60°C to remove the acetone and keep the solute. The non-condensable in the bag, the filtrate solute, the filter paper deposit, and the alumina boat residue were called gas, oil, wax, and solid, respectively. Oil and wax constitute liquid products.2,1.3. Characterization

[0138] To determine the range of temperatures at which degradation occurs, thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) were performed on a TA Instruments Q600 SDT analyzer. Under an N2 atmosphere, the temperature was ramped from room temperature (25°C) to 700°C at 10°C / min and stayed isothermal for 2 h. The gas component was identified on an SRI8610C GC with multigas #3 configuration. The GC was equipped with a Restek 6’ Haysep D column, a Restek 6’ 13X molecular sieve column (6 feet x 2 mm ID), and a 30 m Agilent HP-AL / S column (30 m x 0.530 mm x 15 pm). The 200 mL 1 MNaOH was analyzed on a Thermo Scientific ICS 5000 equipped with AS23 columns and a self-regenerating suppressor. Oil was analyzed using Agilent gas chromatography / mass spectroscopy (GC / MS, 7890A / 5975C). The column was an Agilent HP-5MS UI, 30 m x 0.250 mm, with 0.25 pm coating. Attenuated Total Reflection (ATR) spectra of oil and wax were acquired on a ThermoFisher i S50 ATR, the number of scans was 64, the resolution was 4and the wavelength ranged from 4000 cm1to 400The morphology of the solid was visualized on a scanning electron microscope (SEM, Quanta 250, FEI). XRD patterns were measured on a Rigaku Smart-lab X-ray diffraction system, the scanning range was from 10° to 90° at a rate of 4° / min, and aUWYO / 0121PC(UW 24-030)chopper increment of 0.02°. The elemental composition was measured on a Vario Macro cube CHNOS elemental analyzer.2.2. Gas products converted to ethylene-propylene (EP) copolymer2.2.1. Polymerization

[0139] EP copolymer synthesis typically uses a large volume of C2H4 and C3H6 and are difficult to produce on this lab-scale setup 200. Therefore, gases from gas cylinders were used to simulate the EP copolymer synthesis process. EP molar ratios of the feed gas were determined from the GC results. The catalyst and co-catalyst were vanadium oxychloride (VOCI3, Santa Cruz Biotechnology, Inc.) and ethylaluminum sesquichloride ((C 2145)3 AI2CI3; EASC; Aldrich Chemistry, 97% purity), respectively. Ethyl tri chloroacetate (ETCA, Aldrich, 97% purity) was added as a promoter to keep the catalyst active. The polymerization occurred in an Ace Glass one-piece 500-ml pressure reactor, rated 45 psig (310 kPa) at 100°C; a pressure relief valve was set at 30 psig (207 kPa). The experiment was performed at 25°C. 300 mL of hexane was added to the reactor and the stirrer was maintained at 750 revolutions per minute (rpm). After the air in the reactor was replaced by N2, 3.55 mmol VOCI3, 17.75 mmol ETCA, and 750 mmol EASC were sequentially injected. Before polymerization, the N2 supply was ceased, the feed (C2H4 and C3H6 mixture) was introduced to purge the N2, and the synthesis started by shutting the outlet valve of the reactor. The total feed flow rate was maintained at 400 seem for 30 min. After a suitable period for the polymerization to run, the substance in the reactor was poured into a beaker, 300 ml of ethanol was added as the terminating agent, and the resulting mixture was stirred by a glass rod for 1 min. After standing for 5 min, EP copolymer appeared as a white lump which was subsequently dried in a convection oven (Lab Companion) at 70°C overnight.2.2.2. Characterization

[0140] To analyze the monomer sequence and ratios, NMR spectra were collected. 1 g EP copolymer was dissolved in 10 mL o-di chlorobenzene (ODCB) at 180°C, making a 10% (g / mL) solution. The 10% solution was subsequently loaded into a 10 mm OD NMR sample tube.13C NMR spectra were collected using a Bruker Avance III 600 NMR spectrometer, operating at a Larmor frequency of 150.9 MHz at 125°C. The assignment of the NMR spectral peaks was based on previous studies, shown in Table 5 provided in theUWYO / 0121PC(UW 24-030)Supplementary Results. The monomers of the EP copolymer were quantified using equations (Eq. 1) - (Eq. 4):Ni = Ppp + PpY+ Pyy(Eq. 2) C2W4mol% = (No- N / NQ + IVO X 100% (Eq. 3) C3W6mol% = 100% - C2W4mol% (Eq. 4) wherein: P and S denote the peak area of the primary and secondary carbon atoms, respectively; Noand N are intermediary quantities; C2H4mol% and CsHemoP / o are the molar percentages of C2H4 and C3H6, respectively.

[0141] The molecular parameters of the EP copolymer were calculated by applying equations (Eq. 5) and (Eq. 6):PDI = Mw / Mn(Eq. 6) wherein: M is the average molecular weight of the EP copolymer (g / mol);is the molecular weight of the chain; zr, is the number of chains with molecular weight Mp, and k is a non-negative integer. When k = 0, M is the number-average molecular weight, denoted as Mn; when k = 1, M is the weight-average molecular weight, denoted as Mw. PDI is the poly dispersity index (Mw / Mn) that measures the breadth of the molar mass distribution.

[0142] High-temperature gel permeation chromatograph (HT GPC) was performed by the PolyAnalytic company to analyze the molecular weights (Mn and Mw). For each sample, 200 mg of EP copolymer was cut into fragments and transferred into a wire mesh, and 5 mL 1, 2, 4-tri chlorobenzene (TCB) was added and heated at 150°C for 1 h to fully dissolve the EP copolymer. Approximately 1 mL of the solution was diluted in a 5 mL mobile phase, which was also TCB. The diluted solution was heated for a minimum of 1 h at 150°C and then injected into a Tosoh HLC8321 GPC / HT System instrument.2.3. Oil products converted to carbon nanofibers (CNFs) and supercapacitors 2,3.1. Fabricating CNFs

[0143] CNFs were fabricated by electrospinning owing to the simplicity and flexibility. In the control group, the precursor was 1.2 g of polyacrylonitrile (PAN, Sigma-Aldrich, average Mw of 150,000, CAS No. 25014-41-9). In the experimental group, the precursors were prepared by replacing 25% PAN with the oil product of the same weight, i.e., 0.9 gUWYO / 0121PC(UW 24-030)PAN plus 0.3 g oil product. The precursor was dissolved in 10 mL dimethylformamide (DMF, Sigma-Aldrich, biotech grade > 99.9%, CAS No. 68-12-2) by stirring at 90°C for 12 h. The solutions were loaded into a Luerlock 20-ml syringe with a 24-gauge needle (ID: 1.194 mm). The syringe was placed horizontally, and the needle tip was 90 mm away from the cylindrical collector wrapped in tin foil. During the spinning, the syringe pump was maintained at 0.8 mL / h, voltage was tuned between 7 and 10 kV to maintain the Taylor cone, and the collector rotated at 30 rpm. The spinning time was 10 h. The collected nanofibers were referred to as fresh CNFs (FCNFs). To obtain CNFs, the FCNFs were heat-treated in a tube furnace (Thermo Scientific Lindberg / Blue M). During stabilization, the temperature was ramped at l°C / min to 300°C and maintained for 1 h under 70 seem air. After cooling to 25°C, carbonization was performed by ramping at 10 C / min to 800 C, and then maintaining the temperature at 800°C for 3 h under 70 seem N2. The acquired CNFs were in the form of mat.2,3.2. Characterization

[0144] The CNFs were visualized on SEM (Quanta 250, FEI). To study their pore structures, N2 isothermal adsorption / desorption data were collected on a Micromeritics ASAP 2000 adsorption analyzer. Specific surface area was calculated based on the isotherm type. Total pore volume was determined by the adsorption amount when relative pressure, p / p°, equaled 0.99, where p is the equilibrium pressure at adsorption temperature, 77 K (-196.15°C), and p° is the saturation pressure of N2 at the same temperature. The pore width (pore size) distribution was analyzed by the ASAP 2020 software built-in “N2 @ 77 on Carbon Slit Pores by non-local density functional theory (NLDFT)” method.

[0145] Supercapacitor electrodes were then fabricated using CNFs. One electrode was a 1 cm x 1 cm CNFs wrapped in nickel foam; the other electrode was a 2.5 cm x 2.5 cm, 1 mm thick platinum foil. Their electrochemical properties were measured by a three-electrode system, soaked in 6 M potassium hydroxide (KOH). The CNFs, a platinum foil, and an Hg / HgO electrode (Hg / HgO, CHI instrument, CHI 152) functioned as working, counter, and reference electrodes (WE, CE, and RE), respectively. The test was controlled by a CHI6203D electrochemical analyzer. Cyclic voltammetry (CV) curves were scanned at 0.005 V / s, and the potential ranged from 0 to -0.8 V to avoid electrolyzing the KOH solution. Galvanostatic charge-discharge (GCD) curves were acquired at a constant specificUWYO / 0121PC(UW 24-030)current of 1 A / g (A per unit weight of CNF), with high and low potential of 0 and -0.8 V. Stability (capacitance retention) of the CNFs were tested by 450 of such GCD cycles. Electrochemical impedance spectroscopy (EIS) data were acquired in a frequency ranging from 10000 Hz to 0.01 Hz, and the amplitude was 0.005 V. The specific capacitance was calculated by equation 7 (Eq. 7) and the GCD results.CGCD=Is( 2 ~ G) / IV(G)—^(G)] (Eq- 1) wherein: CGCD is specific capacitances calculated from the GCD curves (in units of F / g); Isis specific current (in units of A / g); t is the time elapsed from the start of the test (in units of seconds, s); V is the voltage between the working and reference electrodes (in units of V); and t2are the beginning and ending time of a discharge segment, respectively (in units of second, s).2.4. Solid products converted to carbon quantum dots (CQDs) and dye-sensitized solar cells (DSSCs)2,4.1. Preparing CQDs and assembling DSSCs

[0146] First, 0.8 g of solid product was ground in a mortar, mixed with 20 mL of 5 vol% hydrogen peroxide (H2O2) in a 50-mL Teflon-lined autoclave, and sealed. Next, a convection oven (Lab Companion) was preheated to 180°C, and the mixture in the autoclave was treated for 6 h to obtain the CQD solution. The solution was vacuum-filtered through a 0.45-pm Fluoropore membrane filter having a diameter of 47 mm. Additional deionized (DI) water was used to thoroughly wash the glassware and autoclave. Finally, 80 mL of the CQD solution was obtained.

[0147] Meanwhile, the photoanodes, based on fluorine-doped tin oxide (FTO) coated glasses (Sigma Aldrich), were prepared. FTO glasses were cut into 1.5 cm x 2 cm FTO glasses, and titanium dioxide (TiOz) paste was deposited by the Doctor’s blade method. Scotch tape (overall thickness 2.3 mil) with a punched 1 / 4” (6.35 mm) hole served as a mask. The glasses were dried at 120°C for 10 min, then heated at 325°C for 5 min, then at 375°C for 5 min, then at 450°C for 15 min, and finally at 500°C for 1 h. This calcination method was adapted from known methods. A transparent TiO2 paste (Solaronix, part No.14411) was deposited and heat-treated, then a diffusive paste was deposited by the same procedure. The diffusive paste was prepared by mixing 2 g TiO2 anatase powder, 0.4 g ethyl cellulose, and 8 mL terpineol and stirring overnight. 40 pL of the CQD solution was spin-UWYO / 0121PC(UW 24-030)coated onto the TiCh paste and dried at 90°C. The glasses were soaked in 1 mM N3 dye (Sigma Aldrich) for 24 h, and the acquired products were photoanodes. To assemble the DSSC, a photoanode and a 1.5 cm * 2.0 cm Pt-coated FTO glass (cathode) sandwiched a 3-mil (76.2 pm) spacer (1.5 cm x 1 cm Kapton polyimide film) with a hole (9 / 32” diameter, i.e., 7.14 mm), and two binder clips held the electrodes. The Supplementary Results, below, provides electrolyte components (Table 8) a schematic of a DSSC (Fig. 22).2,4.2. Characterization

[0148] The CQD particles were visualized by transmission electron microscope (JEOL JEM-21 OOF) operated at 200 kV. The CQD solution was irradiated by an ultraviolet flashlight (Alonefire SV003, wavelength 365 nm, power 10 W) for a preliminary observation since CQDs would emit fluorescence if excited by ultraviolet light. To study the dependence between exciting and emitting wavelengths of CQDs, fluorescent light (FL) spectra contour map (referred to as FL map) was acquired on a Horiba Fluorolog fluorometer. The exciting wavelengths were scanned from 200 nm to 600 nm, with an interval of 4 nm. The emission light was scanned from 294 nm to 700 nm with an interval of 2 nm. The ultraviolet-visible (UV-vis) light spectroscopy was studied on a SpectraMax M2 Ultraviolet-visible spectrometer, with the incident wavelengths from 200 nm to 900 nm, and the sampling interval of 1 nm.

[0149] To examine the electrochemical properties, an LSH-7520 LED solar lamp irradiated the DSSCs. The irradiance spectrum was Air Mass 1.5 Global (AM1.5 G), and the power intensity was 100 mW / cm2. Linear sweep voltammetry data were obtained on a CHI6203D electrochemical analyzer, with the scan from -1 V to 1 V, at 0.02 V / s. Photoconversion efficiencies (PCEs) of the DSSCs were calculated from equations (Eq. 8) - (Eq.12).P = V x J = V x / / A (Eq. 8) Voc = V(J = 0) (Eq. 9) Jsc = J(V = 0) (Eq. 10) FF = Pmax / ^oc *Jsc) (Eq. H) PCE = Pmax / PinX 100% (Eq. 12) wherein: P is the power intensity of the DSSC (in units of mW / cm2); V is the voltage between the working and reference electrodes (in units of V); J is the current density (inUWYO / 0121PC(UW 24-030)units of mA / cm2) at E; I is the measured current (in units of mA) at V A is the size of the active area (in units of cm2); FF is the fill factor; Pmaxis the maximum power intensity (in units of mW / cm2); Jscis the short-circuit current density (in units of mA / cm2); Vocis the open circuit voltage (in units of V); PCE is the photo-conversion efficiency; and Pinis the incident-light power intensity (in units of mW / cm2).

[0150] To better understand the performances of the fabricated DSSCs, external quantum efficiency (EQE) data was obtained on an MKS QuantX300 quantum efficiency measurement system. Besides Jscfrom the J-V curve, another Jscdenoted as / SC(EQE) was calculated by equation 13 (Eq. 13). Jscrefers to the value from J-V curve if not specified. Jscand / sc(EQE) can validate mutually.wherein:minandmaxare the shortest and longest wavelength of the solar lamp light (in units of nm); A is the wavelength of light (in units of nm); Eeis the spectral irradiance generated by the solar lamp (in units of W / cm2 / nm); h is plank constant, 6.626* 10'34J / Hz; v is the frequency of the light (in units of Hz) at a wavelength, v = speed of light / 1; e is the charge of one electron (-1.6* 10'19C); the minus signconverts / SC(EQE) to a positive value.

[0152] The EIS was measured under AMI.5 G on a CHI6230D electrochemical analyzer, with the frequency ranging from 0.01 to 1 M Hz, and the alternating voltage amplitude was set to 10 mV. Nyquist and Bode plots were extracted from EIS data. The Nyquist plot was fitted on EC-Lab VI 0.40 software. The electron lifetime was calculated by equation 14 (Eq. 14).T = l / (27rmax) (Eq. 14) wherein: T is the lifetime (in units of ms), and fmaxis the characteristic frequency (in units of Hz) on the Bode plot.

[0153] The HOMO and LUMO of the CQDs were evaluated by CV. The method was based on previous studies. The working electrode was prepared by dropping the CQD solution on a Pt-coated FTO glass followed by drying at 90°C. The counter electrode was a 25 mm * 25 mm Pt sheet with thickness of 1 mm. The reference electrode was Ag / AgCl. The electrolyte was 0.1 mM tetrabutylammonium hexafluorophosphate in acetonitrile. CV curves were acquired on a CHI6203D electrochemical analyzer and scanning from -1.5 VUWYO / 0121PC(UW 24-030)to 1.5 V at 50 mV / s. When the reference electrode was Ag / AgCl, the HOMO and LUMO were calculated by Equations (Eq. 15) and (Eq. 16), respectively. The energy levels of the FTO coating, TiO2 substrate, I / I redox, and Pt coating are described elsewhere. The HOMO and LUMO of the N3 dye are -5.39 eV and -2.79 eV, respectively.EHOMO — ~ (EOXVSAg-AgCl T 4.4) (Eq. 15) ELUMO ~ ~ (Ered vs. Ag-AgCl T 4.4) (Eq. 16) wherein: EH0M0and ELUM0are the energy level of the HOMO and LUMO (in units of eV), respectively; Eox vsAg-Agciand Ered vsAg-Agciarethe oxidation and reduction potentials vs. Ag / AgCl (in units of V), respectively.3, Non-limiting results and discussion3.1. Preparation of precursors of EP-CNF-CQDs

[0154] The thermal behavior of the plastic mixture was studied by TGA, and the results are shown in FIG. 10 further described below in the Supplementary Results. When the pyrolysis temperature was higher than 497°C, weight loss became negligible, meaning the plastic mixture was completely pyrolyzed. In this study, pyrolysis-reforming produced (1) hydrocarbon gas and hydrogen (H2), (2) liquids including wax and oil, (3) solids remaining in the pyrolysis section, and (4) hydrogen chloride (HC1). The results are shown in FIG. 3 A, and detailed mass balance data at different reforming temperatures is provided in Table 3 of the Supplementary Results.

[0155] At each reforming temperature, the sums of the yields were all above 93%, achieving mass balance. The weight loss was due to evaporation of the oil and wax remaining in the quartz tube. As the reforming temperature increased, the gas yield increased from 7.04% at 500°C to 48.67% at 700°C. Meanwhile, the oil yield decreased from 45.06% to 27.08%. Between 650°C and 700°C, the wax yield increased from a minimum of 8.17% to 10.65%; this was caused by more extensive carbonization and coking (referred to as “wax” for simplicity). Because the pyrolysis section always stayed at 500°C, the solid and HC1 yields changed marginally. FIG. 3B shows the C2H4 and C3H6 yields at different reforming temperatures, and Table 4 and FIG. 11 of the Supplementary Results provides detailed information of the gas composition.

[0156] From 500°C to 650°C, the C2H4 and C3H6 yields increased. At 700°C, the yield of C3H6 dropped. In the meantime, the C2H4 to C3H6 (EP) molar ratio increased slowly fromUWYO / 0121PC(UW 24-030)1.14 to 1.42, and at 700°C, it increased to 1.91. This was because at 700°C, more C3+ was decomposed to C2H4 and smaller molecules. The carbon number distribution of oil is shown in FIG. 3C. The oil included aliphatics and aromatics. Here, the aromatics included monoaromatic hydrocarbons (MAHs), such as benzene, ethylbenzene, and indene, and polyaromatic hydrocarbons (PAHs), such as naphthalene and methylnaphthalene. The Ci6+ products were long-chain aliphatics, C11-15 contained aliphatics and MAHs, and Ce-io contained mainly MAHs and PAHs. The number of carbons reduced as higher temperatures favored bond breaking and aromatization. The distribution of oil aliphatics and aromatics, and functional groups present in the oil and wax are shown in FIG. 12 and FIGS. 13A and 13B, respectively, described in further detail in the Supplementary Results. FIG. 13B suggests that the wax contains mainly long-chain aliphatics at 500-600°C. Functional groups almost disappear at 650-700°C because high temperatures decomposed most of the hydrocarbons and the wax is carbonized.

[0157] FIG. 3D shows an X-ray diffraction (XRD) pattern of the solid. Three peaks appeared at diffraction angles (29) of 25.00°, 43.25°, and 79.89°. These peaks were identified as the 002, 100, and 112 planes of turbostratic carbon black. Elemental analysis revealed that the solid included 96.72 wt% carbon and 3.28 wt% hydrogen. The morphology of the solid was visualized on an electron scanning microscope (SEM) shown in FIG. 14. The SEM image indicated that the solid has multiple pores and fracture surfaces.3.2. Gas products converted to EP copolymers

[0158] The C2H4 content of commercial EP copolymers varies widely depending on the application. Three EP copolymers were prepared based on the EP molar ratio reformed at 500°C, 600°C, and 700°C, and were denoted as EP-500, EP-600, and EP-700, respectively. The EP molar ratios in the feed were 1.14, 1.33, and 1.91, respectively. Photos of the EP copolymers are shown in FIG. 4 A, and the NMR spectra are shown in FIG. 4B. Compared to NMR spectra of other EP copolymers, the peaks for the prepared EP copolymers were located at the same chemical shifts. The peak assignment of13C-NMR of the EP copolymer samples is shown in Table 5 of the Supplementary Results.

[0159] The EP molar ratios of the copolymers were determined to be 1.11 (EP-500), 1.39 (EP-600), and 2.02 (EP-700), which were close to their corresponding feed compositions. For demonstration purposes, HT GPC analysis was performed on EP-500UWYO / 0121PC(UW 24-030)only. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were 44,507 and 129,751 g / mol, respectively, and the PDI was 2.92. The Mw was no higher than 30% of EP copolymers synthesized in other published works. Molecular weight may be increased by extending reaction time, tuning the amount of catalyst, and / or increasing the feed gas pressure. The PDI value of EP-500 indicated a uniform molecular weight distribution.3.3. Oil products converted to CNFs and supercapacitors

[0160] In this study, only oil products were adopted as precursors of CNFs. Wax was not utilized because it precipitated in DMF solution at room temperature. Fortunately, wax by itself is a value-added product. For example, wax may serve as an intermediate for fuel and other chemicals.

[0161] Four samples were prepared, their precursors: (1) 100% PAN and 75% PAN plus 25% oil reformed at (2) 500°C, (3) 600°C, and (4) 700°C. They were labeled as CNF-1 OOP AN, CNF-250H-500, CNF-250H-600, and CNF-250H-700, respectively. The yield after heat treatment of the four samples is listed in Table 6 provided in the Supplementary Results. The data in Table 6 indicates that weight loss may be a result of the loss of residual DMF, nitrogen in PAN, hydrogen, and oil.

[0162] SEM images of the samples are presented in FIGS. 5A-5D. The nanofibers were smooth, and their diameters ranged from 150 to 400 nm. Elemental spectra are shown in FIG. 15, carbon was the only detected element. Since the samples were nanosized fibers, and the composition was carbon, the samples included CNFs only. The peak at 0 keV was due to the noise of the electronic devices in SEM. The elemental spectra were acquired on FEG-450 SEM by Electron Backscatter Diffraction (EBSD) detector, and processed by INCA software.

[0163] Isotherms and pore size distributions of the sample CNFs are shown in FIGS.16A-16D and FIGS. 17A-17D, specifically: CNF- 1 OOP AN (FIGS. 16A and 17 A); CNF-250H-500 (FIGS. 16B and 17B); CNF-250il-600 (FIGS. 16C and 17C); and CNF-25OH-700 (FIGS. 16D and 17D). The isotherms were type I, and the adsorption was governed by micropores. Therefore, Langmuir rather than a Brunauer-Emmett-Teller (BET) model should be used due to its monolayer adsorption. N2 isothermal adsorption / desorption results of CNFs, including specific surface area, SSA, and total pore volume, Vtp, are summarizedUWYO / 0121PC(UW 24-030)in Table 1. Also shown in Table 1 is specific capacitance calculated from a galvanostatic charge-discharge curve, CGCD; charge-transfer resistance, Ret; and capacitance retention.Table 1

[0164] The SSA and Vtp of CNF-100PAN were 360.49 m2 / g and 0.15 cm3 / g, respectively, and those of CNF-250il-500, CNF-250il-600, and CNF-250il-700 were higher. This was because during heat treatment, the long-chain aliphatics in the oil decomposed and vaporized, generating pore spaces. CNF-250il-500 had the highest SSA and Vtp of 566.15 m2 / g and 0.23 cm3 / g, respectively. As the oil was reformed at 600°C and 700°C, the SSA and Vtp dropped. This was because the oil contained fewer long-chain hydrocarbons; thus the porogenic effect was weaker.

[0165] CNFs were tested as working electrodes of supercapacitors, and the cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves are shown in FIG. 6A and FIG. 6B. The CV curves resembled rectangles, which is a typical capacitive feature. According to Eq. 7, the CGCD of CNF- 1 OOP AN was determined to be 155.10 F / g, and that of CNF-250H-500, CNF-250il-600, and CNF-250H-700 were determined to be 226.64 F / g, 184.58 F / g, and 184.11 F / g, respectively. Relative to conventional technologies, the use of oil according to embodiments described herein increased the CGCD by as high as 46.12%, proving its effectiveness. Table 7 provided in the Supplementary Results shows specific surface area and CGCD data of the Example CNF-250H-500 against comparative examples (conventional technologies). To achieve higher specific capacitance, the amount of oil may be adjusted for more pore structures and / or electroactive agents may be introduced to create pseudocapacitance.

[0166] The Nyquist plot is shown in FIG. 6C, where the intercept with Z’ axis represents electrolyte resistance. The semicircle is related to charge-transfer resistances (Ret) at theUWYO / 0121PC(UW 24-030)CNFs / electrolyte interface. The semicircles are followed by a line at 45° caused by Warburg impedance, and the near vertical lines in the low-frequency region show capacitive property and leakage resistance. The CNFs were electric double-layer capacitor (EDLC) electrodes because the CNFs did not contain electroactive cites (for example, metal oxides, conductive polymers, etc.) and no redox peak was found on CV curves. EDLCs store charge by electrostatic process, thus the capacitance depends on high accessible SSA. As shown in Table 1, the higher the SSA, the higher the CGCD. The accessibility of the SSA to charge may be studied by the Warburg coefficient, c (Q / s05). To obtain it, co0 5(angular frequency) was fitted linearly to Z’, and c was equivalent to the slope. The co was at the Warburg diffusion region shown in FIG. 6C. A low c suggests facile mass transport of charge from electrolyte to electrode surface. The c of CNF- 1 OOP AN, CNF-250H-500, -600, and -700 were determined to be 2.76 Q / s0 5, 1.97 Q / s0 5, 2.06 Q / s0 5, and 2.63 Q / s05, respectively. The lower o was due to more pore structure as shown in Table 1. Ret values of CNF- 1 OOP AN, CNF-250H-500, CNF-250H-600, and CNF-250H-700 were determined to be 2.23 Q, 1.01 , 1.30 Q, and 1.97 Q, respectively. The lower Ret was because the aromatics in the oil were carbonized, and the resultant graphite enhanced conductivity. The stabilities of the samples are shown in FIG. 6D. After approximately 100 cycles, the capacitance retention of all samples stabilized. At the end, CNF-100PAN retained 91.45%, and CNF-250H-500, CNF-250H-600, and CNF-250H-700 retained 94.15%, 97.85%, and 96.78%, respectively.

[0167] Possible mechanisms of heat treatment were revealed by attenuated total reflection (ATR) spectra shown in FIGS. 18A-18C. FIGS. 19A-19D show possible mechanisms of the stabilization and carbonization of the CNFs. Stabilization may convert the PAN into a ladder structure. The cyclization may bond the carbon atom of the nitrile group (-C=N) to the nitrogen atom of a neighboring nitrile group. Thus, the nitrile group may form a double bond (C=N). Although cyclization could occur in an inert atmosphere, oxygen (1) may serve as an initiator and inhibitor of cyclization, (2) may cause dehydrogenation, and (3) may produce functional groups, such as carbonyl, hydroxyl, and ether, as indicated in FIG. 19B. Compared with inert stabilization, oxidative stabilization may increase the thermal stability of CNFs and may provide another crosslinking path (intermolecular elimination of water) during carbonization. In the carbonization phase, the ladder molecules may combine by eliminating water, nitrogen, and hydrogen. The oxidationUWYO / 0121PC(UW 24-030)of oil is also a complicated process. First, a hydrocarbon molecule may be initiated to form a radical that absorbs oxygen and forms a peroxyl radical. Hydroperoxyl groups may be produced via hydrogen abstraction. Hydroperoxide is unstable; it may eject a hydroxyl and abstract another hydrogen atom to form a new hydroxyl or it may lose water to become a carbonyl group. Subsequent reactions may produce carboxylic acids and esters. If two hydroxyls substitute aromatic hydrogens to produce dihydroxybenzene, more oxygen would be required to form bridged species and decompose to maleic acid and acetylene. Aromatics may also crosslink with esters or diacetyl peroxides.

[0168] Overall, carbonization may decompose the oxidized oil, which may crack the CNFs when vaporizing, creating surface areas and channels; it may also polymerize aromatics to graphite that reduced Ret. The oxidation of PAN and oil may involve radicals, and they may interact and create structural defects, leading to extra pore spaces. In summary, applying oil may create more paths from the electrolyte to the electrode surface and adsorption area, may reduce charge-transfer resistance, and may strengthen stability. Possible mechanisms of the pyrolysis-reforming operation is described in the Supplementary Results.3.4. Solid products converted to CQDs and DSSCs

[0169] A 365-nm ultraviolet (UV) flashlight-irradiated CQD solution and the fluorescence emission are shown in FIG. 7A. A transmission electron microscope (TEM) image of the CQDs are presented in FIG. 7B. The CQDs are spherical and monodispersed in the solution. The diameter of the CQD particles ranges from 3.84 to 6.90 nm, with an average particle size of 5.20 nm and a standard deviation of 0.95 nm. The size distribution of the CQD particles formed as described herein is shown in FIG. 20. Under the conditions investigated, the CQDs had an average particle size in a range from about 2 nm to about 8 nm, with an average particle size of about 5.20 nm.

[0170] The FL map of the CQD solution shown in FIG. 7C indicated that the emission wavelength was highly dependent on the excitation wavelength. When the excitation wavelength was 290-365 nm, the emission wavelength ranged from 372 nm to 510 nm. An excitation wavelength of 327 nm produced the strongest emission at 438 nm. The FL map also indicated that, at every excitation wavelength, the emission wavelength is larger, indicating a redshift.UWYO / 0121PC(UW 24-030)

[0171] Three absorption peaks of N3 dye and the CQDs were identified in the UV-visible (UV-vis) spectra shown in FIG. 7D. The N3 spectrum included peaks at 249 nm, 308 nm, 375 nm, and 504 nm. The spectrum of the CQDs had three peaks. The peak at 262 nm was attributed to the excitation of 7t — ► 7t* of the aromatic C=C bond. The broad peak at 290-311 nm was due to the n— >7t* transition of the C=O bond. A broad tail extends to the visible range (400-600 nm), and a tiny peak appears at 500 nm, possibly due to other functional groups.

[0172] Different labels were assigned to solar cells. SC-TiCh indicates its photoanode only had blank TiCh paste. The photoanode of SC-CQD was further treated by CQDs. SC-N3 and SC-CQD-N3 were both DSSCs, with the SC-CQD-N3 treated by CQDs and N3 sequentially. An SEM side view of the SC-TiCh is shown in FIG. 21. In some examples, the transparent TiCh layer was 5.76 pm and the diffusive layer was 8.65 pm, therefore the overall thickness of the TiCh substrate was approximately 14.41 pm.

[0173] FIGS. 8A-8D show the performance of solar cells immediately after assembly (at t=0 hours). FIG. 8A shows the J-V curves collected, and the results are summarized in Table 2. In Table 2, Voc refers to open-circuit voltage, Jsc refers to short-circuit current density, FF refers to fill factor, and PCE refers to photoconversion efficiencyTable 2, Loading amount of CQDs and dye of photoanodes, and electrochemical test results of solar cells at t=0 hours

[0174] SC-TiCh and SC-CQD produced zero current density. The Jsc and PCE of SC-N3 were 8.69 mA / cm2and 3.63%. After applying the CQDs, SC-CQD-N3 had better performance, the Jsc and PCE were 10.94 mA / cm2and 4.25%, increasing by 25.89% and 17.08%, respectively. The values for Voc and FF of SC-N3 and SC-CQD-N3 were close. The results were improved over those of a similar study, where graphene quantum dotsUWYO / 0121PC(UW 24-030)(GQDs) co-sensitized with N3 dye, and the Jsc and PCE increased by 17.97% and 11.98% respectively, reaching 5.58 mA / cm2and 2.15%.

[0175] EQE spectra shown in FIG. 8B indicated that SC-TiCh and SC-CQD did not produce any photoelectrons, as they overlapped horizontal axis. Meanwhile SC-N3 and SC-CQD-N3 have a peak at 540 nm. According to Eq. 13, Jsc(EQE) of SC-N3 and SC-CQD-N3 are 8.29 and 10.31 mA / cm2, i.e., 95.40% and 94.24% of their corresponding Jsc values. The small discrepancies between Jsc values and Jsc(EQE) values validate the measurement of the J-V curve and EQE spectra.

[0176] FIG. 8C shows the Nyquist plots and equivalent circuit of DSSCs. From left to right, the frequencies decreased, and three semicircles can be seen. R2, R3, and R4 were obtained by fitting the left, middle, and right semicircles, respectively. Ri is the intercept of the left semicircle with the Z’ axis. Ri is the sheet resistance of FTO layer, R2 is the chargetransfer resistance at the electrolyte / counter electrode interface, R3 is the resistance at the TiC>2 substrate / electrolyte interface, and R4 is due to Nernst diffusion in the electrolyte. C2, Q3, and C4 in FIG. 8C refer to equivalent capacitor at the electrolyte-counter electrode interface, equivalent constant-phase element at electrolyte-TiCh substrate interface, and equivalent capacitor of bulk electrolyte, respectively. Fitting results are summarized in Table 9 provided in the Supplementary Results.

[0177] Ri, R2, and R4 were close because two DSSCs used the same FTO glass, counter electrode, and electrolyte. However, R3 of SC-N3 and SC-CQD-N3 were 18.22 Q and 15.60 Q, respectively. This indicated that CQDs enabled more facile electron transfer from the electrolyte to the TiO2 substrate. To study the electron lifetime, a Bode plot was also acquired (see FIG. 8D). The middle semi-circles in the Nyquist plot were at 600 - 1 Hz, within this band, two peaks on the Bode plot appear at 14.68 Hz and 8.25 Hz. According to Eq. 14, the electron lifetime of SC-N3 and SC-CQD-N3 were 10.84 ms and 19.28 ms. A longer lifetime suggests the recombination of electrons in the TiCh with oxidized electrolyte was suppressed. FIG. 23 shows the long-term stability of the DSSCs, specifically photoconversion efficiency, PCE (FIG. 23 A), short-circuit current density, Jsc (FIG. 23B), open-circuit voltage, Voc (FIG. 23C), and fill factor, FF (FIG. 23D). After 1,000 hours, the PCE (see FIG. 23 A) of SC-N3 and SC-CQD-N3 was 2.44% and 3.20%, respectively, exhibiting 67.22% and 75.29% of the initial values. The long-term stability curves of bothUWYO / 0121PC(UW 24-030)PCE and Jsc (FIG. 23B) of SC-CQD-N3 maintained above that of SC-N3, proving the effectiveness of the CQDs.

[0178] The J-V curves and EQE spectra showed that the CQDs could not sensitize solar cells. This is because the spectral irradiance generated by the solar lamp only covered a wavelength from 400 nm to 1100 nm, while the strong absorption peaks of the CQDs were below 400 nm. However, CQDs were excellent co-sensitizers, and two possible explanations are proposed. First, CQDs may reduce the electron transfer resistance at the TiCh / electrolyte interface. This result is revealed by the Nyquist plot shown in FIG. 8C, corroborated by a diagram of energy level and electron transfer route shown in FIG. 9B, the energy levels are determined by FIG. 9A. Second, CQDs prevented the recombination of electrons, i.e., returning from conduction band of TiCh substrate back to the electrolyte.

[0179] According to the CV curve in FIG. 9A, the reduction and oxidation potentials were -1.38 and 1.04 V. Therefore, the LUMO and HOMO of CQDs were -3.02 and -5.44 eV, respectively (see Eq. 15 and Eq. 16). The results are comparable to those in previous works. The charge-transfer path is shown in FIG. 9B. The dye electrons were excited by incident light and injected into the conduction band (CB) of the TiO2 substrate. The electrolyte iodide (I ) lost electrons to the dye and became oxidized triiodide (h"). The electrons entered the FTO coating and the external circuit before arriving at the Pt coating on the cathode. At the Pt-electrolyte interface, Is received the electrons and was reduced to I . The LUMO and HOMO of the CQDs were between those of N3 and the CB / valence band of the TiO2 substrate. Here, the CQDs may functioned as intermediaries for better energy-level alignment, facilitating electron transfer. Second, the CQDs may prevent the recombination of electrons, for example, returning from CB of the TiO2 substrate to the electrolyte. This was indicated by a longer electron lifetime (see Bode plot in FIG. 8D).4, Non-Limiting Conclusions

[0180] This study presents a novel and atomic-economy-based technology for waste plastic valorization. The gaseous, liquid, and solid products of the pyrolysis-reforming of plastics serve as excellent precursors for high-value and easily marketable EP copolymers, CNFs, and CQDs. Adding oil to PAN increased the specific capacitance of the CNFs by 46.12% to 226.64 F / g, compared with that of pure PAN CNFs. With the aid of CQDs, the short-circuit current density and photo-conversion efficiency of DSSCs increased byUWYO / 0121PC(UW 24-030)25.89% and 17.08%, respectively. The success of this study indicates that waste plastics are a valuable feedstock for manufacturing advanced materials (for example, CNFs) and devices (for example, solar cells) for applications in the energy transition era.5, Supplementary Results5.1. Pyrolysis-reforming

[0181] The range of temperatures where pyrolysis occurred were determined by TGA (weight, solid line) and DTG curves (derivative weight, dashed line), and are shown in FIG.10. The TGA curve shows that the weight loss did not start until the temperature reached approximately 260°C. According to the DTG curve, pyrolysis of the plastic mixture could be divided into three phases at 260-359°C, 410-435°C, and 444-474°C. The first phase was identified as PVC dehydrochlorination, whereby C-Q bonds break and HC1 and polyene forms. The second phase was mainly PS and PP decomposition, and the third was due to degradation of HDPE and LDPE. PS and PP have weaker thermal stability because of side branches and substituents; therefore, they were decomposed at lower temperatures than HDPE and LDPE. The TGA curve shows negligible weight loss at higher than approximately 490°C, indicating pyrolysis was complete. Therefore, the set point of the pyrolysis section was 500°C. The reforming temperatures were no lower than this value to promote further decomposition. According to the experimental results, a reforming temperature of 500-700°C with a 50°C increment was appropriate. A reforming temperature higher than 700°C may only significantly change the products and consume more energy. A 50°C increment would be high enough to make products different and small enough to make results comparable.

[0182] To ensure all products were collected, mass balance analysis was performed. The results are shown in Table 3.Table 3: Mass balance at different reforming temperaturesUWYO / 0121PC(UW 24-030)

[0183] The sums of mass percentages were all above 92%. The weight loss occurred because oil evaporated when heating its solution in acetone, and wax in the quartz tube could not be entirely scrubbed off. The plastic mixture was decomposed into intermediate products in the pyrolysis section and further degraded by reforming. After leaving the furnace, the large and medium-sized molecules condensed into wax and oil, respectively, and the small, non-condensable molecules were collected as gas. When no reforming section was used, the yields of wax, liquid, and gas were 52.39, 33.59%, and 5.00%, respectively. When reformed at 500°C, the corresponding yields became 37.49%, 45.06%, and 7.04%, whereby more large molecules were decomposed into medium ones, and a few were further reduced to small ones. The gas yield increased tremendously at higher reforming temperatures and plateaued at 48.03% at 700°C. The yield of oil decreased as the reforming temperature increased. It is noted that from 500°C to 550°C, the oil yield changed marginally because more large molecules degraded into medium ones and compensated for its loss. The wax was light yellow when the reforming temperature was 500°C and 550°C, and at 600°C, a small amount of black coking could be observed. The wax became dark at 650°C and 700°C, and the quartz tube interior was smoked with black substances. The wax yield reached a minimum of 8.17% at 650°C, increasing to 10.65% at 700°C. This was because high temperature resulted in more coking. Because the pyrolysis section was set at 500°C, the yield of solid and HC1 did not change regardless of the reforming temperatures.

[0184] Yield (%) of gas components are shown in Table 4 and FIG. 11. In FIG. 11, “HC” refers to “hydrocarbon”. The gas product contained H2, alkane, olefin, and aromatics. In FIG. 11, C5+ denotes isomers of pentane, pentene, hexane, hexene, and aromatics. When the reforming temperature was set to 500°C, gas yield increased by 40.68%. When the reforming temperature increased from 500°C to 550°C, the gas yield had the largest increase percentage by 130.24%. However, the increased percentage diminished rapidly to 2.47% from 650°C to 700°C. This result indicated that gas yield was approaching a limit at 650°C. Although the reforming temperature changed the gas yield marginally from 650°C to 700°C,UWYO / 0121PC(UW 24-030)the effect on the gas composition was not negligible. Unlike the yields of H2, Ci, and C2, the yields of C3, C4, and Cs+ decreased. This result may be due to the higher temperature decomposing C3, C4, and C5+ into H2, Ci, and C2.Table 4Table 4 — continued

[0185] FIG. 12 shows GCMS results of distribution of aliphatics, monoaromatic hydrocarbons (MAHs), and polyaromatic hydrocarbons (PAHs). MAHs may include benzene, ethylbenzene, and indene. PAHs may include naphthalene and methylnaphthalene. As shown in FIG. 12, as the reforming temperature increased, the area percentage of aliphatics in the oil diminished and became undetectable at 700°C. Meanwhile, the PAH grew from 1.43% to 30.18%. MAH increased as the reforming temperature increased, but decreased from 650 to 700 °C, which may be due to MAH being converted to PAH at 700°C. This trend of aliphatics and aromatics was consistent with ATR measurements shown in FIG. 13 A. Because the original plastic mixture did not contain any PAH functional groups, reforming facilitated PAH-generating reactions that were weak during pyrolysis.UWYO / 0121PC(UW 24-030)

[0186] According to the ATR spectra of waxes shown in FIG. 13B, except for 650°C and 700°C, the waxes were aliphatics only. Higher reforming temperature converted more wax into lighter products. Temperatures of 500°C and 550°C caused chain scission but little aromatization. Therefore, the decomposed wax mainly contributed to aliphatics in the oil.

[0187] The ATR spectra of oil are shown in FIG. 13 A. The peaks at 2954 cm1and 1377 cm1indicate the antisymmetric stretching and in-plane bending of methyl groups (-CH3). The peaks at 29192855and 1464 cm1suggested C-H asymmetric stretching, symmetric stretching, and in-plane bending of methylene (-CH2) groups, and the peak at 723 cm1belonged to the out-of-plane vibration of long chain (-CH2)n of aliphatic species. These peaks confirmed the presence of aliphatic species. The peaks between 3100 cm1and 3000 900 cmand 675 cm1were assigned to C-H stretching and out-of-plane C-H bending. These peaks indicate the aromatic groups. The peaks between 1625 cm1and 1500 cm ', and 900 cm’1and 675 cm’1indicated the presence of MAH, PAH, and substituted aromatic groups. As the reforming temperature increased, the peaks representing aliphatic groups changed slightly from 500°C to 600°C, but diminished starting from 650°C; conversely, the peaks featuring aromatic groups were weak but grew tremendously at 650°C and 700°C. From 500°C to 600°C, weak peaks are between 1640 cm 980 cm ', and 990 cm ', and a strong peak presented at 910 cm They were assigned to C=C stretching and C-H bending, suggesting the presence of olefin, which is confirmed by the GCMS results. The spectra of wax are shown in FIG. 13B. Wax was dominated by aliphatic species from 500°C to 600°C; the products were long-chain hydrocarbons that could not dissolve in acetone. At 650°C and 700°C, the peaks almost disappeared, suggesting only a small amount of C-H bonds (i.e., hydrocarbons) remained. The high degree of carbonization could be corroborated by the higher H2 yield as shown in FIG. 11. The morphology of the solid is shown in FIG. 14. Multiple pores and fracture surfaces can be seen.5,1.1. Possible mechanisms of pyrolysis-reforming

[0188] Polymer pyrolysis mechanisms may explain the gas component distribution. The pyrolysis of the plastic mixture may be divided into three phases: (1) random scission, (2) P-scission, (3) and termination. Prior to random scission, PVC may experience dehydrochlorination at 250°C as shown in FIG. 10.UWYO / 0121PC(UW 24-030)

[0189] Random scission may initialize the decomposition, in that a polymer (Pn) with n backbone carbons may split into two radicals with k and n-k carbons:Pn — Pk* + Pn-k*

[0190] Radicals may also form by eliminating substituent groups or side branch (*S):Pn-k-l-C(S)-Pk Pn-k-l-O-Pk + *S

[0191] Hydrogen transfer may accompany a change in the location of free electrons. Radicals may degrade by P-scission at the end-chain that releases one monomer:Pk-2-C-O Pk-2* + C=Cor at mid-chain that produces one radical and one long olefin:Pn-k-2- c- c«- Pk Pn-k-2* + C=C-Pk

[0192] Termination phases may convert the radicals to molecules. One path is recombining two radicals:Pm* + Pl* — Pm+1

[0193] Alternatively, one radical may transfer a hydrogen atom (radical) to the other and produce one alkane and one olefin:Pm-2-C-C* + P1-2-C-C* Pm-2- C=C + P1-2-C-C

[0194] The new molecules may repeat this pyrolysis cycle, and the three phases may proceed in parallel. After pyrolysis, the pyrolysis product enters the reforming section and may be further degraded by similar mechanisms.

[0195] Higher reforming temperature was found to be favorable for bond breaking. Thus, the yield shifted towards smaller molecules, thereby increasing the gas yield. C2H4 was likely produced by end-chain P-scission, and C3H6 was produced mainly by mid-chain P-scission when the reforming temperature was 600°C and higher. Because the amount of PP was only 4 wt% in the plastic mixture, and at 600°C and higher, the yield of C3H6 was higher than 4%. Thus, the extra C3H6 was not released from PE, because pyrolysis of PVC and PS produces negligible amounts of C3H6.

[0196] The formation of aliphatic oil was likely due to mid-chain P-scission followed by termination. The formation of aromatics has several paths. The first may be PS degradation, and the second may be PVC dehydrochlorination followed by cyclization. After dehydrochlorination, PVC may form a conjugated polyene:Pk-C(H)-C(Cl)-C(H)-C(Cl)-Pn-k-4 Pk-C=C-C=C-Pn-k-4+ 2 HC1UWYO / 0121PC(UW 24-030)and aromatics may be produced after thermal degradation and cyclization.

[0197] The third path may be a Diels-Alder reaction which converted aliphatics to aromatics. Short-chain diene (usually butadiene) and another short-chain olefin (mainly C2-C4) may produce cyclohexene or its derivatives, followed by dehydrogenation and aromatics formation:C=C-C=C + C=C — cyclohexene — benzene + 2 H2

[0198] There are various paths to explain the conversion from MAH to PAH. For example, hydrogen abstraction acetylene addition (HACA) is a widely accepted theory where two acetylene molecules are added to a phenyl radical. PAH, such as naphthalene, may also be produced by a second Diels- Alder reaction in which butadiene is added to the benzene. Higher reforming temperatures were favorable for the formation of aforementioned molecules and dehydrogenation, therefore, more aromatics were formed.5.2. Valorization5,2.1. EP Copolymers

[0199] The peak assignment of13C NMR of EP copolymer samples is shown in Table 5. In Table five, the letters P, S, and T refer to primary, secondary, and tertiary carbon, respectively; the subscript Greek letters refer to their relative positions on the main chain.Table 5UWYO / 0121PC(UW 24-030)5,2.2. CNFs and supercapacitors

[0200] The yield of the CNF samples after heat treatment is shown in Table 6. The weight loss may be explained by the loss of residual DMF, nitrogen in PAN, hydrogen, and oil.Table 6

[0201] For Table 6, the yield was calculated by the following equation:weight after heat treatmentYield = - - - - - - — - x 100%weight of fresh CNFs

[0202] Table 7 shows a CNF made according to embodiments of the present disclosure (Example, CNF-250il-500) versus comparative examples using carbon nanomaterials as supercapacitor electrodes. In Table 7, PVP refers to polyvinylpyrrolidone, PDPP refers to poly(diaryloxyphosphazene), ahCNF refers to refers to nitrogen-doped activated hollow CNFs, NCNF refers to phosphorous into nitrogen-based carbon fibers, CLCF refers to crosslinked N-doped carbon nanofiber network, and ACF refers to activated carbon nanofiber.Table 7UWYO / 0121PC(UW 24-030)

[0203] The ATR spectra of fresh CNFs (FIG. 18 A), stabilized CNFs (FIG. 18B), and carbonized CNFs (FIG. 18C) are shown in FIGS. 18A-18C. FIG. 18A shows the characteristic peak of PAN, a nitrile group (~C=N), which may be found at 2242The peaks at 29262852 cm and 1452 cm1suggested C-H asymmetric stretching, symmetric stretching, and in-plane bending of methylene (-CH2) groups. The -CH2 groups have strong peaks at 2926 cm1and 2852 cm1on the spectra of CNF-250H-500 and CNF- 250H-600, contributed by oil. The spectrum of CNF-250H-700 showed peaks between 675 cm1and 900 cmthis was due to the oil reformed at 700°C mainly containing aromatics. The spectra of stabilized CNFs are shown in FIG. 18B. The shoulder peaks at 1728 cm1and 1660 cm1were assigned to stretching vibrations of aliphatic and conjugated ketone groups (C=O), respectively. The peak at 1579 cm1was a combination of C=N, C=C, and N-H groups. The peak at 800 cm1was assigned to C-H bond of C=C-H that belonged to the heteroaromatic ring. The shoulder peak at 1231 cm1and the weak peak at 1041 cm1were assigned to C-0 of C-O-C.UWYO / 0121PC(UW 24-030)

[0204] FIG. 18C shows the spectra of carbonized CNFs (i.e., CNFs). The spectra ramp up as the wavenumber decreased, indicated the CNFs had higher absorbance at lower wavenumbers, similar to CNFs in previous works. The broad peak between 1350 cm1and 850 cm1was assigned to C-C stretching vibration. In the spectra shown in FIG. 18C, the peaks observed in FIG. 18B had disappeared, indicating thorough carbonization.5 23. CODs andDSSCs

[0205] Table 8 shows an example electrolyte of DSSCs.Table 8

[0206] Table 9 shows fitted parameters of the equivalent circuit. In Table 9, Q3 is the CPE parameter (F s(a3-1)) and a3 is the order (dimensionless). C2 refers to equivalent capacitor at the electrolyte-counter electrode interface, Q3 and a3 refer to parameters of equivalent constant-phase element at electrolyte-TiCh substrate interface, C4 refers to equivalent capacitor of bulk electrolyte. These are the fitted parameters of FIG. 8C (the equivalent circuit). is a unit of resistance and F is Farady, a unit for capacitance.Table 9UWYO / 0121PC(UW 24-030)

[0207] FIG. 21 shows cross-section view of FTO glass (cut by half in the middle) coated by TiC>2 substrate. TiCh substrate, transparent TiCh layer, FTO layer and glass as indicated by arrows. FIG. 21A shows SEM images of the FTO glass coated by TiO2 substrate (SC-TiO?). FIG. 21 A has lower magnification, the scale bar is 100 pm, and FIG. 21B has higher magnification, the scale bar is 10 pm.

[0208] FIG. 22 is a graphical representation of the architecture of a DSSC 2200 according to at least one embodiment of the present disclosure. The DSSC 2200 may include a photoanode 2208. The photoanode may include a layer 2202a (such as SiCh glass), an FTO layer 2204a disposed adjacent to the layer 2202a, a transparent layer 2216 disposed adjacent to the FTO layer 2204a, and a diffusive layer 2218 disposed adjacent to the transparent layer 2216. In this example, the transparent layer 2216 had a thickness of about 5.76 pm and the diffusive layer 2218 had a thickness of about 8.65 nm, though other thicknesses are contemplated. The transparent layer may be a TiO2 layer. The DSSC may further include a cathode 2210. The cathode 2210 may include a layer 2202b (such as SiO2 glass), an FTO layer 2204b disposed adjacent to the layer 2202b, and a Pt-coating 2206 disposed adjacent to the FTO layer 2204b. Positioned between the photoanode 2208 and the cathode 2210 may be a spacer 2214 and an electrolyte 2212. In this example, the spacer 2214 is a 3-mil (76.2 pm) polyimide film, though other spacers and different dimensions of spacers are contemplated. Illustrative, but non-limiting, components of the 17b" redox electrolyte 2212 are shown in Table 8. The transparent layer 2216 and diffusive layer 2218 may include the N3 dye 2220 and the CQDs . “ox” and “red” refer to oxidation and reduction, respectively. During use, sunlight 2230 hits the N3 dye molecules and CQDs in the DSSC, exciting electrons that are injected into the conduction band of the TiCh layer, creating current.Embodiments Listing

[0209] Embodiment Al. An integrated process for converting (or valorizing) waste plastic, the process comprising:pyrolyzing a waste plastic feed comprising a polyolefin to produce a pyrolysis product comprising an intermediate products and solids;reforming the intermediate products to produce:a gas fraction;UWYO / 0121PC(UW 24-030)an oil fraction; andan optional wax fraction;polymerizing at least a portion of ethylene and propylene present in the gas fraction to form an ethyl ene-propylene copolymer;fabricating carbon nanofibers from at least a portion of the oil fraction; and producing carbon quantum dots from at least a portion of the solids.

[0210] Embodiment A2. The process according to Embodiment Al, wherein, prior to polymerizing and fabricating the nanofibers, the process further comprises separating the gas fraction, the oil fraction, and an optional wax fraction.

[0211] Embodiment A3. The process according to any one of the preceding Embodiments, wherein pyrolyzing is performed under pyrolysis conditions, the pyrolysis conditions comprising:a pyrolysis temperature in a range from about 400°C to about 600°C; a pyrolysis temperature ramping rate from room temperature to the pyrolysis temperature in a range from about l°C / min to about 50°C / min, such as about 10°C / min;a pyrolysis pressure in a range from about 70 to about 500 kPa; or a combination thereof.

[0212] Embodiment A4. The process according to any one of the preceding Embodiments, wherein reforming is performed under reforming conditions, the reforming conditions comprising:a reforming temperature in a range from about 400 to about 800°C, such as from about 450 to about 750°C, such as from about 500 to about 700°C, such as from about 550 to about 650°C;a reforming temperature ramping rate from room temperature to the reforming temperature (or from the pyrolysis temperature to the reforming temperature) in a range from about 1 to about 50°C / min, such as about 10°C / min;a reforming pressure in a range from about 70 kPa to about 500 kPa; or a combination thereof.

[0213] Embodiment A5. The process according to Embodiment A4, wherein increasing the reforming temperature increases a yield of the gas fraction and decreases the yield of a wax fraction, the oil fraction, or a combination thereof.UWYO / 0121PC(UW 24-030)

[0214] Embodiment A6. The process according to any one of the preceding Embodiments, wherein the gas fraction comprises ethylene and propylene.

[0215] Embodiment A7. The process according to Embodiment A6, wherein a reforming temperature is selected to tune a molar ratio of the ethylene to propylene in the gas fraction in a range from about 1:1 to about 2.4:1, such as from about 1.05:1 to about 2.2:1, such as from about 1.1:1 to about 2.1:1 (ethylene:propylene).

[0216] Embodiment A8. The process according to any one of the preceding Embodiments, wherein pyrolysis of the waste plastic feed, reforming the intermediate products, or combinations thereof produces hydrogen chloride.

[0217] Embodiment A9. The process according to Embodiment A8, wherein the process further comprises: neutralizing the hydrogen chloride, for example, with an aqueous alkali material.

[0218] Embodiment A10. The process according to any one of the preceding Embodiments, wherein polymerizing comprises:contacting a feed gas comprising the ethylene and the propylene with a vanadium-based catalyst (for example, vanadium oxychloride or vanadium tetrachloride) and an organoaluminum co-catalyst (for example, ethylaluminum sesquichloride) in the presence of chlorinated ester promoter (for example, ethyl tri chloroacetate); and recovering the EP copolymer, the EP copolymer optionally having a molar ratio of ethylene to propylene that is within ±10% of a molar ratio of ethylene to propylene in the feed gas.

[0219] Embodiment All. The process according to any one of the preceding Embodiments, wherein the gas fraction further comprises CO and EE.

[0220] Embodiment A12. The process according to Embodiment All, wherein the process further comprises:converting the CO and EE in the gas fraction to ethylene, propylene, or combinations thereof (for example, by Fischer-Tropsch reaction); andoptionally polymerizing the ethylene and propylene to the ethyl ene-propylene copolymer.

[0221] Embodiment Al 3. The process according to any one of the preceding Embodiments, wherein the ethylene-propylene copolymer has a molar ratio of ethylene toUWYO / 0121PC(UW 24-030)propylene in a range from about 1:1 to about 2.4:1, such as from about 1.05:1 to about 2.2:1, such as from about 1.1:1 to about 2.1:1 (ethylene: propylene).

[0222] Embodiment A14. The process according to any one of the preceding Embodiments, wherein the ethyl ene-propylene copolymer has:a number-average molecular weight in a range from about 15,000 to about 75,000 g / mol, such as from about 25,000 to about 65,000 g / mol, such as from about 35,000 to about 55,000 g / mol, such as from about 40,000 to about 50,000 g / mol;a weight-average molecular weight in a range from about 100,000 to about 160,000 g / mol, such as from about 110,000 to about 150,000 g / mol, such as from about 120,000 to about 140,000 g / mol, such as from about 125,000 to about 135,000 g / mol;an Mw / Mn in a range from about 1.9 to about 3.9, such as from about 2.4 to about 3.4, such as from about 2.6 to about 3.2; orcombinations thereof.

[0223] Embodiment Al 5. The process according to any one of the preceding Embodiments, wherein the ethylene-propylene copolymer is suitable for use as an elastomer, an impact modifier, or a rubber precursor.

[0224] Embodiment A16. The process according to any one of the preceding Embodiments, wherein the oil fraction comprises aliphatic hydrocarbons, aromatic hydrocarbons, or both.

[0225] Embodiment A17. The process according to any one of the preceding Embodiments, wherein fabricating carbon nanofibers from at least a portion of the oil fraction comprises:forming a precursor mixture comprising:from about 50 wt% to about 99 wt% of a polymer comprising polyacrylonitrile (PAN), polyvinyl acetate (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), poly(diaryloxyphosphazene) (PDPP), or combinations thereof; andfrom about 1 wt% to about 50 wt% oil fraction based on a total wt% of the polymer and the oil fraction, the total wt% of the polymer and the oil fraction equal to 100 wt%;electrospinning the precursor mixture to form nanofibers;UWYO / 0121PC(UW 24-030)stabilizing (oxidizing and / or crosslinking) the nanofibers; andcarbonizing the stabilized nanofibers to form the carbon nanofibers.

[0226] Embodiment A18. The process according to Embodiment A17, wherein stabilizing the nanofibers is performed by heating the nanofibers at a stabilization temperature in a range from about 200 to about 400°C in the presence of 20-500 seem air.

[0227] Embodiment A19. The process according to Embodiment A18, wherein carbonizing the fibers is performed at carbonization temperature in a range from about 500 to about 1000°C, such as from about 700 to about 900°C, such as about 800°C, and under N2, Ar, or combinations thereof.

[0228] Embodiment A20. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers are characterized as having:a pore structure dominated by micropores;a Langmuir-type adsorption isotherm;a total pore volume of greater than 0.15 cm3 / g, such as in a range from about 0.16 to about 0.30 cm3 / g, such as from about 0.18 to about 0.23 cm3 / g;a specific surface area greater than 365 m2 / g, such as in a range from about 370 to about 800 m2 / g, such as from about 400 to about 650 m2 / g, such as from about 450 to about 600 m2 / g, such as from about 458 to about 567 m2 / g; orcombinations thereof.

[0229] Embodiment A21. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers achieve a specific capacitance increase of at least 10%, such as at least 20%, such as at least 30%, such as at least 40%, such as least 50% relative to the carbon nanofibers fabricated from polyacrylonitrile alone under galvanostatic charge-discharge at 1 A / g.

[0230] Embodiment A22. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers have a specific surface area greater than that of carbon nanofibers formed from polyacrylonitrile alone.

[0231] Embodiment A23. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers have a higher specific capacitance when used as an electrode relative to that of carbon nanofibers formed from polyacrylonitrile alone.UWYO / 0121PC(UW 24-030)

[0232] Embodiment A24. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers comprise an electrospun and carbonized product of:a hydrocarbon oil derived from pyrolysis-reforming of a waste plastic; and polyacrylonitrile.

[0233] Embodiment A25. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers are characterized as having:a higher specific surface area than PAN-only carbon nanofibers;a higher total pore volume than PAN-only carbon nanofibers;a higher specific capacitance calculated from a galvanostatic charge-discharge curve (CGCD) at 1 A / g than PAN-only carbon nanofibers;a higher capacitance retention than PAN-only carbon nanofibers;a lower charge-transfer resistance than PAN-only carbon nanofibers; a lower Warburg coefficient than PAN-only carbon nanofibers; or combinations thereof.

[0234] Embodiment A26. The process according to any one of the preceding Embodiments, wherein the carbon nanofibers are characterized as having:a specific surface area of about 400 m2 / g or more, such as about 450 m2 / g or more, such as about 500 m2 / g or more, such as about 550 m2 / g or more (and optionally up to about 900 m2 / g), or in a range from about 400 to about 800 m2 / g, such as from about 450 to about 750 m2 / g, such as from about 500 to about 700 m2 / g, such as from about 550 to about 650 m2 / g, such as from about 550 to about 600 m2 / g;a total pore volume of about 0.16 cm3 / g or more, such as about 0.18 cm3 / g or more, such as about 0.20 cm3 / g or more, such as about 0.22 cm3 / g or more (and optionally up to about 0.40 cm3 / g or more), or in a range from about 0.16 to about 0.4 m2 / g, such as from about 0.18 to about 0.3 m2 / g, such as from about 0.20 to about 0.25 m2 / g;a specific capacitance calculated from a galvanostatic charge-discharge curve (CGCD) at 1 A / g of about 160 F / g or more, such as about 180 F / g or more, such as about 200 F / g or more, such as about 220 F / g or more (and optionally up to about 300 F / g), or in a range from about 160 to about 300 F / g, such as from about 175 to about 275 F / g, such asUWYO / 0121PC(UW 24-030)from about 180 to about 260 F / g, such as from about 200 to about 250 F / g, such as from about 210 to about 240 F / g, such as about 226 F / g;a capacitance retention of greater than 92%, such as greater than 94%, such as greater than 96%, such as greater than 98% (and optionally up to 100%) after at least 450 charge-discharge cycles;a charge-transfer resistance of about 4 Q or less, such as about 3 Q or less, such as about 2.76 Q or less, such as about 2.5 Q or less, such as about 2.23 Q or less, such as about 2.06 Q or less, such as about 1.97 Q or less, such as about 1.30 Q or less, such as about 1.01 Q or less (and optionally down to about 1 Q);a Warburg coefficient of 2.75 Q / s0'5or less, such as about 2.65 or less, such as about 2.2 Q / s0'5or less, such as about 2.0 Q / s0'5or less (and optionally down to about 0.5 Q / s05), or in a range from about 1.0 to about 2.75 Q / s0 5, such as from about 1.5 to about 2.7 Q / s05, such as from about 1.9 to about 2.65 Q / s05; orcombinations thereof.

[0235] Embodiment A27. The process according to any one of the preceding Embodiments, wherein the solids comprise:an amount of carbon in a range from about 90 to about 100 wt%, such as from about 95 to less than 100 wt% based on a total wt% of carbon and hydrogen in the solids, the total wt% of carbon and hydrogen in the solids equal to 100 wt%; andan amount of hydrogen in a range from 0 wt% to 10 wt%, such as from greater than 0 to about 5 wt% based on the total wt% of carbon and hydrogen in the solids.

[0236] Embodiment A28. The process according to any one of the preceding Embodiments, wherein the solids comprise turbostratic carbon black.

[0237] Embodiment A29. The process according to any one of the preceding Embodiments, wherein producing carbon quantum dots from at least a portion of the solids comprises: treating the solids with an oxidizing agent (for example, hydrogen peroxide) at a temperature greater than 150°C, such as in a range from about 150°C to about 250°C, such as about 170°C to about 200°C, such as about 180°C.

[0238] Embodiment A30. The process according to any one of the preceding Embodiments, wherein the carbon quantum dots are characterized as having:UWYO / 0121PC(UW 24-030)an average particle size in a range from about 1 to about 10 nm, such as from about 2 to about 8 nm, such as from about 3 to about 7 nm, such as about 5 nm;an excitation-dependent emission in a range from about 370 to about 510 nm when excited by an excitation wavelength in a range from 290 to 465 nm;an ultraviolet spectrum containing:a Ti— >7t* transition at a wavelength in a range from about 260 to about 265 nm (such as about 262 nm);one or more n— >7t* transitions in a range from about 290 and 311 nm; or a combination thereof;or combinations thereof.

[0239] Embodiment A31. The process according to any one of the preceding Embodiments, wherein the carbon quantum dots function as co-sensitizers in a dye-sensitized solar cell.

[0240] Embodiment A32. The process according to any one of the preceding Embodiments, wherein the carbon quantum dots, when used as co-sensitizers with N3 dye in a dye-sensitized solar cell, increase short-circuit current density by at least 20% and photo-conversion efficiency by at least 10% relative to an otherwise identical dye-sensitized solar cell lacking carbon quantum dots.

[0241] Embodiment A33. The process according to any one of the preceding Embodiments, wherein the polyolefin comprises polyethylene (for example, high density polyethylene, medium density polyethylene, low density polyethylene, or linear low density polyethylene), polypropylene (for example, a polypropylene random block copolymer), or combinations thereof.

[0242] Embodiment A34. The process according to any one of the preceding Embodiments, wherein the polyolefin comprises an isotactic polyolefin, an atactic polyolefin, a syndiotactic polyolefin, or combinations thereof.

[0243] Embodiment A35. The process according to any one of the preceding Embodiments, wherein the polyolefin comprises a polyolefin homopolymer, a polyolefin copolymer, a polyolefin block copolymer, a polyolefin random block copolymer, or combinations thereof.UWYO / 0121PC(UW 24-030)

[0244] Embodiment A36. The process according to any one of the preceding Embodiments, wherein the waste plastic feed comprises an amount of the polyolefin of about 10 wt% or more, such as in a range from about 50 wt% to about 99 wt%, such as from about 55 wt% to about 98 wt%, such as from about 60 wt% to about 95 wt%, such as from about 70 wt% to about 90 wt%, such as from about 75 wt% to about 90 wt% based on a total wt% of the waste plastic feed, the total wt% of the waste plastic feed equal to 100 wt%.

[0245] Embodiment A37. The process according to any one of the preceding Embodiments, wherein the polyolefin comprises a high density polyethylene, a low density polyethylene, a linear low density polyethylene, or combinations thereof.

[0246] Embodiment A38. The process according to any one of the preceding Embodiments, wherein the waste plastic feed further comprises a waste plastic other than the polyolefin.

[0247] Embodiment A39. The process according to Embodiment A38, wherein the waste plastic other than the polyolefin comprises polystyrene, polyester, polyamide, polyurethane, polyphenol, polycarbonate, a halogen-containing polymer, polylactic acid, polyacrylic acid, polyacrylate, polyacetal, or combinations thereof.

[0248] Embodiment A40. The process according to Embodiment A39, wherein, when the waste plastic feed comprises the halogen-containing polymer, the halogen-containing polymer comprises a chlorinated polymer (for example, chlorinated polyethylene), polyvinylchloride, polyvinylidene chloride, a fluorinated polymer (for example, fluorinated polyethylene, such as polytetrafluoroethylene), or combinations thereof.

[0249] Embodiment A41. The process according to any one of Embodiments A38-A40, wherein the waste plastic feed comprises: an amount of the waste plastic other than the polyolefin of about 20 wt% or less, such as about 15 wt% or less, such as about 10 wt% or less, such as about 5 wt% or less, such as about 2 wt% or less based on a total wt% of the waste plastic feed, the total wt% of the waste plastic feed equal to 100 wt%.

[0250] Embodiment A42. The process according to any one of Embodiments A38-A41, wherein the waste plastic feed comprises a halogen content, if present, in an amount of about 100,000 ppm (about 10 wt%) or less, such as 3.6 wt% (about 36,000 ppm) or less, such as about 1 wt% (about 10,000 ppm) or less, such as about 0.5 wt% (about 5,000 ppm) or less, or in a range from greater than 0 to about 3.6 wt%, such as from greater than 0 to about 1UWYO / 0121PC(UW 24-030)wt% based on a total wt% of the waste plastic feed, the total wt% of the waste plastic feed equal to 100 wt%.

[0251] Embodiment A42. The process according to any one of the preceding Embodiments, wherein the waste plastic feed further comprises a virgin plastic.

[0252] Embodiment A43. The process according to any one of the preceding Embodiments, wherein the waste plastic feed comprises:a solid having an average particle size of about 10 cm or less, such as about 1 cm or less, such as about 100 mm or less, such as about 10 mm or less, such as about 5 mm or less, such as about 3 mm or less, such as about 1 mm or less;a solid in pellet form and having an average particle size in a range from about 0.01 to about 10 mm, such as from about 0.1 to about 1 mm;a solid in fluff form and having an average particle size of about 1,500 pm or less, such as about 1,000 pm or less, such as about 500 pm or less, such as about 400 pm or less, such as about 300 pm or less, such as about 100 pm or less, such as about 50 pm or less, such as about 10 pm or less; orcombinations thereof.

[0253] Embodiment A43. The process according to any one of the preceding Embodiments, wherein the gas fraction, oil fraction, and solids derived from the pyrolysis and the reforming are simultaneously valorized to the ethylene-copolymer, the carbon nanofibers, and carbon quantum dots.

[0254] Embodiment A44. The process according to any one of the preceding Embodiments, wherein each of polymerizing to form the ethyl ene-propylene copolymer, fabricating carbon nanofibers, and producing carbon quantum dots are performed simultaneously.

[0255] Embodiment A45. The process according to any one of the preceding Embodiments, wherein the ethylene-propylene copolymer, the carbon nanofibers, and the carbon quantum dots are formed from the same waste plastic feed.

[0256] Embodiment Bl. A system for converting (or valorizing) waste plastic, the system comprising:a pyrolysis reactor;UWYO / 0121PC(UW 24-030)a reforming reactor downstream from, and in fluid communication with, the pyrolysis reactor;a polymerization reactor downstream from, and in fluid communication with, the reforming reactor; anda controller coupled to the pyrolysis reactor, the reforming reactor, the polymerization reactor, or combinations thereof.

[0257] Embodiment B2. The system according to Embodiment Bl, wherein the system further comprises a separation unit, the separation unit positioned between the reforming reactor and the polymerization reactor, the separation unit in fluid communication with the reforming reactor and the polymerization reactor, the controller optionally coupled to the CQD synthesis unit.

[0258] Embodiment B3. The system according to any one of Embodiments B1-B2, wherein:the controller is coupled to the separation unit; andthe controller is configured to cause the separation unit:to receive the hydrocarbon mixture from the reforming reactor;to separate a hydrocarbon gas fraction and a hydrocarbon oil fraction from the hydrocarbon mixture;to discharge a hydrocarbon gas fraction separated from the hydrocarbon mixture; and / orto discharge a hydrocarbon oil fraction separated from the hydrocarbon mixture.

[0259] Embodiment B4. The system according to any one of Embodiments B1-B3, wherein:the controller is coupled to the pyrolysis reactor; andthe controller is configured to cause the pyrolysis reactor:to receive a waste plastic feed comprising a polyolefin;to decompose the polyolefin into a pyrolysis product (for example, under pyrolysis conditions), the pyrolysis product comprising:intermediate products; andsolids;UWYO / 0121PC(UW 24-030)to discharge the intermediate products; andto discharge the solids.

[0260] Embodiment B5. The system according to any one of Embodiments B1-B4, wherein the system further comprises: a carbon quantum dot (CQD) synthesis unit, the CQD synthesis unit coupled to and downstream from the pyrolysis reactor, the controller optionally coupled to the CQD synthesis unit.

[0261] Embodiment B6. The system according to Embodiment B5, wherein:the controller is coupled to the CQD synthesis unit; andthe controller is configured to cause the CQD synthesis unit:to receive the solids from the pyrolysis reactor;to convert the solids (for example, under oxidation conditions) into a carbon quantum dot product; and / orto discharge the carbon quantum dot product.

[0262] Embodiment B7. The system according to any one of Embodiments B1-B6, wherein:the controller is coupled to the reforming reactor; andthe controller is configured to cause the reforming reactor:to receive the intermediate products from the pyrolysis reactor;to convert (for example, under reforming conditions), at least a portion of the intermediate products into:a hydrocarbon mixture comprising a hydrocarbon gas and a hydrocarbon oil; andan optional hydrocarbon wax; and / orto discharge the optional hydrocarbon wax and the hydrocarbon mixture.

[0263] Embodiment B8. The system according to any one of Embodiments B1-B7, wherein:the controller is coupled to the polymerization reactor; andthe controller is configured to cause the polymerization reactor:to receive the hydrocarbon gas fraction from the pyrolysis reactor, the reforming reactor, and / or the separation unit;UWYO / 0121PC(UW 24-030)to convert ethylene and propylene present in the hydrocarbon gas fraction into an ethylene-propylene copolymer (for example, under polymerization conditions); and / orto discharge the ethylene-propylene copolymer.

[0264] Embodiment B9. The system according to any one of Embodiments B1-B8, wherein the system further comprises: a carbon nanofiber (CNF) fabrication unit, the CNF fabrication unit coupled to and downstream from the pyrolysis reactor, the reforming reactor, and / or the separation unit, the controller optionally coupled to the CNF fabrication unit.

[0265] Embodiment BIO. The system according to Embodiment B9, wherein:the controller is coupled to the CNF fabrication unit;the controller is configured to cause the CNF fabrication unit:to receive the hydrocarbon oil fraction from the pyrolysis reactor, the reforming reactor, and / or the separation unit;to convert the hydrocarbon oil fraction to a carbon nanofiber; and / or to discharge the carbon nanofiber.

[0266] Embodiment Bll. The system according to any one of Embodiments Bl -B10, wherein the system further comprises: a neutralization unit downstream from, and in fluid communication with, the reforming reactor, the pyrolysis reactor, or both, the controller optionally coupled to the neutralization unit.

[0267] Embodiment Bl 2. The system according to Embodiment Bl 1, wherein:the controller is coupled to the neutralization unit;the controller is configured to cause the neutralization unit:to receive HC1 from the reforming reactor, the pyrolysis reactor, or both; and / orto neutralize the HC1 with, for example, an aqueous alkali material.

[0268] Embodiment B 13. The system according to any one of Embodiments B1-B12, wherein the system further comprises: a syngas conversion unit downstream from, and in fluid communication with, the pyrolysis reactor, the reforming reactor, the separation unit, or combinations thereof, the controller optionally coupled to the syngas conversion unit.

[0269] Embodiment Bl 4. The system according to Embodiment Bl 3, wherein:UWYO / 0121PC(UW 24-030)the controller is coupled to the syngas conversion unit; andthe controller is configured to cause the syngas conversion unit:to receive CO and H2 from the reforming reactor;to convert at least a portion of the CO and H2 to ethylene, propylene, or a combination thereof; and / orto discharge the ethylene, the propylene, or the combination thereof produced from the CO and H2.

[0270] Embodiment B14. The system according to any one of Embodiments B1-B13, wherein the controller is configured to perform a process described herein, such as the process according to any one of Embodiments A1-A45.

[0271] Embodiment Cl. A DSSC, comprising:carbon quantum dots produced according to embodiments described herein, for example, any one of Embodiments A1-A45 or any one of Embodiments B1-B14.

[0272] Embodiment C2. A DSSC, comprising:a photoanode comprising titanium dioxide;a dye sensitizer, such as a ruthenium-containing dye (for example, N3 dye); and carbon quantum dots produced according to any one of the preceding Embodiments disposed on the photoanode,optionally, wherein the carbon quantum dots increase photocurrent, photoconversion efficiency, or a combination thereof relative to the DSSC without the carbon quantum dots.

[0273] Embodiment C3. A DSSC, comprising:a fluorine-Doped Tin Oxide (FTO) coated glass, a TiO2 paste, sensitized with a ruthenium-containing dye (for example, N3 dye) and co-sensitized by carbon quantum dots produced according to embodiments described herein (for example, any one of Embodiments A1-A45 or any one of Embodiments Bl -Bl 4);a redox electrolyte (for example, an I7E" redox electrolyte); anda platinum-coated cathode.

[0274] Embodiment C4. The DSSC according to any one of Embodiments C1-C3, wherein:UWYO / 0121PC(UW 24-030)the inclusion of the carbon quantum dots increases short-circuit current density (Jsc) by about 5% or more, such as about 10% or more, such as about 15% or more, such as about 20% or more, such as about 25% or more (and optionally up to about 100%) relative to the DSSC without the carbon quantum dots;the inclusion of the carbon quantum dots increases photoconversion efficiency (PCE) by about 5% or more, such as about 10% or more, such as about 15% or more, such as about 20% or more, such as about 25% or more (and optionally up to about 100%) relative to the DSSC without the carbon quantum dots; ora combination thereof.

[0275] Embodiment C5. The DSSC according to any one of Embodiments C1-C4, wherein the DSSC has:a short-circuit current density of about 8.9 mA / cm2or more, such as about 9.5 mA / cm2or more, such as about 10 mA / cm2or more, such as about 10.5 mA / cm2or more (and optionally up to about 20 mA / cm2), or in a range from about 8.9 to about 15 mA / cm2, such as from about 9.5 to about 14 mA / cm2, such as from about 10 to about 13 mA / cm2, such as from about 10.5 to about 12 mA / cm2, such as about 10.9 mA / cm2;a photo-conversion efficiency of about 3.7% or more, such as about 3.9% or more, such as about 4.2% or more (and optionally up to 10%), or in a range from about 3.7% to about 10%, such as from about 3.9% to about 8%, such as from about 4% to about 6%, such as from about 4.2% to about 5%, such as about 4.25%; ora combination thereof.

[0276] Embodiment C6. The DSSC according to any one of Embodiments Cl-C 5, wherein the carbon quantum dots reduce charge-transfer resistance at the TiCh / electrolyte interface and increase electron lifetime relative to the DSSC without the carbon quantum dots.

[0277] Embodiment C7. The DSSC according to any one of Embodiments C1-C6, wherein:the carbon quantum dots increase electron lifetime by about 50% or more, such as about 75% or more, such as about 78% or more (up to about 100%), or in a range from about 50% to about 100%, such as from about 60% to about 90%, such as from about 70% to about 80% relative to the DSSC without the carbon quantum dots;UWYO / 0121PC(UW 24-030)the electron lifetime of the DSSC is about 11 ms or more, such as about 15 ms or more, such as about 19 ms or more (and optionally up to about 100 ms), or in a range from about 11 to about 100 ms, such as from about 13 to about 50 ms, such as from about 15 to about 30 ms, such as about 18 to about 25 ms, such as from about 19 to about 23 ms, such as about 19.3 ms.

[0278] Embodiment C8. The DSSC according to any one of Embodiments C1-C7, wherein the carbon quantum dots are characterized as having:a highest occupied molecular orbital in a range from about -7.50 to about -4.90 eV, such as from about -5.52 to about -5.36 eV, such as about -5.44 eV; and / ora lowest unoccupied molecular orbital in a range from about -4.2 to about 0 eV, such as from about -3.09 to about -2.95 eV, such as about -3.02 eV.

[0279] Embodiment DI. An electrode comprising carbon nanofibers described herein, for example, the carbon nanofibers produced according to any one of the Embodiments Al-A45 or any one of Embodiments B1-B14.

[0280] Embodiment D2. An electrode, comprising:carbon nanofibers (or a mat of carbon nanofibers) comprising an electrospun and carbonized product of:a hydrocarbon oil derived from pyrolysis-reforming of a waste plastic; andpolyacrylonitrile.

[0281] Embodiment El. A supercapacitor, comprising: carbon nanofibers described herein.

[0282] Embodiment E2. A supercapacitor, comprising:a working electrode, the working electrode comprising: an electrode described herein, such as the electrode according to any one of Embodiments D1-D2.

[0283] In the foregoing, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and / or over the prior art, whether or not a particular advantage is achieved by aUWYO / 0121PC(UW 24-030)given embodiment is not limiting of the disclosure. Thus, the foregoing embodiments, features, aspects, implementations, and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter described herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).Definitions

[0284] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2nd Ed (1997), may be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0285] Generally, groups of elements are indicated using the numbering scheme indicated in the version of the periodic table of elements published in Chemical and Engineering News, 63(5), 27, 1985. In some instances, a group of elements may be indicated using a common name assigned to the group; for example, alkali metals for Group 1 elements, alkaline earth metals for Group 2 elements, transition metals for Group 3-12 elements, and halogens or halides for Group 17 elements.

[0286] When a compound is described herein such that a particular isomer, enantiomer, or diastereomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomer and enantiomer of the compound described individual or in any combination. For example, any general structure, formula, or name presented is also intended to encompass all structural isomers, conformational isomers, regioisomers, stereoisomers (such as enantiomers, diastereomers, and other optical isomers whether in enantiomeric or racemic forms, as well as mixtures of stereoisomers, as the context permits or requires) that may arise from a particular set of substituents, unlessUWYO / 0121PC(UW 24-030)indicated otherwise. Thus, a general reference to a compound includes all structural isomers unless specified to the contrary or the context clearly indicates otherwise. For example, reference to a hydrocarbon without specifying a particular isomer (such as butyl) expressly discloses all isomers (such as n-butyl, iso-butyl, sec-butyl, and tert-butyl). For example, reference to a C4 hydrocarbon expressly discloses all isomers thereof.

[0287] The term “hydrocarbon” whenever used in this specification and claims refers to a compound containing only carbon and hydrogen. Other identifiers may be utilized to indicate the presence of particular groups in the hydrocarbon (for example, halogenated hydrocarbon indicates the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the hydrocarbon). Non-limiting examples of hydrocarbons include alkanes, alkenes, aromatics, and aromatic alkanes groups, amongst other groups. Hydrocarbons may be linear or branched, cyclic or acyclic, saturated or unsaturated, aromatic or non-aromatic. Regarding saturation, hydrocarbons may be fully saturated, partially unsaturated, or fully unsaturated.

[0288] The term “polymer” is used herein generically to include olefin homopolymers, copolymers, terpolymers, and the like, as well as alloys and blends thereof. The term “polymer” also includes impact, block, graft, random, and alternating copolymers. A copolymer is derived from an olefin monomer and one olefin comonomer, while a terpolymer is derived from an olefin monomer and two olefin comonomers. Accordingly, “polymer” encompasses copolymers and terpolymers derived from any olefin monomer and comonomer(s) described herein. Similarly, the scope of the term “polymerization” includes homopolymerization, copolymerization, and terpolymerization. Therefore, an ethylene polymer includes ethylene homopolymers, ethylene copolymers (for example, ethylene / a-olefin copolymers), ethylene terpolymers, and the like, as well as blends or mixtures thereof, (a-olefin refers to alpha-olefin). Thus, an ethylene polymer encompasses polymers often referred to in the art as LLDPE (linear low density polyethylene) and HDPE (high density polyethylene). The term “polymer” also includes all possible geometrical configurations, unless stated otherwise, and such configurations may include isotactic, syndiotactic, and random symmetries. Moreover, unless stated otherwise, the term “polymer” also is meant to include all molecular weight polymers, and is inclusive of lower molecular weight polymers.UWYO / 0121PC(UW 24-030)

[0289] The term “co-catalyst” is used generally herein to refer to compounds such as aluminoxane compounds, organoboron or organoborate compounds, ionizing ionic compounds, organoaluminum compounds, organozinc compounds, organomagnesium compounds, organolithium compounds, and the like, that may constitute one component of a catalyst. The term “co-catalyst” is used regardless of the actual function of the compound or any chemical mechanism by which the compound may operate.

[0290] The term “olefin” is used herein in accordance with the definition specified by IUPAC: acyclic and cyclic hydrocarbons having one or more carbon-carbon double bonds apart from the formal ones in aromatic compounds. The class “olefins” subsumes alkenes and cycloalkenes and the corresponding polyenes. Ethylene, propylene, 1 -butene, 2-butene, 1 -hexene, and the like are non-limiting examples of olefins.

[0291] Olefin polymers, or polyolefins, may include those made from an alpha olefin. The term “alpha olefin” refers to an olefin that has a double bond between the first and second carbon atom of the longest contiguous chain of carbon atoms. The term “alpha olefin” includes linear and branched alpha olefins unless expressly stated otherwise. The polyolefins may include a polyolefin homopolymer, a polyolefin copolymer, a polyolefin block copolymer, a polyolefin random block copolymer, or combinations thereof. The polyolefins may include an isotactic polyolefin, an atactic polyolefin, a syndiotactic polyolefin, or combinations thereof. Polyolefin copolymers and terpolymers are contemplated. A copolymer is derived from an olefin monomer and one olefin comonomer, while a terpolymer is derived from an olefin monomer and two olefin comonomers. As an example of polyolefin copolymers, an ethylene copolymer may be derived from ethylene and a comonomer, such as 1 -butene, 1 -hexene, or 1 -octene.

[0292] Unless specified to the contrary or the context clearly indicates otherwise, the term “halogen” refers to fluorine, chlorine, bromine, and iodine, regardless of whether these elements are in neutral or anionic form or occur as molecular or polymeric substituents or atoms in a solid-state structure.

[0293] As is apparent from the foregoing general description and the specific embodiments, while forms of the embodiments have been illustrated and described, various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby.UWYO / 0121PC(UW 24-030)Likewise, the term “comprising” is considered synonymous with the term “including.” Likewise whenever a formulation, a composition, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same formulation, composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “Is” preceding the recitation of the formulation, composition, element, or elements and vice versa, for example, the terms “comprising,” “consisting essentially of,” “consisting of’ also include the product of the combinations of elements listed after the term.

[0294] References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information may be employed herein, if desired, to exclude specific embodiments that are in the prior art.

[0295] For purposes of this present disclosure, and unless otherwise specified, all numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and consider experimental error and variations that would be expected by a person having ordinary skill in the art. It will be further understood that there are a number of values disclosed therein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. In embodiments, use of the term “about” may refer to ±20% of the stated value, ±15% of the stated value, ±10% of the stated value, ±5% of the stated value, ±3% of the stated value, ±2% of the stated value, or ±1% of the stated value.

[0296] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited. For example, by disclosing a temperature of from 70°C to 80°C, an intent is to recite individually 70°C, 71 °C,UWYO / 0121PC(UW 24-030)72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, and 80°C, including any sub-ranges and combinations of sub-ranges encompassed therein such that any of the foregoing numbers may be used singly to describe an open-ended range or in combination to describe a close-ended range. Moreover, all numerical end points of ranges disclosed herein are approximate, unless excluded by proviso. As a representative example, if one or more operations in the processes described herein may be conducted at a temperature in a range from 10°C to 75°C, this range should be interpreted as encompassing temperatures in a range from “about” 10°C to “about” 75°C. As another example, when a chemical moiety having a certain number of carbon atoms is disclosed or claimed, the intent is to disclose or claim individually every possible number that such a range could encompass, consistent with the disclosure herein. For example, the disclosure of a C1-C5 hydrocarbon refers to a hydrocarbon that may have 1, 2, 3, 4, or 5 carbon atoms, as well as any range between these two numbers (for example, a C1-C3 hydrocarbon), and also including any combination of ranges between these two numbers (for example, a C2-C4 hydrocarbon and a C3-C5 hydrocarbon).

[0297] The indefinite article “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. For example, embodiments comprising “a polyolefin” include embodiments comprising one, two, or more polyolefins, unless specified to the contrary or the context clearly indicates only one polyolefin is included.

[0298] While the foregoing is directed to embodiments of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

UWYO / 0121PC(UW 24-030)ClaimsWhat is claimed is:

1. An integrated process for converting waste plastic, the process comprising:pyrolyzing a waste plastic feed comprising a polyolefin to produce a pyrolysis product comprising intermediate products and solids;reforming the intermediate products to produce:a gas fraction; andan oil fraction;polymerizing at least a portion of ethylene and propylene present in the gas fraction to form an ethyl ene-propylene copolymer;fabricating carbon nanofibers from at least a portion of the oil fraction; and producing carbon quantum dots from at least a portion of the solids.

2. The process according to claim 1, wherein pyrolyzing is performed under pyrolysis conditions, the pyrolysis conditions comprising:a pyrolysis temperature in a range from about 400°C to about 600°C;a pyrolysis temperature ramping rate from room temperature to the pyrolysis temperature in a range from about l°C / min to about 50°C / min;a pyrolysis pressure in a range from about 70 kPa to about 500 kPa; or combinations thereof.

3. The process according to claim 1, wherein reforming is performed under reforming conditions, the reforming conditions comprising:a reforming temperature in a range from about 400°C to about 800°C;a reforming temperature ramping rate from room temperature to the reforming temperature in a range from about l°C / min to about 50°C / min;a reforming pressure in a range from about 70 kPa to about 500 kPa; or combinations thereof.UWYO / 0121PC(UW 24-030)4. The process according to claim 3, wherein the reforming temperature is selected to increase a yield of the gas fraction and to decrease the yield of a wax fraction, the oil fraction, or both the wax fraction and oil fraction.

5. The process according to claim 1, wherein polymerizing at least a portion of the ethylene and propylene comprises:contacting a feed gas comprising the ethylene and the propylene with a catalyst system to form the ethyl ene-propylene copolymer, the ethylene-propylene copolymer having a molar ratio of ethylene to propylene that is within ±10% of a molar ratio of ethylene to propylene in the feed gas.

6. The process according to claim 1, wherein the ethylene-propylene copolymer has:a number-average molecular weight in a range from about 15,000 to about 75,000 g / mol;a weight-average molecular weight in a range from about 100,000 to about 160,000 g / mol;an Mw / Mn in a range from about 1.9 to about 3.9; orcombinations thereof.

7. The process according to claim 1, wherein the process further comprises:converting CO and H2 present in the gas fraction to ethylene, propylene, or combinations thereof.

8. The process according to claim 1, wherein fabricating the carbon nanofibers from at least a portion of the oil fraction comprises:forming a precursor mixture comprising:from about 50 wt% to about 99 wt% of a polymer comprising polyacrylonitrile, polyvinyl acetate, polyvinyl butyral, polyvinylpyrrolidone, poly(diaryloxyphosphazene), or combinations thereof based on a total wt% of the polymer and the oil fraction, the total wt% of the polymer and the oil fraction equal to 100 wt%; andUWYO / 0121PC(UW 24-030)from about 1 wt% to about 50 wt% oil fraction based on a total wt% of the polymer and the oil fraction;electrospinning the precursor mixture to form nanofibers;stabilizing the nanofibers; andcarbonizing the stabilized nanofibers to form the carbon nanofibers.

9. The process according to claim 1, wherein the carbon nanofibers are characterized as having:a pore structure dominated by micropores;a Langmuir-type adsorption isotherm;a total pore volume of greater than 0.15 cm3 / g;a specific surface area greater than 365 m2 / g; orcombinations thereof.

10. The process according to claim 1, wherein the carbon nanofibers achieve a specific capacitance increase of at least 10% relative to the carbon nanofibers fabricated from polyacrylonitrile alone under galvanostatic charge-discharge at 1 A / g.

11. The process according to claim 1, wherein the carbon nanofibers are characterized as having:a specific capacitance calculated from a galvanostatic charge-discharge curve (CGCD) at 1 A / g of about 160 F / g or more;a capacitance retention of greater than 92% after at least 450 charge-discharge cycles;a charge-transfer resistance of about 2.5 or less;a Warburg coefficient of 2.75 / s05or less; orcombinations thereof.

12. The process according to claim 1, wherein producing the carbon quantum dots from at least a portion of the solids comprises:treating the solids with an oxidizing agent at a temperature greater than 150°C.UWYO / 0121PC(UW 24-030)13. The process according to claim 1, wherein the polyolefin comprises polyethylene, polypropylene, or combinations thereof.

14. The process according to claim 1, wherein the waste plastic feed comprises a waste plastic other than the polyolefin.

15. The process according to claim 1, wherein:each of polymerizing to form the ethyl ene-propylene copolymer, fabricating carbon nanofibers, and producing carbon quantum dots is performed simultaneously;each of the ethyl ene-propylene copolymer, the carbon nanofibers, and the carbon quantum dots are formed from the same waste plastic feed; ora combination thereof.

16. A system for converting waste plastic, the system comprising:a pyrolysis reactor;a reforming reactor downstream from, and in fluid communication with, the pyrolysis reactor;a polymerization reactor downstream from, and in fluid communication with, the reforming reactor; anda controller coupled to the pyrolysis reactor, the reforming reactor, the polymerization reactor, or combinations thereof.

17. The system according to claim 16, wherein the controller is configured:to cause the pyrolysis reactor to decompose polyolefin into a pyrolysis product comprising intermediate products and solids;to cause the reforming reactor to receive the intermediate products from the pyrolysis reactor and to convert at least a portion of the intermediate products into a hydrocarbon gas and a hydrocarbon oil; andUWYO / 0121PC(UW 24-030)to cause the polymerization reactor to receive the hydrocarbon gas from the reforming reactor and to polymerize ethylene and propylene present in the hydrocarbon gas into an ethyl ene-propylene copolymer.

18. The system according to claim 16, wherein the system further comprises:a carbon quantum dot synthesis unit, the carbon quantum dot synthesis unit coupled to and downstream from the pyrolysis reactor;a carbon nanofiber fabrication unit, the carbon nanofiber fabrication unit coupled to and downstream from the reforming reactor; ora combination thereof,wherein the controller is further coupled to the carbon quantum dot synthesis unit, the carbon nanofiber fabrication unit, or both.

19. The system according to claim 16, wherein:the system further comprises a syngas conversion unit downstream from, and in fluid communication with, the reforming reactor;the controller is further coupled to the syngas conversion unit, andthe controller is configured to cause the syngas conversion unit:to receive CO and H2 from the reforming reactor; andto convert at least a portion of the CO and H2 to ethylene, propylene, or a combination thereof.

20. An electrode, comprising:carbon nanofibers, the carbon nanofibers comprising an electrospun and carbonized product of:a hydrocarbon oil derived from pyrolysis-reforming of a waste plastic; and polyacrylonitrile,the carbon nanofibers characterized as having:a higher specific surface area than PAN-only carbon nanofibers;a higher total pore volume than PAN-only carbon nanofibers;UWYO / 0121PC(UW 24-030)a higher specific capacitance calculated from a galvanostatic chargedischarge curve (CGCD) at 1 A / g than PAN-only carbon nanofibers;a higher capacitance retention than PAN-only carbon nanofibers;a lower charge-transfer resistance than PAN-only carbon nanofibers; a lower Warburg coefficient than PAN-only carbon nanofibers; or combinations thereof.

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