Method for producing pyrolysis oil from used plastics

Abstract

A method for producing pyrolysis oil from used plastics is provided, the method comprising (i) supplying used plastic material, (ii) melting the used plastic material to form molten plastic material, (iii) pyrolysis of the molten plastic material in an oxygen-free atmosphere to yield pyrolysis gas and carbonized material, and (iv) condensing the pyrolysis gas to yield pyrolysis oil, the method further comprising dispersing a zeolite material in the used plastic material or molten plastic material, the zeolite material comprising a zeolite having a molar ratio of silica to alumina (SAR) of 10 to 140 and an average crystal diameter of about 200 nm or less, and the zeolite material having a thickness of at least 0.30 cm 3 Mesopore volume of / g and at least 0.10 cm 3 It has a micropore volume of / g.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing pyrolysis oil from used plastics, and more particularly to a method comprising dispersing a zeolite material in the used plastics before pyrolysis and condensing the pyrolysis gases to obtain pyrolysis oil. In particular, the method introduces a catalytic zeolite material that improves the quality of the final product and can itself be reused for further processing. In particular, the method identifies a catalyst that appears unaffected by the presence of impurities in the used plastics, and this results in a significant improvement without adding complexity to the process. [Background technology]

[0002] Mesoporous zeolites are a class of zeolites with high mesopore volume (in contrast to conventional zeolites with low or no mesoporosity) and are well known for their improved diffusion properties. Faster diffusion within the mesopores allows reactants to access catalytic sites within the zeolite micropores, potentially leading to improved catalytic activity of these materials.

[0003] Increasing mesoporosity in zeolites can be achieved by various methods. One method is to use mesoporogens during zeolite synthesis. Mesoporogens are typically organic compounds that form and fill mesopores during zeolite synthesis. Another method is the synthesis of nano-sized zeolites with short diffusion distances within individual crystals and intercrystalline mesoporosity. Yet another method is the selective removal of a portion of the zeolite structure, where the resulting voids are within the mesopore size range. Selective removal of the zeolite structure is typically carried out by a desiliconization process of the zeolite using a suitable base. A portion of the zeolite structure may dissolve during the desiliconization process, resulting in material loss and potentially increasing manufacturing costs.

[0004] ZSM-5 zeolite (MFI framework, defined by IZA) is used in many petrochemical applications. ZSM-5 zeolite can be synthesized with or without the use of organic structural direction agents (OSDAs), such as tetrapropylammonium bromide. ZSM-5 zeolite with improved mesoporosity, produced with minimal loss during desiliconization, can be advantageous for these applications.

[0005] Chemical recycling of used plastics is an emerging technology designed to recycle mixed waste plastics into various liquid hydrocarbon products. The waste plastics used in such processes may include, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), and / or polypropylene (PP).

[0006] Plastic waste is currently a major global challenge, causing a vast number of environmental problems. The pyrolysis of waste plastics is widely accepted as a highly promising solution to this problem.

[0007] Pyrolysis is known as the process of converting these waste plastics into liquid hydrocarbon products by heating, and then pumping the plastic feed in molten form into a reaction vessel. The reaction vessel is heated to a temperature exceeding 350°C by a combustion system. This generates abundant saturated hydrocarbon vapor from the molten plastic. This vapor flows out of the reaction vessel through a contact vessel, condensing the heavier vapor fraction and maintaining a target outlet temperature setpoint determined by the specifications of the final product. This vapor is then distilled at near atmospheric pressure in a downstream condensation column. This process yields so-called pyrolysis oil.

[0008] International Publication No. 2021123822 (and UK Patent No. 2589936) discloses a method for thermally decomposing a plastic material. The method includes heating the plastic material to increase its concentration, transporting the plastic material to one or more reactors, and thermally decomposing the plastic material in one or more reactors. The plastic material is kept heated during the transport process.

[0009] International Publication No. 2016030460 discloses a pyrolysis reactor system suitable for processing used plastics.

[0010] International Publication No. 2011077419 also discloses a process for processing waste plastic material to yield at least one spec-free fuel product. The plastic material is melted (4) and then pyrolyzed in an oxygen-free atmosphere to yield pyrolysis gases. The pyrolysis gases come into contact with plates (13) in a contact vessel (7) so that several long-chain gas components condense and return for further pyrolysis, thereby achieving pyrolysis. The short-chain gas components exit the contactor in gaseous form and proceed to distillation to yield one or more spec-free fuel products. There is a pipe (12) that directly connects a pyrolysis chamber (6) to the contactor (7), which is suitable for transporting the pyrolysis gases moving upward and the long-chain liquid for pyrolysis flowing downward. There is a vacuum distillation column (26) for further processing the liquid feed from a first (atmospheric pressure) distillation column (20). It has been found that having pyrolysis in the contactor and pyrolysis chamber and having a second vacuum distillation column is particularly helpful in yielding a high-quality spec-free liquid fuel.

[0011] By thermally decomposing plastics, they are broken down into hydrocarbon-rich oils. These oils can then be used to produce monomer species through a refining process. Once in monomer form, the molecules can then polymerize to form virgin-grade plastics. This effectively closes the loop in the plastic manufacturing process, reducing waste and environmental impact. Furthermore, all of these aforementioned methods and processes are suitable for obtaining pyrolysis oils that can be used as fuel, and are particularly suitable for transport purposes.

[0012] U.S. Patent No. 5,107,061 relates to the removal of organic chlorides from hydrocarbon streams using highly crystalline molecular sieve materials such as zeolites, particularly sodium form of zeolite X, and to the removal of organic chlorides from hydrocarbon streams containing olefin compounds using such molecular sieves in combination with alumina for the purpose of decomposing the organic chlorides into corresponding unsaturated hydrocarbon molecules and chlorinated hydrocarbon molecules, wherein the chlorinated hydrocarbons are removed from the hydrocarbon stream by adsorption onto the adsorbent material of the highly crystalline molecular sieve so that unsaturated hydrocarbon molecules can be recovered from the resulting hydrocarbon stream with a reduced amount of organic chlorides.

[0013] U.S. Patent No. 4,721,824 relates to a method for removing trace amounts of organic chlorides from a raw material by flowing the raw material and contacting it with a guard bed catalyst containing molded particles formed by extruding a mixture of magnesium oxide and a binder that is inert to the raw material. The process is particularly important in that it removes organic chlorides from the toluene raw material before contacting toluene with a disproportionation or alkylation catalyst containing magnesium-ZSM-5.

[0014] U.S. Patent No. 3,862,900 relates to a method for processing chemically bonded chlorine-containing hydrocarbons, which involves passing the hydrocarbon through a molecular sieve layer with an effective pore size ranging from 7 to 11 angstroms to remove chemically bonded chlorine and other impurities.

[0015] European Patent No. 1728551 relates to the desulfurization of gasoline fractions by adsorption on faujasite zeolite. This is for silicon / aluminum molar ratios of 1 to 10 and 0.25 to 0.4 cm³. 3 Volume of mesoporous and macroporous material per g, 0.12-0.35 cm³ 3 It has a microporous volume of / g and a crystal size of less than 3 microns.

[0016] The article "Influence of mesoporous structure ZSM-5 zeolite on the degradation of urban plastics waste" (Journal of Thermal Analysis and Calorimetry, 2019, 138, 3689-3699) concerns the mesoporous ZSM-5 zeolite structure as a thermal decomposition catalyst.

[0017] "Catalytic Cracking of a Polyolefin Mixture over Different Acid Solid Catalysts" Ind.Eng.Chem.Res.2000,39,5,1177-1184 relates to the use of zeolites with nanometer crystal size in the catalytic cracking of polyolefin mixtures.

[0018] European Patent No. 3907267 relates to a process for purifying crude pyrolysis oil obtained from the thermal decomposition of plastic waste by subjecting it to a trapping agent, the trapping agent being selected from a broad list including elemental metals of Group 1, 2, 6, 7, 8, 9, 10, 11, 12 and / or 13, oxides of such metals, alkoxides of Group 1 and / or 2 metals, and solid sorbents.

[0019] International Publication No. 2018025104 relates to the simultaneous pyrolysis and dechlorination reaction of mixed plastics, including contacting the mixed plastics with a zeolite catalyst in a pyrolysis unit.

[0020] International Publication No. WO 2018 / 025103 relates to the treatment of hydrocarbon streams via a process involving a dechlorination reaction, the process comprising introducing a hydrocarbon stream and / or a hydrocarbon stream precursor, a first zeolite catalyst, and a stripping gas into a devolatilization extruder to produce an extruder effluent.

[0021] Republic of Korea Patent No. 10-2019-0002793 relates to the co-catalytic co-pyrolysis of e-printed circuit boards (e-PCBs) and plastics using zeolites, specifically the HZSM-5 or HY zeolite catalyst, preferably a large pore zeolite, as a co-catalyst for epoxy printed electronic circuits. An example of an e-PCB uses FR-4, a known composite material composed of a glass fiber woven fabric having an epoxy resin binder.

[0022] China Patent No. 102039155 relates to catalysts for catalytic reforming of waste plastic catalytic cracking and methods for their preparation, and discloses a modified HZSM molecular sieve for catalytic reforming of pyrolysis oil.

[0023] UK Patent No. 2613166 provides a method for removing impurities from pyrolysis oil obtained from used plastics, the method comprising contacting the pyrolysis oil with an absorbent selected from the group consisting of large pore zeolites, activated alumina, and mixtures thereof to obtain a purified pyrolysis oil.

[0024] European Patent No. 1728551 describes the application of cesium-exchanged X-type, Y-type or LSX-type faujasites for the strong desulfurization of FCC gasoline, and a method for preparing the zeolite.

[0025] International Publication No. WO 2020 / 056838 relates to molecular sieves having a hierarchical pore FAU structure, methods for their preparation, and modified molecular sieves having a hierarchical pore FAU structure, belonging to the fields of molecular sieve modification, adsorbent preparation, and catalyst preparation. SUMMARY OF THE INVENTION [Problems that the invention aims to solve]

[0026] Therefore, an object of the present invention is also to provide a method for producing pyrolysis oil from used plastics in which impurities are reduced and / or the need for post-production purification is reduced. One of the problems with zeolite ZSM-5 is that it is known for increasing the yield to gas at the expense of the distillate yield. Therefore, it is a further object to increase the distillate yield, or at least address the problems related to the prior art, or to provide a commercially viable alternative thereto. [Means for solving the problem]

[0027] In a first aspect of the present invention, a method for producing pyrolysis oil from used plastics is provided, the method being: (i) Supplying used plastic materials, (ii) Melting used plastic material to form molten plastic material, (iii) Thermal decomposition of molten plastic material in an oxygen-free atmosphere to produce thermal decomposition gas and carbonized material, (iv) Condensing pyrolysis gas to produce pyrolysis oil, The method further comprises dispersing a zeolite material in used plastic material or molten plastic material, wherein the zeolite material comprises zeolites having a silica-to-alumina ratio (SAR) of 10 to 140 and an average crystal diameter of approximately 200 nm or less, and the zeolite material is at least 0.30 cm 3 Mesopore volume of / g and at least 0.10 cm 3 It has a micropore volume of / g. [Modes for carrying out the invention]

[0028] The Disclosure is hereby described further. Different aspects / embodiments of the Disclosure are defined in more detail in the following sections. Each of the aspects / embodiments defined in this way may be combined with any other aspects / embodiments or aspects / embodiments unless it is expressly indicated otherwise. In particular, any feature shown as preferred or advantageous may be combined with any other feature shown as preferred or advantageous.

[0029] definition "Micropore volume" or "V マイクロ The term "micropore volume" is used to refer to the total volume of pores with a diameter of less than 20 angstroms. "Initial micropore volume" refers to the micropore volume of a newly manufactured crystalline material before it is exposed to any desiliconization conditions. The evaluation of micropore volume is particularly derived from BET measurement techniques using an evaluation method called the t-plot method (sometimes simply called the t-method), as described in the literature (Journal of Catalysis 3, 32 (1964)).

[0030] In this specification, the terms "mesopore volume" or "mesoporosity" or "V" are used. メソ " is the volume of pores with a diameter greater than 20 angstroms and with a limiting diameter of up to 600 angstroms, as determined by applying the BJH method to the desorbing branches of the N2 isotherm.

[0031] In this specification, “parent zeolite” or “parent material” refers to the initial zeolite material that is subject to desiliconization before being exposed to any desiliconization conditions.

[0032] "As defined by the Structure Commission of the International Zeolite Association (IZA)" is intended to mean those structures including, but not limited to, the structures described in "Atlas of Zeolite Framework Types," ed. Baerlocher et al., Sixth Revised Edition (Elsevier 2007), which are incorporated herein by reference in their entirety.

[0033] The silica loss is calculated as follows: Silica loss = 1 - SAR d / SAR p wherein SAR d is the SAR of the alkali or ammonium form after dealumination, and SAR p is the SAR of the parent non-dealuminated zeolite, expressed as a percentage.

[0034] ΔV is calculated as the difference between the mesopore volume of the ammonium-exchanged dealuminated zeolite and the mesopore volume of the ammonium-exchanged non-dealuminated zeolite (parent material), and is expressed in cc / g.

[0035] ΔV / silica loss is calculated as the ratio of ΔV to silica loss and represents the increase in mesopore volume per percentage of silica loss.

[0036] "Average crystal diameter" is the average diameter of zeolite crystals along the longest crystal dimension averaged for 100 crystals randomly selected from SEM micrographs.

[0037] To address the above-mentioned problems related to plastic pyrolysis, the inventors have found that dealuminated small crystal zeolites are unexpectedly effective additives, and the present invention relates to a method for producing pyrolysis oil from used plastics including the use of such zeolites.

[0038] The method comprises (i) feeding a used plastic material, (ii) Melting used plastic material to form molten plastic material, (iii) Thermal decomposition of molten plastic material in an oxygen-free atmosphere to produce thermal decomposition gas and carbonized material, (iv) A general step of condensing the pyrolysis gas to obtain pyrolysis oil.

[0039] Such processes are known in the art, and steps (i) to (iv) provide the processes necessary for the thermal decomposition of plastics and the recovery of the distillate as thermal decomposition oil. The method very importantly further involves dispersing a zeolite material in the used plastic material or molten plastic material, i.e., before thermal decomposition. Thus, step (iii) of thermal decomposition of the molten plastic material is carried out in the presence of zeolite (i.e., including thermal decomposition of a mixture of the molten plastic material and the zeolite material).

[0040] The inventors have found that there are specific problems with the use of pyrolysis oil obtained from the pyrolysis of used plastics, whether used as a raw material for cracking processes or as a transport fuel. In particular, compared to natural oil materials, pyrolysis oil obtained from used plastics contains unacceptably high levels of mercury and phosphorus, as well as typical sulfur and chlorine contaminants. While we do not wish to be bound by theory, the amount of these impurities is considered to be a direct result of the contaminants mixed with the plastics during their original service life.

[0041] This method first requires the supply of used plastic material. Used plastic or contaminated plastic waste raw materials for the chemical recycling of plastics may be received, for example, from public collection facilities, recycling plants, or other plastic collection sources. During the pretreatment process, the raw materials may be purified so that they contain only plastics suitable for the chemical recycling process, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), and / or polypropylene (PP). Unsuitable materials such as metals, paper and cards, as well as glass (glass fiber), and moisture derived from plastic waste may be removed. Therefore, it is preferable that the plastic material contains at least 90 wt% plastic (e.g., organic polymer) by weight of the plastic material, and it is particularly preferable that the plastic material is essentially free of plastic. In particular, it is preferable that the plastic material does not contain metallic contaminants.

[0042] Used plastic materials can be obtained from mixed sources, including mixed plastic waste from common sources, municipal sources, or local sources, and / or from waste streams of polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene, and / or polystyrene. Furthermore, the waste may also include thermoplastic elastomers and thermosetting rubbers derived from tires and other articles made from natural rubber, polybutadiene, styrene-butadiene, butyl rubber, and ethylene propylene diene monomer rubber (EPDM). The waste may also include one or more plastics classified as plastic identification codes 1-7 by the Plastics Industry Association. For example, the waste may include one or more of the following plastics: polyethylene terephthalate classified as PIC1, high-density polyethylene classified as PIC2, ​​polyvinyl chloride classified as PIC3, low-density polyethylene classified as PIC4, polypropylene classified as PIC5, polystyrene classified as PIC6, and polycarbonate classified as PIC7, and other plastics. In some embodiments, the plastic is preferably a hydrocarbon plastic (plastics that are essentially composed of carbon and hydrogen, such as PE, PP, and PS). For example, the plastic material may consist of mostly hydrocarbon plastics, preferably at least 80 wt% or at least 90 wt%, or be essentially composed of hydrocarbon plastics. In some embodiments, the plastic material is substantially free of halogenated plastics such as PVC. It is preferable that the plastic material is free of metallic contaminants.

[0043] Pyrolysis oils can be obtained by heat treatment of these plastic materials. International Publication No. 2021123822 discloses a process optimized for this pyrolysis, and the contents of that document are incorporated herein by reference in their entirety. Due to their source, this type of pyrolysis oil typically contains several impurities, including sulfur, chlorine; phosphorus; metals: particularly mercury, arsenic, lead, nickel; silica; oxygen, and nitrogen. As is understood, elements, especially metals, can exist in their elemental forms, but typically exist as compounds such as salts and / or organic impurities containing those elements (i.e., organic sulfur impurities, etc.).

[0044] This method involves melting used plastic material to form molten plastic material. Preferably, the used plastic material is melted in step (ii) in an extruder heated to a temperature of 250 to 350°C.

[0045] This method involves thermally decomposing a molten plastic material in an oxygen-free atmosphere to yield a thermal decomposition gas and a carbonized material. Preferably, the thermal decomposition in step (iii) is carried out in a potentially stirred thermal decomposition reactor at a temperature of 350 to 450°C.

[0046] This method involves condensing the pyrolysis gas to obtain pyrolysis oil. Preferably, step (iv) includes distilling the pyrolysis gas from a contactor in a distillation column.

[0047] Preferably before step (iv), the method is: The pyrolysis gas of step (iii) is passed through a contactor having a bank of elements such that several long-chain gas components condense on the liquefied elements, yielding a condensed long-chain material. The condensed long-chain material is returned to process (iii) for further thermal decomposition, The method further includes discharging the short-chain gas components from the contactor in gaseous form before condensation in step (iv).

[0048] Importantly, this method further comprises dispersing a zeolite material in used plastic material or molten plastic material as described herein. The inventors have surprisingly found that the addition of such zeolite materials to the plastic energy process can catalyze the pyrolysis process, resulting in a higher yield of lighter oils. Particularly surprising is that the zeolite material can be added along with the feedstock without needing to be added to the pyrolysis chamber. The zeolite material appears unaffected by the presence of impurities in the used plastic, and this results in a significant improvement without adding complexity to the process.

[0049] Zeolites are well known for their use in various industrial processing processes and are generally classified by their pore size. Particular attention is paid to the number of atoms forming their largest ring size, due to practical limitations regarding the ease with which molecules can diffuse into and out of the zeolite during the process. Small-pore zeolites have rings of eight atoms, medium-pore zeolites have rings of ten atoms, and large-pore zeolites have rings of twelve atoms. The zeolite used is preferably an aluminosilicate zeolite, having a framework of Al and Si atoms. A further characteristic of zeolites is the form in which they are supplied, such as Na+ or H+ form. Furthermore, zeolites can be substituted with additional metal species, particularly for catalytic purposes, such as the introduction of copper in SCR catalysts. In this invention, it is preferable that the zeolite does not contain the catalytic metal thus added.

[0050] Preferably, the zeolite material includes a medium-porous zeolite. The zeolite optimized for use in this method is a zeolite having an MFI framework, most preferably ZSM-5. Surprisingly, the inventors have found that selecting a zeolite having an MFI framework with specific parameters can be advantageously used to desilicify such materials with higher efficiency (higher ΔV / silica loss) than conventional commercially available zeolites having an MFI framework. Even more surprisingly, the inventors have found that the presence of OSDA in the parent zeolite can be advantageously used to desilicify such materials with even higher efficiency (higher ΔV / silica loss) than conventional commercially available zeolites having an MFI framework or zeolites having an MFI framework in a calcined OSDA-free form. Preferably, the zeolite is used in an H-exchange type to catalyze the pyrolysis reaction. Preferably, the zeolite does not contain any additive metals. In other words, preferably, the zeolite consists of Al2O3 and SiO2 (i.e., aluminosilicate), and in the Na exchange type, it consists of Na2O (i.e., sodium aluminosilicate).

[0051] The zeolite material is included in an amount of 0.05 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, based on the total weight of the plastic material and the zeolite material.

[0052] It is also known that the zeolite material can be recovered and reused, meaning that the addition of this further material does not outweigh the benefits of the process. It can be regenerated in a high-temperature atmosphere, which can substantially increase the lifespan of the catalyst. Preferably, this method further includes recovering the zeolite material from the carbonized material, preferably by burning the carbonized material to ash and physically separating the zeolite material from the ash. Such recovery is considered simpler if the plastic material used in the process consists of plastic in nature and therefore substantially free of other contaminants such as metals and glass. Thus, the process can be made more efficient and sustainable.

[0053] Methods for pyrolysis of used plastics are well known in the art, including, for example, International Publication Nos. 2021123822, 2016030460, and 2011077419, which are incorporated herein by reference, respectively. Preferred methods of pyrolysis are described in more detail here.

[0054] Preferably, a method for thermally decomposing used plastics is: Melting waste plastic materials, The process of thermally decomposing a molten material in an oxygen-free atmosphere to produce thermal decomposition gases. The pyrolysis gas is introduced into a contactor having a bank of elements such that several long-chain gas components condense on the liquefaction elements. The condensed long-chain material is returned and further thermally decomposed to achieve thermal decomposition, and the short-chain gaseous components are discharged from the contactor in gaseous form, and This includes distilling the pyrolysis gas from the contactor of a distillation column to obtain one or more fuel products.

[0055] End-of-life plastic (ELP) from walking-floor silos is discharged into an extruder hopper designed to deliver heated ELP to the reactor. The extruder is supplied with a variable-speed drive that allows for lower flow rates to the reactor if necessary during extruder startup and shutdown. The extruder uses the shear force generated by the rotation of the extruder screw to heat the plastic from ambient conditions to a target set temperature. The high temperature at the extruder outlet is necessary to ensure that plastic temperatures lower than the reactor's operating temperature do not adversely affect the reactor's thermal performance during loading.

[0056] The extruder barrel can be electrically heated, especially during startup. During normal operation, the electric heating function is not used because the shear force from the auger screw provides sufficient heat to melt the plastic.

[0057] The plasticized ELP is discharged under high pressure from the extruder into a molten supply line that connects the extruder to three reactors via a header pipe. Multiple pieces of equipment monitor the pressure and temperature along the molten supply line as it is being supplied to ensure smooth flow.

[0058] The plant has multiple jacketed reactors that form the core of the process. Each cone-based reactor is surrounded by a reactor jacket that supplies the heat required to decompose the ELP and produce the desired hydrocarbon vapors. Each reactor is physically positioned above the carbide receiving section and below the contactor (liquefaction element).

[0059] Each individual reactor is equipped with a stirrer designed to maintain the thermal efficiency of the process by keeping the steel-to-steel clearance with the vessel wall close, thereby minimizing the accumulation of carbides on the reactor wall; to suspend any carbides generated in the plastic mass during pyrolysis to prevent accumulation on the inside of the reactor; to homogenize the molten ELP in the reactor during processing; and to remove the carbides once pyrolysis is complete and the carbides have dried.

[0060] The agitator homogenizes the container mass by pushing the ELP downwards towards the reactor walls, towards the center of the container, and upwards towards the agitator shaft as it moves forward. When moving in the reverse direction, it pushes the medium downwards towards the agitator shaft and from the center of the container towards the container walls. This facilitates the removal of carbides through the bottom outlet nozzle located at the lowest point of the conical, dish-shaped end of the container.

[0061] Each reactor is designed to process 5 tons of ELP per day. The next generation will have even higher capacities. The reactors are grouped into sets of three, and in each set of three reactors, only one of the three vessels is supplied with fresh ELP at any given time, while the other two either complete the pyrolysis or process the char.

[0062] ELP is supplied to the reactor by its respective extruder. The reactor operates at 380-450°C and a maximum of 0.5 barg in an inert, oxygen-free environment. At these temperatures, the ELP polymer chains decompose into shorter hydrocarbon chains, which vaporize to form abundant saturated hydrocarbon vapor. This vapor exits the vessel through outlets located at the top of the vessel, leading to each contactor in the reactor.

[0063] The reactor is designed to operate in cycles. Each cycle consists of three phases. The first phase is the ELP supply phase, known as the "feed-in" phase, in which ELP is introduced into the reactor and thermally decomposed. The second phase is when the thermal decomposition is complete and the non-thermally decomposable material (carbides) in the reactor is dried, making it easy to handle after removal from the reactor in preparation for the next feed-in of ELP. This phase is called the "heating" phase. The third phase is called the "removal" phase and involves removing the carbides from the reactor by opening the outlet valve at the bottom of the reactor, inverting the reactor stirrer, and then draining the carbides from the reactor into a carbide receiving section below. Once all the carbides have been removed, the bottom outlet valve can be closed and the supply of plastics can be resumed.

[0064] The carbides are formed primarily from carbonaceous materials, plastic polymer-forming additives, pigments, and ELP contaminants. The carbides form continuously in the reactor throughout the entire pyrolysis process and must be removed before the start of another input, otherwise the effective volume of the reactor decreases. The carbides of this invention further include added zeolite material. The zeolite can be recovered from the carbides by burning them in air, removing carbon materials and other impurities. It has been found that the zeolite is unaffected by this combustion, even at temperatures up to 550°C. In addition, such combustion helps to further regenerate the zeolite for further use.

[0065] Carbides are removed through the bottom outlet nozzle and valve (BOV). When carbide removal is required, the bottom outlet valve is opened to the carbide receiving section below. The agitator is then set in the reverse direction to assist in the removal of the carbides. The carbides should fall out of the chamber under gravity due to the conical shape of the reactor; however, if this does not occur, the agitator is designed to assist by breaking up any carbide clumps that may form in the nozzle.

[0066] Preferably, the contactor element comprises multiple plates that form a complex, high-resistance channel for the pyrolysis gases in the contactor. In addition, preferably, the plates are inclined downward for the outflow of condensed long-chain hydrocarbons and include openings to allow the pyrolysis gases to travel upward. In one embodiment, the contactor element comprises an array of plates on both sides of the gas passage. Preferably, the contactor element plates are stainless steel plates. The contactor may be actively cooled by a heat exchanger for at least one contactor element, etc.

[0067] An alternative cooling method comprises a contactor jacket, into which the cooling fluid is directed. A valve may be present connecting the jacket to the flue; opening the valve causes cooling by a downward airflow, and closing the valve causes heating. The valve may provide access to the flue for the exhaust gases of the combustion unit of the pyrolysis chamber.

[0068] Preferably, there is a pipe directly connecting the pyrolysis chamber and the contactor, and the pipe is configured to transport the pyrolysis gas moving upward and the long-chain liquid flowing downward for pyrolysis.

[0069] Preferably, the feeding into the pyrolysis chamber is controlled by monitoring the amount of molten plastic in the chamber, so that it is detected by a gamma-ray detector configured to emit gamma rays passing through the chamber and detect the radiation on the opposite side, and the intensity of the received radiation indicates the density of the chamber contents.

[0070] Preferably, the pyrolysis chamber is agitated by the rotation of at least two helical blades configured to rotate near the inner surface of the pyrolysis chamber. Optionally, the pyrolysis chamber is further agitated by a central auger. Advantageously, the auger can be positioned so that its reverse motion causes the discharge of carbides through a carbide outlet.

[0071] Preferably, the temperature of the pyrolysis gas at the contactor outlet is maintained in the range of 240°C to 280°C. The contactor outlet temperature can be maintained by a heat exchanger at the contactor outlet.

[0072] The bottom of the distillation column is preferably maintained at a temperature in the range of 200°C to 240°C, preferably 210°C to 230°C. The top of the distillation column is preferably maintained at a temperature in the range of 90°C to 110°C, preferably about 100°C.

[0073] Optionally, several materials are further distilled in the vacuum distillation column. The heavy or waxy oil fraction can be withdrawn from the bottom of the vacuum distillation column and returned to the pyrolysis chamber for recirculation. Pyrolysis oil of the desired grade and specification can be withdrawn from the middle of the vacuum distillation column. The light fraction is withdrawn from the top of the vacuum distillation column and condensed.

[0074] The inventors of this invention have found that the zeolite material has certain parameters, particularly a molar ratio of silica to alumina (SAR) of 10 to 140, an average crystal diameter of about 200 nm or less, and at least 0.30 cm. 3 Mesopore volume of / g and at least 0.10 cm 3 We unexpectedly found advantages when using zeolites with a micropore volume of / g.

[0075] In particular, the inventors have found unexpected benefits when zeolites have such small crystal diameters and are desiliconized, thereby having a low SAR of preferably 10 to 100, preferably 10 to 50. More preferably, the zeolite material has an SAR of at least 15 and / or up to 30, preferably up to 25. These ranges are particularly optimized for waste plastic mixtures, i.e., those obtained from public collection facilities, recycling plants or other plastic collection sources, and are particularly advantageous for the purpose of reducing residue and enhancing the pyrolysis efficiency of plastic waste. For example, the plastic may essentially consist of a mixture of low-density polyethylene, high-density polyethylene, polypropylene and / or polystyrene, and optionally other plastics (preferably in small amounts when present), such as polyvinyl chloride, polyethylene terephthalate and / or polycarbonate. Preferably, the zeolite material has an average crystal diameter of about 100 nm or less, preferably about 50 nm or less. The crystal diameter can be determined by several different techniques, including laser diffraction or sieving, or by SEM as described herein.

[0076] Preferably, the zeolite material is at least 0.40 cm 3 / g, more preferably at least 0.50cm 3 / g, and / or up to 0.90cm 3 It has a mesopore volume of 0.40 cm² / g. Preferably, the zeolite material has a maximum of 0.40 cm². 3 / g, preferably a maximum of 0.20cm 3 It has a micropore volume of / g.

[0077] These parameters, which result in a unique combination of zeolite characteristics that have been found to enhance the process of plastic pyrolysis, In a base solution, a parent zeolite having an average crystal diameter of 200 nm or less is mixed to form a desiliconized slurry, The recovery of the solid by filtration or other separation method, To dry, This can be achieved by using desiliconized zeolites, such as those obtainable by processes including the optional firing of solids. The parent zeolite is 0.40 cm 3 Mixed in a base solution containing 1 to 20 mmol of base per gram of anhydrous hydrophilic zeolite at a temperature in the range of 0°C to 100°C for a sufficient time to produce a mesopore volume of 1 / g or more. The solid content, defined as the weight percentage of anhydrous hydrophilic zeolite relative to the total weight of the desiliconized slurry, ranges from 1 to 40 wt%. The total desiliconization time can range from 0.5 to 24 hours.

[0078] Desiliconization can be carried out using a suitable base such as sodium hydroxide or potassium hydroxide. The mixture of zeolite and base solution is defined as a desiliconization suspension or desiliconization slurry. Optionally, quaternary ammonium compounds in salt or hydroxide form can be added to the desiliconization slurry. Preferably, the base is selected from LiOH, NaOH, KOH, NH4OH, and tetraalkylammonium hydroxide. Preferably, the zeolite material is obtained by a process having a ΔV / silica loss ratio of at least 0.8.

[0079] At least one quaternary ammonium compound, either in salt or hydroxide form, can be optionally added to the desiliconization slurry in a range of 0.1 to 10 mmol / g of quaternary ammonium compound per gram of anhydrous zeolite. The desiliconized form of the zeolite can be subjected to ion exchange to remove alkali cations from the zeolite. Ion exchange is typically carried out using ammonium salts such as ammonium nitrate or ammonium chloride.

[0080] In an alternative process for obtaining zeolite for use in the plastic pyrolysis method of the present invention, an acid such as nitric acid or hydrochloric acid may be added to any ammonium salt during ion exchange to promote the dealuminization of the desiliconized mesoporous zeolite. Ion exchange is preferably carried out using 1 to 50 mmol of ammonium salt and 1 to 20 mmol of acid per gram of anhydrous zeolite. The temperature of the ion exchange process may be in the range of 20°C to 100°C. The total time of ion exchange may be in the range of 0.5 to 24 hours. The ion exchange can be repeated to obtain the desired amount of alkali in the zeolite.

[0081] The inventors have found that using low SAR, small-crystal zeolites significantly improves the total conversion rate of plastics to distillates (pyrolysis oil) and gases (so-called synthesis gas). More specifically, the inventors have surprisingly found that, compared to simply desiliconized low-SAR zeolites and small-crystal-diameter zeolites, the increase in total conversion rate is even more significantly related to the conversion rate of more useful pyrolysis oils, thereby resulting in an improvement in the ratio of distillates to synthesis gas. Thus, specific combinations of mesopore and micropore volumes, as well as SAR and average crystal diameter in particular, provide an unexpected synergistic effect that is advantageous for plastic pyrolysis applications.

[0082] Therefore, the yield of the carbonized material is preferably less than 20 wt%, more preferably less than 10 wt%, in this method. The yield of the pyrolysis oil is also preferably at least 40 wt%, more preferably at least 50 wt%,. Thus, in certain preferred embodiments, the weight ratio of pyrolysis oil to pyrolysis gas remaining after condensation of pyrolysis oil from pyrolysis gas is at least 1.2:1.

[0083] In another aspect, the present invention relates to the use of a desilicate zeolite material to increase the weight ratio of pyrolysis oil to pyrolysis gas, which remains after the pyrolysis oil has been condensed from the pyrolysis gas, compared to conventional zeolites. [Examples]

[0084] Examples The following non-limiting embodiments are intended to be illustrative and further clarify the disclosure.

[0085] Sample 1 Fifty grams of calcined OSDA-free 51SAR ZSM-5 zeolite with an average SEM crystal diameter of 50 nm, as shown in Table 1, were added to 238 grams of DI water and mixed at room temperature. Twenty-nine grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for two hours. The desiliconized zeolite was then filtered and washed with DI water.

[0086] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0087] Sample 2 50 grams of the same starting material as in Sample 1 were added to 229 grams of DI water and mixed at room temperature. 38 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for 2 hours. The desilicate zeolite was then filtered and washed with DI water.

[0088] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0089] Sample 3 50 grams of the same starting material as in Sample 1 were added to 257 grams of DI water and heated to 40°C. 9.5 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at 40°C for 2 hours. The desilicate zeolite was then filtered and washed with DI water.

[0090] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0091] Sample 4 50 grams of the same starting material as in Sample 1 were added to 248 grams of DI water and heated to 60°C. 19 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at 60°C for 2 hours. The desilicate zeolite was then filtered and washed with DI water.

[0092] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0093] Sample 5 As shown in Table 1, 100 grams of 30SAR ZSM-5 zeolite in its as-synthesized OSDA-containing form with an average crystal diameter of 40 nm was added to 421 grams of DI water and mixed at room temperature. 71 grams of 50 wt% sodium hydroxide solution was added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0094] Acidic ammonium exchange of desilicate zeolite was performed at 80°C for 2 hours using a mixture of nitric acid and ammonium nitrate solution (0.6:2.5:1 nitric acid:ammonium nitrate:zeolite weight ratio) and ammonium nitrate solution (2.5 ammonium nitrate weight ratio to zeolite). After each contact, the zeolite was filtered and washed with DI water. The ion-exchanged samples were dried in air at 105°C. The ion-exchanged samples exhibited the characteristics summarized in Table 1.

[0095] Comparison Sample 1 Comparative CBV 5524G zeolite, a commercially available zeolite manufactured by Zeolyst International with an average crystal diameter of 230 nm as shown in Table 1, was treated under the same conditions as ZSM-5 for Sample 1. 50 grams of comparative ZSM-5 zeolite were added to 232 grams of DI water and mixed at room temperature. 28 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0096] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0097] Comparison Sample 2 A commercially available zeolite manufactured by Zeolyst International, comparative CBV 5524G zeolite, was treated under the same conditions as ZSM-5 in Sample 2. 50 grams of comparative ZSM-5 zeolite were added to 223 grams of DI water and mixed at room temperature. 37 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0098] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0099] Comparison Sample 3 A commercially available zeolite manufactured by Zeolyst International, comparative CBV 5524G zeolite, was treated under the same conditions as ZSM-5 in Sample 3. 50 grams of comparative ZSM-5 zeolite were added to 251 grams of DI water and heated to 40°C. 9.3 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at 40°C for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0100] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0101] Comparison Sample 4 A commercially available zeolite manufactured by Zeolyst International, comparative CBV 5524G zeolite, was treated under the same conditions as ZSM-5 in Sample 4. 50 grams of comparative ZSM-5 zeolite were added to 241 grams of DI water and heated to 60°C. 19 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at 60°C for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0102] Ammonium exchange of desilicate zeolite was performed using two contacts with ammonium nitrate solution (2.5-ammonium nitrate by weight ratio to zeolite) at 80°C for 2 hours. After each contact, the zeolite was filtered and washed with DI water. The ammonium-exchanged samples were dried in air at 105°C. The ammonium-exchanged samples exhibited the characteristics summarized in Table 1.

[0103] Comparison Sample 5 Comparative 25 SAR ZSM-5 zeolite, a commercially available CBV 2314 zeolite manufactured by Zeolyst International, was treated under the same conditions as ZSM-5 of Sample 5. 100 grams of comparative ZSM-5 zeolite were added to 421 grams of DI water and mixed at room temperature. 71 grams of 50 wt% sodium hydroxide solution were added to the zeolite suspension aqueous solution, and the resulting mixture was stirred at room temperature for 2 hours. The desiliconized zeolite was then filtered and washed with DI water.

[0104] Acidic ammonium exchange of desilicate zeolite was performed at 80°C for 2 hours using a mixture of nitric acid and ammonium nitrate solution (0.6:2.5:1 nitric acid:ammonium nitrate:zeolite weight ratio) and ammonium nitrate solution (2.5 ammonium nitrate weight ratio to zeolite). After each contact, the zeolite was filtered and washed with DI water. The ion-exchanged samples were dried in air at 105°C. The ion-exchanged samples exhibited the characteristics summarized in Table 1.

[0105] [Table 1]

[0106] Example 1 Three zeolites were subjected to the same operating conditions (350°C, 2 hours, 1 bar). g It was tested in a pilot plant for plastic pyrolysis under the following conditions.

[0107] 1. Desiliconized zeolite ZSM-5 (SAR=22.4 and average crystal diameter approximately 200 nm) produced by post-synthesis modification of commercially available zeolite ZSM-5. 2. Nano-sized zeolite ZSM-5 (SAR=27.2 and average crystal diameter approximately 50 nm) 3. Desiliconized nano-sized zeolite ZSM-5 (SAR=19.5 and average crystal diameter approximately 50 nm) The results of the pyrolysis reactions using these three catalysts are shown below (Table 2).

[0108] [Table 2]

[0109] These results demonstrate that nanoscale ZSM-5 zeolite is more active than desiliconized ZSM-5 zeolite (conversion rates of 86.7% vs. 70.2%, respectively). However, desiliconized ZSM-5 is more selective for distillates than nanoscale zeolite (distillate-to-synthesis gas ratio of 1.16 vs. 1.12, respectively).

[0110] Nano-sized desiliconized ZSM-5 is the best zeolite of the three, as it exhibits a conversion rate of 94.6% compared to 86.7% and 70.2%, and a distillate-to-synthesis ratio of 1.21 compared to 1.16 and 1.12.

[0111] These results clearly demonstrate the superior advantages of using desiliconized nano-sized zeolites to improve ZSM-5 zeolite activity and selectivity for distillates in ELP pyrolysis.

[0112] Where used herein, the singular “a,” “an,” and “the” include plural references unless the context explicitly indicates otherwise. The use of the term “comprising” is intended to be interpreted as including such features but not excluding other features, and further intended to include a selection of features that are necessarily limited to those described. In other words, the term also includes the limitations of “consisting of essential ~” (meaning certain additional components may be present as long as they do not materially affect the essential features of the described features) and “consisting of” (meaning, when components are expressed as percentages by their proportions, no other features may be included so that they total 100%, taking into account any unavoidable impurities).

[0113] The detailed description provided herein is provided for illustrative purposes and examples only and is not intended to limit the scope of the appended claims. Many variations of the currently preferred embodiments illustrated herein will be obvious to those skilled in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A method for producing pyrolysis oil from used plastics, wherein the method is (i) Supplying used plastic materials, (ii) Melting the used plastic material to form a molten plastic material, (iii) to thermally decompose the molten plastic material in an oxygen-free atmosphere to produce a thermal decomposition gas and a carbonized material, (iv) Condensing the pyrolysis gas to obtain the pyrolysis oil, The method further comprises dispersing a zeolite material in the used plastic material or the molten plastic material, wherein the zeolite material comprises a zeolite having a molar ratio of silica to alumina (SAR) of 10 to 140 and an average crystal diameter of about 200 nm or less, and the zeolite material is at least 0.30 cm ３ Mesopore volume of / g and at least 0.10 cm ３ A method having a micropore volume of / g.

2. The method according to claim 1, wherein the zeolite material has a medium-pore zeolite, preferably an MFI skeleton type, and more preferably includes ZSM-5.

3. The method according to claim 1 or 2, wherein the zeolite material has at least 15 and / or up to 30 SARs.

4. The method according to any of the preceding claims, wherein the zeolite material is included in an amount of 0.05 wt% to 10 wt%, preferably 0.1 wt% to 5 wt%, based on the total weight of the plastic material and the zeolite material.

5. The method according to any one of the preceding claims, wherein the zeolite material has an average crystal diameter of about 100 nm or less, preferably about 50 nm or less.

6. The zeolite material is at least 0.40 cm ３ / g, and / or up to 0.90 cm ３ The method according to any of the preceding claims, having a mesopore volume of 1 / g.

7. The method according to any of the preceding claims, wherein the zeolite material is of the H-exchange type.

8. The zeolite material is up to 0.40 cm ３ / g, preferably a maximum of 0.20 cm ３ The method according to any of the prior claims, having a micropore volume of 1 / g.

9. The method according to any of the preceding claims, further comprising recovering the zeolite material from the carbonized material, preferably recovering it by burning the carbonized material to ash and physically separating the zeolite material from the ash.

10. The method according to any one of the preceding claims, wherein the used plastic material is melted in step (ii) in an extruder heated to a temperature of 250 to 350°C.

11. The method according to any one of the preceding claims, wherein the thermal decomposition in step (iii) is carried out in a thermal decomposition reactor which may be stirred at a temperature of 350 to 450°C.

12. Before step (iv), the method described above, The pyrolysis gas of step (iii) is passed through a contactor having a bank of elements such that several long-chain gas components condense on the liquefied elements, yielding a condensed long-chain material. The condensed long-chain material is returned to step (iii) for further thermal decomposition, The method according to any of the preceding claims, further comprising discharging the short-chain gas components from the contactor in gaseous form before condensation in step (iv).

13. The method according to any of the preceding claims, wherein step (iv) includes distilling the pyrolysis gas from the contactor in a distillation column.

14. The aforementioned zeolite material The process involves mixing a parent zeolite having an average crystal diameter of 200 nm or less in a base solution to form a desiliconized slurry, The solid is recovered by filtration or other separation method, To dry, Obtained by a process that includes optionally firing the solid, The parent zeolite is 0.40 cm ３ Mixed in a base solution containing 1 to 20 mmol of base per gram of anhydrous hydrophilic zeolite at a temperature in the range of 0°C to 100°C for a sufficient time to create a mesopore volume of 1 / g or more, The method according to any of the preceding claims, wherein the solid content, defined as a weight percentage of the anhydrous hydrophilic zeolite with respect to the total weight of the desiliconized slurry, is in the range of 1 to 40 wt%.

15. The aforementioned bases are LiOH, NaOH, KOH, NH ４ The method according to claim 14, selected from OH and tetralkylammonium hydroxide.

16. The method according to claim 14 or 15, wherein the zeolite material is obtained by a process having a ΔV / silica loss ratio of at least 0.

8.

17. The method according to any of the preceding claims, wherein the yield of the carbonized material is less than 20 wt%, preferably less than 10 wt%.

18. The method according to any of the preceding claims, wherein the yield of the pyrolysis oil is at least 40 wt%, preferably at least 50 wt%.

19. The method according to any one of the preceding claims, wherein the weight ratio of the pyrolysis oil to the pyrolysis gas remaining after condensing the pyrolysis oil from the pyrolysis gas is at least 1.2:1.

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