Circular economy of waste plastics to polypropylene via refined FCC and alkylation units

Abstract

Provided is a continuous process for converting waste plastics into polypropylene for recycling. The process includes selecting waste plastics containing polyethylene and / or polypropylene and passing the waste plastics through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolysis effluent. The pyrolysis effluent is separated into off-gas, a naphtha / diesel fraction, a heavy fraction, and a char. The pyrolysis oil and wax (including the naphtha / diesel fraction and the heavy fraction) are sent to a refinery FCC unit. A C3-C5 olefin / paraffin mixture of liquefied petroleum gas is recovered from the FCC unit and passed to a refinery alkylation unit. A propane fraction is recovered from the alkylation unit and passed to a dehydrogenation unit to produce propylene. The propylene is passed to a propylene polymerization reactor.

Description

[Technical field]

[0001] (background) The world has witnessed a very rapid growth in plastic production. According to PlasticsEurope Market Research Group, global plastic production was 335 million tonnes in 2016, 348 million tonnes in 2017, and 359 million tonnes in 2018. According to McKinsey & Company, the global volume of plastic waste was estimated at approximately 260 million tonnes per year in 2016 and is projected to reach 460 million tonnes per year by 2030 if the current trajectory continues. [Background technology]

[0002] Single-use plastic waste is becoming an increasingly significant environmental issue. At present, there appear to be few options for recycling polyethylene and polypropylene waste plastics into value-added chemical and fuel products. Currently, only small amounts of polyethylene and polypropylene are recycled via chemical recycling, and this recycled and cleaned polymer pellets are pyrolyzed in pyrolysis units to produce fuels (naphtha, diesel), steam cracker feedstock, or slack wax.

[0003] Processes for converting waste plastics into hydrocarbon lubricants are known. For example, US Patent No. 3,845,157 discloses the cracking of waste or virgin polyolefins to form gaseous products such as ethylene / olefin copolymers, which are further processed to produce synthetic hydrocarbon lubricants. US Patent No. 4,642,401 discloses the heating of pulverized polyolefin waste at temperatures between 150 and 500°C and pressures between 20 and 300 bar to produce liquid hydrocarbons. US Patent No. 5,849,964 discloses a process for depolymerizing waste plastic materials into volatile and liquid phases. The volatile phase is separated into a gas phase and a condensate. The liquid, condensate and gas phases are refined into liquid fuel components using standard refining techniques. US Patent No. 6,143,940 discloses a procedure for converting waste plastics into heavy wax compositions. US Patent No. 6,150,577 discloses a process for converting waste plastics into lubricating oils. EP 0 620 264 A1 discloses a process for producing lubricants from waste or virgin polyolefins by thermally cracking the waste in a fluidized bed to form a waxy product, optionally using hydrotreating, followed by catalytic isomerization and fractionation to recover the lubricants.

[0004] Other documents relating to processes for converting waste plastics into lubricants include U.S. Patent Nos. 6,288,296, 6,774,272, 6,822,126, 7,834,226, 8,088,961, 8,404,912 and 8,696,994, and U.S. Patent Application Publication Nos. 2019 / 0161683, 2016 / 0362609 and 2016 / 0264885. The aforementioned patent documents are incorporated herein by reference in their entirety.

[0005] Current methods of chemical recycling via pyrolysis are not capable of making a significant impact on the plastics industry. Current pyrolysis operations produce poor quality fuel components (naphtha and diesel range products) but in small enough quantities that these products can be blended into the fuel supply. However, to recycle the very large quantities of waste polyethylene and waste polypropylene required to address environmental concerns, such simple blending cannot continue. The raw products from pyrolysis units are too poor quality to be blended in large quantities (e.g., 5-20 vol.% blends) into transportation fuels.

[0006] However, more robust processes are needed to industrially recycle single-use plastics on a large scale and reduce their environmental impact. These improved processes should establish a "circular economy" for waste polyethylene and polypropylene plastics, effectively recycling post-consumer waste plastics as starting material for polymers and high-value by-products. Summary of the Invention

[0007] Provided is a continuous process for converting waste plastics to recycle for polypropylene polymerization. The process includes selecting waste plastics comprising polyethylene and / or polypropylene and passing the waste plastic through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into off-gas, naphtha / diesel fraction, heavy fraction, and char.

[0008] The integration of this process into oil refineries is a key aspect of the process, allowing for a circular economy with single-use waste plastics such as polypropylene. Thus, pyrolysis oil and optionally pyrolysis wax (including naphtha / diesel fraction and heavy fraction) are passed to a refinery FCC unit, from which liquefied petroleum gas C is produced. 3 -C 5 An olefin / paraffin mixture is recovered. The liquefied petroleum gas fraction is passed to a refinery alkylation unit. The propane fraction is recovered from the alkylation unit and passed to a dehydrogenation unit to produce propylene.

[0009] A refinery generally has its own supply of hydrocarbons that flow through the refinery units. The volume of pyrolysis oil and wax streams generated from the pyrolysis of waste plastics and flowing to the refinery units can constitute any practical or accommodable volume percent (vol%) of the total flow (total flow) to the refinery units. In general, the flow rate of pyrolysis oil and wax generated from the pyrolysis of waste plastics can be up to about 50 vol% of the total flow (i.e., refinery flow rate and pyrolysis flow rate) for practical reasons. In one embodiment, the flow rate of pyrolysis oil and wax amounts to up to about 20 vol% of the total flow rate.

[0010] Among other factors, it has been shown that the waste pyrolysis oil and waste pyrolysis wax can be upgraded to higher value products such as gasoline and diesel by adding refinery operations. It has also been shown that the waste pyrolysis oil can be efficiently and effectively converted to clean propane and propylene for the ultimate production of polypropylene polymer by adding refinery operations. Positive economics are realized throughout the process from recycled plastics to polypropylene products with product qualities equivalent to virgin polymers. [Brief description of the drawings]

[0011] [Figure 1] Figure 1 shows the current practice of pyrolyzing waste plastics to produce fuel or wax (base case).

[0012] [Diagram 2] Figure 2 illustrates this process for establishing a circular economy for waste plastics.

[0013] [Diagram 3] Figure 3 shows the classification of plastic types for recycling waste plastics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] This process provides a method to recycle waste polyethylene and / or waste polypropylene into virgin polypropylene, establishing a circular economy by combining separate industrial processes. The majority of polyethylene and polypropylene polymers are used for single-use plastics and are discarded after use. This single-use plastic waste is becoming an increasingly important environmental issue. At present, there seem to be few options to recycle polyethylene and polypropylene waste plastics into value-added chemical and fuel products. Currently, only a small amount of polyethylene / polypropylene is recycled via chemical recycling, and this recycled and cleaned polymer pellets are pyrolyzed in a pyrolysis unit to produce fuels (naphtha, diesel), steam cracker feedstock, or slack wax.

[0015] Polypropylene is widely used in a variety of consumer and industrial products. It has mechanical durability and high chemical resistance, making it the second most widely produced commodity plastic after polyethylene. Polypropylene is widely used in packaging, films, carpet and clothing fibers, molded articles, and extruded pipes. Today, only a small fraction of post-consumer polypropylene products are collected for recycling. This is due to the inefficiency and ineffectiveness of recycling efforts mentioned above.

[0016] Figure 1 shows a diagram of waste plastic fuel or wax pyrolysis as commonly practiced in the industry today. As mentioned above, typically polyethylene and polypropylene waste are sorted together (1). The cleaned polyethylene / polypropylene waste 2 is converted to off-gas 4 and pyrolysis oil (liquid products) in pyrolysis unit 3. The off-gas 4 from the pyrolysis unit is used as fuel to operate the pyrolysis unit 3. An on-site distillation unit separates the pyrolysis oil to produce naphtha and diesel 5 products, which are sold to the fuel market. The heavy pyrolysis oil fraction 6 is recycled to the pyrolysis unit 3 to maximize fuel yield. Char 7 is removed from the pyrolysis unit 3. The heavy fraction 6 is rich in long-chain linear hydrocarbons and is highly waxy (i.e., forms paraffinic wax when cooled to ambient temperature). Wax can be separated from the heavy fraction 6 and sold to the wax market.

[0017] The process converts waste plastics into pyrolyzed polypropylene and / or polyethylene in bulk by integrating the waste polymer pyrolysis product stream into an oil refinery operation. The resulting process produces polymer feedstocks (liquefied petroleum gas (LPG) propane stream for a propane dehydrogenation unit), high quality gasoline and diesel fuels, and / or high quality base oils.

[0018] In general, the process provides a circular economy for polypropylene plants. Polypropylene is produced via polymerization of pure propylene. Clean propylene can be produced from a propane dehydrogenation unit. Clean propane for the dehydrogenation unit can be obtained from an oil refinery alkylation unit, which produces mixed C (from fluid catalytic cracking (FCC)). 3 -C 5 After alkylation of the olefins with isobutane, pure propane liquefied petroleum gas (LPG) is produced.

[0019] By adding refining operations to upgrade the waste pyrolysis oil and wax to higher value products (gasoline and diesel) and to produce clean propane and propylene for ultimate polypropylene polymer production, positive economics are realized throughout the process from recycled plastics to a polypropylene product with product qualities equivalent to virgin polymer.

[0020] The pyrolysis unit produces low quality products containing contaminants such as calcium, magnesium, chlorides, nitrogen, sulfur, dienes, and heavy components, which cannot be used in large quantities for blending transportation fuels. It has been found that by passing these products through a refinery unit, the contaminants can be captured in a pre-treatment unit and their negative impacts can be mitigated. The fuel components are further upgraded in a suitable refinery unit with chemical conversion processes, and the final transportation fuel produced by the integrated process is of higher quality and can meet the fuel quality requirements. The integrated process produces a much cleaner and purer propane stream for the propane dehydrogenation unit and ultimately for polypropylene production. The mass production of these to specification makes a viable "circular economy" of recycled plastics possible.

[0021] The carbon going in and out of the refinery is “transparent,” meaning that not all molecules from the waste plastics are cycled back to the polyolefin plant and become the exact olefin product, but it is nevertheless considered a “credit” since the net “green” carbon going in and out of the refinery is positive. These integrated processes result in a significant reduction in the amount of virgin feedstock required for a polypropylene plant.

[0022] FIG. 2 shows the present integrated process integrating refining operations with recycling for efficient polypropylene production. In FIG. 2, mixed waste plastics are sorted together (21). The cleaned waste plastics 22 are converted in a pyrolysis unit 23 into off-gas 24, pyrolysis oil (liquid product) and optionally wax (solid product at ambient temperature). The off-gas 24 from the pyrolysis unit can be used as fuel to operate the pyrolysis unit 23. The pyrolysis oil is separated into naphtha / diesel fraction 25 and heavy fraction 26, typically by an on-site distillation unit. After completion of the pyrolysis process, char 27 is removed from the pyrolysis unit 23.

[0023] The pyrolysis unit can be located near the waste plastic collection site, which can be remote from the refinery, near the refinery, or within the refinery. If the pyrolysis unit is located remote from the refinery, the pyrolysis oils (naphtha / diesel and heavy oils) can be transported to the refinery by truck, barge, rail car, or pipeline. However, it is preferred that the pyrolysis unit be located at the plastic collection site or within the refinery.

[0024] The preferred starting material for the process is sorted waste plastics containing mainly polyethylene and polypropylene (plastic recycling classification types 2, 4, and 5). The pre-sorted waste plastics are washed, shredded or pelletized, and fed to the pyrolysis unit for pyrolysis. Figure 1 shows the plastic type classification for waste plastic recycling. Classification types 2, 4, and 5 are high density polyethylene, low density polyethylene, and polypropylene, respectively.

[0025] Proper sorting of waste plastics is very important to minimize contaminants such as N, Cl, and S. Plastic waste including polyethylene terephthalate (Plastic Recycle Classification Type 1), polyvinyl chloride (Plastic Recycle Classification Type 3) and other polymers (Plastic Recycle Classification Type 7) should be sorted to less than 5%, preferably less than 1%, and most preferably less than 0.1%. The process can tolerate moderate amounts of polystyrene (Plastic Recycle Classification Type 6). Waste polystyrene should be sorted to less than 30%, preferably less than 20%, and most preferably less than 5%.

[0026] Washing of waste plastics removes metallic contaminants such as sodium, calcium, magnesium, aluminum, and non-metallic contaminants from other waste sources. Non-metallic contaminants include contaminants from Group IV of the periodic table such as silica, contaminants from Group V such as phosphorus and nitrogen compounds, contaminants from Group VI such as sulfur compounds, and halide contaminants from Group VII such as fluorides, chlorides, iodides, etc. Residual metal, non-metallic contaminants, and halides should be removed to less than 50 ppm, preferentially less than 30 ppm, and most preferentially less than 5 ppm.

[0027] If washing does not adequately remove the metal, non-metallic contaminants, and halide impurities, a separate guard bed can be used to remove the metal and non-metallic contaminants.

[0028] Pyrolysis is carried out by contacting the plastic material feedstock under pyrolysis conditions in a pyrolysis zone, where at least a portion of the feedstock is decomposed, thereby forming a pyrolysis zone effluent comprising 1-olefins and n-paraffins. The pyrolysis conditions include a temperature of about 400°C to about 700°C, preferably about 450°C to about 650°C. Conventional pyrolysis techniques teach operating conditions at pressures above atmospheric pressure (see, for example, U.S. Pat. No. 4,642,401). Furthermore, it has been found that the yield of desired products can be controlled by adjusting the pressure downward (see, for example, U.S. Pat. No. 6,150,577). Thus, in some embodiments where such control is desired, the pyrolysis pressure is below atmospheric pressure.

[0029] FIG. 2 illustrates this integrated process in which the entire liquid fraction from the thermal cracking unit 23 is sent to an FCC unit 28 and then to alkylation 29. The liquid fraction from the thermal cracking unit 23 includes naphtha / diesel 25 and heavy fraction 26. Cracking the thermal cracking liquid oil combined with the petroleum derived oil in the FCC unit produces liquefied petroleum gas (LPG) C. 3 -C 4 Or C 3 -C 5 An olefin / paraffin mixture 30 is produced, as well as gasoline 42 and heavy distillates 31. C 3 -C 4 The olefin / paraffin mixture 30 is sent to an alkylation plant 29 which produces a stream of pure propane 32 and n-butane 33. The pure propane 32 can be fed to a propane dehydrogenation unit 34 to prepare propylene 35 and ultimately polypropylene 36.

[0030] The fluid catalytic cracking (FCC) process is widely used in the refining industry to convert atmospheric gas oil, vacuum gas oil, atmospheric residual oil and heavies recovered from other refining operations into high octane gasoline, light fuel oil, heavy fuel oil, olefin-rich light gas (LPG) and coke. FCC uses highly active zeolite catalysts to crack heavy hydrocarbon molecules at reactor temperatures of 950-990°F in the riser with short contact times of a few minutes or less. LPG streams containing olefins (propylene, butylene) are typically upgraded to produce alkylate gasoline or for use in the production of chemical products. Conventional FCC units can be used.

[0031] A refinery generally has its own supply of hydrocarbons that flow through the refining unit. The volume of pyrolysis oil and wax streams generated from the pyrolysis of waste plastics and flowing to the refining unit (here the FCC unit) can constitute any practical or accommodable volume percent (vol%) of the overall flow (total flow rate) to the refining unit. In general, the flow rate of pyrolysis oil and wax fractions generated from the pyrolysis of waste plastics can be up to about 50 vol% of the total flow rate (i.e., refining flow rate and pyrolysis flow rate) for practical reasons. In one embodiment, the pyrolysis oil and wax flow rate is up to about 20 vol% of the total flow rate. In another embodiment, the pyrolysis oil and wax flow rate is up to about 10 vol% of the total flow rate. It has been found that about 20 vol% is a very practical amount in terms of impact on the refinery, while at the same time providing good results and being accommodable. Of course, the amount of pyrolysis oil generated from pyrolysis can be controlled so that the fractions passed to the refining unit provide the desired volume percent of the flow rate.

[0032] When pyrolysis liquid oil combined with petroleum-derived oil is cracked in an FCC unit, C 3 -C 5 Liquefied petroleum gas (LPG) of olefin / paraffin mixture 30, as well as gasoline and heavy distillates 31, are produced. 3 -C 5The olefin / paraffin mixture 30 is sent to an alkylation plant 29 which produces pure propane 32 and n-butane 33 streams.

[0033] The alkylation process combines light olefins (propylene, butylene, typically from FCC units) with isobutane to produce alkylate gasoline, a highly branched, paraffinic fuel. Alkylate gasoline is a highly desirable gasoline blending component because it is a clean-burning, high octane, low sulfur, low RVP gasoline blending component that contains no olefinic or aromatic compounds. Conventional alkylation processes use either a sulfuric acid catalyst, which operates at reactor temperatures of 30-60°F, or a hydrofluoric acid catalyst, which operates at reactor temperatures of 90-95°F.

[0034] Dehydrogenation of propane is widely used in industry to produce propylene. The reaction is endothermic and conversion is maintained by multi-stage reactors and interstage heaters. The units are typically operated at high temperature (>900°F) and low pressure (<50 psig) in the presence of a precious metal (Pt) catalyst. The multi-stage process produces a propylene / propane mixture of approximately 85% purity. This stream is sent to a propane / propylene (PP) splitter, a highly efficient distillation column. The splitter produces a pure propylene stream of 99.5-99.8% purity.

[0035] The propane dehydrogenation unit can be located away from the refinery, near the refinery, or within the refinery. The propane stream is sent to the propane dehydrogenation unit from the alkylation unit by truck, barge, rail car, or pipeline. The propane dehydrogenation unit is preferably in close proximity to the refinery alkylation unit or polypropylene chemical plant.

[0036] The propylene prepared in the process can be polymerized in a propylene polymerization unit 40 to prepare polypropylene, from which polypropylene product 41 can be produced.

[0037] Polypropylene is produced from the monomer propylene via chain growth polymerization. Ziegler-Natta or metallocene catalysts are used to catalyze the polymerization of propylene into polypropylene polymers to achieve the desired properties. These catalysts are activated with specialized cocatalysts, including organoaluminum compounds. Industrial polymerization processes use either gas phase polymerization in fluidized bed reactors or bulk polymerization in loop reactors. Gas phase polymerization is typically performed using H 2 The polymerization is carried out at temperatures of 50-90°C and pressures of 8-35 atm in the presence of propylene. The bulk polymerization proceeds at 60-80°C and at a pressure of 30-40 atm to keep the propylene in a liquid state.

[0038] The propylene polymerization unit is preferably located near the refinery so that the feedstocks (propane and propylene) can be transported via pipeline. For petrochemical plants located remotely from the refinery, the feedstocks can be delivered via truck, barge, rail car, or pipeline.

[0039] The alkylation unit 29 also produces clean high octane gasoline 37. The alkylate gasoline 37 and FCC gasoline 42 fractions are sent to the refinery's gasoline blending pool 39. The heavy hydrocarbon products 31 from the FCC unit and the n-butane stream from the alkylation unit can be sent to a suitable refining unit 38 for upgrading to clean gasoline, diesel, or jet fuel.

[0040] The benefits of a circular economy and effective and efficient recycling campaigns are realised through this integrated process.

[0041] The following examples are provided to further illustrate the present process and its advantages. These examples are intended to be illustrative and not limiting. EXAMPLES

[0042] Example 1: Characterization of pyrolysis oils and waxes from commercial sources

[0043] Pyrolysis oil and wax samples were obtained from commercial sources. Their properties are summarized in Table 1. These pyrolysis samples were prepared from waste plastics, mainly containing polyethylene and polypropylene, via pyrolysis in a pyrolysis reactor at approximately 400-600 °C and near atmospheric pressure without the addition of gas or catalyst. Pyrolysis units typically produce gas, liquid oil products, optional wax products, and char. The overhead gas stream of the pyrolysis unit containing the thermally decomposed hydrocarbons was cooled and the condensate was collected as pyrolysis oil (liquid at ambient temperature) and / or pyrolysis wax (solid at ambient temperature). Pyrolysis oil is the primary product of the pyrolysis unit. Some pyrolysis units produce pyrolysis wax as a separate product in addition to pyrolysis oil. [Table 1]

[0044] Specific gravity measurements were performed using ASTM D4052 method. Simulated boiling point distribution curves were obtained using ASTM D2887 method. Carlo-Erba analysis for carbon and hydrogen was performed according to ASTM D5291 method. Bromine number measurements were performed according to ASTM D1159 method. Hydrocarbon type analysis was performed using a high resolution magnetic mass spectrometer, scanning the magnet from 40 to 500 Daltons. Total sulfur was determined using XRF according to ASTM D2622 method. Nitrogen was determined using chemiluminescence detection according to modified ASTM D5762 method. Total chloride content was measured using a combustion ion chromatography instrument according to modified ASTM 7359 method. Oxygen content in the boiling range of naphtha and distillate was estimated using GC with GC / MS measurement equipped with an electron ionization detector with an m / Z range of 29 to 500. Trace metal and nonmetallic elements in the oils were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0045] Industrial pyrolysis processes of sorted plastics, sourced primarily from polyethylene and polypropylene waste, have produced high-quality hydrocarbon streams with specific gravities in the range of 0.7-0.9 and boiling points in the range of 18-1100°F, as in the case of pyrolysis oil or pyrolysis wax.

[0046] The pyrolysis products are fairly pure hydrocarbons consisting mainly of carbon and hydrogen. The hydrogen to carbon molar ratio varies from 1.7 to nearly 2.0. The bromine numbers range from 14 to 60, indicating varying degrees of unsaturation due to olefins and aromatics. The aromatic content ranges from 5 to 23 vol%, with more severe pyrolysis units producing more aromatics. Depending on the process conditions of the pyrolysis unit, the pyrolysis products show paraffin contents ranging from the mid-20s to the mid-50s vol.%. The pyrolysis products contain significant amounts of olefins. Samples A and B are pyrolysis oils produced under more severe conditions, such as higher pyrolysis temperatures and / or longer residence times, which result in higher aromatics and less paraffin, with H / C molar ratios of about 1.7 and high bromine numbers of 50 to 60. Samples C and D were produced under less severe conditions and their pyrolysis oils are more paraffinic, resulting in H / C molar ratios closer to 2.0 and bromine numbers around 40. Sample E (pyrolysis wax) is mostly paraffinic saturated hydrocarbons with a significant amount of linear (as opposed to branched) hydrocarbons and a bromine number of only 14.

[0047] The following Examples 2 to 5 show the evaluation of waste plastic pyrolysis oil as a transportation fuel.

[0048] [Example 2] Fractional distillation of pyrolysis oil for evaluation as a transportation fuel

[0049] Sample D was distilled to separate multiple fractions of hydrocarbons, namely, gasoline (350°F - ) fraction, jet (350-572°F) fraction, diesel (572-700°F) fraction, and heavy (700°F + Table 2 summarizes the boiling point distribution and impurity distribution of each fraction of the distillation product. [Table 2]

[0050] [Example 3] Evaluation of pyrolysis oil fractions for gasoline fuel

[0051] Sample F (a fraction of pyrolysis oil with a boiling point range for gasoline fuel) was evaluated for its usability as a gasoline fuel. The carbon number range of sample F is C5 to C12, which is typical for gasoline fuel.

[0052] Because pyrolysis oils are olefinic in nature, oxidation stability (ASTM D525) and gum formation tendency (ASTM D381) were identified as the most important properties to be investigated. Research Octane Number (RON) and Motor Octane Number (MON) are also important properties for engine performance. RON and MON values ​​were estimated from detailed GC analysis of the hydrocarbons. [Table 3]

[0053] Sample F (a fraction of pyrolysis oil in the boiling range of gasoline fuel) is of poor quality and cannot be used alone as a gasoline fuel for motor vehicles. The gasoline fraction from pyrolysis oil showed very poor oxidation stability in that sample F failed after only 90 minutes compared to the target stability of over 1440 minutes. The pyrolysis gasoline exceeded the wash gum target of 4 mg / 100 mL, indicating a strong tendency for gum formation. The pyrolysis gasoline has a lower octane number compared to the reference gasoline. Premium unleaded gasoline was used as the reference gasoline.

[0054] We also investigated the possibility of blending limited amounts of pyrolysis gasoline fractions into the reference gasoline. Our work showed that up to 15% by volume of sample F could potentially be blended into refined gasoline while still achieving the fuel property targets. By integrating pyrolysis gasoline products with refined fuels, the overall product quality can be maintained.

[0055] These results indicate that the as-produced gasoline fraction of pyrolysis oil has limited usefulness as a gasoline fuel. Upgrading in a refinery unit is preferred to convert this gasoline fraction of pyrolysis oil into hydrocarbons that meet gasoline fuel property targets.

[0056] [Example 4] Evaluation of pyrolysis oil fractions for jet fuel

[0057] Sample G (a fraction of pyrolysis oil with a boiling point range equivalent to jet fuel) was evaluated for its potential use as jet fuel. The carbon number range of sample G is C9 to C18, which is typical of jet fuel.

[0058] Due to the olefinic nature of pyrolysis oil, the jet fuel thermal oxidation test (D3241) was considered the most important test. Sample G, the pure jet fraction of pyrolysis oil, had an oxidation stability of only 36 minutes, indicating that the pure pyrolysis jet fraction is unsuitable for use as jet fuel.

[0059] We prepared a 5% by volume blend of the pyrolysis jet fraction (Sample G) into refinery produced jet fuel. This blend still failed the jet fuel oxidation test, as shown in Table 4. [Table 4]

[0060] These results indicate that the as-produced jet fraction of pyrolysis oil is completely unsuitable for jet fuel and that upgrading in a refining unit is necessary to convert this jet fraction of pyrolysis oil into hydrocarbons that meet the property targets for jet fuel.

[0061] [Example 5] Evaluation of pyrolysis oil fractions for diesel fuel

[0062] Sample H (a fraction of pyrolysis oil with a boiling point range for diesel fuel) was evaluated for its potential use as diesel fuel. The carbon number range of Sample H is C14 to C24, which is typical for diesel fuel.

[0063] Sample H contains a significant amount of normal hydrocarbons, which tend to exhibit wax-like properties, so cold flow properties such as pour point (ASTM D5950-14) and cloud point (ASTM D5773) were considered the most important tests.

[0064] We prepared two blends of Sample H at 10% and 20% by volume in refinery produced diesel fuel, but both blends still failed the target pour point of less than -17.8°C (0°F). [Table 5]

[0065] These results indicate that pyrolysis oil as is is completely unsuitable for diesel fuel and that upgrading in a refinery unit is required to convert the diesel fraction of pyrolysis oil into hydrocarbons that meet the property targets for diesel fuel.

[0066] [Example 6] Co-processing of pyrolysis products in an FCC unit or FCC pre-processing unit

[0067] The results in Table 1 show that the industrial pyrolysis process of sorted plastics, mainly sourced from polyethylene and polypropylene waste, produces high quality pyrolysis oil or pyrolysis wax, composed mainly of carbon and hydrogen. With good sorting and efficient operation of the pyrolysis unit, nitrogen and sulfur impurities are at sufficiently low levels that modern refineries can handle cofeeding of pyrolysis feedstock to processing units without detrimental effects.

[0068] However, some pyrolysis oils or waxes may still contain significant amounts of metals (Ca, Fe, Mg) and other non-metals (S, N, P, Si, Cl, O) that can adversely affect the performance of the refinery's conversion units. In the case of pyrolysis, products with high impurity levels are preferentially fed to the FCC feedstock processor before the FCC unit, where most of the impurities are effectively removed by the processor.

[0069] By feeding the entire pyrolysis feedstock to an FCC unit as shown in FIG. 2 or feeding it to an FCC pre-treatment unit before the FCC unit, the pyrolysis oil and wax are converted into off-gas, LPG paraffins and olefins, FCC gasoline, and heavy hydrocarbon components. FCC gasoline is a valuable gasoline blending component. The heavy fraction, light cycle oil (LCO) and heavy cycle oil (HCO) are further converted in subsequent conversion units including jet hydrotreater unit, diesel hydrotreater unit, hydrocracker unit and / or coker unit to produce more gasoline, jet and diesel fuel with satisfactory product properties. The LPG paraffins and olefins are further processed in an alkylation unit or partially used to produce petrochemical products with recycled components. C 3 A mixed vapor of propane and propylene is a valuable raw material for producing polypropylene.

[0070] Examples 7 and 8 below demonstrate the conversion of waste plastic pyrolysis products into high quality transportation fuels in a refinery and conversion unit (using an FCC unit as an example).

[0071] [Example 7] Conversion of pyrolysis oil in FCC

[0072] To study the effect of coprocessing waste plastic pyrolysis oil on FCC, a series of laboratory tests were carried out using Sample A and Sample C. Vacuum gas oil (VGO) is a typical feedstock for FCC. The FCC performance of a 20 volume percent blend of pyrolysis oil with VGO and pure pyrolysis oil was compared with that of pure VGO feedstock.

[0073] The FCC experiments were carried out in a Model C ACE (advanced cracking evaluation) unit manufactured by Kayser Technology Inc., using regenerated equilibrium catalyst (Ecat) from a refinery. The reactor was operated with N 2 The catalytic cracking experiments were carried out at atmospheric pressure and a reactor temperature of 900°F. The catalyst / oil ratio was varied between 5 and 8 by varying the amount of catalyst. The gas products were collected and analyzed using a refinery gas analysis unit (RGA) equipped with a GC with FID detector. In situ regeneration of the spent catalyst was carried out in the presence of air at 1300°F and the regenerated flue gas was passed through the LECO to determine the coke yield. The liquid products were weighed and analyzed by GC using simulated distillation (D2887) and C 5 - Compositional analysis was performed. Mass balance showed that the crude oil was composed of coke, dry gas components, LPG components, gasoline (C5, ~430°F), light cycle oil (LCO, 430-650°F), and heavy cycle oil (HCO, 650°F). + The yield of 1,2-dichloro-1,2-diphenyl-2,3-diphenyl-1,4-tetrahydrofuran (1,2-diphenyl-2,4-diphenyl-1,5-dimethyl-2,6-dimethyl-2,7-dimethyl-2,8-diphenyl-1,5 ...7- [Table 6]

[0074] The results in Table 6 show that co-feeding up to 20% by volume of pyrolysis oil only results in a negligible change in the performance of the FCC unit, indicating that co-processing up to 20% of pyrolysis oil is readily feasible. Blending 20% ​​by volume of Sample A or Sample C resulted in a negligible decrease in coke and dry gas yields, a slight increase in gasoline yield, and a slight decrease in LCO and HCO, which are favorable in most situations. Because pyrolysis oil is paraffinic, blending 20% ​​of Sample A or Sample C resulted in a decrease in octane number of about 3-5. Depending on the operational flexibility of the refinery, these octane number losses can be compensated for by adjusting the blending or feed position.

[0075] The FCC unit cracks the pyrolysis oil into fuel range hydrocarbons, reduces impurities, and isomerizes n-paraffins to isoparaffins. All these chemical properties improve the fuel properties of the pyrolysis oil and wax. By co-feeding the pyrolysis oil through the FCC process unit with a zeolite catalyst, the fuel range oxygen and nitrogen impurities were significantly reduced from about 300-1400 ppm nitrogen (N) to about 30 ppm and from about 250-540 ppm oxygen (O) to about 60-80 ppm. The hydrocarbon composition of all these co-feed products is well within the range of typical FCC gasoline.

[0076] FCC operation of 100% pyrolysis oil showed a significant octane minus (minus about 13–14), indicating that co-processing of pyrolysis oil is preferable over processing of pure 100% pyrolysis oil.

[0077] [Example 8] Co-processing of pyrolysis wax in FCC

[0078] A series of laboratory tests were conducted using Sample E and VGO to study the effect of coprocessing waste plastic pyrolysis wax on FCC. As in Example 7, the FCC performance of a 20% blend of pyrolysis wax with VGO and pure pyrolysis wax was compared to the FCC performance of pure VGO feedstock. The results are summarized in Table 7 below. [Table 7]

[0079] The results in Table 7 show that co-feeding up to 20% by volume of pyrolysis wax results in only a negligible change in the FCC unit performance, indicating that co-processing of up to 20% pyrolysis wax is readily feasible. Blending 20% ​​by volume of Sample E resulted in little change in coke and dry gas yields, a significant increase in LPG olefins yield, a negligible increase in gasoline yield, and a slight decrease in LCO and HCO, which are favorable in most situations. Because pyrolysis oil wax is paraffinic, blending 20% ​​of Sample E resulted in a slight octane loss of 1.5. Due to refinery blending flexibility, this octane loss can easily be made up with minor blend adjustments.

[0080] FCC operation of 100% pyrolysis wax showed a significant increase in conversion and a negative octane number (negative 6), indicating that co-processing of pyrolysis wax is preferable over processing of 100% pyrolysis wax.

[0081] [Example 9] Supply of LPG olefins (co-processed with waste plastic pyrolysis products) from FCC units to refining and alkylation units

[0082] Co-feeding of pyrolysis oil to the refinery FCC unit provides significant amounts of C, including recycled content. 3 -C 5 Olefins are produced. C 4 Flow only, C3 -C 4 Flow, or C 3 -C 5 A stream is separated from the FCC light ends recovery unit and fed to an alkylation unit. The reaction of LPG olefins with isobutane in the alkylation reactor produces propane, butane, and alkylate gasoline. Alkylate gasoline and butane are highly valuable gasoline blending components. Clean propane from the alkylation unit is a valuable feedstock for the production of chemicals.

[0083] [Example 10] Recycled C for propylene production 3 and the subsequent manufacture of polypropylene resin and polypropylene consumer products.

[0084] As in Example 9, clean propane from the alkylation unit is dehydrogenated to produce propylene for a polymerization unit to produce polypropylene polymer with a recycle content.

[0085] Polypropylene resins containing recycled polyethylene / polypropylene derived materials have a high quality that is indistinguishable from virgin polypropylene resins made entirely from virgin petroleum resources. This polypropylene resin containing recycled materials is further processed to produce a variety of polypropylene products that meet consumer product needs. Although these polypropylene consumer products contain chemically recycled circular polymers, the quality of these products is indistinguishable from those made entirely from virgin polypropylene polymers. These chemically recycled polymer products are different from mechanically recycled polymer products, which are of inferior quality to polymer products made from virgin polymers.

[0086] The above mentioned examples clearly demonstrate a new and effective way to recycle large amounts of polyethylene and polypropylene derived waste plastics by chemical recycling via pyrolysis followed by co-feeding of pyrolysis products with refinery FCC via efficient integration, which enables the production of high quality fuels and circular polymers.

[0087] As used in this disclosure, the words "comprises" or "comprising" are intended as open-ended transitional phrases, meaning the inclusion of the indicated elements, but not necessarily the exclusion of other unspecified elements. The phrase "consists essentially of" or "consisting essentially of" is intended to mean excluding other elements that are essential to the composition. The phrase "consisting of" or "consists of" is intended as a transitional phrase, meaning the exclusion of all other than the recited elements, except for only trace impurities.

[0088] All patents and publications referenced herein are incorporated herein by reference to the extent not inconsistent therewith. It will be understood that the specific above-described structures, functions, and operations of the above-described embodiments are not necessary to practice the present invention, but are included in the description merely to complete the exemplary embodiment or embodiments. It will be further understood that the specific structures, functions, and operations described in the above-referenced patents and publications can be practiced in combination with the present invention, but are not essential to its practice. Thus, it should be understood that the present invention can be practiced as specifically described without actually departing from the spirit and scope of the present invention, as defined by the appended claims.

Claims

1. A continuous process for converting waste plastics into recycling for polypropylene polymerization, comprising: (a) selecting waste plastics comprising polyethylene and / or polypropylene; (b) passing the waste plastic from (a) through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolyzed effluent; (c) separating the pyrolyzed effluent into an off-gas, a naphtha / diesel fraction, a heavy fraction, and a char; (d) passing the pyrolysis oil and wax (including naphtha / diesel and heavy fractions) through a refinery FCC unit; (e) removing C from the refining FCC unit; ３ -C ５ recovering the liquefied petroleum gas comprising the olefin / paraffin mixture; (f) passing the liquefied petroleum gas fraction through a refinery alkylation unit; (g) recovering a propane fraction from the refinery alkylation unit; (h) passing the propane fraction through a dehydrogenation unit to produce propylene; The above process comprising:

2. 10. The process of claim 1, wherein the gasoline and heavy fractions are recovered from a refinery FCC unit.

3. The process of claim 1, wherein the pyrolysis oil and wax of (d) are treated in a pyrolysis reactor and contaminants are removed in the pyrolysis reactor.

4. 10. The process of claim 1, wherein the propylene produced in (h) is passed to a propylene polymerization reactor to produce polypropylene.

5. 5. The process of claim 4, wherein the polypropylene consumer product is prepared from polymerized propylene.

6. 2. The process of claim 1, wherein the waste plastics selected in (a) are from plastic classification groups 2, 4, and / or 5.

7. 3. The process of claim 2, wherein gasoline recovered from a refinery FCC unit is combined with an alkylate gasoline fraction recovered from a refinery alkylation unit.

8. 2. The process of claim 1, wherein isobutane is added to the liquid petroleum gas fraction that is passed to the refinery alkylation unit.

9. 10. The process of claim 1, wherein a heavy fraction is recovered from the refinery FCC unit and further processed in a refinery into clean gasoline, diesel, or jet fuel.

10. The process of claim 1, wherein the volumetric flow rate of pyrolysis oil and wax flowing to the refining FCC unit in (d) constitutes up to about 50 volume percent of the total hydrocarbon flow rate flowing to the refining FCC unit.

11. The process described in claim 10, wherein the volumetric flow rate of pyrolysis oil and wax flowing to the refining FCC unit in (d) constitutes up to about 20 volume percent of the total hydrocarbon flow rate flowing to the refining FCC unit.

12. 1. A process for converting waste plastics into chemicals useful for the preparation of polypropylene, comprising: (a) selecting waste plastics comprising polyethylene and / or polypropylene; (b) pyrolyzing the waste plastics and recovering pyrolysis oils and waxes, including naphtha / diesel fractions and heavy fractions; (c) passing the pyrolysis oil and wax through a refinery FCC unit; (d) extracting C from the refining FCC unit; ３ -C ５ recovering the olefin / paraffin mixture; (e) The above C ３ -C ５ passing the olefin / paraffin mixture into a refinery alkylation unit; (f) recovering propane from the refinery alkylation unit; The above process comprising:

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