Circular economy of waste plastics into polyethylene via refineries and crude units

Abstract

Provided is a continuous process for converting waste plastics into feedstock for polyethylene polymerization. The process includes selecting waste plastics containing polyethylene and polypropylene and then 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 then separated into off-gas, pyrolysis oil (including naphtha / diesel / heavy fractions), and char. The pyrolysis oil is passed to a crude refinery unit, from which a naphtha fraction (C5-C8) or a propane and butane (C3-C4) fraction is recovered. The naphtha fraction or the propane and butane (C3-C4) fraction is then passed to a steam cracker for ethylene production.

Description

Technical Field

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

Background Art

[0002] Disposable plastic waste has become an increasingly important environmental problem. At present, there seem to be few options for recycling polyethylene and polypropylene waste plastics into value-added chemical products or fuel products. Currently, only a small amount of polyethylene and polypropylene are recycled via chemical recycling, and these recycled and purified polymer pellets are pyrolyzed in a pyrolysis unit to produce fuel (naphtha, diesel), steam cracker feedstock, or slack wax.

[0003] Processes for converting waste plastics into hydrocarbon lubricants are known. For example, U.S. Patent No. 3,845,157 discloses the decomposition of waste polyolefins or unused polyolefins to form gaseous products such as ethylene / olefin copolymers, which are then further processed to produce synthetic hydrocarbon lubricants. U.S. Patent No. 4,642,401 discloses the production of liquid hydrocarbons by heating crushed polyolefin waste at temperatures of 150-500°C and pressures of 20-300 bar. U.S. 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 phase, condensate, and gas phase are purified into liquid fuel components using standard refining techniques. U.S. Patent No. 6,143,940 discloses a procedure for converting waste plastics into a heavy wax composition. U.S. Patent No. 6,150,577 discloses a process for converting waste plastics into lubricating oil. European Patent Application Publication No. 0620264 discloses a process for producing lubricating oil from waste polyolefins or unused polyolefins, comprising thermally decomposing the waste in a fluidized bed to form a waxy product, optionally using a hydrogenation treatment, and then recovering the lubricating oil by catalytic isomerization and fractional distillation.

[0004] Other documents relating to processes for converting waste plastics into lubricants include U.S. Patents 6,288,296, 6,774,272, 6,822,126, 7,834,226, 8,088,961, 8,404,912, and 8,696,994, as well as U.S. Patent Application Publications 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 cannot have a significant impact on the plastics industry. Current pyrolysis operations produce low-quality fuel components (products in the naphtha and diesel ranges), but these are produced in sufficiently small quantities to be blended into fuel feed. However, to address environmental concerns and recycle the very large quantities of waste polyethylene and waste polypropylene, such simple blending cannot be sustained. The products directly from the pyrolysis unit are too poor in quality to be blended in large quantities (e.g., 5-20 vol%) into transport fuel.

[0006] To reduce the environmental impact of industrially recycling single-use plastics on a large scale, more robust processes are needed. These improved processes should establish a "circular economy" for waste polyethylene and polypropylene plastics, ensuring that used plastics are effectively recycled as starting materials for polymers and high-value by-products. [Overview of the Initiative]

[0007] The process offered is a continuous process for converting waste plastics into naphtha for polyethylene polymerization. This process first involves selecting waste plastics, including polyethylene and / or polypropylene. These waste plastics are then passed through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste, producing pyrolyzed effluent. The pyrolyzed effluent is separated into off-gas, pyrolysis oil and wax (including naphtha / diesel fractions and heavy fractions), and char.

[0008] Integrating this process into an oil refinery is a key aspect of this process, enabling a circular economy using disposable waste plastics such as polyethylene. Thus, the recovered pyrolysis oil and wax are passed through the refinery's crude unit. The naphtha fraction (C5-C8) is recovered from the distillation column and passed through a steam cracker for ethylene production.

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

[0010] In another embodiment, a continuous process is provided for converting waste plastics containing polyethylene into a C3-C4 stream for polyethylene polymerization. This process includes selecting waste plastics containing polyethylene and polypropylene. The selected waste plastics are passed through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste, producing a pyrolysis effluent. The pyrolysis effluent is separated into off-gas, pyrolysis oil and wax (including naphtha / diesel / heavy fractions), and char. The pyrolysis oil and / or optionally the wax are passed through a crude unit distillation column of a refinery. A portion of the propane and butane (C3-C4) fractions are recovered from the distillation column and passed through a steam cracker for ethylene production.

[0011] In particular, among other factors, it has been found that adding a refinery operation can upgrade waste pyrolysis oil and waste pyrolysis wax into high-value products such as gasoline and diesel. Furthermore, it has been shown that adding a refinery operation allows for the efficient and effective production of clean naphtha (C5-C8) or C3-C4 from waste pyrolysis oil and waste pyrolysis wax, enabling the production of ultimate polyethylene polymer. Positive economic benefits are realized throughout the entire process, from recycled plastics to polyethylene products with product quality equivalent to unused polymers. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 illustrates current practices for generating fuel or wax by pyrolysis of waste plastics (basic case).

[0013] [Figure 2] Figure 2 illustrates the process for establishing a circular economy for waste plastics.

[0014] [Figure 3] Figure 3 shows the classification of plastic types for recycling waste plastics. [Modes for carrying out the invention]

[0015] This process provides a method for recycling waste polyethylene and / or waste polypropylene into virgin polyethylene, establishing a circular economy by combining separate industrial processes. The majority of polyethylene and polypropylene polymers are used in single-use plastics, which are then discarded. This single-use plastic waste is becoming an increasingly significant environmental problem. Currently, there appear to be few options for recycling waste polyethylene and polypropylene plastics into value-added chemical or fuel products. Currently, only small amounts of polyethylene / polypropylene are recycled through chemical recycling, and these recycled and purified polymer pellets are pyrolytically decomposed in pyrolysis units to produce fuels (naphtha, diesel), steam cracker feedstock, or slack wax.

[0016] Ethylene is the most widely produced building block of petrochemicals. Hundreds of millions of tons of ethylene are produced annually through steam cracking. Steam crackers use either gaseous feedstocks (ethane, propane, and / or butane) or liquid feedstocks (naphtha or gaseous oil). Steam cracking is a non-catalytic decomposition process carried out at extremely high temperatures, up to 850°C.

[0017] Polyethylene is widely used in a variety of consumer and industrial products. It is the most common plastic, with over 100 million tons of polyethylene resin produced annually. Its primary use is in packaging (plastic bags, plastic films, geomembranes, bottles, and other containers). Polyethylene is produced in three main forms, all sharing the same chemical formula (C2H4). n However, their molecular structures are different: high-density polyethylene (HDPE, approximately 0.940-0.965 g / m²) -3 ), linear low-density polyethylene (LLDPE, approximately 0.915~0.940 g / cm³) -3 ), low-density polyethylene (LDPE, <0.930 g / cm³)-3 HDPE has a low degree of branching and short side chains, while LDPE has a very high degree of branching and long side chains. LLDPE is a substantially linear polymer with a considerable number of short branches and is usually produced by copolymerization of ethylene and short-chain alpha-olefins.

[0018] Low-density polyethylene (LDPE) is produced by radical polymerization at very high pressures of 1,000 to 3,000 atmospheres and 150 to 300°C. This process uses small amounts of oxygen and / or organic peroxide initiators to produce a highly branched polymer with approximately 4,000 to 40,000 carbon atoms per average polymer molecule. High-density polyethylene (HDPE) is produced at relatively low pressures (10 to 80 atmospheres) and temperatures of 80 to 150°C in the presence of a catalyst. Ziegler-Natta organometallic catalysts (titanium(III) chloride with aluminum alkyl) and Phillips-type catalysts (chromium(IV) oxide supported on silica) are typically used, and this production is carried out via a slurry process using a loop reactor or a gas-phase process using a fluidized bed reactor. Hydrogen is mixed with ethylene to control the polymer chain length. The production conditions for linear low-density polyethylene (LLDPE) are the same as those for HDPE, except for the copolymerization of ethylene with short-chain alpha-olefins (1-butene or 1-hexene).

[0019] Today, only a small fraction of used polyethylene products are collected for recycling. This is due to the inefficiencies and ineffectiveness of the recycling efforts described above.

[0020] Figure 1 shows a diagram of the pyrolysis of waste plastic fuel or wax commonly carried out in today's industry. As described above, generally, polyethylene and polypropylene waste are sorted together (1). The washed polyethylene / polypropylene waste 2 is converted in the pyrolysis unit 3 into off-gas 4 and pyrolysis oil (liquid product), and in some cases into wax. The off-gas 4 from the pyrolysis unit is used as fuel to operate the pyrolysis unit 3. An on-site distillation unit (not shown) separates the pyrolysis oil to produce naphtha and diesel products 5, which are sold on the fuel market. The heavy pyrolysis oil fraction 6 is recycled to the pyrolysis unit 3 to maximize the fuel yield. The char 7 is removed from the pyrolysis unit 3. The heavy fraction 6 is rich in long-chain straight-chain hydrocarbons and is very waxy (i.e., forms paraffin wax when cooled to ambient temperature). This wax can be separated from the heavy fraction 6 and sold on the wax market.

[0021] This process converts large amounts of waste plastics of pyrolyzed polyethylene and / or polypropylene by integrating the pyrolysis product stream of waste polymers into an oil refinery operation. The resulting process produces polymer feedstocks (naphtha or C3-C4 for ethylene crackers), as well as high-quality gasoline and diesel fuels, and / or high-quality base oils.

[0022] Generally, this process provides a circular economy for polyethylene plants. Polyethylene is produced via the polymerization of pure ethylene. Clean ethylene can be produced using a steam cracker. Either a naphtha or C3-C4 stream can be fed to the steam cracker. Then, the ethylene is polymerized to produce polyethylene.

[0023] By adding purification operations to upgrade waste pyrolysis oil and waste pyrolysis wax to high-value products (gasoline and diesel), and to produce clean LPG and naphtha for steam crackers for the production of ultimate polyethylene polymers, it is possible to generate a plus in economic efficiency throughout the process from recycled plastics to polyethylene products with quality equivalent to virgin polymers.

[0024] The pyrolysis unit produces low-quality products containing contaminants such as calcium, magnesium, chlorides, nitrogen, sulfur, dienes, and heavy components, and these products cannot be used in large quantities for blending transportation fuels. It has been found that by passing these products through a purification unit, the contaminants can be captured in a pretreatment unit and their adverse effects can be reduced. The fuel components can be further upgraded in a suitable purification unit with a chemical conversion process, and the final transportation fuels produced by the integrated process are of higher quality and can meet the fuel quality requirements. The integrated process generates a much cleaner naphtha stream as a steam cracker feedstock for ethylene production and polyethylene manufacturing. These mass productions according to the specifications enable a viable "circular economy" of recycled plastics.

[0025] The carbon flowing in and out in the purification operation is "transparent", which means that not all molecules from waste plastics circulate back to the polyolefin plant and become the exact olefin products. Nevertheless, it is regarded as a "credit" because the net "green" carbon flowing in and out of the purification plant is positive. This integrated process will significantly reduce the amount of virgin feedstock required for the polyethylene plant.

[0026] Figure 2 shows this integrated process, which combines refining operations with recycling for efficient polyethylene production. In Figure 2, mixed waste plastics are sorted together (21). The washed waste plastics 22 are converted in a pyrolysis unit 23 into off-gas 24 and pyrolysis oil (liquid product) and possibly 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 generally separated into naphtha / diesel fraction 25 and heavy fraction 26 in an on-site distillation unit. After the completion of the pyrolysis process, char 27 is removed from the pyrolysis unit 23.

[0027] The pyrolysis unit can be located near a waste plastic collection site, which may be located away from, near, or within the refinery. If the pyrolysis unit is located away from the refinery, the pyrolysis products (naphtha / diesel and heavy oil) can be transported to the refinery by truck, barge, railcar, or pipeline. However, it is preferable that the pyrolysis unit be located at the plastic collection site or within the refinery.

[0028] The preferred starting material for this process is sorted waste plastics, mainly polyethylene and polypropylene (plastic recycling classification types 2, 4, and 5). The pre-sorted waste plastics are washed, shredded or pelletized, and fed into a pyrolysis unit for pyrolysis. Figure 3 shows the classification of plastic types for waste plastic recycling. Classification types 2, 4, and 5 are high-density polyethylene, low-density polyethylene, and polypropylene, respectively. Polyethylene and polypropylene waste plastics can be used in any combination. It is preferable to use at least some polyethylene waste plastics in this process.

[0029] Proper sorting of waste plastics is crucial to minimize contaminants such as N, Cl, and S. Plastic waste containing polyethylene terephthalate (plastic recycling classification type 1), polyvinyl chloride (plastic recycling classification type 3), and other polymers (plastic recycling classification type 7) needs to be sorted to less than 5%, preferably less than 1%, and most preferably less than 0.1%. This process can tolerate a moderate amount of polystyrene (plastic recycling classification type 6). Waste polystyrene needs to be sorted to less than 30%, preferably less than 20%, and most preferably less than 5%.

[0030] Washing waste plastics removes contaminants such as sodium, calcium, magnesium, and aluminum, as well as 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 halogenated contaminants from Group VII, such as fluorides, chlorides, and iodides. Residual metals, non-metallic contaminants, and halides should be removed to less than 50 ppm, preferably less than 30 ppm, and most preferably less than 5 ppm.

[0031] If metal, non-metallic contaminants, and halide impurities are not adequately removed by cleaning, a separate guard floor can be used to remove the metal and non-metallic contaminants.

[0032] Pyrolysis is carried out by contacting the plastic material raw material with pyrolysis conditions in a pyrolysis zone, where at least a portion of the feed material is decomposed, thereby forming a pyrolysis zone effluent containing olefins and n-paraffins. The pyrolysis conditions include temperatures 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. Patent No. 4,642,401). Furthermore, it has been found that the yield of the desired product can be controlled by adjusting the pressure downward (see, for example, U.S. Patent No. 6,150,577). Therefore, in some embodiments where such control is desired, the pyrolysis pressure is below atmospheric pressure.

[0033] Figure 2 illustrates this integrated process in which the entire pyrolysis oil and wax from the pyrolysis unit are sent to the refinery crude unit desalination unit 28. The crude unit desalination unit removes contaminants from the pyrolysis products, which are then sent to the crude unit distillation column (not shown as part of the refinery crude unit). Alternatively, the pyrolysis oil and wax can be treated at the pyrolysis site to remove contaminants and then directly injected into the refinery crude distillation unit.

[0034] A refinery crude unit separates crude oil into multiple fractions such as liquefied petroleum gas (LPG), naphtha, kerosene, diesel, and gas oil, and then processes them further to produce useful petroleum products. A refinery crude unit includes a crude oil processing section, commonly known as a desalination unit, and a crude oil distillation section or crude oil fractionation section. The distillation section typically includes atmospheric distillation units and vacuum distillation units.

[0035] The pyrolysis oil (and wax) is supplied to a desalination unit to remove salts and solids contained in the oil, protecting downstream equipment from the harmful effects of contaminants. To remove the salt, water is mixed with the oil and heated to a temperature typically between 215°F and 280°F, and then separated in a desalination apparatus.

[0036] A refinery generally has its own supply of hydrocarbons flowing through its refining units. The volume of the pyrolysis oil and wax flow produced from the pyrolysis of waste plastics and flowing into the refining units can constitute any practical or tolerable volume % (vol%) of the total flow to the refining units. Generally, for practical reasons, the flow rate of pyrolysis oil and wax produced 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). In one embodiment, the flow rate of pyrolysis oil and wax is up to about 20 vol% of the total flow rate. In another embodiment, the flow rate of pyrolysis oil and wax is up to about 10 vol% of the total flow rate. About 20 vol% has been found to be a very practical amount in terms of impact on the refinery, while also providing excellent results and being tolerable. Of course, the amount of pyrolysis oil and wax produced from pyrolysis can be controlled so that the fraction passed through the refining units provides a desired volume % of the flow rate.

[0037] Desalted oils and waxes are sent to atmospheric distillation units heated to approximately 340–372°C (644–700°F) at the bottom of the distillation column, where liquids are removed at various points in the fractional distillation column to produce a variety of fuels. Fuel from the crude unit is sent to various upgrade units in the refinery, where impurities (nitrogen, sulfur) can be removed and the fractions catalytically converted to improve product properties such as octane and cetane numbers. The bottom residue from the atmospheric distillation column (also known as atmospheric residue) is typically sent to a vacuum distillation column to produce vacuum diesel (650–1050°F) and vacuum residue. Vacuum diesel can be used to produce lubricating oil or further broken down to produce gasoline, jet, and diesel fuels. The entire process can produce LPG (<80°F), gasoline (80–400°F), jet fuel (360–500°F), and diesel fuel (300–700°F). The boiling points of these fractions are adjusted according to seasonal and regional specifications.

[0038] From the refinery and crude distillation unit, C5-C8 naphtha streams 29, C5-C7 naphtha preferentially, and C5-C6 naphtha streams most preferentially are collected. The light naphtha stream is rich in linear paraffins and is an excellent light naphtha feedstock for the steam cracker 30 for ethylene production. The ethylene is passed through the polymerization unit 40 to produce polyethylene. The polyethylene is further processed to produce various polyethylene products 41 to meet the needs of consumer products. The heavy portion of the pyrolysis oil is combined with hydrocarbons from the crude unit distillation and sent to the appropriate refining unit as heavy naphtha, diesel, and atmospheric diesel streams 31 to be upgraded to clean gasoline, diesel, or jet fuel.

[0039] Ethylene polymerization units are preferably located near the refinery so that raw materials (propane, butane, naphtha) can be transported via pipeline. In the case of petrochemical plants located far from the refinery, raw materials can be delivered by truck, barge, railcar, or pipeline.

[0040] In another embodiment, the C3-C4 fraction 32 is recovered from the refinery / crude unit 28. This stream can also be fed to a steam cracker 30 for the production of ethylene. The ethylene is passed through a polymerization unit 40 to produce polyethylene. The polyethylene is further processed to produce a variety of polyethylene products 41 to meet the needs of consumer products.

[0041] The benefits of a circular economy and effective and efficient recycling campaigns will be realized through this integrated process.

[0042] The following examples are provided to further illustrate this process and its benefits. These examples are illustrative and not intended to be limiting. [Examples]

[0043] [Example 1] Characteristics of pyrolysis oils and waxes from commercial sources

[0044] Samples of pyrolysis oil and wax were obtained from commercial sources. Their properties are summarized in Table 1. These pyrolysis samples were prepared from waste plastics, mainly polyethylene and polypropylene, via pyrolysis in a pyrolysis reactor at approximately 400–600°C and near atmospheric pressure, without the addition of gases or catalysts. Pyrolysis units typically produce gas, liquid oil products, optionally wax products, and char. The overhead gas stream containing thermally decomposed hydrocarbons from the pyrolysis unit was cooled, and the condensates were collected as pyrolysis oil (liquid at ambient temperature) and / or pyrolysis wax (solid at ambient temperature). Pyrolysis oil is the main product of the pyrolysis unit. Some pyrolysis units produce pyrolysis wax as a separate product in addition to pyrolysis oil. [Table 1]

[0045] Specific gravity was measured using the ASTM D4052 method. The simulated boiling point distribution curve was obtained using the ASTM D2887 method. Carlo-Erba analysis of carbon and hydrogen was performed according to the ASTM D5291 method. Bromine number was measured according to the 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 the ASTM D2622 method. Nitrogen was determined using chemiluminescence detection according to the modified ASTM D5762 method. Total chloride content was measured using a combustion ion chromatography instrument according to the modified ASTM 7359 method. Oxygen content in the boiling range of naphtha and distillates was estimated using GC by GC / MS measurement with an electron ionization detector in the m / Z range of 29 to 500. Trace metal and nonmetal elements in the oil were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0046] In industrial pyrolysis processes for sorted plastics, primarily supplied from polyethylene and polypropylene waste, high-quality hydrocarbon streams with a specific gravity in the range of 0.7–0.9 and a boiling point range of 18–1100°F were produced, similar to pyrolysis oils or pyrolysis waxes.

[0047] The pyrolysis products are fairly pure hydrocarbons, mainly composed of carbon and hydrogen. The molar ratio of hydrogen to carbon varies from nearly 1.7 to 2.0. The bromine number ranges from 14 to 60, indicating varying degrees of unsaturation due to olefins and aromatic compounds. The aromatic content ranges from 5 to 23% by volume, with more aromatic compounds produced in units with more severe pyrolysis conditions. Depending on the process conditions of the pyrolysis unit, the pyrolysis products exhibit paraffin content ranging from mid-20% to mid-50% by volume. The pyrolysis products contain a considerable amount of olefins. Samples A and B are pyrolysis oils produced under more severe conditions, such as higher pyrolysis temperatures and / or longer residence times, resulting in higher aromatic and lower paraffin content, and consequently, a high H / C molar ratio of approximately 1.7 and a high bromine number of 50-60. Samples C and D were produced under less stringent conditions, and their pyrolysis oils were more paraffinic, resulting in an H / C molar ratio close to 2.0 and a bromine number of approximately 40. Sample E (pyrolysis wax) was mostly paraffinic saturated hydrocarbons, containing a considerable amount of straight-chain hydrocarbons (in contrast to branched hydrocarbons), and had a bromine number of only 14.

[0048] Examples 2 through 5 below illustrate the evaluation of waste plastic pyrolysis oil as a transport fuel.

[0049] [Example 2] Fractional distillation of pyrolysis oil for evaluation as a transport fuel

[0050] Sample D was distilled to obtain multiple hydrocarbon fractions, namely gasoline (350°F - ) fraction, jet (350~572°F) fraction, diesel (572~700°F) fraction, and heavy (700°F + The following fractions were produced. Table 2 summarizes the boiling point distribution and impurity distribution of each fraction of the distillation product. [Table 2]

[0051] [Example 3] Evaluation of fractions of pyrolysis oil for gasoline fuel

[0052] The potential for use as gasoline fuel was evaluated for sample F (a fraction of pyrolysis oil within the boiling point range of gasoline fuel). The carbon number range of sample F is C5 to C12, which is typical for gasoline fuel.

[0053] Because the pyrolysis oil is olefinic, oxidation stability (ASTM D525) and gum formation tendency (ASTM D381) were identified as the most important properties to investigate. Research octane number (RON) and motor octane number (MON) are also important properties for engine performance. The RON and MON values ​​were estimated from detailed GC analysis of hydrocarbons. [Table 3]

[0054] Sample F (a fraction of pyrolysis oil within the boiling point range of gasoline fuel) is of poor quality and cannot be used alone as automotive gasoline fuel. The gasoline fraction from the pyrolysis oil showed very low oxidation stability, with Sample F failing after only 90 minutes compared to the target stability of over 1440 minutes. The pyrolysis gasoline exceeded the target wash gum of 4 mg / 100 mL, indicating a strong tendency for gum formation. The pyrolysis gasoline had a lower octane rating compared to the reference gasoline. Premium unleaded gasoline was used as the reference gasoline.

[0055] We also investigated the possibility of blending a limited amount of pyrolytic gasoline fraction with reference gasoline. Our study showed that it may be possible to blend up to 15 volume% of sample F with refined gasoline while achieving the target fuel properties. Integrating pyrolytic gasoline products with refined fuels can maintain the overall quality of the product.

[0056] These results indicate that the gasoline fraction produced from pyrolysis oil has limited utility as a gasoline fuel. To convert this gasoline fraction from pyrolysis oil into hydrocarbons that meet the target gasoline fuel properties, an upgrade in the refining unit is preferable.

[0057] [Example 4] Evaluation of fractions of pyrolysis oil for jet fuel

[0058] The usability of sample G (a fraction of pyrolysis oil within the boiling point range of jet fuel) as jet fuel was evaluated. The carbon number range of sample G is C9 to C18, which is typical for jet fuel.

[0059] Because the pyrolysis oil is olefinic, the thermal oxidation test of the jet fuel (D3241) was considered the most important test. Sample G, which was the pure jet fraction of the pyrolysis oil, had an oxidation stability of only 36 minutes, indicating that the pure pyrolysis jet fraction is unsuitable for use as jet fuel.

[0060] We prepared a blend of pyrolysis jet fraction (sample G) at 5% by volume with jet fuel produced at a refinery. This blend still failed the oxidation test of the jet fuel, as shown in Table 4. [Table 4]

[0061] These results indicate that the jet fraction produced from pyrolysis oil is completely unsuitable for jet fuel, and that an upgrade in the refining unit is necessary to convert this jet fraction of pyrolysis oil into hydrocarbons that meet the characteristic targets of jet fuel.

[0062] [Example 5] Evaluation of fractions of pyrolysis oil for diesel fuel

[0063] The usability of sample H (a fraction of pyrolysis oil within the boiling point range of diesel fuel) as diesel fuel was evaluated. The carbon number range of sample H is C14 to C24, which is typical for diesel fuel.

[0064] Sample H contains a considerable amount of straight-chain hydrocarbons. Because straight-chain hydrocarbons tend to exhibit waxy properties, low-temperature flow characteristics such as the pour point (ASTM D5950-14) and cloud point (ASTM D5773) were considered the most important tests.

[0065] We prepared two blends of sample H by blending it with refined diesel fuel at 10% and 20% volume. However, both of these blends still failed to meet the target pour point of -17.8°C (0°F). [Table 5]

[0066] These results indicate that pyrolysis oil, in its raw form, is completely unsuitable for diesel fuel, and that an upgrade in the refining unit is necessary to convert the diesel fraction of the pyrolysis oil into hydrocarbons that meet the characteristic targets of diesel fuel.

[0067] [Example 6] Co-treatment of pyrolysis products into a crude unit or desalination unit

[0068] The results in Table 1 show that industrial pyrolysis processes of sorted plastics, primarily supplied from polyethylene and polypropylene waste, produce high-quality pyrolysis oil or pyrolysis wax, mainly composed of carbon and hydrogen. Good sorting and efficient operation of pyrolysis units result in sufficiently low levels of nitrogen and sulfur impurities, allowing modern refineries to handle cofeeding of pyrolysis raw materials to processing units without harmful effects.

[0069] However, some pyrolysis oils or waxes may still contain large amounts of metals (Ca, Fe, Mg) and other nonmetals (P, Si, Cl, O), which can negatively affect the performance of the refinery's conversion unit. In the case of pyrolysis, products with high levels of impurities are preferentially fed to the desalination unit before the crude unit, where the majority of the impurities are effectively removed.

[0070] By supplying the entire pyrolysis material to a crude unit, or to a desalination unit prior to the crude unit, the pyrolysis oil and wax are fractionated into multiple components and then further converted in subsequent conversion units, including a paraffin isomerization unit, a jet hydrotreatment unit, a diesel hydrotreatment unit, a fluid catalytic cracking (FCC) unit, an alkylation unit, a hydrocracking unit, and / or a coker unit, to produce gasoline, jet, and diesel fuels with satisfactory product characteristics. The conversion units (FCC or hydrocracking unit) also convert heavy fractions (corresponding to sample I) or wax (sample E) into high-quality transport fuels.

[0071] After the crude unit, the pyrolysis oil and wax are further converted in subsequent crude units. Examples 7 and 8 below demonstrate the conversion of waste plastic pyrolysis products into high-quality transport fuel in a refinement conversion unit (using an FCC unit as an example).

[0072] [Example 7] Conversion of pyrolytic oil in FCC

[0073] To study the effects of coprocessing waste plastic pyrolysis oil into FCC, a series of laboratory tests were conducted using samples A and C. Vacuum gasoline (VGO) is a typical feedstock for FCC. The FCC performance of a 20% blend of pyrolysis oil using VGO and pure pyrolysis oil was compared to that of pure VGO feedstock.

[0074] FCC experiments were performed using a Model C ACE (advanced cracking evaluation) unit from Kayser Technology Inc., employing regenerated equilibrium catalyst (Ecat) from a refinery. The reactor was a fixed fluid reactor using N2 as the fluidizing gas. Catalytic cracking experiments were conducted at atmospheric pressure and a reactor temperature of 900°F. The catalyst / oil ratio was varied between 5 and 8 by changing the amount of catalyst. Gas products were collected and analyzed using a refined gas analysis unit (RGA) equipped with a GC with an FID detector. In-situ regeneration of spent catalyst was performed in the presence of air at 1300°F, and the regenerated flue gas was passed through a LECO to determine the coke yield. Liquid products were weighed and analyzed by GC for simulated distillation (D2887) and C5 - A compositional analysis was performed. Based on the mass balance, the components were identified as 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 ) was determined. The results are summarized in Table 6 below. [Table 6]

[0075] The results in Table 6 show that co-feeding up to 20% by volume of pyrolysis oil results in only a slight change in the performance of the FCC unit, indicating that co-feeding up to 20% pyrolysis oil is easily feasible. Blending 20% ​​by volume of sample A or sample C resulted in a slight decrease in coke and dry gas yields, a slight increase in gasoline yields, and a slight decrease in LCO and HCO. These are acceptable in most situations. Because pyrolysis oil is paraffinic, blending 20% ​​of sample A or sample C resulted in an octane rating decrease of approximately 3–5. Due to refinery operational flexibility, these octane ratings can be compensated for by adjusting the blend or feed position. By co-supplying pyrolysis oil together with a zeolite catalyst through the FCC process unit, the oxygen and nitrogen impurities within the fuel range were significantly reduced: nitrogen (N) from approximately 300–1400 ppm to approximately 30 ppm, and oxygen (O) from approximately 250–540 ppm to approximately 60–80 ppm. The hydrocarbon composition of all these co-supply products falls well within the range of typical FCC gasoline.

[0076] In the FCC operation using 100% pyrolysis oil, a significant decrease in octane rating (approximately 13-14) was observed. This indicates that co-treatment with pyrolysis oil is preferable to treatment with pure 100% pyrolysis oil.

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

[0078] To study the effects of coprocessing of pyrolysis wax from waste plastics with FCC, a series of laboratory tests were conducted using sample E and VGO. Similar to Example 7, the FCC performance of a 20% blend of pyrolysis wax using VGO and pure pyrolysis wax was compared to that of pure VGO-supplied raw material. 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 slight change in the performance of the FCC unit, indicating that co-feeding up to 20% pyrolysis wax is easily feasible. A 20% by volume blend of Sample E resulted in little change in coke and dry gas yields, a significant increase in LPG olefin yield, a slight increase in gasoline yield, and a slight decrease in LCO and HCO. These are good in most situations. Because pyrolysis oil wax is paraffinic, a 20% blend of Sample E resulted in a slight decrease in octane rating of 1.5. Due to the blending flexibility of the refinery, this negative octane rating can be easily compensated for with minor blend adjustments.

[0080] In the FCC operation with 100% pyrolysis wax, the conversion rate increased significantly, and a negative octane rating (negative rating of 6) was observed. This indicates that co-treatment with pyrolysis wax is preferable to treatment with 100% pyrolysis wax alone.

[0081] [Example 9] Raw materials for C3-C4 and / or naphtha production from the co-supply of waste plastic pyrolysis products to refinery / crude processing units.

[0082] By supplying the entire pyrolysis material to the crude unit, or to a desalination unit before the crude unit, the pyrolysis oil and wax are fractionated into multiple components. Co-supplying of the pyrolysis oil allows the refinery crude unit to generate a considerable amount of clean propane, butane, and naphtha streams, as well as other streams for refinery conversion units.

[0083] [Example 10] Supply of recycled C3-C4 and / or naphtha to a steam cracker for ethylene production, and subsequent production of polyethylene resin and polyethylene consumer products.

[0084] Propane, butane, and naphtha flows are generated by co-feeding the pyrolysis products to a crude unit (Example 9). These flows are suitable raw materials for co-feeding to a steam cracker to produce ethylene containing recycled components. At least some (if not all) of these flows are fed to the steam cracker. The ethylene is processed into a polymerization unit to produce polyethylene resin containing recycled polyethylene / polypropylene-derived materials. The quality of the newly produced polyethylene is indistinguishable from unused polyethylene made from entirely unused petroleum resources. This polyethylene resin containing recycled materials is further processed to produce a variety of polyethylene products to meet consumer product needs. These polyethylene consumer products contain chemically recycled, circular polymers, but their quality is indistinguishable from those made from entirely unused polyethylene polymers. These chemically recycled polymer products are different from mechanically recycled polymer products, which are of lower quality than polymer products made from unused polymers.

[0085] Where used in this disclosure, the words “comprises” or “comprising” are intended as open-ended transitional terms meaning to include the indicated elements, but not necessarily to exclude other unindicated elements. The phrases “consists essentially of” or “consisting essentially of” are intended to mean to exclude other elements that are essentially important to the composition. The phrases “consisting of” or “consists of” are intended as transitional terms meaning to exclude everything other than the elements described, except for trace amounts of impurities.

[0086] All patents and publications referenced herein are incorporated herein by reference to the extent that they do not conflict with this specification. It will be understood that the specific structures, functions, and operations of the above embodiments are not necessary for carrying out the invention and are included in the description merely to complete the exemplary embodiments or multiple embodiments. Furthermore, it will be understood that while specific structures, functions, and operations described in the above-referenced patents and publications can be carried out in combination with the invention, they are not essential for its implementation. Therefore, it should be understood that the invention can be carried out as specifically described without actually departing from the spirit and scope of the invention as defined by the appended claims. The invention described in the original claims of this application is as follows: [Section 1] A continuous process for converting waste plastics into naphtha for polyethylene polymerization, (a) A step of selecting waste plastics including polyethylene and / or polypropylene, (b) A step of passing the waste plastic from (a) through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolysis effluent, (c) A step of separating the pyrolysis effluent into off-gas, pyrolysis oil and optionally pyrolysis wax (including naphtha / diesel fraction and heavy fraction), and char. (d) A step of passing the pyrolysis oil and wax through a crude processing unit of a refinery, (e) From the crude unit, the naphtha fraction (C 5 -C 8 The process of recovering ) (f) A step of passing the naphtha fraction through a steam cracker for ethylene production, The above process, including. [Section 2] The process according to item 1, wherein the pyrolysis oil and wax of (c) are passed directly through the refinery / crude unit, and contaminants are removed in the crude unit desalination unit. [Section 3] The process described in Section 1, wherein the contaminants are removed at a pyrolysis site. [Section 4] The process described in item 1, wherein the ethylene produced in (f) is subsequently polymerized. [Section 5] The process according to item 4, wherein the polyethylene product is prepared from polymerized ethylene. [Section 6] The process described in item 1, wherein heavy naphtha / diesel / atmospheric diesel fuel is recovered from a crude unit and further processed at a refinery into clean gasoline, diesel, or jet fuel. [Section 7] The process according to item 6, wherein the amount of unused crude oil processed by the crude oil processing unit is reduced by recycled pyrolysis oil. [Section 8] The process described in item 1, wherein the waste plastic selected in (a) is from plastic classification groups 2, 4, and / or 5. [Section 9] The process according to item 1, wherein the volumetric flow rate of pyrolysis oil and wax flowing into the crude unit of the refinery constitutes up to 50 volume percent of the total flow rate of hydrocarbons flowing into the crude unit. [Section 10] The process according to item 9, wherein the flow rate of the pyrolysis oil and wax constitutes a maximum of about 20 volume percent. [Section 11] Waste plastics are used for polyethylene polymerization. 3 -C 4 A continuous process for converting into flow, (a) A step of selecting waste plastics including polyethylene and / or polypropylene, (b) A step of passing the waste plastic from (a) through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolysis effluent, (c) A step of separating the pyrolysis effluent into off-gas, pyrolysis oil and optionally wax (including naphtha / diesel fraction and heavy fraction), and char. (d) A step of passing the pyrolysis oil through a crude processing unit of a refinery, (e) From the crude unit, propane and butane (C 3 -C 4 ) A process to recover a portion of the fraction, (f) Above (C 3 -C 4 ) The process of passing the fraction through a steam cracker for ethylene production, The above process, including. [Section 12] The process according to item 11, wherein the pyrolysis oil and wax of (c) are passed directly through the refinery / crude unit and contaminants are removed in the crude unit desalination unit. [Section 13] The process described in Section 11, wherein the contaminants are removed at a pyrolysis site. [Section 14] The process according to item 11, wherein the ethylene produced in (f) is subsequently polymerized. [Section 15] The process according to item 11, wherein the polyethylene product is prepared from polymerized ethylene. [Section 16] The process described in Section 11, wherein heavy naphtha / diesel / atmospheric diesel fuel is recovered from a crude unit and further processed at a refinery into clean gasoline, diesel, or jet fuel. [Section 17] The process according to item 11, wherein the volumetric flow rate of pyrolysis oil and wax flowing into the crude unit of the refinery constitutes up to 50 volume percent of the total flow rate of hydrocarbons flowing into the crude unit. [Section 18] The process according to item 17, wherein the flow rate of the pyrolysis oil and wax constitutes a maximum of 20% by volume. [Section 19] The process described in Section 11, wherein the waste plastic selected in (a) is from plastic classification groups 2, 4, and / or 5. [Section 20] A process for converting waste plastics into chemicals useful for the preparation of polyethylene, (a) A step of selecting waste plastics including polyethylene and / or polypropylene, (b) A step of thermally decomposing the waste plastic and recovering the thermal decomposition oil and wax (including naphtha / diesel / heavy fractions), (c) A step of passing the pyrolysis oil through a crude processing unit of a refinery, The above process, including.

Claims

1. A continuous process for converting waste plastics into naphtha for polyethylene polymerization, (a) A step of selecting waste plastics including polyethylene and / or polypropylene, (b) A step of passing the waste plastic from (a) through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolysis effluent, (c) A step of separating the pyrolysis effluent into off-gas, pyrolysis oil and pyrolysis wax (including naphtha / diesel fraction and heavy fraction), and char. (d) A step of passing the pyrolysis oil and pyrolysis wax through a crude unit of a refinery, wherein the volumetric flow rate of the pyrolysis oil and pyrolysis wax flowing to the crude unit constitutes a maximum of 50 volume percent of the total flow rate of hydrocarbons flowing to the crude unit. (e) From the crude unit, the naphtha fraction (C ５ -C ８ The process of recovering ) (f) A step of passing the naphtha fraction through a steam cracker for ethylene production, (g) A step of recovering heavy naphtha, diesel and light oil fractions from the crude unit and sending them to a refining unit to be upgraded to gasoline and diesel, The above process, including.

2. The process according to claim 1, wherein the pyrolysis oil and pyrolysis wax of (c) are passed directly through the crude unit and contaminants are removed by the crude unit desalination device.

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

4. The process according to claim 1, wherein the ethylene produced in (f) is then polymerized to produce polymerized ethylene, and polyethylene products are prepared from the polymerized ethylene.

5. The process according to claim 1, wherein heavy naphtha / diesel / atmospheric diesel fuel is recovered from a crude unit and further processed in a refinery into clean gasoline, diesel, or jet fuel.

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

7. The process according to claim 1, wherein the volumetric flow rate of the pyrolysis oil and pyrolysis wax flowing to the crude unit constitutes a maximum of 20 volume percent of the total flow rate of hydrocarbons flowing to the crude unit.

8. Waste plastics are used for polyethylene polymerization. ３ -C ４ A continuous process for converting into flow, (a) A step of selecting waste plastics including polyethylene and / or polypropylene, (b) A step of passing the waste plastic from (a) through a pyrolysis reactor to thermally decompose at least a portion of the polyolefin waste and produce a pyrolysis effluent, (c) A step of separating the pyrolysis effluent into off-gas, pyrolysis oil and pyrolysis wax (including naphtha / diesel fraction and heavy fraction), and char. (d) A step of passing the pyrolysis oil and pyrolysis wax through a crude unit of a refinery, wherein the volumetric flow rate of the pyrolysis oil and pyrolysis wax flowing to the crude unit constitutes a maximum of 50 volume percent of the total flow rate of hydrocarbons flowing to the crude unit. (e) From the crude unit, propane and butane (C ３ -C ４ ) A process to recover a portion of the fraction, (f) The above (C ３ -C ４ ) The process of passing the fraction through a steam cracker for ethylene production, (g) A step of recovering heavy naphtha, diesel and light oil fractions from the crude unit and sending them to a refining unit to be upgraded to gasoline and diesel, The above process, including.

9. The process according to claim 8, wherein the pyrolysis oil and pyrolysis wax of (c) are passed directly through the crude unit and contaminants are removed by the crude unit desalination device.

10. The process according to claim 8, wherein the pyrolysis oil and pyrolysis wax of (c) are treated in a pyrolysis reactor, and contaminants are removed in the pyrolysis reactor.

11. The process according to claim 8, wherein the ethylene produced in (f) is then polymerized to produce polymerized ethylene, and polyethylene products are prepared from the polymerized ethylene.

12. The process according to claim 8, wherein heavy naphtha / diesel / atmospheric diesel fuel is recovered from a crude unit and further processed in a refinery into clean gasoline, diesel, or jet fuel.

13. The process according to claim 8, wherein the volumetric flow rate of the pyrolysis oil and pyrolysis wax flowing to the crude unit constitutes a maximum of 20 volume percent of the total flow rate of hydrocarbons flowing to the crude unit.

14. The process according to claim 8, wherein the waste plastic selected in (a) is from plastic classification groups 2, 4, and / or 5.

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