Circular Economy of Waste Plastics to Polypropylene and Base Oil via Refinery & Crude Unit

Abstract

Provided is a continuous process for converting waste plastics to recycle for polypropylene polymerization. The process includes the steps of selecting waste plastics comprising polyethylene and / or polypropylene, and preparing a stable blend of petroleum and the selected plastics. The amount of plastics in the blend constitutes less than 20 wt% of the blend. The blend is passed to a refinery-crude unit. A liquefied petroleum gas C3 olefin / paraffin mixture is recovered from the refinery-crude unit. The C3 paraffins and C3 olefins are separated into different fractions, the C3 olefin fraction is passed to a propylene polymerization reactor, and the C3 paraffin fraction is passed to a dehydrogenation unit to produce additional propylene. The product stream from the crude unit can also be passed to a hydrocracking unit, and the recovered heavy fraction can then be passed to an isomerization dewaxing unit to prepare base oil.

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, 359 million tonnes in 2018, and 367 million tonnes in 2020. According to McKinsey & Company, global plastic waste is estimated to be 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. The vast majority (>80%) is incinerated, landfilled, or disposed of.

[0003] 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) in quantities small enough 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 into transportation fuels.

[0004] 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.

[0005] US Patent Application Publication No. 2021 / 0130699 discloses a process and system for producing recycle-containing hydrocarbons from recycled waste. The recycled waste is pyrolyzed to form a pyrolysis oil composition, at least a portion of which can be cracked to form a recycled olefin composition.

[0006] 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.

[0007] Globally, recycling and upcycling of plastic waste has attracted great interest to save resources and the environment. Mechanical recycling of plastic waste is quite limited due to the different types, properties, additives, and contaminants of the collected plastics. Usually, recycled plastics are of reduced quality. Chemical recycling into starting materials or value-added chemicals has emerged as a more desirable method.

[0008] However, more robust processes are needed for industrial large-scale chemical recycling of single-use plastics to 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 or value-added chemical products or fuels. Summary of the Invention

[0009] Provided is a continuous process for converting waste plastics into recycling for polypropylene polymerization. The process includes selecting waste plastics that include polyethylene and / or polypropylene. These waste plastics are blended with a petroleum feedstock. The resulting blend is generally a stable blend and homogenous mixture, especially at temperatures below the melting point of the waste plastics. The blend contains up to about 20 wt% of the selected waste plastic. The blend is then passed through a crude unit of a refinery along with conventional refined hydrocarbon feedstocks such as crude oil.

[0010] Integrating this process into oil refinery is an important aspect of the process and can achieve a circular economy with single-use waste plastics such as polypropylene. Thus, the blend is passed to the refinery-crude unit. The blend is passed above the pour point so that the blend can be pumped to the refinery-crude unit. The blend is heated above the melting point of the plastics before being injected into the crude distillation unit. From the crude unit, a liquefied petroleum gas C3 olefin / paraffin mixture is recovered. The C3 olefin / paraffin mixture is separated into a C3 paraffin fraction and a C3 olefin fraction. The C3 olefins are passed to a propylene polymerization reactor to produce polypropylene. The C3 paraffins are sent to a dehydrogenation unit to produce additional propylene. This propylene can be used to produce polypropylene.

[0011] In another embodiment, a stream from the refinery-crude unit is fed to the refinery-hydrocracking unit. The feed to the hydrocracking unit includes at least a heavy fraction from the crude unit. An LPG stream containing C3 hydrocarbons is recovered from the hydrocracking unit. The C3 stream can be sent to a propane / propylene splitter to separate the C3 paraffins and C3 olefins. The C3 olefins are passed to a propylene polymerization reactor to produce polypropylene, and the C3 paraffins are sent to a dehydrogenation unit to produce additional propylene. A heavy fraction is also recovered from the hydrocracking unit, and this fraction is passed to an isomerization / dewaxing unit. Quality base oil is recovered from the dewaxing unit and sent to a hydrofinishing unit for further processing to produce truly premium base oils.

[0012] Refineries generally have their own supply of hydrocarbons that flows through the refinery units. A key aspect of this process is that it does not adversely affect the refinery's operations; the refinery must still produce valuable chemicals and fuels. Otherwise, integrating this process into an oil refinery would not be a viable solution. Therefore, the flow rates must be carefully monitored.

[0013] The volume of waste plastic / petroleum blend flow to the refinery unit can comprise any practical or accommodable volume percent (vol%) of the total flow (total flow) to the refinery unit. In general, the blend flow rate can be up to about 50 vol% of the total flow rate. In one embodiment, the blend flow rate is up to about 25 vol% of the total flow rate (i.e., refinery flow rate plus blend flow rate).

[0014] Among other factors, it has been found that the addition of a refinery operation can efficiently and effectively recycle waste plastics while complementing the refinery operation in the preparation of high value products such as gasoline, base oil, jet fuel and diesel. However, it has also been found that the addition of a refinery operation can efficiently and effectively produce clean propane and propylene from waste plastics and the ultimate polypropylene polymer. Positive economics are realized throughout the process from recycled plastics to polypropylene products with product quality equivalent to virgin polymers. The process can also recycle waste plastics to prepare fine / premium base oils while also preparing polypropylene products. [Brief description of the drawings]

[0015] [Figure 1] Figure 1 shows the current practice of pyrolyzing waste plastics to produce fuel or wax (base case).

[0016] [Diagram 2] Figure 2 illustrates the present process for preparing a homogenous liquid blend of plastic and petroleum feedstocks at high temperature and feeding the blend to a refining and conversion unit.

[0017] [Diagram 3] FIG. 3 shows the details of the stable blend preparation process and how the stable blend is fed to the purification and conversion unit.

[0018] [Figure 4] Figure 4 shows the classification of plastic types for recycling waste plastics.

[0019] [Diagram 5] Figure 5 shows the process where the prepared blend is passed to the refinery crude unit.

[0020] [Figure 6] Figure 6 shows the present process for establishing a circular economy of waste plastics, in which the blend is passed through a refinery crude unit and a hydrocracking unit.

[0021] [Figure 7] FIG. 7 graphically illustrates the thermogravimetric analysis (TGA) of the thermal stability of polyethylene and polypropylene. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 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. In one embodiment, the process and refinery integration can provide premium base oil. Most of the 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 chemicals and fuel products. Currently, only a small amount of polyethylene / polypropylene is recycled via chemical recycling, and the recycled and cleaned polymer pellets are pyrolyzed in a pyrolysis unit to produce fuels (naphtha, diesel), steam cracker feedstock, or slack wax.

[0023] 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.

[0024] FIG. 1 shows a diagram of waste plastic fuel or wax pyrolysis as commonly practiced in industry today. Typically, waste plastics are sorted together (1). The cleaned waste plastics 2 are converted to off-gas 4 and pyrolysis oil (liquid products) in a pyrolysis unit 3. The off-gas 4 from the pyrolysis unit is used as fuel to operate the pyrolysis unit. 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 very 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.

[0025] However, in this process, waste plastics are not pyrolyzed. Rather, a stable mixture of petroleum feedstock and waste plastics is prepared. Thus, the pyrolysis step can be avoided, which is a significant energy saving.

[0026] The blend is prepared in a high temperature blend preparation unit with an operating temperature above the melting point of the plastic (approximately 150-250°C) to create a hot, homogeneous liquid blend of plastic and oil that can be fed directly to the refining unit.

[0027] Alternatively, the blend is prepared in a stable blend preparation unit and the hot homogenous liquid blend is cooled in a controlled manner to ambient temperature for easy storage and transport. Using this method, the stable blend can be prepared at a facility away from the refinery and transported to the refining unit. The stable blend is then heated to a temperature above the melting point of the plastics and fed to the refining conversion unit. The stable blend is a physical mixture of micron-sized plastic particles finely suspended in a petroleum-based oil. The mixture is stable and the plastic particles do not settle or agglomerate even when stored for long periods of time.

[0028] The significance of heating the blend above the melting point of the plastic is clear when a single plastic is used. However, when the waste plastic is composed of multiple waste plastics, the melting point of the plastic with the highest melting point will be exceeded. Thus, the melting points of all the plastics must be exceeded. Similarly, when the blend is cooled to a temperature below the melting point of the plastic, the temperature must be below the melting points of all the plastics that make up the blend.

[0029] Compared to pyrolysis units, these blend preparation units operate at much lower temperatures (approximately 500-600°C versus 120-250°C). Therefore, the process is a much more energy-efficient process for preparing refined feedstock from waste plastics than thermal decomposition processes such as pyrolysis.

[0030] The use of the waste plastic / petroleum blend of the present invention further increases the overall yield of hydrocarbons obtained from waste plastics. This increase in yield is significant. The hydrocarbon yield using the present blend can reach up to 98%. In contrast, pyrolysis produces a significant amount of light products from plastic waste, about 10-30 wt% and about 5-10 wt% char. These light hydrocarbons are used as fuel to run the pyrolysis plant, as mentioned above. Thus, the liquid hydrocarbon yield from the pyrolysis plant is up to 70-80%.

[0031] When the blend is passed through a refinery unit, such as a crude unit, only a small amount of off-gas is produced. The refinery unit uses a (catalytic) catalytic cracking process, which is different from the thermal cracking process used in pyrolysis. The catalytic process minimizes the production of undesirable light by-products such as methane and ethane. The refinery unit provides efficient product fractionation, allowing efficient utilization of all hydrocarbon product streams to produce high value materials. The refinery co-feed produces only about 2% off-gas (H2, methane, ethane, ethylene). The C3 and C4 streams are captured to produce useful products such as cyclic polymers and / or high quality fuel products (including base oils). Thus, the use of the oil / plastic blend of the present invention not only leads to increased hydrocarbons from waste plastics, but also provides a more energy-efficient recycling process compared to thermal treatment processes such as pyrolysis.

[0032] The process converts single-use waste plastics on a large scale by blending them with petroleum product streams and integrating them into oil refinery operations. The resulting process produces feedstocks for polymers (liquefied petroleum gas (LPG), C3 streams for propylene polymerization units), high-quality gasoline, diesel fuel, jet fuel, and / or high-quality base oils.

[0033] In general, the process provides a circular economy for polypropylene plants. Polypropylene is produced via polymerization of pure propylene. Clean C3 streams can be obtained from oil refineries, crude units and other conversion units. Clean propylene can be produced from propane dehydrogenation units. Pure propylene can be separated from paraffin / olefin mixtures using propane / propylene splitters, high efficiency distillation columns (PP splitters).

[0034] By adding a refinery operation to upgrade the waste plastics to higher value products (gasoline, jet fuel, diesel, and base oils) and to produce clean propane and propylene for the production of ultimate polypropylene polymer, positive economics are realized throughout the process from recycled plastics to a polypropylene product with qualities equivalent to virgin polymer. Also, by integrating the recycling process with an oil refinery operation, a more energy efficient and effective process is achieved while avoiding the problems of refinery operations.

[0035] The integration of refinery operations is also very important in another aspect. Waste plastics contain contaminants such as calcium, magnesium, chlorides, nitrogen, sulfur, dienes, and heavy components, which prevent their products from being 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 pretreatment unit and their negative impacts can be reduced. The fuel components can be further upgraded in a suitable refinery unit using chemical conversion processes, and the final transportation fuel produced by the integrated process can be of higher quality and 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 specifications makes the "circular economy" of recycled plastics possible.

[0036] 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.

[0037] In some cases, the energy required to convert waste plastics into clean fuels is less than the energy required to produce fuels from virgin petroleum feedstocks. As collection and processing of waste plastics improves, energy efficiency will improve further. Such fuels and base oils produced from blends of waste plastics and oils contain recycled content and have a lower carbon footprint than corresponding fuels and base oils produced from pure petroleum feedstocks. The process allows the production of clean gasoline, jet fuel, diesel and base oils from waste plastics that contain recycled content and have a lower CO2 footprint (low carbon footprint).

[0038] FIG. 2 shows a method for preparing a hot homogenous blend of plastic and oil feedstock for use in the process, which is injected directly into the refinery unit, in which a hot homogenous liquid blend of plastic and oil is prepared in a hot blend preparation unit. The preferred range of plastic composition in the blend is about 1-20 wt%. When high molecular weight polypropylene (average molecular weight 250,000 or more) waste plastic or high density polyethylene (density greater than 0.93 g / cc) is mainly used as waste plastic, for example at least 50 wt%, the amount of waste plastic used in the blend is more preferably about 10 wt%. This is because the pour point and viscosity of the blend will be higher.

[0039] Preferred conditions for the preparation of hot homogenous liquid blends include vigorously mixing the plastic with the petroleum feedstock while heating it to a temperature above the melting point of the plastic. Preferred process conditions include heating to a temperature of 250-550°F, a residence time at the final heating temperature of 5-240 minutes, and atmospheric pressure of 0-10 psig. This can be done in open air or preferably under an oxygen-free inert atmosphere.

[0040] Referring to FIG. 2 of the drawings, a step-by-step preparation process for preparing a hot homogenous liquid blend is shown. The mixed waste plastics are sorted to produce post-consumer waste plastics 21 including polyethylene and / or polypropylene. The waste plastics are cleaned (22) and then mixed with oil 24 in a hot blend preparation unit 23. After mixing in 23, a homogenous blend of plastics and oil is recovered (25). Optionally, a filtration device can be added (not shown) to remove undissolved plastic particles or solid impurities present in the hot liquid blend. The hot blend of plastics and oil can then be combined with a refinery feedstock, such as crude oil 50, resulting in a mixture of plastic / oil blend and crude oil 26, which can then be passed to a refinery unit. In this process, in one embodiment, the refinery unit is a crude unit.

[0041] FIG. 3 shows a method for preparing a stable blend of plastics and oil for use in the present process. The stable blend is made by a two-step process in a stable blend preparation unit. In the first step, a hot homogeneous liquid blend of plastic melt and oil feedstock is produced. This step is the same as the hot blend preparation described in FIG. 2. The preferred range of plastic composition in the blend is about 1-20 wt%. If high molecular weight polypropylene (average molecular weight ≧250,000) waste plastics or high density polyethylene (density above 0.93 g / cc) are mainly used as waste plastics, for example at least 50 wt%, the amount of waste plastic used in the blend is more preferably about 10 wt%. The reason is that the pour point and viscosity of the blend will be higher.

[0042] Preferred conditions for the preparation of hot homogenous liquid blends include vigorously mixing the plastic with the petroleum feedstock while heating it to a temperature above the melting point of the plastic. Preferred process conditions include heating to a temperature of 250-500°F, a residence time at the final heating temperature of 5-240 minutes, and atmospheric pressure of 0-10 psig. This can be done in open air or preferably under an oxygen-free inert atmosphere.

[0043] In the second step, the hot blend is cooled to a temperature below the melting point of the plastic while continuing to vigorously mix with the oil feedstock, and then further cooled to a lower temperature, preferably ambient temperature, to produce a stable blend of plastic and oil.

[0044] The stable blend is found to be an intimate physical mixture of plastic and oil feedstock. The plastic is in a "deagglomerated" state. The plastic maintains a fine dispersion of solid particles in the oil feedstock below the melting point of the plastic, especially at ambient temperatures. The blend is stable and easy to store and transport. At the refinery, the stable blend is heated in a preheater above the melting point of the plastic to produce a hot homogenous liquid blend of plastic and oil. This hot liquid blend can then be fed to the refinery unit as a co-feed along with conventional refinery feedstocks.

[0045] Further details of the preparation of the stable blend are shown in FIG. 3. The stable blend is made by a two step process in the stable blend preparation unit 100. As shown, clean waste 22 is passed through the stable blend preparation unit 100. Selected plastic waste 22 is heated and mixed with refinery feedstock oil 24. The plastic waste is heated to a temperature above the melting point of the plastic to melt the plastic. The petroleum feedstock is mixed with the heated plastic at 23. The mixing is often very vigorous. The mixing and heating conditions can generally be heating at a temperature in the range of about 250-500°F with a residence time of 5-240 minutes at the final heating temperature. The heating and mixing can be done in open air or under an oxygen-free inert atmosphere. The result is a hot homogenous liquid blend of plastic and oil 25. Optionally, a filtration device can be added (not shown) to remove any undissolved plastic particles or solid impurities present in the hot homogenous blend.

[0046] The hot blend 25 is then cooled to a temperature below the melting point of the plastic while continuing to mix with the oil feedstock 101. Cooling is typically continued to ambient temperature to produce a stable blend of plastic and oil 102. At the refinery, the stable blend can be fed to a preheater 29, which heats the blend above the melting point of the plastic to produce a mixture of plastic / oil blend and VGO 26, which is then fed to a refinery conversion unit. In this process, in one embodiment, the refinery unit is a crude unit.

[0047] The preferred plastic 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 blend preparation unit. Figure 4 shows the plastic type classification for waste plastics 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 preferred to use at least some polypropylene waste plastic in the process. Polystyrene (class 6) can also be present in limited amounts.

[0048] 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 20%, preferably less than 10%, and most preferably less than 5%.

[0049] Washing of waste plastics can remove metal 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.

[0050] 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.

[0051] The petroleum with which the waste plastics are blended is generally the petroleum feedstock for the refinery. The petroleum blend oil is preferably the same as the petroleum feedstock for the refinery. The petroleum may also include petroleum-derived oil or petroleum-based materials. In one embodiment, the petroleum feedstock may include atmospheric gas oil, vacuum gas oil (VGO), atmospheric resid, or heavies recovered from other refining operations. In one embodiment, the petroleum feedstock with which the waste plastics are blended includes VGO. In one embodiment, the petroleum feedstock with which the waste plastics are blended includes light cycle oil (LCO), heavy cycle oil (HCO), FCC naphtha, gasoline, diesel, toluene, and aromatic solvents derived from petroleum.

[0052] FIG. 5 illustrates one embodiment of the integrated process of the present invention where the blend is sent to a crude unit. The same numbers in FIG. 5 that correspond to FIG. 2 and FIG. 3 refer to the same items / units. As shown, the selected waste 21 is cleaned (2) and then passed to a blend preparation unit 23 where plastics and refinery feedstocks 24 are blended to create a hot blend of plastics and oils 25. Crude oil 50, preferably desalted crude oil, is added to this blend, if necessary. If the plastic / oil blend is still hot (25 in FIG. 2), it can be mixed with the co-feed oil 50 immediately. However, if the stable blend of plastics / oil needs to be heated for storage or transportation (102 in FIG. 3), the blend is generally heated to a temperature above the melting point of the plastics, for example, using a preheater (preheater 29 in FIG. 3), before mixing with the co-feed crude oil. This homogenous plastic / oil blend and crude oil 26 are then sent to the crude unit 27 of the refinery. In another embodiment, the heated blend and crude oil co-feeds are each passed directly, but separately, to a crude unit.

[0053] Refinery-crude units separate crude oil into multiple fractions, such as liquefied petroleum gas (LPG), naphtha, kerosene, diesel, and gas oil, which are further processed into useful petroleum products. Refinery-crude units consist of a crude oil processing section, commonly known as a desalter, a preheater section, and a crude oil distillation or fractionation section. The distillation section typically includes atmospheric and / or vacuum distillation units.

[0054] The blend and any co-feeds are fed to a preheater unit or downstream of the preheater unit. The blend and co-feeds should not be fed to a desalter, which removes salts and solids contained in the oil and protects downstream equipment from the harmful effects of contaminants. Desalter units are typically operated at temperatures between about 215°F and about 280°F, which is too low and may result in some loss of plastic particles in the blend.

[0055] A refinery generally has its own hydrocarbon feed that flows through the refinery unit. In this case, the hydrocarbon feed is crude oil 50, as shown in FIG. 5. The volume of the blend stream flowing to the refinery unit (here the FCC unit) can constitute any practical or accommodable volume percent (vol%) of the overall stream (total flow) to the refinery unit. In general, the blend flow rate can be up to about 50 vol% of the total flow rate (i.e. refinery flow rate plus blend flow rate) for practical reasons. In another embodiment, the blend volumetric flow rate is an amount up to about 25 vol% of the total flow rate. About 50 vol% has been found to be a very practical amount in terms of impacts on the refinery, while at the same time providing good results and being accommodable. It is important to avoid adverse effects on the refinery and its products. If the amount of plastic in the final blend exceeds 20 wt% of the final blend, problems may arise in the operation of the crude unit. By final blend, we mean the plastic / oil blend and any co-feed petroleum.

[0056] The crude unit's atmospheric distillation unit is heated to approximately 340-372 °C (644-700 °F) at the bottom of the distillation column, and liquids are removed at various points in the fractionation column to produce a variety of fuels. Fuels from the crude unit are sent to various upgrading units within the refinery to remove impurities (nitrogen, sulfur) and convert the fractions with catalysts to improve product properties such as octane and cetane numbers.

[0057] In FIG. 5, bottoms or heavy fractions 30 are recovered from the atmospheric distillation column of the refinery's crude unit 27. Heavy naphtha and diesel fractions 33 and straight run naphtha (C5-C8) 32 can also be recovered. All fractions can be sent to various upgrading processes 34 to produce streams that can be passed to gasoline, jet fuel and diesel fuel pools 35. This overall 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.

[0058] From the refinery and crude unit, a C3 LPG (liquefied petroleum gas) stream 31 is collected. The C3 stream 31 is passed to a propane / propylene splitter (PP splitter) 43 and separated to produce streams of propane 44 and propylene 45. The propylene 45 is fed to a propylene polymerization unit 41 to produce polypropylene. Clean C3 (46) from various upgrading processes 34 can also contribute to the feed to the PP splitter 43.

[0059] Pure propane 44 can be fed to a propane dehydrogenation unit 40 to produce additional propylene, and then finally to a propylene polymerization unit 41 to produce polypropylene.

[0060] 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.

[0061] The PP splitter unit and / or the propane dehydrogenation unit can be located away from the refinery, near the refinery, or within the refinery. The propane / propylene mixture is sent to the PP splitter by truck, barge, rail car, or pipeline. The PP splitter unit and the propane dehydrogenation unit are preferably located in close proximity to the refining FCC unit.

[0062] The polypropylene polymer 47 produced in the propylene polymerization unit 41 can be made into a consumer product 42 .

[0063] Referring to FIG. 6, as in FIG. 5, the same numbers as in FIG. 2 and FIG. 3 refer to the same streams, blends, or units. Selected waste 21 is cleaned (22) and then passed to a blend preparation unit 23 where plastics and refinery feedstocks 24 are blended to create a stable blend of plastics and oil 25. Crude oil 50 is added to this blend, if necessary. If the plastic / oil blend is still hot (25 in FIG. 2), it can be immediately mixed with the co-feed oil 50. However, if the stable plastic / oil blend needs to be heated for storage or transportation (102 in FIG. 3), the blend is typically heated to a temperature above the melting point of the plastics, for example, using a preheater (preheater 29 in FIG. 3), before mixing with the co-feed crude oil. This homogenous plastic / oil blend and crude oil 26 are then sent to the crude unit 27 of the refinery.

[0064] The bottoms from the atmospheric distillation tower of crude unit 27, also known as atmospheric resid, are typically sent to the vacuum distillation tower of the crude unit, which produces vacuum gas oil (650-1050°F) and vacuum resid. Vacuum gas oil may be used to make lubricating oil or may be further cracked to produce gasoline, jet fuel and diesel fuel. This overall 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.

[0065] In FIG. 6, streams from a refinery-crude unit 27, including vacuum gas oil 20, are passed to a refinery-hydrocracker unit 28. Any suitable hydrocracking operation may be performed. The catalyst in the hydrocracker may be selected from any known hydrocracking catalyst. Hydrocracking conditions generally include temperatures ranging from 175° C. to 485° C., hydrogen to hydrocarbon molar ratios ranging from 1 to 100, pressures ranging from 0.5 to 350 bar, and liquid hourly space velocities (LHSVs) ranging from 0.1 to 30. In the hydrocracking reactor, larger molecules are cracked into smaller molecules. Hydrocracking catalysts typically include a large pore zeolite, such as USY, and various combinations of Group VI and Group VIII base metals, such as nickel, cobalt, molybdenum, and tungsten, finely dispersed on an alumina or oxide support.

[0066] From the hydrocracking unit, a C3 stream 51 of LPG, a clean effluent stream 52 including gasoline, jet fuel and diesel fuel fractions, and a heavy fraction 54 are recovered. The heavy fraction 54 is passed to an isomerization / dewaxing unit 55. In the dewaxing reactor, the feed may first be contacted with a hydrotreating catalyst under hydrotreating conditions in a hydrotreating zone or guard bed to provide a hydrotreated feed. Hydrotreating catalysts typically contain various combinations of Group VI and Group VIII base metals such as nickel, cobalt, molybdenum and tungsten, which are finely dispersed on an alumina or oxide support. Contacting the feed with the hydrotreating catalyst in the guard bed can effectively hydrogenate aromatics in the feed and remove N- and S-containing compounds from the feed to protect the hydroisomerization catalyst of the catalytic system. By "effectively hydrogenating aromatics" it is meant that the hydrotreating catalyst can reduce the aromatic content of the feed by at least about 20%. The hydrotreated feed generally contains C 10+ n-paraffins and slightly branched isoparaffins, and the wax content is typically at least about 20%.

[0067] Hydroisomerization catalysts useful in the present process typically contain catalytically active hydrogenation metals. The presence of catalytically active hydrogenation metals results in product improvements, particularly in viscosity index (VI) and stability. Typical catalytically active hydrogenation metals include chromium, molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and palladium. The metals platinum and palladium are particularly preferred, with platinum being most particularly preferred. When platinum and / or palladium are used, the total amount of active hydrogenation metals typically ranges from 0.1 wt% to 5 wt% of the total catalyst, usually 0.1 wt% to 2 wt%. Additionally, hydroisomerization catalysts typically contain a medium pore size zeolite, such as ZSM-23, ZSM-48, ZSM-35, SSZ-32, SSZ-91, etc., dispersed on an oxide support.

[0068] The refractory oxide support may be selected from oxide supports conventionally used in catalysts, including silica, alumina, silica-alumina, magnesia, titania, and combinations thereof.

[0069] Conditions within isomerization / dewaxing reactor unit 55 generally include a temperature range of about 390°F to about 800°F (199°C to 427°C). In one embodiment, hydroisomerization dewaxing conditions include a temperature range of about 550°F to about 700°F (288°C to 371°C). In further embodiments, the temperature may range from about 590°F to about 675°F (310°C to 357°C). Total pressure may range from about 500 to about 3000 psig (0.10 to 20.68 MPa), typically from about 750 to about 2500 psig (0.69 to 17.24 MPa).

[0070] From the isomerization / dewaxing unit 55, a dewaxed oil 56 can be recovered, which can be used as a base oil. The oil can also be passed to a hydrofinishing unit 57 to prepare a premium base oil 58. In the hydrofinishing unit 57, hydrofinishing can be carried out in the presence of a hydrofinishing catalyst, as known in the art. The hydrofinishing catalyst used in hydrofinishing can include, for example, platinum, palladium, or combinations thereof on an alumina support. Hydrofinishing can be carried out at temperatures ranging from about 350°F to about 650°F (176°C to about 343°C) and pressures ranging from about 400 psig to about 4000 psig (2.76 to 27.581 MPa). Hydrofinishing to produce lubricating oils is described, for example, in U.S. Pat. No. 3,852,207, the disclosure of which is incorporated herein by reference.

[0071] The C3LPG stream 51 may be passed to a PP splitter 43. The naphtha stream 52 may be passed in whole or in part to a gasoline pool or upgrading process for upgrading fuel fractions.

[0072] PP splitter 43 produces streams of propane 44 and propylene 45. Propylene 45 is fed to propylene polymerization unit 41 to produce polypropylene. Pure propane 44 can be fed to propane dehydrogenation unit 40 to remove additional propylene before finally producing polypropylene in propylene polymerization unit 41.

[0073] 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 carried out at temperatures between 50 and 90 °C and pressures between 8 and 35 atm in the presence of H2. Bulk polymerization proceeds at 60-80 °C and at pressures of 30-40 atm to keep the propylene in a liquid state.

[0074] The propylene polymerization unit 43 is preferably located near the refinery so that the feedstock (propylene) can be transported via pipeline. For petrochemical plants located remotely from the refinery, the feedstock can be delivered via truck, barge, rail car, or pipeline.

[0075] The benefits of a circular economy and effective and efficient recycling campaigns are realised through this integrated process.

[0076] 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

[0077] [Example 1] Characteristics of plastic samples and raw materials used for blend preparation

[0078] Four plastic samples were purchased (low density polyethylene (LDPE, Plastic A), high density polyethylene (HDPE, Plastic B), and two polypropylene samples with average molecular weights of approximately 12,000 (PP, Plastic C) and approximately 250,000 (PP, Plastic D)) and their properties are summarized in Table 1. [Table 1]

[0079] The petroleum feedstocks used to prepare stable blends with plastics include hydrotreated vacuum gas oil (VGO), Aromatic 100 solvent, light cycle oil (LCO), and diesel, the properties of which are shown below in Table 2. Aromatic 100 is a commercially available aromatic solvent produced from petroleum-based materials and contains primarily C9-C10 di- and tri-alkylbenzenes. [Table 2]

[0080] Thermogravimetric analysis (TGA) was performed on Plastic A (LDPE) and Plastic C (polypropylene) to confirm that the plastic materials are thermally stable at temperatures well above the melt preparation temperature. The TGA results, shown in Figure 7, indicate that the LDPE sample is stable up to 800°F and the polypropylene sample is stable up to 700°F.

[0081] [Example 2] Feedstock for C3-C4 and / or naphtha production from co-feeding waste plastic / oil blends to refinery crude units

[0082] The plastic / oil blend is fed, with or without co-feeds, to a crude unit where the blend is fractionated into its components. The refinery / crude unit produces large quantities of clean propane, butane, and naphtha streams, as well as other streams for the refinery conversion units. The conversion units downstream of the crude unit (such as FCC units and hydrocracking units) produce even larger quantities of clean propane, butane, and naphtha streams, as well as other streams.

[0083] [Example 3] Processing of plastic and petroleum blends in a crude unit followed by a conversion unit to produce fuels and base oils with recycled content and a low CO2 footprint

[0084] From the crude unit, the heavy fraction is sent to a conversion unit (such as an FCC unit or a hydrocracking unit) where the heavy hydrocarbon molecules are cracked and can be converted into gasoline, jet fuel, diesel, and heavy fractions. These blending components can be sent to corresponding blending pools and blended into finished gasoline, jet fuel, diesel, or marine oils that contain recycled components and have a low CO2 footprint. A portion of the heavy fraction can be further processed in an isomerization / dewaxing unit to prepare base oils or white oils that contain recycled components and have a low CO2 footprint.

[0085] [Example 4] Feeding recycled C3 to a PP splitter for the production of propylene and subsequent production of polypropylene resin and polypropylene consumer products

[0086] According to Example 2 (Figure 5), a propane stream is produced via co-feeding the plastic / oil blend to the crude unit, and these streams are suitable feedstocks for the production of propylene with recycled content. At least a portion of this stream (if not all) is fed to the PP splitter. The propylene can be processed in a polymerization unit to produce polypropylene resin containing recycled polyethylene / polypropylene derived material, but the quality of the newly produced polypropylene is indistinguishable from virgin polypropylene made entirely from virgin petroleum resources. This polypropylene resin containing recycled material can be further processed to produce a variety of polypropylene products for consumer product needs. These polypropylene consumer products contain chemically recycled circular polymers, but the quality of those 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. [Example 5] Hydrocracking of VGO obtained from a blend of plastics and petroleum

[0087] Hydrocracking of the heavy fractions, including plastics and VGO, produces a C3 stream that can be fed to a PP splitter to obtain propylene for polypropylene production (Figure 6). Materials in the gasoline, jet fuel and diesel boiling ranges are sent to corresponding blending pools where they can be blended into finished gasoline, jet fuel and diesel, respectively. The bottoms product, boiling in the range of 650-1000°F, is a waxy oil.

[0088] [Example 6] Dewaxing of hydrocracker bottoms obtained from plastics and petroleum blends

[0089] The bottoms fraction from Example 5 can be dewaxed to produce base oil (Figure 6). The heavy fraction from the hydrocracking unit can be passed to an isomerization / dewaxing unit. A dewaxed oil, i.e., base oil, can be recovered from the unit. The base oil can then be further passed to a hydrofinishing unit to prepare premium base oil or white oil.

[0090] 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.

[0091] All patents and publications referenced herein are incorporated herein by reference to the extent that they are 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 will 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) preparing a blend of petroleum and the selected waste plastic, the blend comprising no more than 20 wt.% of the selected waste plastic; (c) passing the blend through a refinery crude unit at a temperature above the melting point of the plastic; (d) extracting liquefied petroleum gas C from the crude unit; ３ recovering the olefin / paraffin mixture; (e) The above C ３ Paraffin and C ３ separating the olefins into different fractions; (f) The above C ３ passing the olefins through a propylene polymerization reactor; The above process comprising:

2. 10. The process of claim 1, wherein gasoline and heavy distillates are recovered from a refinery crude unit.

3. 2. The process of claim 1, wherein the blend of (b) is a high temperature homogenous blend of waste plastic and petroleum.

4. 2. The process of claim 1, wherein the blend of (b) is a stable blend of waste plastic and petroleum.

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

6. 10. The process of claim 1, wherein a naphtha stream and a heavy fraction are recovered from the crude unit and further processed in a refinery to obtain clean gasoline, diesel, or jet fuel.

7. 2. The process of claim 1, wherein the volumetric flow rate of the blend in (c) flowing to the refinery crude unit comprises up to about 50 volume percent of the total hydrocarbon flow rate flowing to the crude unit.

8. 8. The process of claim 7, wherein the blended flow rate comprises up to about 25 volume percent of the total flow rate to the crude unit.

9. 2. The process of claim 1, wherein in (b) the blend of petroleum and selected waste plastic is prepared by heating the waste plastic to a temperature above the melting point of the plastic, mixing with petroleum, and then cooling the blend to a temperature below the melting point of the waste plastic.

10. 2. The process of claim 1, wherein the petroleum oils in the blend include atmospheric gas oils, vacuum gas oil (VGO) atmospheric resid, petroleum derived oils, petroleum based materials, and / or heavies recovered from refining operations.

11. 2. The process of claim 1, wherein the petroleum in the blend comprises light cycle oil (LCO), heavy cycle oil (HCO), FCC naphtha, gasoline, diesel, toluene, and / or petroleum derived aromatic solvents.

12. A continuous process for converting waste plastics into recycling for polypropylene polymerization, comprising: (a) selecting waste plastics comprising polyethylene and / or polypropylene; (b) preparing a blend of petroleum and the selected waste plastic, the blend comprising no more than 20 wt.% of the selected plastic; (c) passing the blend through a refinery crude unit; (d) extracting liquefied petroleum gas C from the crude unit; ３ recovering the olefin / paraffin mixture; (e) The above C ３ Paraffin and C ３ separating the olefins into different fractions; (f) The above C ３ passing the olefins through a propylene polymerization reactor; (g) The above C ３ passing the paraffins through a dehydrogenation unit to produce propylene; The above process comprising:

13. 13. The process of claim 12, wherein gasoline and heavy distillates are recovered from a refinery crude unit.

14. 13. The process of claim 12, wherein the blend of (b) is a high temperature homogenous blend of waste plastic and petroleum.

15. 13. The process of claim 12, wherein the blend of (b) is a stable blend of waste plastic and petroleum.

16. 13. The process of claim 12, wherein the waste plastics selected in (a) are plastics from classification groups 2, 4, and / or 5.

17. 13. The process of claim 12, wherein naphtha and heavy fractions are recovered from the crude unit and further processed in a refinery to obtain clean gasoline, diesel, or jet fuel.

18. 13. The process of claim 12, wherein the volumetric flow rate of the blend in (c) flowing to the refinery crude unit comprises up to about 50 volume percent of the total hydrocarbon flow rate flowing to the crude unit.

19. 20. The process of claim 18, wherein the blended flow rate comprises up to about 25 volume percent of the total flow rate to the crude unit.

20. 13. The process of claim 12, wherein the blend of petroleum and the selected waste plastic in (b) is prepared by heating the waste plastic to a temperature above the melting point of the plastic, mixing with petroleum, and then cooling the blend to a temperature below the melting point of the waste plastic.

21. 13. The process of claim 12, wherein the petroleum oils in the blend include atmospheric gas oils, vacuum gas oils (VGO), atmospheric residua, petroleum-derived oils, petroleum-based materials, and / or heavies recovered from refining operations.

22. 13. The process of claim 12, wherein the petroleum oils in the blend include light cycle oil (LCO), heavy cycle oil (HCO), FCC naphtha, gasoline, diesel, toluene, and / or petroleum derived aromatic solvents.

23. 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) preparing a blend of petroleum and the selected waste plastic, the blend comprising no more than 20 wt.% of the selected plastic; (c) passing the blend through a refinery crude unit; Including the above process.

24. A continuous process for converting waste plastics into recycling for polypropylene polymerization, comprising: (a) selecting waste plastics comprising polyethylene and / or polypropylene; (b) preparing a blend of petroleum and the selected waste plastic, the blend comprising no more than 20 wt.% of the selected waste plastic; (c) passing the blend through a refinery crude unit at a temperature above the melting point of the plastic; (d) recovering a heavy fraction from the crude unit and passing the heavy fraction to a refinery / hydrocracking unit; (e) recovering a heavy fraction from the hydrocracking unit and passing the heavy fraction to an isomerization dewaxing unit; The above process comprising:

25. 25. The process of claim 24, wherein the base oil is recovered from the isomerization dewaxing unit and passed to a hydrofinishing unit.

26. A continuous process for converting waste plastics into recycling for the preparation of low carbon footprint fuels and base oils, comprising: (a) selecting waste plastics comprising polyethylene and / or polypropylene; (b) preparing a blend of petroleum and the selected waste plastic, the blend comprising no more than 20 wt.% of the selected waste plastic; (c) passing the blend through a refinery-crude unit at a temperature above the melting point of the plastics in the blend; (d) recovering a heavy fraction from the crude unit and passing the heavy fraction to a hydrocracking unit; (e) recovering a heavy fraction from the hydrocracking unit and passing the heavy fraction to a refinery isomerization / dewaxing unit; (f) recovering a base oil from the isomerization dewaxing unit; The above process comprising:

27. 27. The process of claim 26, wherein the low carbon footprint fuel comprises gasoline, jet fuel, diesel, and / or marine oil.

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