New supplies for co-processing waste plastics in refineries

Abstract

A stable blend is provided of petroleum bottom distillation column (ATB) feedstock and 1 to 20% by weight of plastic based on the weight of the blend, wherein the plastic includes polyethylene and / or polypropylene, and the plastic in the blend includes finely dispersed microcrystalline particles having an average particle size of 10 to less than 100 microns. A method is also provided for preparing a stable blend of plastic and petroleum, comprising mixing the petroleum feedstock with the plastic containing polyethylene and / or polypropylene, and heating the mixture to a temperature above the melting point of the plastic but below 500°F. The liquid blend of the plastic molten material and the petroleum feedstock is then cooled to a temperature below the melting point of the plastic while mixing.

Description

Background Art

[0001] Cross - reference to related applications This application was filed as a PCT international application on May 22, 2024, claiming the benefit and priority of U.S. Provisional Patent Application No. 63 / 503,994, filed on May 24, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] The world has experienced extremely rapid growth in plastic production. According to the PlasticEurope 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 amount of plastic waste in the world was estimated to be approximately 260 million tons per year in 2016 and is predicted to reach 460 million tons per year by 2030 if the current trend continues.

[0003] Single - use plastic waste has become an increasingly important environmental issue. At present, there seem to be few options for recycling polyethylene and polypropylene waste plastics into value - added chemical substances and fuel products. Currently, only a small amount of polyethylene / polypropylene is recycled by chemical recycling, and the recycled and washed plastic pellets are pyrolyzed in a pyrolysis unit to produce fuel (naphtha, diesel), steam cracker feed, or slack wax. More than 80% of the majority is incinerated, landfilled, or discarded.

[0004] Current methods of chemical recycling through 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 feedstocks. However, this simple blending is unsustainable when very large quantities of waste polyethylene and polypropylene must be recycled to address environmental concerns. The products from pyrolysis units are too low in quality to be blended in large quantities into transport fuels (e.g., 5-20% by volume).

[0005] Methods for converting waste plastics into hydrocarbon lubricants are known. For example, U.S. Patent No. 3,845,157 discloses the production of synthetic hydrocarbon lubricants by cracking waste polyolefins or virgin polyolefins to form gaseous products such as ethylene / olefin copolymers, which are then further processed. 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 method 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 method for converting waste plastics into lubricating oil. European Patent Application Publication No. 0620264 discloses a method for producing lubricating oil from waste polyolefins or virgin polyolefins, comprising thermal cracking of the waste in a fluidized bed to form a waxy product, optionally using a hydrogenation treatment, then catalytically isomerizing it, and fractionating it to recover the lubricating oil.

[0006] U.S. Patent Application Publication No. 2021 / 0130699 discloses a method and system for producing recycled hydrocarbons from recycled waste materials. Recycled waste can be pyrolyzed to form a pyrolysis oil composition, and then at least a portion thereof can be cracked to form a recycled olefin composition.

[0007] Other literature on methods for converting waste plastics into lubricants includes 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, as well as 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.

[0008] Globally, the reuse or upcycling of plastic waste is attracting significant attention as a way to conserve resources and protect the environment. Mechanical recycling of plastic waste is considerably limited due to differences in type, properties, additives, and contaminants in the collected plastics. Recycled plastics are typically of lower quality. Chemical recycling into starting materials or value-added chemicals is emerging as a more desirable route.

[0009] However, more robust methods are needed to achieve industrially significant chemical recycling of single-use plastics and reduce their environmental impact. Such methods may require specialized handling and manipulation of waste plastics. The use of available supplies can also increase the overall efficiency of the method, thereby having a positive impact on the economy. [Overview of the Initiative]

[0010] In one embodiment, a novel composition of a stable blend of waste plastic and petroleum-based feedstock is provided for the direct conversion of waste plastic in a refining unit.

[0011] In one embodiment, a method is provided for preparing a blend of plastic and a specific petroleum-based feedstock, which is the bottom fraction (ATB) of an atmospheric distillation column. This method includes mixing the ATB petroleum-based feedstock and the plastic together and heating the mixture to a temperature above the melting point of the plastic but below 500°F. By continuously mixing the liquid blend of the plastic molten material and the ATB feedstock, the composition and method prepare a homogeneous blend of plastic and ATB feedstock. Optionally, the liquid blend of plastic molten material and ATB feedstock may be cooled to a temperature below the melting point of the plastic.

[0012] In particular, this composition and method prepares a stable blend of plastic and ATB feedstock. This blend of plastic and ATB feedstock provides a means for efficiently and effectively supplying waste plastic to a refining process for converting waste plastic into high-yield products in large quantities. The composition and method of the present invention enables the mechanistic use of ATB residue in waste plastic recycling processes in refineries. It has been found that by preparing this blend and supplying it to refining operations such as FCC units, plastic waste can be efficiently and effectively recycled while complementing refinery operations in the preparation of high-value products such as gasoline, jet fuel, base oils, and diesel fuels. Polyethylene and polypropylene can also be produced efficiently and effectively from waste plastic. In fact, a positive economic impact is realized by the entire recycling process, in which the product quality is equivalent to that of virgin polymers. Energy is also saved in the use of this blend, and it is more environmentally friendly than conventional recycling processes. And all of this is achieved by using residue from atmospheric distillation columns. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows the current implementation (base case) of producing fuel or wax by thermally decomposing waste plastics.

[0014] [Figure 2] This diagram illustrates the method for preparing a high-temperature homogeneous liquid blend of plastic and petroleum ATB feedstock, and how the blend can be supplied to a purification and conversion unit.

[0015] [Figure 3] This diagram details the process for preparing the stable blend and how the stable blend can be supplied to the purification and conversion unit.

[0016] [Figure 4] This diagram shows the classification of plastic types for recycling waste plastics.

[0017] [Figure 5] This figure shows the method, in which the prepared blend is sent to a conversion FCC unit at a refinery to produce value-added chemicals and fuels, as well as chemicals for preparing recycled polyethylene.

[0018] [Figure 6] This figure shows the method, in which the prepared blend is sent to a conversion unit in a refinery to generate chemicals for preparing recycled polypropylene.

[0019] [Figure 7] This diagram shows the process of sending the prepared blend to a conversion unit in a refinery to produce chemical substances.

[0020] [Figure 8] This graph shows the thermogravimetric analysis (TGA) results for low-density polyethylene and polypropylene polymers.

[0021] [Figure 9]It is a graph showing thermogravimetric analysis (TGA) of the thermal stability of four waste plastic samples.

Embodiments for Carrying Out the Invention

[0022] A method for preparing a stable blend of a plastic and an ATB residue feedstock for the blending of a novel plastic and a petroleum-based feedstock and for the direct conversion of a plastic in a refining process unit is disclosed.

[0023] The petroleum-based feedstock includes a bottom fraction of an atmospheric distillation column. The bottom fraction of an atmospheric distillation column (ATB) is the residue from the distillation of an atmospheric distillation column. ATB generally boils above 650°F (343°C). Generally, depending on quality and demand, ATB is sent to several different units. These units can include a fluid catalytic cracking (FCC) unit, or a vacuum distillation unit for recovering heavy distillates for further processing into lubricating oils and waxes. Otherwise, the ATB is simply burned to recover energy. The ATB can be processed at the same refinery where the ATB is produced, or optionally, transported to another refinery for use. Since ATB is a heavy petroleum fraction, heated equipment is required for pipeline transportation.

[0024] This method includes supplying ATB to an FCC unit as a machine-utilized feedstock, and optionally transporting the ATB before FCC processing. Here, waste plastics are dissolved in ATB before being supplied to the FCC unit, where they are cracked to form a typical FCC product containing precursors for recycled plastic production. Waste plastics can be dissolved in ATB before or after transport of ATB, or even during transport to another facility. Since ATB already requires special equipment for transport, plastics in the ATB blend are likely to be able to be handled without modification in existing equipment. ATB can be transported to another facility, for example, by heated barges, tucks, trains, or heated pipelines. Waste plastics can be mixed with ATB before transport, or the mixing to produce the blend can be done at the facility where the ATB is transported.

[0025] In one embodiment, a method is provided for preparing a blend of plastics, preferably waste plastics, and ATB for supply to storage, transport, or refining units. The method first involves sorting plastics, preferably waste plastics, that contain polyethylene and / or polypropylene. These waste plastics are then passed through a blending unit for producing a stable or homogeneous blend of waste plastics and ATB. The blend is supplied to a refining and conversion unit, such as an FCC unit or coker unit, for direct conversion of the waste plastics into value-added chemicals and fuels.

[0026] The stable blend is produced by a two-step process. In the first step, a high-temperature, homogeneous liquid blend of the plastic molten material and the ATB petroleum feedstock is produced. The preferred range for the plastic composition in the blend is about 1 to 20% by weight. Generally, the amount of plastic in the blend is less than 20% by weight, 1 to 20% by weight, and in one embodiment, the amount is in the range of 1 to 10% by weight. Preferred conditions for preparing the high-temperature liquid blend include vigorously mixing the plastic with the ATB petroleum feedstock while heating the plastic to a temperature above the melting point of the plastic. Preferred process conditions include heating to a temperature of 250 to 500°F, a residence time of 5 to 240 minutes at the final heating temperature, and a gauge pressure of 0 to 10 psig. This can be done in an open atmosphere or, preferably, in an oxygen-free, inert atmosphere.

[0027] In the second step, the high-temperature blend is cooled to below the melting point of the plastic while being continuously and vigorously mixed, and then further cooled to an even lower temperature, preferably ambient temperature, to produce a stable blend. Depending on the petroleum feedstock, the stable blend is either an oily liquid or a waxy solid at ambient temperature.

[0028] In one embodiment, the stable blend is made from petroleum ATB feedstock and 1-20% by weight of waste plastic, where the plastic is in the form of finely dispersed micron-sized particles having an average particle size of 10 to less than 100 microns.

[0029] This blend and its use offer several advantages. For example, the stable blend of plastic and ATB feedstock can be stored for extended periods at ambient temperature and pressure. During storage, no aggregation, polymer particle sedimentation, or chemical / physical degradation of the blend is observed. This allows for easier handling of waste plastic materials for storage.

[0030] Because ATB is a heavy petroleum fraction, transporting ATB, whether as part of a blend or not, generally requires heated facilities for transport. Blends can be handled by using standard pumps, which are typically used when handling ATB. Whether ATB is transported alone or in a blend, heated facilities are required and are used to transport ATB by barge, truck, train, or pipeline. However, refineries are often equipped with them for handling ATB. During heating, polymer aggregation is not observed.

[0031] To supply to a refining unit, preferably an FCC unit or a coker unit, the stable blend is further heated to a temperature at least above the melting point of the plastic to produce a homogeneous liquid blend of ATB and plastic. The high-temperature homogeneous liquid blend is supplied directly to the FCC refining unit to convert the waste plastic and ATB into a high-value product in high yield.

[0032] Purification conversion units, such as fluid catalytic cracking (FCC) units, convert a high-temperature, homogeneous liquid blend of plastics and petroleum ATB feedstock in the presence of a catalyst, resulting in the simultaneous conversion of both the plastics and the petroleum ATB feedstock. The presence of a catalyst within the conversion unit allows for the conversion of waste plastics into higher-value products at operating temperatures lower than typical pyrolysis temperatures. The yield of undesirable by-products (off-gas, tar, coke) is lower than in typical pyrolysis processes. In the case of hydrogenation processing units (hydrocracking units and hydrotreatment units), hydrogen can be added to the unit to improve the conversion of plastics. In blends, additional synergistic benefits may arise from the interaction between the plastics and petroleum ATB feedstock during the conversion process. Fluid catalytic cracking and hydrocracking processes are preferred modes of catalytic conversion of stable blends.

[0033] In one embodiment, a stable blend of plastic and petroleum feedstock can be sent to a coker unit for the thermal conversion of waste plastics. In this case, there is no substantial advantage in reactor temperature or product yield compared to a pyrolysis process. The advantage of the coker unit lies in its supply flexibility, as the unit can handle blends containing a very large amount of nitrogen, sulfur, and metal impurities.

[0034] A stable blend of plastics and petroleum ATB feedstocks can provide higher utility for ATB while enabling more efficient recycling of waste plastics. The use of this blend is often far more energy-efficient than current pyrolysis processes, and enables recycling with a lower carbon footprint. Improved methods enable the establishment of a much larger circular economy by efficiently converting waste plastics into virgin-quality polymers or value-added chemicals and fuels.

[0035] Figure 1 shows a simplified process diagram of the base case for the waste plastic pyrolysis process. Figure 2 shows the preparation of a high-temperature homogeneous liquid blend of plastic and petroleum-based feedstock. Figure 3 illustrates in detail the preparation of a stable blend of waste plastic and petroleum-based feedstock. These figures illustrate the two process steps involved in blend preparation.

[0036] As described above, Figure 1 shows a diagram of the pyrolysis of waste plastic fuel or wax, which is commonly used in industry today. Generally, waste plastics are separated together 1. The washed plastic waste 2 is converted into off-gas 4 and pyrolysis oil (liquid products) in a pyrolysis unit 3. The off-gas 4 from the pyrolysis unit 3 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 or as feedstock for chemical production. The heavy pyrolysis oil fraction 6 is returned to the pyrolysis unit 3 for reuse to maximize fuel yield. Carbides 7 are 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 paraffinic wax when cooled to ambient temperature). The wax can be separated from the heavy fraction 6 and sold to the wax market.

[0037] However, the use of this blend avoids the thermal decomposition of waste plastics. Instead, a blend of petroleum ATB feedstock and waste plastics can be prepared and supplied to the refining unit. Thus, the thermal decomposition process can be avoided, resulting in significant energy savings.

[0038] This blend can be prepared in a high-temperature blend preparation unit, where the operating temperature exceeds the melting point of the plastic (approximately 150-250°C) to produce a high-temperature homogeneous liquid blend of plastic and ATB. The high-temperature homogeneous liquid blend of plastic and ATB can be fed directly into the purification unit.

[0039] Alternatively, the blend can be prepared in a stable blend preparation unit, where the high-temperature homogeneous liquid blend is cooled to ambient temperature in a controlled manner to facilitate storage and transport. By using this method, the stable blend can be prepared at a facility away from the refinery and transported to the refinery unit. The stable blend is then heated to a temperature above the melting point of the plastic for supply to the refinement conversion unit. The stable blend is a physical mixture of micron-sized plastic particles finely suspended in ATB, with an average particle size of 10 to less than 100 microns. The mixture is stable, and the plastic particles do not settle or aggregate during long-term storage.

[0040] The implications of heating a blend to a temperature higher than the melting point of a single plastic are clear when a single plastic is used. However, if the waste plastic contains two or more types of waste plastic, the temperature must exceed the melting point of the highest-melting-point plastic. Therefore, the temperature must exceed the melting point of all plastics. Similarly, if the blend is cooled to a temperature below the melting point of a single plastic, the temperature must be below the melting point of all plastics that make up the blend.

[0041] Compared to pyrolysis units, these blend preparation units operate at much lower temperatures (approximately 500-600°C vs. 120-250°C). Therefore, using this blend in conjunction with a refinery can provide a much more energy-efficient method than thermal cracking processes such as pyrolysis.

[0042] The use of the waste plastic / petroleum blend of the present invention further increases the overall hydrocarbon yield obtained from waste plastics. This increase in yield is remarkable. The hydrocarbon yield using this blend can be as high as 98%. In contrast, pyrolysis produces a considerable amount of light hydrocarbons from plastic waste, about 10–30% by weight and about 5–10% by weight of carbides. These light hydrocarbons are used as fuel to operate the pyrolysis plant, as described above. Therefore, the liquid hydrocarbon yield from the pyrolysis plant is up to 70–80%.

[0043] When this blend is sent to a refining unit such as an FCC unit, only a small amount of off-gas is produced. The refining unit uses a catalytic cracking process, which is different from the thermal cracking process used in pyrolysis. The catalytic process minimizes the generation of undesirable light fraction by-products such as methane and ethane. The refining unit has efficient product fractionation capabilities and can efficiently utilize all hydrocarbon product streams to produce high-value materials. In co-supply at the refinery, the off-gas produced (H2, methane, ethane, ethylene) is only about 2%. C3 and C4 streams are captured to produce useful products such as cyclic polymers and / or high-quality fuel products. Therefore, the use of this petroleum / plastic blend provides an increase in hydrocarbons from plastic waste and a more energy-efficient recycling process compared to thermal processes such as pyrolysis. The advantages of this blend are significant when considering the recycling of waste plastics.

[0044] In some cases, converting waste plastics into clean fuels requires less energy than producing fuel from virgin petroleum feedstock. Further improvements in waste plastic collection and processing can enhance energy efficiency. Such fuels, produced from blends of waste plastics and oil, contain recycled components and have a lower carbon footprint than the corresponding fuels made from pure petroleum feedstock. This method allows for the production of clean gasoline, jet fuel, and diesel from waste plastics, which contain recycled components and have a lower CO2 (lower carbon) footprint.

[0045] Figure 2 shows a method for preparing a high-temperature homogeneous blend of plastic and petroleum feedstock that can be used for direct injection into a refining unit. The preferred range for the plastic composition in the blend is about 1 to 20% by weight. Generally, the amount of plastic in the blend is less than 20% by weight, 1 to 20% by weight, and in one embodiment, the amount is in the range of 1 to 10% by weight. When high molecular weight polypropylene (average molecular weight of 250,000 or more) or high-density polyethylene (density greater than 0.93 g / cc) is used as the main waste plastic, for example, at least 50% by weight, the amount of waste plastic used in the blend is more preferably about 1 to 10% by weight. This is because it increases the pour point and viscosity of the blend. In one embodiment, the plastic has an average molecular weight in the range of 5,000 to 150,000 M w This may include polypropylene having the following characteristics: In another embodiment, the plastic has an average molecular weight M in the range of 150,000 to 400,000. w It may include polypropylene having the following properties.

[0046] Preferred conditions for preparing a high-temperature homogeneous liquid blend include vigorously mixing the plastic with petroleum feedstock while heating the plastic to a temperature above its melting point. Preferred process conditions include heating to a temperature of 250–500°F and a gauge pressure of 0–10 psig, with a residence time of 5–240 minutes at the final heating temperature. This can be carried out in an open atmosphere or under an oxygen-free, inert atmosphere.

[0047] High-temperature homogeneous blends of plastic molten material and petroleum feedstock are prepared by mixing the petroleum feedstock and plastic together, and then heating the mixture to a temperature above the melting point of the plastic but below 500°F while thoroughly mixing. Alternatively, they can be prepared by melting only the plastic and then adding the plastic molten material to warm or hot petroleum ATB feedstock while thoroughly mixing. Alternatively, they can be prepared by heating only the ATB feedstock to a temperature above the melting point of the plastic, and then slowly adding the solid plastic to the high-temperature petroleum ATB liquid while thoroughly mixing the mixture and maintaining the temperature above the melting point of the plastic.

[0048] Referring to Figure 2 of the drawings, a stepwise preparation process for preparing a high-temperature homogeneous liquid blend is shown. Mixed waste plastics are separated to produce used waste plastics 21, including polyethylene and / or polypropylene. The waste plastics are washed 22 and then mixed with oil 24 in a high-temperature blend preparation unit 23. After mixing in 23, a homogeneous blend of plastics and oil is recovered 25. Optionally, a filtration device (not shown) may be added to remove any undissolved plastic particles or solid impurities present in the high-temperature liquid blend. The high-temperature blend of plastics and oil can then be sent to a refining unit. Optimally, the high-temperature blend 25 can be combined with refinery feedstock such as vacuum diesel 20, and this mixture is then sent to the refining unit.

[0049] Figure 3 shows a method for preparing a stable blend of plastic and oil. The stable blend is produced in a stable blend preparation unit by a two-step process. In the first step, a high-temperature homogeneous liquid blend of the plastic molten material and the petroleum feedstock is produced, which is the same as the high-temperature blend preparation described in Figure 2. The preferred range for the plastic composition in the blend is about 1 to 20% by weight. Generally, the amount of plastic in the blend is less than 20% by weight, or 1 to 20% by weight, based on the weight of the blend, and in one embodiment, the amount is in the range of 1 to 10% by weight. When high molecular weight polypropylene (average molecular weight of 250,000 or more) or high-density polyethylene (density greater than 0.93 g / cc) is used as the main waste plastic, for example, at least 50% by weight, the amount of waste plastic used in the blend is more preferably about 1 to 10% by weight. This is because it increases the pour point and viscosity of the blend.

[0050] Preferred conditions for preparing a high-temperature homogeneous liquid blend include vigorously mixing the plastic with petroleum feedstock while heating the plastic to a temperature above its melting point. Preferred process conditions include heating to a temperature of 250–500°F and a gauge pressure of 0–10 psig, with a residence time of 5–240 minutes at the final heating temperature. This can be carried out in an open atmosphere or under an oxygen-free, inert atmosphere.

[0051] In the second step, a high-temperature blend containing petroleum feedstock is continuously and vigorously mixed while being cooled to below the melting point of the plastic, and then further cooled to an even lower temperature, preferably ambient temperature, to produce a stable blend of plastic and ATB oil.

[0052] The stable blend was found to be a tightly packed physical mixture of plastic and petroleum feedstock. The plastic is in a "de-aggregated" state. The plastic maintains a fine dispersion of solid particles in the petroleum feedstock at temperatures below the melting point of the plastic, especially at ambient temperature. The blend is stable and can be easily stored and transported. In a refinery, the stable blend can be heated in a preheater to a temperature above the melting point of the plastic to produce a high-temperature homogeneous liquid blend of plastic and petroleum. The high-temperature liquid blend can then be supplied to the refining unit as a co-feed with conventional refinery feedstocks.

[0053] Figure 3 shows further details of the preparation of the stable blend. The stable blend is produced in the stable blend preparation unit 100 by a two-step process. As shown in the figure, clean waste 22 is sent to the stable blend preparation unit 100. The sorted plastic waste 22 is heated and mixed with refinery feedstock oil 24. The plastic waste is heated to a temperature higher than the melting point of the plastic in order to melt the plastic. The petroleum feedstock is mixed with the heated plastic 23. The mixing is often very vigorous. Mixing and heating conditions can generally include heating at a temperature in the range of about 250 to 500°F with a residence time of 5 to 240 minutes at the final heating temperature. Heating and mixing can be carried out in an open atmosphere or in an oxygen-free inert atmosphere. The result is a high-temperature homogeneous liquid blend 25 of plastic and oil. Optionally, a filtration device (not shown) may be added to remove any undissolved plastic particles or any solid impurities present in the high-temperature homogeneous liquid blend.

[0054] Next, the high-temperature blend 25 is cooled to below the melting point of the plastic while continuing to mix the plastic with the petroleum feedstock 101. Cooling is generally continued, usually to ambient temperature, to produce a stable blend of plastic and oil 102. In the refinery, the stable blend can be fed into a preheater 29, which heats the blend to a temperature above the melting point of the plastic to produce a mixture 26 of the plastic / oil blend with, for example, VGO, which is then fed into the refinery conversion unit.

[0055] The preferred plastic starting materials for use in this blend are separated waste plastics (plastic recycling classification types 2, 4, and 5), primarily containing polyethylene and polypropylene. The pre-separated waste plastics are washed and shredded or pelletized for feeding into the blend preparation unit. Figure 4 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. Any combination of polyethylene and polypropylene waste plastics can be used. Polystyrene (classification 6) may also be present in limited amounts.

[0056] Proper segregation 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) should be segregated to less than 5%, preferably less than 1%, and most preferably less than 0.1%. This method can tolerate a moderate amount of polystyrene (plastic recycling classification type 6). Waste polystyrene should be segregated to less than 20%, preferably less than 10%, and most preferably less than 5%.

[0057] Washing waste plastics can remove metallic contaminants such as sodium, calcium, magnesium, and aluminum, as well as non-metallic contaminants originating from other waste sources. Non-metallic contaminants include those from Group IV of the periodic table, such as silica; those from Group V, such as phosphorus and nitrogen compounds; those 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 halogens should be removed to less than 50 ppm, preferably less than 30 ppm, and most preferably less than 5 ppm.

[0058] Petroleum-based feedstocks include bottom fractions of atmospheric distillation columns. Bottom fractions of atmospheric distillation columns (ATB) are the residues from atmospheric distillation. ATB generally boils above 650°F (343°C). Generally, ATB is sent to several different units depending on quality and demand. These units may include fluid catalytic cracking (FCC) units, or vacuum distillation units that recover heavy distillates for further processing into lubricants and waxes. Otherwise, ATB is simply burned to recover energy. ATB can be processed at the same refinery where it was produced, or optionally transported to another refinery for use.

[0059] This method includes supplying ATB as a machine-utilized feedstock to a refining and conversion unit, preferably an FCC unit, and optionally transporting the ATB to another refinery before FCC processing. Here, the waste plastic is dissolved in the ATB before being supplied to the FCC unit, where it is cracked to become a typical FCC product containing precursors for recycled plastic production. The waste plastic can be dissolved before or after transport, or even during transport at another facility. Since ATB already requires special equipment for transport, the plastic in the ATB blend is likely to be able to be handled without modification in existing equipment.

[0060] While not wishing to be bound by theory, this method prepares a stable blend, which is a tightly packed physical mixture of plastic and petroleum feedstock, for catalytic conversion in a refining unit. The method produces a stable blend of petroleum feedstock and plastic, in a "de-aggregated" state. The plastic maintains a state as "finely dispersed" solid particles within the petroleum feedstock at ambient temperature. This blend is stable and can be easily stored and transported. In a refinery, the stable blend can be preheated to a temperature above the melting point of the plastic to produce a high-temperature homogeneous liquid blend of plastic and petroleum, which is then supplied to a conversion unit. In a conversion unit such as a fluid catalytic cracking (FCC), coker unit, or hydrocracking (HCR) unit, both the ATB petroleum feedstock and the plastic are simultaneously converted using a typical refining catalyst containing zeolite and other active ingredients, such as silica-alumina, alumina, and clay.

[0061] The flow rate of the blend to the refining unit, such as an FCC unit, can constitute any practical or sufficient volume percentage of the total flow to the refining unit. Generally, for practical reasons, the blend flow may be up to about 50 volume percent of the total flow, i.e., the refinery flow and the blend flow. In one embodiment, the blend flow is up to about 100 volume percent of the total flow. The volume percentage of the blend also depends on the desired final product. In another embodiment, the volume flow of the blend is up to about 25 volume percent of the total flow, or in one embodiment, 25 to about 50 volume percent. It is important to avoid any adverse effects on the refinery and its products. If the amount of plastic in the final blend (including the plastic / oil blend and co-supplied petroleum) exceeds 20 wt percent of the final blend, operation in the FCC unit may become difficult. The final blend means the plastic / ATB blend of the present invention and any co-supplied petroleum. The plastic / ATB blend can constitute up to 100 volume percent of the feed to the refining unit. Some petroleum supplies, such as VGO, can preferably be supplied to the refining unit together with the blend.

[0062] This blend can be sent to a refining and conversion unit to provide building blocks for chemicals, fuel products, such as gasoline, jet fuel, diesel fuel, and base oils. The building blocks can also be used for the recycling of polyethylene and propylene.

[0063] For example, in Figure 5, the cracking of the plastic / ATB high-temperature blend 25 can be sent alone or in combination with co-supplied petroleum feedstocks to the conversion FCC unit 27 via 26. The symbols in Figure 5 are the same as in Figures 2 and 3, and refer to the same flows or units. The FCC unit 27 produces liquefied petroleum gas (LPG) flows 31 and 32 of C3 and C4 olefin / paraffin, as well as naphtha 33 and heavy fraction 30. The C3 olefin / paraffin mix flow, the propane and propylene mix 31, can be sent to the steam cracker 36 via 38 to produce ethylene 37. The ethylene 37 is fed to the ethylene polymerization unit 40 to produce polyethylene, ultimately producing polyethylene product 41.

[0064] At least a portion of the C432 and naphtha 33 can also be sent to the steam cracker 36 via 39 to produce ethylene 37. The ethylene is fed to the ethylene polymerization unit 40 to produce polyethylene, ultimately producing polyethylene product 41. Other hydrocarbon product streams from the FCC unit 27, such as heavy fraction 30, are sent to a suitable refining unit 34 to improve their quality for clean gasoline, diesel, or jet fuel. The naphtha / gasoline 33 from the FCC unit may be sent directly to the gasoline pool 35, or it may be further improved before being sent to the gasoline pool (not shown).

[0065] In Figure 6, the cracking of the plastic / ATB high-temperature blend 25 can be sent alone or in combination with co-supplied petroleum feedstocks to the conversion FCC unit 27 via 26. The symbols in Figure 5 are the same as in Figures 2 and 3, and refer to the same flows or units. The FCC unit 27 produces liquefied petroleum gas (LPG) flows 31 and 32 of C3 and C4 olefin / paraffin, as well as naphtha 33 and heavy fraction 30. The propane and propylene mix 31, which is the C3 olefin / paraffin mix flow, is sent to a propane / propylene splitter (PP splitter) 50, where it can be separated to produce pure vapors of propane 51 and propylene 52. The propylene 52 is fed to a propylene polymerization unit 52 to produce polypropylene.

[0066] Pure propane 51 is supplied to the propane dehydrogenation unit 54 to produce additional propylene 55, and then in the propylene polymerization unit 53, finally polypropylene can be produced.

[0067] The dehydrogenation of propane is widely carried out in industry to produce propylene. The reaction is endothermic, and the conversion is maintained by a multi-stage reactor and interstage heaters. The unit typically operates at high temperatures (above 900°F) and low pressures (below 50 psig) in the presence of a precious metal (Pt) catalyst. The multi-stage process produces a propylene / propane mixture with a purity of approximately 85%. This flow is directed to a propane / propylene (PP) splitter, which is a high-efficiency distillation column. The splitter produces a pure propylene stream with a purity of 99.5–99.8%.

[0068] The PP splitter unit and / or propane dehydrogenation unit may be located away from, near, or within the refinery. The propane / propylene mix is ​​delivered to the PP splitter by truck, barge, rail vehicle, or pipeline. The PP splitter unit and propane dehydrogenation unit are preferably located close to the refined FCC unit.

[0069] The C432 and other hydrocarbon product stream from the FCC unit 27, such as the heavy fraction 30, is sent to a suitable refining unit 34 to improve its quality into clean gasoline, diesel, or jet fuel. The gasoline 33 from the FCC unit may be sent directly to the gasoline pool 35, or it may be further improved before being sent to the gasoline pool (not shown).

[0070] The polypropylene polymer 56 produced in the propylene polymerization unit 53 can be used to make polypropylene products 57, which are then further incorporated into consumer products.

[0071] Figure 7 shows one embodiment of the integration method, in which the blend is sent to a fluid catalytic cracking (FCC) unit. The same numbers in Figure 7 that correspond to Figures 2 and 3 refer to the same items / units. As shown, blend 25 is prepared and then sent to the FCC conversion unit 27 via 26. The blend may or may not be mixed with co-supplied vacuum gas oil (VGO). The blend is generally heated to a temperature higher than the melting point of the plastic before being sent to the FCC conversion unit 27.

[0072] In Figure 7, when the plastic / ATB high-temperature blend is cracked in the FCC unit 27, either alone or in combination with a co-supplied petroleum feedstock, C3 and C4 olefin / paraffin liquefied petroleum gas (LPG) flows 31 and 32, as well as naphtha 33 and heavy fraction 30. The C3 olefin / paraffin mix flows of propane and propylene can be sent to a propane / propylene splitter (PP splitter), where they can be separated to produce pure flows of propane and propylene.

[0073] The C432 and other hydrocarbon product stream from the FCC unit 28, such as the heavy fraction 30, is sent to a suitable refining unit 34 to improve its quality into clean gasoline, diesel, or jet fuel. The naphtha / gasoline 33 from the FCC unit may be sent directly to the gasoline pool 35, or it may be further improved before being sent to the gasoline pool (not shown).

[0074] A portion of the naphtha 33 can be sent for chemical production. For example, naphtha can be sent to an aromatic separation unit 60. Benzene, toluene, xylene, and ethylbenzene can be recovered from 60 and sent for intermediate processing 62 and / or other chemical production 63. The chemicals obtained from the intermediate processing 62 can be sent to a polymerization process unit 64. Polymers such as polyethylene terephthalate and polystyrene can be made from the processed chemicals recovered and sent for polymerization. For example, para-xylene is readily used to prepare polyethylene terephthalate (PET).

[0075] LPG and naphtha can be recovered and fed to a steam cracker to produce ethylene, and then ethylene-derived chemicals such as polyethylene, ethylene oxide, and polyalphaolefins. C3 olefins in the LPG can be recovered to produce propylene and / or propylene oxide. C4 olefins in the LPG can be recovered to produce low-density copolymers (process scheme not shown in the diagram).

[0076] In one embodiment, the conversion unit 27 is not located in the refinery, and only the ATB feedstock / plastic blend is sent to the unit. The recovery of naphtha for aromatic production is then emphasized. At this point, the naphtha can be transported to the refinery if desired.

[0077] The following examples are provided to illustrate specific embodiments, but are not intended to limit them.

[0078] Example 1: Properties of plastics and ATB Table 1 shows the properties of typical plastics that can be used in blend preparation. This concept was demonstrated using low-density polyethylene (LDPE). [Table 1]

[0079] Table 2 summarizes the simulated distillation boiling point distribution of ATB and compares it with that of vacuum gasoline (VGO). Compared to VGO, ATB has a much broader boiling point distribution and a much higher endpoint (approximately 1100°F vs. 1350°F). [Table 2]

[0080] Example 2: Dissolution of LDPE into ATB A blend of plastic and ATB for FCC performance testing was prepared using the following procedure. The plastic used was low-density polyethylene (LDPE) with a density of 0.925 g / mL at 25°C. The ATB was heated to 270°F (132°C), and then LDPE was added so that the final product was 5 wt% LDPE. The mixture was stirred at 270°F (132°C) until all the LDPE was dissolved.

[0081] Example 3: ACE test To study the effects of co-treating plastics and atmospheric pressure distillation bottom fraction (ATB) in a purified FCC unit, laboratory tests using a fluid catalytic cracking (FCC) process were conducted using a homogeneous blend of plastics and ATB (Example 2) with an FCC catalyst containing USY zeolite.

[0082] Catalytic cracking experiments were conducted using an Advanced Cracking Evaluation (ACE) Model C unit manufactured by Kayser Technology Inc. (Texas, USA). The reactor used in the ACE unit was a 1.6 cm bore fixed fluidized reactor. Nitrogen was used as the fluidizing gas and was introduced from both the bottom and the top. The feed, injected via a three-way valve from a calibrated syringe feed pump, was transported using the top fluidizing gas. Catalytic cracking was performed at atmospheric pressure and a temperature of 975°F. For each experiment, a fixed amount of feed was injected at a rate of 1.2 g / min for 75 seconds. The catalyst / oil ratio was varied from 4 to 8. After 75 seconds of feed injection, the catalyst was stripped with nitrogen for a period of 525 seconds.

[0083] During the catalytic cracking and stripping processes, the liquid product was collected in a sample vial mounted on a glass receiver located at the end of the reactor outlet and maintained at -15°C. The gaseous product was collected in a sealed stainless steel container (12.6 L) pre-filled with N2 at 1 atm. Immediately after feed injection was complete, the gaseous product was mixed with an electric stirrer rotating at 60 rpm. After stripping, the gaseous product was mixed for a further 10 minutes to ensure homogeneity. The final gaseous product was analyzed using a refined gas analyzer (RGA).

[0084] After the stripping process was completed, in-situ catalyst regeneration was performed in the presence of air at 1300°F. The regenerated flue gas was passed through a catalytic converter filled with CuO pellets (LECO Inc.) to oxidize CO to CO2. The flue gas was then analyzed using an online infrared (IR) analyzer located downstream of the catalytic converter. The amount of coke deposited during the cracking process was calculated from the CO2 concentration measured by the IR analyzer.

[0085] A base case containing only ATB feed (Example 3-1) was compared to a blend run containing a 5 / 95% LDPE / ATB blend (Example 3-2). The catalyst was an operational equilibrium catalyst extracted from a commercial FCC plant. The results of the cracking experiment with a catalyst-to-oil ratio of 6 are summarized in Table 3. [Table 3-1] [Table 3-2]

[0086] The results in Table 3 show that the FCC unit performance showed only a very slight change with 5 wt% plastic co-supply, indicating that co-processing of up to 5 wt% plastic is easily feasible. While it is expected that up to 20% can be processed without performance issues, appropriate equipment with good control will be necessary to address the increase in viscosity and pour point.

[0087] Because plastic cracked more easily than ATB, the conversion rate increased slightly in the blend. The addition of plastic to the FCC feed resulted in a very slight increase in the yields of coke and dry gas, but the change was small and can be controlled by adjusting the conversion and operating conditions. A moderate increase in LPG was observed, while a slight decrease in the yields of LCO and HCO was observed. Gasoline yields were similar. Due to the paraffinic nature of the decomposition products resulting from plastic, the inventors anticipated that the octane rating might decrease slightly in the blend with plastic. In the blend with 5 wt% plastic, the decrease in octane rating was within the experimental margin of error. Due to the flexibility of refinery operations, such octane rating disadvantages can be easily compensated for by blending or by adjusting the operation of the FCC process and the formulation of catalysts / additives. The hydrocarbon composition of all co-supply products is well within the range of typical FCC gasoline.

[0088] Example 4: Characteristics of waste plastic samples Four types of waste plastic samples were purchased, and their properties are summarized in Table 4. The general properties of the plastics were confirmed using FT-IR. In addition to identifying the main polymer species, the FT-IR data also revealed that all of these recycled plastics contained varying amounts of calcium carbonate and talc. To estimate the amount of potentially recoverable hydrocarbons, each sample was calcined under N2 at 1000°F for 3 hours. The recoverable hydrocarbons were assumed to be equal to the % loss on ignition (LOI). Inorganic residues from calcination were analyzed by ICP analysis. Using the LOI values ​​and ICP analysis, the weight percentage of impurities in the as-received plastics was estimated and reported in Table 4 below. The most common impurities in waste plastics are Ca, Mg, Si, and Ti, which can originate from the manufacture of plastic consumer products as calcium carbonate, silica, and talc, which are commonly used filler materials. Al, Fe, P, and Zn are also present in significant amounts. [Table 4]

[0089] Thermogravimetric analysis (TGA) was performed on waste plastic samples to confirm that the plastic material is sufficiently thermally stable at temperatures higher than the melt preparation temperature. The TGA results shown in Figures 8 and 9 indicate that the waste plastic samples are stable up to 700°F.

[0090] Where used in this disclosure, the terms “comprises” or “comprising” are intended as an open-ended transition meaning that the specified elements are included, but not necessarily that other unspecified elements are excluded. The phrases “consists essentially of” or “consisting essentially of” are intended to mean the exclusion of other elements that are essentially important to the composition, whatever they may be. The phrases “consisting of” or “consists of” are intended as a transition meaning that all elements other than those listed are excluded, except for trace amounts of impurities.

[0091] 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 certain 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 (one or more) embodiments. In addition, it will be understood that certain structures, functions, and operations shown in the above-referenced patents and publications can be carried out in conjunction with the invention, but they are not essential to carrying out the invention. Therefore, it should be understood that the invention may be carried out in ways other than those specifically described without actually departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A blend of feedstock from the bottom fraction (ATB) of petroleum at atmospheric pressure distillation columns and 1 to 20% by weight of plastic based on the weight of the blend, wherein the plastic includes polyethylene and / or polypropylene, and the plastic in the blend includes finely dispersed micron-sized particles having an average particle size of 10 microns to less than 100 microns.

2. The blend according to claim 1, wherein the amount of plastic in the blend constitutes 1 to less than 20% by weight of the blend.

3. The blend according to claim 1, wherein the plastic comprises low-density polyethylene.

4. The blend according to claim 1, wherein the plastic comprises high-density polyethylene.

5. The blend according to claim 4, comprising 1 to 10% by weight of high-density polyethylene.

6. The aforementioned plastic has an average molecular weight M in the range of 5,000 to 150,000. ｗ The blend according to claim 1, comprising polypropylene having the following properties.

7. The aforementioned plastic has an average molecular weight M in the range of 150,000 to 400,000. ｗ The blend according to claim 1, comprising polypropylene having the following properties.

8. The blend according to claim 7, comprising 1 to 10% by weight of polypropylene.

9. The blend according to claim 1, wherein the plastic comprises a mixture of polyethylene and polypropylene.

10. The blend according to claim 1, wherein the plastic is a mixture of waste plastics including polyethylene and polypropylene.

11. The blend according to claim 1, wherein the finely dispersed particles have an average particle size in the range of 10 to 50 microns.

12. The blend according to claim 1, wherein the finely dispersed particles have an average particle size in the range of 10 to less than 100 microns.

13. The blend according to claim 1, further comprising vacuum diesel fuel.

14. The blend according to claim 1, wherein the blend is a high-temperature homogeneous liquid blend that is hotter than the melting point of the aforementioned plastic.

15. A method for preparing a blend of plastic and petroleum according to claim 1, (a) Mixing petroleum ATB supply raw materials and plastics including polyethylene and / or polypropylene together, and heating the mixture while mixing at a temperature higher than the melting point of the plastics but less than 500°F, (b) Cooling the liquid blend of the molten plastic and the petroleum supply material to a temperature lower than the melting point of the plastic. A method that includes this.

16. The method according to claim 15, wherein the cooling in (b) is carried out while continuously stirring.

17. The method according to claim 15, wherein the heating is carried out at a temperature of 250 to 450°F with a residence time of 5 to 240 minutes at the final heating temperature.

18. The method according to claim 16, wherein the cooling is continued until the ambient temperature is reached.

19. The method according to claim 15, wherein the plastic is a waste plastic mixture containing polyethylene and polypropylene.

20. (a) Sorting waste plastics containing polyethylene and / or polypropylene, (b) Preparing a blend of ATB supply material and the sorted waste plastic, wherein the blend contains about 20% by weight or less of the sorted waste plastic. (c) Passing the blend through an FCC unit at a temperature higher than the melting point of the waste plastic in the blend, (d) Recovering the C3 olefin / paraffin mixture from the FCC unit, (e) Sending the C3 mixture to a steam cracker to produce ethylene A method for converting waste plastics into reusable materials for polyethylene polymerization, including a method for this purpose.

21. The method according to claim 20, wherein the volume flow of the blend to the FCC unit in (c) constitutes a maximum of 100 volume percent of the total hydrocarbon flow to the FCC unit.

22. The method according to claim 20, wherein the volume flow of the blend to the FCC unit in (c) constitutes a maximum of 50 volume percent of the total hydrocarbon flow to the FCC unit.

23. (a) Sorting waste plastics containing polyethylene and / or polypropylene, (b) Preparing a blend of ATB supply material and the sorted waste plastic, wherein the blend contains about 20% by weight or less of the sorted waste plastic. (c) Passing the blend through an FCC unit at a temperature higher than the melting point of the plastic, (d) Recovering the C3 olefin / paraffin mixture from the FCC unit, (e) Separating the C3 paraffin and C3 olefin into separate fractions, (f) Sending the C3 olefin to a propylene polymerization reactor A method for converting waste plastics into reusable materials for polypropylene polymerization, including a method for this purpose.

24. The method according to claim 23, wherein the volume flow of the blend to the FCC unit in (c) constitutes a maximum of 100 volume percent of the total hydrocarbon flow to the FCC unit.

25. The method according to claim 23, wherein the volume flow of the blend to the FCC unit in (c) constitutes a maximum of 50 volume percent of the total hydrocarbon flow to the FCC unit.

26. (a) Sorting waste plastics containing polyethylene and / or polypropylene, (b) Preparing a blend of ATB supply material and the sorted waste plastic, wherein the blend contains about 20% by weight or less of the sorted waste plastic. (c) Passing the blend through an FCC unit at a temperature higher than the melting point of the waste plastic in the blend, (d) Recovering the naphtha mixture from the FCC unit, (e) Sending the naphtha mixture to the aromatic separation unit A continuous method for converting waste plastics into aromatic and chemical monomers, including [specific components / materials].

27. The method according to claim 26, wherein benzene, toluene, xylene, ethylbenzene, or a mixture thereof is recovered from the aromatic separation unit.

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