Process for stable blending of waste plastics and petroleum feedstock for feeding to petroleum refinery units and preparation process thereof.

Abstract

Provided is a blend of a petroleum feedstock with 1-20 wt% plastic, based on the weight of the blend, the plastic comprising polyethylene and / or polypropylene, the plastic in the blend comprising finely dispersed crystalline particles having an average particle size of 10 to less than 100 microns. A process for preparing a plastic and petroleum blend is provided, the process comprising mixing together a petroleum feedstock and a plastic comprising polyethylene and / or polypropylene and heating the mixture to a temperature above the melting point of the plastic but below 500° F. The process then comprises cooling the combined blend of plastic melt and petroleum feedstock liquid to a temperature below the melting point of the plastic.

Description

[Technical field]

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

[0002] Single-use plastic waste is becoming an increasingly significant environmental issue. At present, there appear to be few options for recycling polyethylene and polypropylene waste plastics into value-added chemical and fuel products. Currently, only a small amount of polyethylene / polypropylene is recycled via chemical recycling, and this recycled and cleaned plastic pellets are pyrolyzed in pyrolysis units to produce fuel (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) but in quantities small enough that these products can be blended into the fuel supply. However, if very large quantities of waste polyethylene and waste polypropylene must be recycled to address environmental concerns, such simple blending cannot continue. The raw products from pyrolysis units are too poor quality to be blended in large quantities (e.g., 5-20 vol.% blends) into transportation fuels.

[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-scale chemical recycling of single-use plastics to reduce their environmental impact, and such processes may require unique handling and manipulation of the waste plastics. Summary of the Invention

[0009] In one embodiment, provided is a composition of a stable blend of waste plastics and petroleum-based feedstocks for direct conversion of waste plastics in a refinery process unit.

[0010] The stable blend comprises a petroleum-based feedstock and 1-20 wt % plastic, which in one embodiment is comprised primarily of polyethylene and / or polypropylene, and the plastic in the blend is present as finely dispersed, crystalline particles having an average particle size of 10 microns to less than 100 microns, preferably less than 80 microns.

[0011] Also provided in one embodiment is a process for preparing a plastic and petroleum blend, the process including mixing a petroleum-based feedstock and a plastic together and heating the mixture to a temperature above the melting point of the plastic but not exceeding 500° F. As mixing continues, the blend of plastic melt and petroleum feedstock liquid is cooled to a temperature below the melting point of the plastic.

[0012] Among other factors, the process prepares a stable blend of plastics and petroleum-based feedstocks. This blend of plastics and petroleum-based feedstocks provides a means to efficiently and effectively feed waste plastics into a refinery process and convert the waste plastics into high yields and large quantities of products. It has been found that by preparing the blend and adding the blend to a refinery operation, waste plastics can be efficiently and effectively recycled while complementing the refinery operation in the preparation of high value products such as gasoline, jet fuel, base oil, and diesel fuel. Polyethylene and polypropylene can also be efficiently and effectively produced from waste plastics. In fact, positive economics are realized in the overall recycling process with product quality comparable to virgin polymers. The use of the blend also saves energy, making it more environmentally friendly than traditional recycling processes. [Brief description of the drawings]

[0013] [Figure 1] Figure 1 shows the current practice of pyrolyzing waste plastics to produce fuel or wax (base case).

[0014] [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.

[0015] [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.

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

[0017] [Diagram 5] FIG. 5 graphically illustrates the results of thermogravimetric analysis (TGA) of low density polyethylene and polypropylene polymers.

[0018] [Figure 6] FIG. 6 shows optical microscopy of the polyethylene prepared blend in bright field mode (A) and cross-polarized light mode (B).

[0019] [Figure 7] FIG. 7 shows optical microscopy in cross-polarized mode of the polyethylene prepared blends at various temperatures during heating and cooling.

[0020] [Figure 8] FIG. 8 shows optical microscopy of the polypropylene prepared blend in bright field mode (A) and cross-polarized light mode (B).

[0021] [Figure 9] FIG. 9 shows optical microscopy in cross-polarized mode of the polypropylene prepared blends at various temperatures during heating and cooling.

[0022] [Figure 10] FIG. 10 graphically illustrates the thermogravimetric analysis (TGA) of the thermal stability of four waste plastic samples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Disclosed are novel blends of plastics and petroleum-based feedstocks and processes for preparing stable blends of plastics and petroleum-based feedstocks for direct conversion of plastics in refinery process units.

[0024] In one embodiment, provided is a process for preparing a stable blend of plastics, preferably waste plastics, and petroleum for storage, transportation, or feeding to a refinery unit. The process includes first selecting plastics, preferably waste plastics, including polyethylene and / or polypropylene. These waste plastics are then passed through a blend preparation unit to produce a stable blend of waste plastics and petroleum. The stable blend is fed to a refinery conversion unit for direct conversion of the waste plastics into value-added chemicals and fuels.

[0025] Stable blends are made by a two-step process. In the first step, a hot homogenous liquid blend of the plastic melt and the oil feedstock is produced. The preferred range of plastic composition in the blend is about 1-20 wt%. Preferred conditions for the preparation of hot homogenous liquid blends include vigorously mixing the plastic with the oil 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.

[0026] In the second step, the hot blend is cooled with continued vigorous mixing to a temperature below the melting point of the plastic and then further cooled to a lower temperature, preferably ambient temperature, to produce a stable blend that is either an oily liquid or a waxy solid at ambient temperature, depending on the petroleum feedstock.

[0027] In one embodiment, the stable blend is made from a petroleum feedstock and 1-20 wt% waste plastic, where the plastic is in the form of finely dispersed micron-sized particles with an average particle size of 10 microns to less than 100 microns.

[0028] There are several advantages realized by the present blends and their use. For example, the stable blends of plastics and petroleum feedstocks can be stored for long periods at ambient temperature and pressure. No agglomeration, settling of polymer particles, and chemical / physical degradation of the blends are observed during storage. This allows for easy handling of waste plastic materials for storage or transportation.

[0029] Stable blends can be easily handled using standard pumps typically used in refineries or warehouses, or by using pumps with transfer tanks. Depending on the blend, it may be necessary to heat the blend above its pour point in order to pump it for transport or for feeding into the conversion unit of the refinery. No agglomeration of the polymer is observed during heating.

[0030] To feed the refinery unit, the stable blend is further heated to a temperature above the melting point of plastics to produce a homogenous liquid blend of oil and plastics. The hot homogenous liquid blend is fed directly to the oil refinery process unit for converting waste plastics into high value products with high yields.

[0031] Refining and conversion units such as fluid catalytic cracking (FCC) units, hydrocracking units, and hydrotreaters convert high-temperature homogeneous liquid mixtures of plastics and oil feedstocks with simultaneous conversion of plastics and oil feedstocks in the presence of a catalyst. The presence of a catalyst in the conversion units allows for the conversion of waste plastics to high-value products at lower operating temperatures than typical pyrolysis temperatures. The yield of undesirable by-products (off-gas, tar, coke) is lower than in typical pyrolysis processes. In hydroprocessing units (hydrocracking and hydrotreaters), hydrogen is added to the units to improve the conversion of plastics. This blending may produce additional synergistic effects resulting from the interaction of plastics and oil feedstocks during the conversion process. Fluid catalytic cracking and hydrocracking processes are the preferred modes of catalytic conversion of stable blends.

[0032] In one embodiment, a stable blend of plastic and petroleum feedstocks can be sent to a coker unit for thermal conversion of waste plastics. In this case, there is no substantial advantage in reactor temperature or product yield compared to the pyrolysis process. The advantage of the coker unit is its feed flexibility in that it can handle blends with very high nitrogen, sulfur, and metal impurities.

[0033] A stable blend of plastics and petroleum feedstocks allows for more efficient recycling of waste plastics. The use of this blend is much more energy efficient than current pyrolysis processes, allowing for recycling with a lower carbon footprint. The improved process allows for the establishment of a circular economy on a much larger scale by efficiently converting waste plastics into virgin quality polymers or value-added chemicals and fuels.

[0034] A simplified process diagram for the base case of the waste plastic pyrolysis process is shown in Figure 1. The preparation of a high temperature homogenous liquid blend of plastic and petroleum feedstock is shown in Figure 2. Figure 3 shows in detail the preparation of a stable blend of waste plastic and petroleum-based feedstock. These diagrams show the two process steps involved in the preparation of the blend.

[0035] As mentioned above, FIG. 1 shows a diagram of waste plastic fuel or wax pyrolysis as commonly practiced in the 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.

[0036] However, by using the present blend, the pyrolysis of waste plastics is avoided. Rather, a stable blend of petroleum feedstock and waste plastics is prepared and this blend can be fed to the refinery unit. Thus, the pyrolysis step can be avoided, which is a significant energy saving.

[0037] 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 produce a hot, homogeneous liquid blend of plastic and oil that can be fed directly to the refining unit.

[0038] 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 remote 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 petroleum-based oil, with the average particle size of the plastic particles being 10 microns to less than 100 microns. The mixture is stable and the plastic particles do not settle or agglomerate even when stored for long periods of time.

[0039] 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.

[0040] Compared to pyrolysis units, these blend preparation units operate at much lower temperatures (approximately 500-600°C versus 120-250°C). Therefore, the use of the blends in combination with refineries can provide a much more energy efficient process than thermal cracking processes such as pyrolysis.

[0041] 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%.

[0042] When the blend is passed through a refinery unit, such as an FCC 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 high-quality fuel products. 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. The advantages of the blend are enormous when considering the recycling of waste plastics.

[0043] 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 produced from blends of waste plastics and oils contain recycled content and have a lower carbon footprint than corresponding fuels produced from pure petroleum feedstocks. The process allows the production of clean gasoline, jet fuel and diesel from waste plastics that contain recycled content and have a low CO2 footprint (low carbon footprint).

[0044] FIG. 2 shows a method for preparing a hot homogenous blend of plastics and petroleum feedstocks that can be used for direct injection into a refinery unit. 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 primarily used as waste plastics, for example at least 50 wt%, the amount of waste plastics used in the blend is more preferably about 10 wt%. This is because the pour point and viscosity of the blend will be higher. In one embodiment, the plastics are of average molecular weight M in the range of 5,000-150,000. w In another embodiment, the plastic can include polypropylene having an average molecular weight M in the range of 150,000 to 400,000. w The polypropylene may include

[0045] 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 under an oxygen-free inert atmosphere.

[0046] Hot homogenous blends of plastic melts and oil feedstocks are prepared by mixing the oil feedstock and plastic together and then thoroughly mixing while heating the mixture to a temperature above the melting point of the plastic but not exceeding 500° F. Alternatively, they are prepared by melting only the plastic and then adding the plastic melt to the warm or hot oil feedstock while thoroughly mixing. Alternatively, they are prepared by heating only the oil to a temperature above the melting point of the plastic and then slowly adding the solid plastic to the hot oil liquid while thoroughly mixing the mixture and maintaining the temperature above the melting point of the plastic.

[0047] 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 is then combined with a refinery feedstock such as vacuum gas oil (VGO) 20 to produce a mixture of plastic / oil blend and VGO 26, which can then be passed through a refinery unit.

[0048] FIG. 3 shows a method for preparing a stable blend of plastic and oil. 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%. When high molecular weight polypropylene (average molecular weight ≧250,000) waste plastic or high density polyethylene (density above 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%. The reason is that the pour point and viscosity of the blend will be higher.

[0049] 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 under an oxygen-free inert atmosphere.

[0050] In the second step, the hot blend is cooled to a temperature below the melting point of the plastic while being continuously and vigorously mixed with the oil feedstock, and then further cooled to a lower temperature, preferably ambient temperature, to produce a stable blend of plastic and oil.

[0051] 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 can be 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.

[0052] 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 in order 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.

[0053] 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.

[0054] The preferred plastic starting material for use in the present blends 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. Polystyrene (class 6) can also be present in limited amounts.

[0055] 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%.

[0056] 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.

[0057] 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 / or petroleum-derived aromatic solvents.

[0058] In one embodiment, the petroleum feedstock for preparing the blend includes vacuum gas oil, atmospheric gas oil, reformate, light cycle oil, heavy fuel oil, refinery hydrocarbon streams containing toluene; xylene; heptane or benzene, or pure toluene, pure xylene, coker naphtha, C5-C6 isomerized paraffin naphtha, FCC naphtha, hydrocracker bottoms, gasoline, jet fuel, diesel, or mixtures thereof.

[0059] The most preferred petroleum feedstocks are light oils, heavy reformate, or various recycle streams fed to a catalytic conversion unit. The plastics and petroleum feedstocks in the blend are then co-converted via catalytic conversion into high value products.

[0060] Multiple oil feedstocks can be used to optimize blend properties, for example, viscosity and pour point can be reduced by adding lighter oil feedstocks such as light cycle oil, gasoline, or diesel.

[0061] Optionally, a solvent such as benzene, toluene, xylene or heptane may be added to the blend of plastic and petroleum feedstock to reduce the viscosity or pour point of the blend to make it easier to handle.

[0062] Without wishing to be bound by theory, the process prepares a stable blend, which is an intimate physical mixture of plastic and oil feedstock, for catalytic conversion in a refinery unit. The process produces a stable blend of oil feedstock and plastic, where the plastic is in a "deagglomerated" state. The plastic remains as "finely dispersed" solid particles in the oil feedstock at ambient temperature. The blend is stable and easy to store and transport. In the refinery, the stable blend can be preheated to a temperature above the melting point of the plastic to produce a hot homogenous liquid blend of plastic and oil, which can then be fed to a conversion unit. Both the oil feedstock and the plastic are then simultaneously converted in a conversion unit, such as a fluid catalytic cracking (FCC) unit or a hydrocracking (HCR) unit, and typical refinery catalysts used include zeolites and other active components such as silica-alumina, alumina, and clay.

[0063] 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

[0064] [Example 1] Characteristics of virgin plastic samples and petroleum feedstocks used for blend preparation

[0065] Four commercially available 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]

[0066] 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]

[0067] 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 blend preparation temperatures for melting of the plastics. The TGA results shown in Figure 5 indicate that the LDPE sample is stable up to 800°F and the polypropylene sample is stable up to 700°F.

[0068] [Example 2] Preparation of stable blends of VGO and virgin plastics

[0069] Several blends of VGO and plastics were prepared by adding plastic pellets (Plastics A-D in Table 1) to hydrotreated vacuum gas oil (petroleum feedstock #1 in Table 2).

[0070] The following procedure was used: At ambient temperature, the VGO feed (waxy solid) was added to a beaker. The VGO was heated in a heating mantle while being stirred with a magnetic stirrer. The temperature of the VGO was gradually increased to 275-400°F, after which pre-weighed plastic pellets (solids) were slowly added to the hot VGO while being stirred and heated. After the plastic pellets were dissolved, the stirred solution was held at the final temperature (an additional 30 minutes for the LDPE and Plastic C polypropylene blends, or 60 minutes for the HDPE and Plastic D polypropylene blends). Visual observation showed the blends to be completely homogenous. Upon cooling to ambient temperature, the plastic and VGO blends showed the appearance of the waxy solid of VGO, but the cure temperature (or freezing temperature or pour point) was different from that of the starting VGO.

[0071] The pour point (per ASTM D5950-14) and viscosity (per ASTM D445) of the blends were measured to assess the need for material handling. The stability of the material was observed by visual observation. The blends of plastic melt and VGO were stable and no changes were observed during the observation period of 3 months. Table 3 below summarizes the list of samples prepared and their properties. [Table 3]

[0072] [Example 3] Preparation of stable blends of aromatic solvents and plastics

[0073] Several blends of the aromatic solvent and the four plastic samples were prepared by adding plastic pellets to the aromatic solvent (petroleum feedstock #2 in Table 2).

[0074] These blends were prepared using the procedure described in Example 2, except that the melt temperature before the addition of the plastic was 250° F., and the final hold time was 60 minutes. The properties of these blends are shown in Table 4 below. [Table 4]

[0075] [Example 4] Preparation of blends of VGO and virgin plastics

[0076] Several blends of vacuum gas oil (VGO) and two plastic samples (Plastics A and C from Table 1) were prepared by adding plastic pellets to hydrotreated vacuum gas oil (petroleum feedstock #1 in Table 2) using an autoclave.

[0077] The following procedure was used: At ambient temperature, pre-weighed plastic pellets (solids) and VGO feed (waxy solids) were added to a batch autoclave unit. The autoclave was purged with N2 gas to remove air from the vessel, after which the inlet and outlet valves were closed. The mixture was heated to a target temperature of 177°C (350°F) or 232°C (450°F) by increasing the temperature set point by 10°C every 10 minutes with an external heating jacket while stirring the mixture at 1600 RPM with an impeller. The temperature was then held at the target temperature for 2 hours and cooled to ambient temperature while maintaining stirring. The pressure was monitored throughout. Typically, the pressure rose to 8 psig at 450°F and then returned to 1 psig upon cooling, indicating no reaction between the plastic and VGO. The slight pressure increase near the target heating temperature was due to the evaporation of light materials in the VGO.

[0078] The blended products at ambient temperature showed no visible plastic residue and were completely homogeneous upon visual inspection. The blends of plastic and VGO showed the appearance of a waxy solid of VGO. The blends of plastic and VGO were stable and no changes were observed over the 3 month observation period.

[0079] The pour point (per ASTM D5950-14) and viscosity (per ASTM D445) of the blends were measured to assess the need for material handling. Additionally, the hot heptane insolubles content was measured according to the procedure of ASTM D3279. The hot heptane insolubles method measures the weight percent of material in an oil that is insoluble in hot heptane at 80°C. This method uses a 0.8 micron membrane filter to separate the insoluble material. The heptane insolubles content provides information about the undissolved plastic in the blend. Table 5 below summarizes the list of samples prepared and their properties. [Table 5]

[0080] The pour point and viscosity values ​​are used as a guide for equipment selection and operating procedures. Blends made with plastic additives have a moderate increase in pour point and viscosity compared to the pure VGO system case. These changes can be handled with little or no modification using typical refinery operating equipment. The blending tank is heated above the pour point, changing the physical state of the blend to an easily transportable liquid. The liquid blend can then be transferred to a shipping vessel or refining unit via pumping, gravity drainage, or pressure differential transfer.

[0081] The stable blends remain physical mixtures at temperatures up to 80°C. It was possible to separate the plastics from the blends using a high temperature heptane insolubility test. At 80°C, all of the wax in the VGO was dissolved in the heptane solvent (Example 2-1 in Table 5). The weight percent of the heptane insoluble material is from the undissolved plastic filtered through a 0.8 micron membrane filter. The amount recovered as solid material is in good agreement with the amount of plastic added to the blend preparation. The heptane insolubility results in Table 5 clearly show that the plastic is a physical mixture of solid particles dispersed in the VGO in the blends at 80°C, and the majority of the plastic particles can be effectively separated with a 0.8 micron filter. Optical microscopy analysis shows that the plastics are finely dispersed microcrystalline particles with particle sizes ranging from approximately 10 microns to 80 microns (see Example 5).

[0082] [Example 5A] Optical microscopy of stable blends using low density polyethylene

[0083] FIG. 6 shows optical microscope images in bright field mode (A) and cross polarized mode (B) of an as-prepared blend (Example 4-1) of polyethylene (Plastic A) and VGO at ambient temperature. At ambient temperature, the blend was a physical mixture of finely dispersed plastic particles and petroleum. The average particle size of the polyethylene particles was 10 microns. The fine, micron-sized polyethylene was uniformly dispersed in the VGO and had the visual appearance of micelles.

[0084] Figure 7 shows optical microscopy (OLM) images in cross polarized mode of an as-prepared blend of polyethylene (Plastic A) and VGO (Example 4-1) at various temperatures during heating and cooling. At ambient temperature, the polyethylene remains as fine crystalline particles with an average particle size of 10 microns (Figures 6 and 7A). Upon heating to 90°C, most of the polyethylene melts, and at 106°C, all the polyethylene is completely melted and forms a homogeneous hot liquid blend with VGO. Upon cooling, the polyethylene starts to recrystallize near 90°C and becomes crystalline particles again at an ambient temperature of 25°C (Figure 7F). The recrystallized plastic shown in Figure 7F shows a larger average particle size of about 19 microns compared to the plastic particles of the as-prepared blend shown in Figure 7A. This is likely due to the fact that the blend was cooled at the OLM stage without stirring the plastic / VGO blend. This result suggests that the blend may contain plastic particles with larger particle size when cooled without stirring. The results suggest that continuous vigorous stirring during the cooling process is desirable to produce a stable mixture of petroleum and micron-sized plastic particles.

[0085] [Example 5B] Optical microscopy of stable blends using polypropylene

[0086] Figure 8 shows optical microscope images in bright field mode (A) and cross polarized mode (B) of the as-prepared blend of polypropylene (Plastic C) and VGO (Example 4-4) at ambient temperature. The average particle size of the polypropylene was about 20 microns. The fine microcrystalline polypropylene was uniformly dispersed in the VGO and has the visual appearance of micelles.

[0087] FIG. 9 shows optical microscopy (OLM) images in cross polarized mode of an as-prepared blend of polypropylene (Plastic C) and VGO (Example 4-4) at various temperatures during heating and cooling. At ambient temperature, the polypropylene remains as microcrystalline particles with an average particle size of 20 microns (FIG. 8 and FIG. 9A). Upon heating to 129°C, most of the polypropylene melts, and at 132°C, all of the polypropylene is completely melted, forming a homogeneous hot liquid blend. Upon cooling, the polypropylene begins to recrystallize around 93°C and becomes crystalline particles again at ambient temperature. The average particle size of the recrystallized particles is larger, about 78 microns, because the blend was cooled at the OLM stage without stirring with VGO. Again, the recrystallized plastic shown in FIG. 9F shows a much larger average particle size compared to the plastic particles of the as-prepared blend shown in FIG. 9A. This result suggests that continuous vigorous stirring during the cooling process is desirable to produce a stable mixture of petroleum and micron-sized plastic particles.

[0088] [Example 6] Preparation of VGO and plastic blends using HDPE and high molecular weight polyethylene

[0089] Two blends of vacuum gas oil (VGO) and plastics (Plastics B and D in Table 1) were prepared using an autoclave. The VGO is similar to petroleum feedstock #1 but has a higher pour point. The procedure described in Example 4 was used to prepare these blends, except that the heating temperature was 232°C (450°F) and the hold time at 450°F was 4 hours. The resulting blends were solid at ambient temperature and had the appearance of a VGO wax. The properties of the blends are shown in Table 6. [Table 6]

[0090] [Example 7] Improving the viscosity of stable blends using light petroleum additives

[0091] This example shows that the addition of light cycle oil (LCO, feedstock #3) or diesel (feedstock #4) significantly reduces the viscosity, making the feedstock easier to handle.

[0092] Example 7-1 was prepared by adding 20 wt% light cycle oil to Example 6-2 (a blend of 10 wt% HDPE plastic B in VGO). A procedure similar to that described in Example 4 was used to prepare this blend. The mixture was heated to 350°F, held at that temperature for 1 hour, and then cooled to ambient temperature with stirring throughout. The pressure was monitored during heating. The pressure rose to 4 psig at 350°F and then returned to 0 psig upon cooling, indicating no reaction between the plastic, VGO, and LCO. The slight pressure increase near the target temperature was due to the vaporization of the light materials in the LCO.

[0093] Example 7-2 was prepared in a manner similar to Example 7-1, except diesel was used instead of LCO.

[0094] The final products, Examples 7-1 and 7-2, were waxy light brown solids at ambient temperature that appeared homogenous upon visual observation and contained no visible plastic residue. The blends of plastic, LCO (or diesel), and VGO were stable and no changes were observed over the two week observation period. Table 7 below summarizes the list of samples prepared and their properties. [Table 7]

[0095] [Example 8] Direct conversion of plastics and VGO via FCC using USY catalyst

[0096] To investigate the effect of treatment in a refinery FCC unit of waste plastics and vacuum gas oil, laboratory tests were carried out on a fluid catalytic cracking (FCC) process using a stable blend of plastics and VGO (Examples 2-3, 2-9, and 2-10) with an FCC catalyst containing USY zeolite. The catalyst was an equilibrium catalyst taken from a commercial FCC plant.

[0097] FCC experiments were performed in a Model C ACE (advanced cracking evaluation) unit manufactured by Kayser Technology Inc., using regenerated equilibrium catalyst (Ecat) from a refinery. The reactor was a fixed flow reactor using N2 as the fluidizing gas. Catalytic cracking experiments were performed at atmospheric pressure and a reactor temperature of 975°F. The catalyst / oil ratio was varied between 5 and 8 by varying the amount of catalyst. Gas products were collected and analyzed using a refinery gas analysis unit (RGA) equipped with a GC with an FID detector. In-situ regeneration of the spent catalyst was performed in the presence of air at 1300°F, and the regenerated flue gas was passed through an IR cell to determine the flue gas composition, which was used to calculate the coke yield. The liquid products were weighed and subjected to simulated distillation (D2887) and C5- compositional analysis on the GC. The mass balance shows that the crude oils are coke, dry gas components, LPG components, gasoline (C5, ~430°F), light cycle oil (LCO, 430-650°F), and heavy cycle oil (HCO, 650°F). + The yield of 1,000,000 sucrose was determined. The results are summarized in Table 8 below. [Table 8]

[0098] The results in Table 8 show that co-feeding 5-10 wt% plastics results in negligible changes in FCC unit performance, indicating that co-processing of plastics is readily feasible up to 10 wt%. Up to 20% wt% may be feasible without performance issues, but equipment with appropriate controls is required to address the increased viscosity and pour point.

[0099] Because plastics are more easily cracked than VGO, the blends slightly increased conversion. The addition of plastics to the FCC feed slightly increased the coke yield, but did not significantly change the dry gas yield. The yields of LPG and C3 and C4 olefins increased moderately, and the yields of LCO and HCO decreased slightly. The gasoline yield was similar. Because the cracked products made from plastics are paraffinic, the blends with plastics reduced the octane number by about 1-2. Due to the flexibility of the refinery's operations, these octane losses can be compensated for by using blends or by adjusting the FCC process operation and catalyst / additive mix. The hydrocarbon compositions of all these co-feed products are within the range of typical FCC gasoline.

[0100] [Example 9] Characteristics of waste plastic samples and blend preparation

[0101] Four waste plastic samples were purchased for blend preparation and their properties are summarized in Table 9. FT-IR was used to identify the general nature of the plastics. 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 at 1000°F for 3 hours under N2. The recoverable hydrocarbons were assumed to be equal to the loss-on-ignition (LOI) (%). The inorganic residue after calcination was analyzed by ICP analysis. The LOI values ​​and ICP analysis were used to estimate the impurities (wt%) in the as-received plastics and are reported in Table 9 below. The most common impurities present in waste plastics are Ca, Mg, Si, and Ti, which can originate from the manufacturing of plastic consumer products where they are commonly used as fillers, such as calcium carbonate, silica, and talc. Al, Fe, P, and Zn are also present in significant amounts. [Table 9]

[0102] Thermogravimetric analysis (TGA) was performed on the waste plastic samples to confirm that the plastic material is thermally stable at temperatures well above the melt preparation temperature. The TGA results shown in Figure 10 indicate that the waste plastic samples are stable up to 700°F.

[0103] Blends of the above waste plastic samples with VGO were prepared using the procedure of Example 4, except that the dissolution temperature was 400° F. After dissolving 10 wt% plastic, solid precipitation was observed (presumably from the filler) and the blend exhibited very high viscosity (presumably due to the presence of solids). For dissolution of 5 wt% plastic, a significant decrease in viscosity was observed when the blend was filtered to remove the solid filler. [Table 10]

[0104] [Example 10] Direct conversion of waste plastics and VGO blends via FCC using USY catalyst

[0105] Laboratory tests were conducted using a fluid catalytic cracking (FCC) process with a stable blend of waste plastics and VGO using an FCC catalyst containing USY zeolite to study the effect of processing waste plastics and vacuum gas oil in a refinery FCC unit. The plastics used were Waste Plastic #1 (Plastic E) and Waste Plastic #2 (Plastic F). A base case using only VGO feed (Example 10-1) was compared to two blend runs including a 5 / 95% blend of Plastic E / VGO (Example 10-2) and a 5 / 95 wt% blend of Plastic F / VGO (Example 10-3). The catalyst was an equilibrium catalyst taken from a commercial FCC plant. [Table 11]

[0106] The results in Table 11 show that co-feeding 5 wt% waste plastics only results in a small change in the performance of the FCC unit, indicating that co-processing of 5 wt% waste plastics is readily feasible.

[0107] Because waste plastics are more easily cracked than VGO, blends increased conversion slightly. The addition of waste plastics to the FCC feed increased coke yields slightly, but dry gas yields were largely unchanged. LPG, C3, and C4 olefin yields increased moderately, and LCO and HCO yields decreased slightly. Gasoline yields were comparable. Because the cracked products made from plastics are paraffinic, blends with plastics reduced octane numbers by about 1-1.5. Due to the flexibility of refinery operations, such octane reductions can be easily compensated for by using blends or by adjusting FCC process operations and catalyst / additive mixes. The hydrocarbon compositions of all co-feed products are within the range of typical FCC gasoline.

[0108] 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.

[0109] 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. 1. A blend of a petroleum feedstock with 1-20 wt % plastic, based on the weight of the blend, wherein the plastic comprises polyethylene and / or polypropylene, and the plastic in the blend comprises finely dispersed micron-sized particles having an average particle size of 10 microns to less than 100 microns.

2. 10. The blend of claim 1, wherein the amount of plastic in the blend comprises 1 to 10 wt % of the blend.

3. 10. The blend of claim 1, wherein the plastic comprises low density polyethylene.

4. 10. The blend of claim 1, wherein the plastic comprises high density polyethylene.

5. 5. The blend of claim 4, wherein the blend comprises 1 to 10 wt.% high density polyethylene.

6. The plastic has an average molecular weight M in the range of 5,000 to 150,000. ｗ 2. The blend of claim 1, comprising a polypropylene having

7. The plastic has an average molecular weight M in the range of 150,000 to 400,000. ｗ 2. The blend of claim 1, comprising a polypropylene having

8. 8. The blend of claim 7, wherein the blend comprises 1 to 10 wt.% polypropylene.

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

10. 10. The blend of claim 1, wherein the plastic comprises a waste plastic mixture comprising polyethylene and polypropylene.

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

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

13. The petroleum feedstock in the blend is selected from the group consisting of vacuum gas oil, atmospheric gas oil, reformate, light cycle oil, heavy fuel oil, refinery hydrocarbon streams containing toluene, xylene, heptane or benzene, coker naphtha, C ５ -C ６ 10. The blend of claim 1 comprising isomerized paraffin naphtha, FCC naphtha, hydrocracker bottoms, gasoline, jet fuel, diesel, or mixtures thereof.

14. 10. The blend of claim 1, wherein the petroleum feedstock in the blend comprises a light oil or a heavy reformate.

15. 14. The blend of claim 13, wherein the blend comprises light cycle oil, gasoline, or diesel.

16. 15. The blend of claim 14, wherein the blend comprises light cycle oil, gasoline, or diesel.

17. 14. The blend of claim 13, wherein the blend comprises benzene, toluene, xylene, or heptane.

18. 15. The blend of claim 14, wherein the blend comprises benzene, toluene, xylene, or heptane.

19. 10. The blend of claim 1, wherein the blend is at a temperature above the melting point of the plastic and is a homogeneous liquid blend at elevated temperature.

20. 20. The blend of claim 19 further comprising a petroleum feedstock added to the blend.

21. 1. A process for preparing a blend of plastic and petroleum, comprising: (a) mixing together an oil feedstock and a plastic comprising polyethylene and / or polypropylene and, while mixing, heating the mixture to a temperature above the melting point of the plastic but below 500° F.; (b) cooling the blend of plastic melt and oil feedstock liquid to a temperature below the melting point of the plastic; The above process comprising:

22. 22. The process of claim 21, wherein the cooling in (b) is conducted with continuous stirring.

23. 22. The process of claim 21, wherein the heating is at a temperature of 250 to 450°F with a residence time of 5 to 240 minutes at the final heating temperature.

24. 22. The process of claim 21, wherein cooling is continued until ambient temperature is reached.

25. 22. The process of claim 21, wherein the plastic is a waste plastic mixture comprising polyethylene and polypropylene.

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