Conversion of waste plastic and oil blend with a contaminant removal step

Abstract

A novel process for the conversion of waste plastics via cofeeding waste plastic melt with a refinery feedstock is provided. The process can generate a mixed product which can be further treated or purified to produce value-added products or chemical precursors.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Ser. No. 63 / 645,299 filed May 10, 2024, the complete disclosure of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates to a process for effectively converting waste plastics into petroleum products and suitable feedstock for cracker or chemical production. More specifically, for waste plastic with a high contamination level, a filtration step is used to control the feedstock quality.BACKGROUND

[0003] The production of plastics has more than doubled since the turn of the century, and more plastic than ever is being used and discarded. The bulk of this discarded plastic accumulates in landfills, with less than 10% of plastics being successfully recycled. One reason underlying the lack of recycling rests in the currently anemic market for recycled plastics.

[0004] Much has been done in attempting to advance the recycled plastics market. Indeed, the production of items made from secondary plastics (plastic made using recycled waste plastics) has more than quadrupled from 2000 to 2019. Yet despite this, secondary plastics account for only about 6% of the total plastics produced. Thus, while the increase in items manufactured from secondary plastics represents noble progress, more must be done to create a separate and well-functioning market for recycled waste plastics.

[0005] Beyond their use in the creation of secondary plastic, waste plastics are generally well known to be suitable in the production of value-added chemical and fuel products. However, the ability to use waste plastics in the creation of value-added chemicals and fuel products remains limited. As such, chemical recycling accounts for only a small amount of total waste plastic recycling.

[0006] The typical chemical recycling process involves cleaning waste plastics, turning said plastics into polymer pellets, and pyrolyzing said plastics in a pyrolysis unit to make fuels (naphtha, diesel), steam cracker feed, or slack wax. However, this current practice of pyrolysis operation produces poor-quality fuel components. Moreover, the current volume of chemical recycling remains too small to function as a substantial independent market for recycled waste plastics, limiting a potentially positive impact on the environment and plastics industry. Expanding the volume of the chemical recycling of single use plastics to an industrially significant quantity requires more robust processes. Thus, improved processes establishing a circular economy for waste plastic where spent waste plastics are not only recycled effectively but generate high value byproducts would be of great interest to the industry.SUMMARY

[0007] A summary of certain embodiments disclosed herein is sets forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are note intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0008] The present process provides a new, useful, and efficient process for the conversion of waste plastics via cofeeding a blend of waste plastic and a refinery feedstock. Contaminants are captured during the blend preparation. In one embodiment, a hot blend of plastic and petroleum oil, such as VGO, is prepared, which blend is then filtered to remove solids. The temperature used for preparing the blend of plastic and petroleum oil is in the range of from about 300-450° F., and the hot blend is filtered while still hot.

[0009] In one embodiment the process comprises sorting a feedstock of mixed waste plastic into desirable and undesirable plastics. The desirable plastics can be polyolefins, for example polypropylene and polyethylene. These desirable plastics can then be cleaned. A refinery feedstock can then be added to a blend preparation unit. In one embodiment the refinery feedstock comprises vacuum gas oil. In another embodiment the refinery feedstock comprises atmospheric gas oil. In another embodiment the refinery feedstock comprises atmospheric resid. In still another embodiment the refinery feedstock comprises vacuum resid. The desirable waste plastic can then be added to the blend preparation unit where the plastic and feedstock are heated and mixed to prepare a homogenous blend. The residence time for the desirable plastic and refinery feedstock in the blend preparation unit is sufficiently long to melt the plastic and have the refinery feedstock and desirable plastic mixed until a homogeneously mixed product is achieved. In one embodiment the blend preparation unit comprises a filter for filtering the mixed product to remove any remaining solids. In one embodiment these solids are removed as a filter cake. In another embodiment the solids are removed as a slurry.

[0010] The mixed product can be collected from the blend preparation unit and supplied to a refinery conversion unit. In one embodiment the refinery conversion unit comprises a fluid catalytic cracker. In one embodiment the refinery conversion unit comprises a hydrocracker. In one embodiment the refinery unit comprises a high-production compact reactor. In one embodiment the refinery unit comprises a coker. In one embodiment the product of the refinery conversion unit can be used in the creation of high value petroleum products and sustainable feedstock for cracker reactions or chemicals production.

[0011] Among other factors the present process permits the effective conversion of waste plastics via cofeeding waste plastic melt with a refinery feed, for example VGO. Before sending the feed stream containing waste plastic to refinery units, the contaminants are captured in the blend preparation process. With a lower contamination level, the refinery conversion units will operate more effectively. The plastic / petroleum oil blend is upgraded with appropriate refinery units with conversion processes. The final transportation fuels produced by the integrated process will be higher quality and will meet the fuels quality requirements. Our process will produce valuable products, such as high quality gasoline, jet, diesel and base oil, and valuable intermediate / feedstocks for chemicals production. The integrated process will generate a much cleaner naphtha stream for steam cracker feedstock for ethylene generation for polyethylene production or a propane / propylene stream ultimately for polypropylene production. These large productions would allow a “circular economy” for plastics recycle. The use of the present process offers significant economic and environmental benefits if adopted in industrial refineries.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 depicts the current operation of waste PE / PP pyrolysis units where the unit produces small volume of naphtha and diesel product.

[0013] FIG. 2 depicts plastic types desirable for use with the present process.

[0014] FIG. 3 depicts a comparison chart showing the differences in thermal stability between polyethylene, polypropylene, and polyvinyl chloride.

[0015] FIG. 4 depicts one embodiment of the present integrated process.

[0016] FIG. 5 depicts a detailed view of one embodiment of the blend preparation unit.

[0017] FIG. 6 depicts a detailed view of one embodiment of the blend preparation unit, wherein the refinery feedstock comprises vacuum gas oil.

[0018] FIG. 7 depicts a detailed view of one embodiment of the blend preparation unit, wherein the refinery feedstock comprises atmospheric gas oil.

[0019] FIG. 8 depicts a detailed view of one embodiment of the blend preparation unit, wherein the refinery feedstock comprises vacuum resid.DETAILED DESCRIPTION

[0020] Before the processes of the conversion of waste plastics and oil blend with contaminant removal step is disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms “a,”“an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a step” may include multiple steps, reference to “producing” or “products” of a reaction or treatment should not be taken to be all of the products of a reaction / treatment, and reference to “treating” may include reference to one or more of such treatment steps. As such, the step of treating can include multiple or repeated treatment of similar materials / streams to produce identified treatment products.

[0021] Numerical values with “about” include typical experimental variances. As used herein, the term “about” means within a statistically meaningful range of a value, such as a stated particle size, concentration range, time frame, molecular weight, temperature, or pH. Such a range can be within an order of magnitude, typically within 10%, and more typically within 5% of the indicated value or range. Sometimes, such a range can be within the experimental error typical of standard methods used for the measurement and / or determination of a given value or range. The allowable variation encompassed by the term “about” will depend upon the particular system under study, and can be readily appreciated by one of ordinary skill in the art. Whenever a range is recited within this application, every whole number integer within the range is also contemplated as an embodiment of the invention.

[0022] The present application, in one embodiment, relates to the conversion of waste plastics via cofeeding waste plastic melt with a refinery feedstock. In one embodiment the waste plastics can be sorted into desirable and undesirable waste plastics. Polyethylene (PE) and polypropylene (PP) plastics are particularly attractive options for processing in refinery units. However, waste plastics with PE and PP plastic sometimes contain substantial amounts of undesirable materials such as other undesirable plastics (polyvinyl chloride, polyethylene terephthalate, nylon, etc.), inorganic filler materials (CaCO3, MgO, silica, talc, TiO2 etc.), additives and colors. The amount of undesirable material can be in the range of 0.1 to 30 wt. %. Contamination with polyvinyl chloride (PVC) is highly undesirable since its decomposition product, HCl, could corrode the refinery equipment and cause serious reliability issues if water is present in the process streams. Other unwanted plastic that are common in the waste plastic feed sources may include polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), variety of nylon polymers (e.g., nylon 66, nylon 6). In one embodiment the desirable waste plastics can be washed to further remove any contaminants.

[0023] For recycling of polyethylene and polypropylene plastic, an advanced recycling process utilizing a catalytic conversion process is the most energy efficient and effective recycling process. However, due to impurities in the waste plastic feedstock, it is difficult to use catalysts for advanced recycling. In order to feed the plastic / VGO blend to the catalytic processes such as fluid catalytic cracking (FCC) or hydrocracking (HCR), impurities in the blend need to be removed before feeding the plastic / VGO blend to the catalytic conversion unit.

[0024] The source of impurities in the waste plastic feedstocks can be classified broadly into two different groups. The first group of impurities were originated during manufacturing of plastic resins or plastic products, such as plastic films, molds, etc. Plastic resins contain additives, catalyst residue from the polymer manufacturing, and inorganic filler materials such as talc, silica, alumina, diatomaceous earth, nepheline syenite, and calcium carbonate, which were added to improve the manufacturing process or properties of plastic resins. Plastic product manufacturers add more inorganic filler materials, pigments or create multi-layer films with different plastic mixes or with metallic layering materials. These additives and filler materials cannot be removed by a mechanical cleaning process and can cause a serious problem for advanced recycling processes utilizing catalytic conversion units. In particular, those impurities may deactivate the catalyst in the conversion unit prematurely and / or cause downstream processing issues with fines generation.

[0025] The second group of impurities are undesirable plastics coming from imperfect sorting of recycling process. Sorting and mechanical cleaning processes still leave undesirable plastics in the recycled plastic feed. Undesirable plastic materials include, but are not limited to, nylon, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PET). These undesirable plastic materials may cause issues in plant operation and equipment reliability. The presence of PVC is particularly harmful as it evolves HCl that could cause corrosion in refinery equipment. High nitrogen containing plastic, such as nylon and ABS may deactivate the catalyst in the conversion unit.

[0026] The present process offers a superior blend preparation process for plastic with a petroleum feed such as VGO for advanced recycling of waste plastic comprising polyethylene (PE) and polypropylene (PP). The process comprises the preparation of a plastic and oil blend at a temperature around 300-450° F., followed by hot filtration at a similar temperature range. This process purifies the PE or PP plastic / oil blend by removing undissolved, undesirable plastics and inorganic filler materials from the plastic / oil blend.

[0027] In one embodiment of the present process, waste plastic and a petroleum refinery feed are fed to a blend preparation unit and mixed until the waste plastic has melted and essentially dissolved in and combined with the refinery feedstock to form a mixed product. In one embodiment the refinery feedstock can comprise vacuum gas oil (VGO). In another embodiment the refinery feedstock can comprise atmospheric gas oil (AGO). In another embodiment the refinery feedstock can comprise atmospheric resid (AR). In still another embodiment the refinery feedstock can comprise vacuum resid (VR). The amount of polyethylene (PE) and polypropylene (PP) added to the refinery feedstock in the blend preparation unit can range from 1-20 wt. % of the mixed product and in one embodiment from 1-10 wt. % of the mixed product, and in another embodiment from 1-5 wt. %. The amount of plastic in the blend is generally less than 20 wt. %. The amount of high-density PP or high-density PE added to the refinery feedstock in the blend preparation unit can generally range from 1-10 wt. % of the mixed product.

[0028] In one embodiment the operating temperature of the blend preparation melting unit is about 300-450° F., and in another embodiment about 300-400° F., and in another embodiment about 350-400° F. At this temperature, all PE and PP plastics can be dissolved while the decomposition of PVC is minimized. PVC, which decomposes at 450-600° F. and produces a substantial amount of HCl and some organic chlorides. PE is stable up to 800° F. and PP is stable up to 700° F., at which temperatures they begin to decompose. Hydrocarbons in VGO are stable for the entire temperature window up to 1100° F., but it contains light hydrocarbon components that start to boil at 400° F. and above. Unwanted plastics such as nylon, PET, PVC, and ABS can be further minimized using this operating temperature as these plastics do not melt in petroleum oil at 450° F. or below. Thus, the operating temperature maximizes the melting of PE and PP while at the same time minimizing contamination from other plastics and organic chlorides in the blend.

[0029] In one embodiment the blend preparation unit can contain a filtration unit to further remove solid contaminants. Solid removals can be done via filtration using continuous slurry removal or use of a filter press or a centrifuge. The filtration unit can also remove solid contaminants and unwanted plastics (nylon, PET, ABS, PVC) from the hot blend of plastic and petroleum oil. This filtration step is particularly critical if the hot homogeneous blend is fed to a refinery conversion unit such as an FCC or HCR unit, where the catalyst stability will be negatively affected by the solid contaminants in the hot homogeneous blend of plastic and petroleum oil. In one embodiment the bottom stream containing solids (the reject stream containing solids) can be sent to a coker unit for additional hydrocarbon recovery, or further filtered. The solids can be disposed of as a filter cake. In one embodiment the plastic / VR blend can be fed to coker unit. A coker unit does not contain any catalyst that needs to be protected, thus the coker unit can handle the plastic / VR feed with a higher amount of solids and an additional solid removal step may not be necessary. If the solid content of the plastic / VR feed is too high to cause an issue for the coke quality, then, a portion of the solids in the plastic / VR feed can be removed to control the residual solid content of the coke. In one embodiment the plastic / VR feed can be sent to a visbreaker or deasphalting unit.

[0030] In one embodiment the upgraded mixed product produced can be high-quality gasoline, jet, diesel, and base oil, and valuable intermediates / feedstocks for chemical production. The final transportation fuel produced by the integrated process can be high quality and meet fuel quality requirements. In one embodiment, a naphtha fraction is recovered from the refinery conversion unit. The integrated process generates a much cleaner naphtha stream for steam cracker feedstock for ethylene generation for polyethylene production or a propane / propylene stream ultimately for the polypropylene production. The naphtha fraction can also be further processed in the refinery to gasoline, diesel, base oil, or jet fuel. In another embodiment, a gasoline fraction can be recovered from the conversion unit which is then sent to a gasoline blending pool in the refinery. This large on-spec production would allow a feasible “circular economy” for plastics recycling.

[0031] FIG. 1 shows a diagram of the pyrolysis of waste plastics fuel or wax that is generally operated in the industry today. Generally, the waste plastics are sorted together 1. The cleaned plastic waste 2 is converted in a pyrolysis unit 3 to off gas 4 and pyrolysis oil (liquid product). 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 fuel markets. The heavy pyrolysis oil fraction 6 is recycled back to the pyrolysis unit 3 to maximize the 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 upon cooling to ambient temperature). Wax can be separated from the heavy fraction 6 and sold to the wax markets.

[0032] Use of the present blend, however, avoids the pyrolysis of the waste plastic. Rather, a stable blend of petroleum feedstock and the waste plastic is prepared, which can be fed to the refinery conversion units. Thus, the pyrolysis can be avoided, which is a significant energy savings as well as equipment cost savings.

[0033] The preferred plastic starting material for use in the present blend is sorted waste plastics containing predominantly polyethylene and polypropylene (plastics recycle classification types 2, 4, and 5). The pre-sorted waste plastics are washed and shredded or pelleted to feed to a blend preparation unit. FIG. 2 depicts the plastic type classification for waste plastics recycling. Classification types 2, 4, and 5 are high density polyethylene, low density polyethylene and polypropylene, respectively. Any combination of the polyethylene and polypropylene waste plastics can be used. Polystyrene, classification 6, can also be present in a limited amount.

[0034] Sorting of waste plastics is important in order to minimize contaminants such as N, Cl, and S. Plastics waste containing polyethylene terephthalate (plastics recycle classification type 1), polyvinyl chloride (plastics recycle classification type 3) and other polymers (plastics recycle classification type 7) need to be sorted out to less than 5%, preferably less than 1% and most preferably less than 0.1%. The present process can tolerate a moderate amount of polystyrene (plastics recycle classification type 6). Waste polystyrene needs to be sorted out to less than 20%, preferably less than 10% and most preferably less than 5%.

[0035] Washing of waste plastics can remove metal contaminants such as sodium, calcium, magnesium, aluminum, and non-metal contaminants coming from other waste sources. Non-metal contaminants include contaminants coming from the IUPAC Periodic Table Group 14, such as silica, contaminants from Group 15, such as phosphorus and nitrogen compounds, contaminants from Group 16, such as sulfur and oxygen compounds, and halide contaminants from Group 17, such as fluoride, chloride, and iodide. The residual metals, non-metal contaminants, and halides need to be removed to less than 50 ppm, preferentially less than 30 ppm and most preferentially to less than 5 ppm.

[0036] The petroleum with which the waste plastic is blended is generally a petroleum based feedstock for the refinery. It is preferred that the petroleum blending oil is the same as the petroleum feedstock for the refinery. The petroleum can also comprise any petroleum derived oil or petroleum based material. In one embodiment, the petroleum feedstock oil can comprise atmospheric gas oil, vacuum gas oil (VGO), atmospheric residue, or heavy stocks recovered from other refinery operations. In one embodiment, the petroleum feedstock oil with which the waste plastic is blended comprises VGO. In one embodiment, the petroleum feedstock oil with which the waste plastic is blended comprises light cycle oil (LCO), heavy cycle oil (HCO), FCC naphtha, gasoline, diesel, toluene, and / or an aromatic solvent derived from petroleum.

[0037] In one embodiment, the petroleum feedstocks for the blend preparation include 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 paraffinic naphtha, FCC naphtha, hydrocracker bottom, gasoline, jet fuel, diesel, or mixtures of some these.

[0038] In one embodiment, an alternative hydrocarbon feedstock or hydrocarbon solvent can be used for the blend preparation. The alternative feedstock can be derived from other hydrocarbon sources such as from bio feedstock, coal, natural gas, or plastic pyrolysis.

[0039] In one embodiment, the petroleum feedstocks are gas oil, heavy reformate, or various recycle streams that will be fed to a catalytic conversion unit. In one embodiment, the blend is sent to the conversion unit at a temperature above the melting point of the highest melting plastic in the blend. The volume flow of the blend to the refinery unit can comprise up to 100 vol. % of the total flow of hydrocarbons to the conversion unit, and in one embodiment up to 50 vol. %, and in another embodiment up to 25 vol. % of the total hydrocarbon flow to the conversion unit. Then, the plastic and petroleum feedstock in the blend are converted together to a higher value product via catalytic conversion.

[0040] FIG. 3 depicts the thermal stability of PE, PP, and PVC as shown by thermal gravimetric analysis. PVC decomposes at 450-600° F. and produces a substantial amount of HCl, and may generate organic chlorides. PE is stable up to 800° F. and PP is stable up to 700° F. The hydrocarbons in VGO, for example, are stable for the entire temperature window up to 1100° F., but it does contain light hydrocarbon components that start to boil at 400° F. and above.

[0041] FIG. 4 shows one embodiment of the integrated process. Mixed waste plastic is sorted to obtain post-consumer or post-industrial PE / PP 4001. Post-consumer or post-industrial PE / PP is then cleaned producing clean plastic 4002, which is fed to a blend preparation unit 4003, along with a refinery feedstock 4004. The blend preparation unit melts plastic and prepares a hot homogeneous blend of plastic and petroleum oil 4005 that can be fed to a refinery unit 4006 to produce high value petroleum products and sustainable feedstock for cracker or chemicals production 4007.

[0042] FIG. 5 depicts a detailed view of one embodiment of the blend preparation unit. Clean waste 5001 and oil feedstock 5002 are added to the blend preparation unit 5003. The clean waste 5001 and oil feedstock 5002 are heated and mixed 5010 producing a hot homogeneous liquid blend of plastic and oil 5004. The hot homogeneous liquid blend of plastic and oil 5004 is filtered for solid removal using filter 5005, producing a filtered homogeneous blend of plastic and oil 5006 and removed solids 5007. The temperature of the filtration 5005 is about the same as the temperatures used in the heating and mixing 5010, and is in the range of about 300-450° F. The filtered homogenous blend of plastic and oil 5006 is then passed to a hydrocarbon conversion unit 5008 to produce high value hydrocarbon products and sustainable feedstock for cracker or chemicals production 5009. The oil feedstock can be a refinery feedstock or hydrocarbon solvent derived from other feedstock sources such as from bio feedstock, coal, natural gas, or plastic pyrolysis. The blend preparation unit and hydrocarbon conversion unit may be located near the waste collection facility, near plastic recycling facility or near a chemical production plant.

[0043] FIG. 6 depicts a detailed view of one embodiment of the blend preparation unit. Clean waste 6001 and vacuum gas oil 6002 are added to the blend preparation unit 6003. The clean waste 6001 and vacuum gas oil 6002 are heated and mixed 6012 producing a hot homogeneous liquid blend of plastic and oil 6004. The hot homogeneous liquid blend of plastic and oil 6004 is filtered for solid removal using filter 6005, producing a filtered homogeneous blend of plastic and oil 6006 and removed solids 6007. The filtered homogenous blend of plastic and oil 6006 is then passed to a refinery conversion unit 6008 to produce high value petroleum products and sustainable feedstock for cracker or chemicals production 6009. The removed solids 6007 are removed as a slurry steam 6010 which can be sent to a coker, or a filter cake 6011. The filter cake 6011 can be sent to a waste handling facility for disposal or to a cement manufacturing facility to be used as fuel.

[0044] FIG. 7 depicts a detailed view of one embodiment of the blend preparation unit. Clean waste 7001 and atmospheric gas oil 7002 are added to the blend preparation unit 7003. The clean waste 7001 and atmospheric gas oil 7002 are heated and mixed 7012 producing a hot homogeneous liquid blend of plastic and oil 7004. The hot homogeneous liquid blend of plastic and oil 7004 is filtered for solid removal using filter 7005, producing a filtered homogeneous blend of plastic and oil 7006 and removed solids 7007. The filtered homogenous blend of plastic and oil 7006 is then passed to a refinery conversion unit 7008 to produce high value petroleum products and sustainable feedstock for cracker or chemicals production 7009. The removed solids 7007 are removed as a slurry steam 7010 which can be sent to a coker, or a filter cake 7011. The filter cake 7011 can be sent to a waste handling facility or to a cement manufacturing facility.

[0045] FIG. 8 depicts a detailed view of one embodiment of the blend preparation unit. Clean waste 8001 and vacuum resid 8002 are added to the blend preparation unit 8003. The clean waste 8001 and vacuum resid 8002 are heated and mixed 8009 producing a hot homogeneous liquid blend of plastic and oil 8004. Solids are not removed in this embodiment. The homogenous blend of plastic and oil 8004 is then passed to a refinery conversion unit 8007 to produce high value petroleum products and sustainable feedstock for cracker or chemicals production 8008. Optionally, a portion of the hot homogeneous liquid blend of plastic and oil 8004 is filtered for solid removal using filter 8005 as needed, producing a filtered homogeneous blend of plastic and oil 8006 to improve the quality of the petroleum products and sustainable feedstock for cracker or chemicals production 8008. If the filter unit is used, then solids are removed either as a slurry steam or as a filter cake.

[0046] The following examples are provided to aid in illustrating the present process and its advantages. The examples are meant to be illustrative and not limiting.Example 1: Properties of PE and PP Plastic Samples and Petroleum Feedstock Used for Blend Preparations

[0047] Four commercial plastic samples, low density polyethylene (LDPE, Plastic A), high density polyethylene (HDPE, Plastic B), two polypropylene samples with average molecular weight of ˜12,000 (PP, Plastic C) and ˜250,000 (PP, Plastic D), were purchased and their properties are summarized in Table 1.TABLE 1Properties of Virgin Plastics UsedLDPEHDPEPPPP(Plastic A)(Plastic B)(Plastic C)(Plastic D)FormPelletsPelletsPelletsPelletsMelt Index25 g / 10 min12 g / 10 min—12 g / 10 min(190° C. / 2.16 kg)(190° C. / 2.16 kg)(230° C. / 2.16 kg)Melting Point, ° C.116125-140157160-165Transition Temp, ° C.93, softening125, softening163, softening—Density, g / mL at 25° C.0.9250.9520.90.9Hardness—66—100Average molecular weight, Mw——~12,000~250,000Average molecular weight, Mn——~5,000~67,000

[0048] Petroleum feedstocks that can be used to prepare stable blends with plastic include hydrotreated vacuum gas oil (VGO), Aromatic 100 solvent, and light cycle oil (LCO), and diesel. Their properties are shown in Table 2. Aromatic 100 is a commercially available aromatic solvent manufactured from petroleum-based material, mainly containing C9-C10 dialkyl and trialkyl benzenes.TABLE 2Properties of Petroleum Feedstocks for Blend PreparationsHydrotreatedAromaticVGO100LCODieselPetroleumPetroleumPetroleumPetroleumFeed #1Feed #2Feed #3Feed #4Specific Gravity0.8970.8720.9560.811Carbon, wt %87.8489.9090.5086.4Hydrogen, wt %12.6910.109.5014.6H / C Molar Ratio1.731.331.262.0Bromine Number2——0.1Total S, ppm1500900<2Total N, ppm2730N / A<0.1Ni, ppm<0.60<0.2<0.2V, ppm<0.60<0.2<0.2Simdist, ° F.IBP (0.5%)462297235536 5 wt %57332540555310 wt %61632744156330 wt %70633049060150 wt %77533654163870 wt %85434460767390 wt %96235568970295 wt %1008362718709FBP (99.5%)1107376786717Example 2—Preparation of VGO and Pure PE and PP Plastic Blends (Base Case)

[0049] Several blends of vacuum gas oil (VGO) and the two plastic samples (Plastic A and C from Table 1) were prepared by adding the plastic pellets to a hydrotreated vacuum gas oil (Petroleum Feed #1 of Table 2) using an autoclave unit.

[0050] The following procedure was used. At ambient temperature, pre-weighed plastic pellets (solids) and the VGO feed (waxy solids) were added to a batch autoclave unit. The autoclave was purged with N2 gas to remove air in the vessel, and then the inlet and outlet valves were closed. The mixture was stirred with an impeller at 1600 RPM while the mixture was heated with an external heating jacket to the target temperature of 177° C. (350° F.) or 232° C. (450° F.) by raising the temperature set point by 10° C. for every 10 minutes. Then, the temperature was held at the target temperature for 1 to 2 hours, then cooled down to ambient temperature with the stirring maintained. The pressure was monitored for the entire time. Typically, the pressure was built up to as high as 8 psig at 450° F., and then back to 1 psig upon cooling, indicating no reaction between plastic and VGO. The slight pressure build-up near the target heating temperature was due to vaporization of light material in VGO.

[0051] Upon cooling, the hot homogeneous liquid blend of plastic and VGO became a waxy solid that has the typical look of VGO's waxy solids. The blend product at ambient temperature showed no visible separate phase of plastic and looked completely homogeneous per visual observation. The blend of plastic and VGO was stable at ambient conditions, and no change was observed for a 3-month period of observation.

[0052] To assess material handling, a pour point (per ASTM D5950-14) and viscosity (per ASTM D445) of the blend were measured. The hot heptane insoluble test method (ASTM D3279) was used to determine the weight percent of plastic in oils as plastic is insoluble in hot heptane at 80° C. The method isolates the plastic material using a 0.8-micron membrane filter. Table 3 below summarizes the list of samples prepared and their properties.TABLE 3Preparation for Stable Blend of Plastic and VGOWt %PrepPourViscosityHeptaneExamplePlastic MeltTemp, ° C.Point, ° C.at 180° C., cPInsolubles, wt %Example 2-1None—251.810.01Example 2-210 wt % LDPE (Plastic A)1772531.89.9Example 2-310 wt % LDPE (Plastic A)2322031.49.4Example 2-420 wt % LDPE (Plastic A)2328023919.5Example 2-510 wt % PP (Plastic C)177335.588.1Example 2-610 wt % PP (Plastic C)232375.587.9Example 2-720 wt % PP (Plastic C)232~4014.216.1

[0053] The blends made with the addition of PE or PP plastic showed moderate increases of pour point and viscosity compared with the pure VGO base case. These changes can be handled with typical refinery operating equipment with minor or no modifications. The blend tank needs to be heated above the melting point of plastic to keep the blend as an easily transferable liquid. Then, the liquid blend can be transferred to a transportation vessel or to a refinery conversion unit via pumping, gravity force or via pressure differential.

[0054] At 80° C., all the wax in VGO was dissolved in the heptane solvent and the weight percent of heptane insoluble was only 0.01% (Example 2-1). The hot heptane insoluble test separated the plastic from the stable blend. For the blend material (Examples 2-2 through 2-7), the weight percent of heptane insoluble was coming from undissolved plastic that was filtered out with the 0.8-micron membrane filter. The amount of recovered plastic as solid material matched well with the amount of plastic added to the blend preparations. The heptane insoluble results in Table 3 clearly indicate that the blend was a physical mixture of solid plastic particles dispersed in VGO and that the bulk of plastic particles can be re-separated from the VGO.Example 3: Pure Plastic Samples Studied for Impurity Removal

[0055] Four pure plastic samples were purchased to study the effectiveness of the present process in removing undesirable plastic components in recycled plastic materials. Polyvinyl chloride (PVC, Plastic E), acrylonitrile butadiene styrene (ABS, Plastic F), nylon (Nylon-6, Plastic G), and polyethylene terephthalate (PET, Plastic H) are commonly present in waste PE and PP streams as undesirable plastic components. Properties of these four plastic samples are summarized in Table 4.TABLE 4Properties of Undesirable PlasticsPlasticPVCABSNylon-6PET(Plastic E)(Plastic F)(Plastic G)(Plastic H)FormPowderPelletsPelletsGranularMelting Point, ° C.100-260~200228.5250-255Glass Transition8210562.567-81Temp, ° C.Density, g / mL at 25° C.1.41.06-1.081.081.68Hardness———120Average Molecular48,000———Weight, MwExample 4: Removal of Undesirable Plastic from Plastic / V GO Blends

[0056] A blend of each plastic in Example 3 and VGO from Example 1 was prepared using the following procedure. At ambient temperature, 8 g of pre-weighed plastic pellets (corresponding to 5 wt. % plastic in the blend) and 152 g the VGO feed (corresponding to 95 wt. % VGO in the blend) were added to a 300 cc batch autoclave unit. The autoclave was purged with N2 gas to remove air in the vessel, and then the inlet and outlet valves were closed. The mixture was stirred with an impeller at 1600 RPM while the mixture was heated with an external heating jacket to the target temperature of 177° C. (350° F.) by raising the temperature set point by 10° C. for every 10 minutes. Then, the temperature was held at the target temperature for 1 hour. The hot plastic / VGO blend was immediately filtered, in a hot oven that maintained the temperature at 204° C. (400° F.), with a laboratory filter paper with a nominal pore opening of either 0.7 micron or 20-25 micron.

[0057] The filtered blend was analyzed for the hot heptane insoluble test method (ASTM D3279) to determine the weight percent of plastic remaining in VGO and the chloride content using the combustion ion chromatography test (ASTM D7359). The results are summarized in Table 5.TABLE 5Removal of Undesirable Plastics from Plastic / BlendBy Our Blend Preparation ProcessExample NumberExample 4-1Example 4-2Example 4-3Example 4-4Plastic for Blend PrepPVCABSNylon-6PET(Plastic E)(Plastic F)(Plastic G)(Plastic H)Blend Preparation ProcedureWt % plastic in blend5 wt %5 wt %5 wt %5 wt %Blend preparation temp, ° F.350350350350Filtration temp, ° F.400400400400Properties of Blend After FiltrationChloride, ppm1121.3<1—Heptane Insolubles, wt %0.040.040.050.05% Removal of undesirable99.299.29999plastic by the process

[0058] It was found that PVC, ABS, Nylon-6 and PET do not melt in VGO at the 350° F. and can be removed nearly completely by the hot filtration process. A minute amount of PVC was decomposed during the preparation and the filtered blend had 112 ppm chlorides. The theoretical amount of chloride in the blend that could come from 5 wt. % of PVC is 2,940,000 ppm, and only 112 ppm chloride was observed in the filtered blend, again indicating nearly all of PVC was removed by the hot filtration. These results clearly show that selecting the optimum temperature for melting and dissolution of waste plastic in VGO is critical to reducing contamination with undesirable plastic. Hot filtration physically removes these undissolved plastics from the VGO blend.Example 5: Master Batch Plastic Containing Inorganic Filler Material

[0059] Four pure master batch plastic samples were obtained to study the effectiveness of the present process in removing undesirable inorganic filler components in recycled plastic materials. Properties of samples comprising linear low-density polyethylene (LLDPE) plastic containing 50 wt. % talc (Plastic I), LDPE plastic containing 50 wt % Diatomaceous Earth (Plastic J), LDPE plastic containing 50 wt % Nepheline Syenite (Plastic K), and LLDPE plastic containing 75 wt. % calcium carbonate (Plastic L) are summarized in Table 6.TABLE 6Properties of Master Batch Plastic Containing Filler MaterialsPlasticPlastic IPlastic JPlastic KPlastic LFormPelletsPelletsPelletsPelletsFiller MaterialTalcDiatomaceousNephelineCalciumEarthSyenitecarbonateFiller Content in50505075plastic, wt %Nature of Polymer inLLDPELDPELDPELLDPEPlasticPolymer Content in50505025Plastic, wt %Example 6: Removal of Undesirable Inorganic Filler Material from Plastic / VGO Blends

[0060] A blend of each plastic in Example 5 and VGO from Example 1 was prepared using the procedure described in Example 4. The hot heptane insoluble test method (ASTM D3279) was conducted for the blend sample before the filtration as well as for the blend sample after the filtration to determine the amount of insoluble material removed by filtration, and the weight percent of PE plastic still remaining in the blend after the filtration. The filtered blend was analyzed for metals concentration (an in house developed ICP elemental analysis method), and chloride content using the combustion ion chromatography test (ASTM D7359). The results are summarized in Table 7.TABLE 7Properties of Undesirable-Filler Containing Plastics / VGOBlend Prepared Our Blend Preparation ProcessExample NumberExample 6-1Example 6-2Example 6-3Example 6-4Plastic for Blend PrepPlastic IPlastic JPlastic KPlastic LBlend Preparation ProcedureWt % plastic in blend5 wt %5 wt %5 wt %5 wt %Wt % PE in the blend  2.5(a)  2.5(a)   2.5(a)    1.25(b)Blend preparation temp, ° F.400 400 350400Filtration temp, ° F.400 400 400400Properties of Blend Before FiltrationHeptane Insolubles, wt %  6.2———Properties of Filtered BlendChloride, ppm<1<1 <1 <1Heptane Insoluble, wt %  2.9—   2.9   1.5Metals, ppmAl<10 <11 297<31Ca<23 <24 <661040 Fe<8<8<22<24Mg24<8<22<24Na<4<4163<12Si3662604<36Ti<12 <12 <33<26Total metals detected, ppm60621064 1040 % Removal of undesirable  53(c)—  42(d)  70(d)material from the plastic bythe process(a)Assumed the blend had exactly 5 wt % of filler-containing plastic material and 50% of the plastic was made of inorganic fillers.(b)Assumed the blend had exactly 5 wt % of filler-containing plastic material and 75% of the plastic was made of calcium carbonate inorganic filler.(c)Calculation was done using the heptane insolubles test data for samples before and after the filtration.(d)Calculation was done using heptane insolubles test data for samples after the filtration assuming the starting blend had exactly 5 wt % of filler-containing plastic material.

[0061] The results in Table 7 show that the present blend preparation method was able to separate the inorganic fillers embedded in the plastic resin and removed them nearly completely by the hot filtration process. After the hot filtration, the blends contained small amounts of total metals, only up to 1064 ppm. Considering the starting plastic materials contained 50 to 75 wt % of mineral materials, the reduction of the metal contents was quite remarkable. Heptane insoluble data of filtered products showed that the filtered blends still contained the PE plastic from the master batch samples. These results clearly show that melting and dissolution of waste plastic in VGO followed by hot filtration is very effective in reducing contamination by undesirable inorganic filler materials while keeping the desirable PE and PP plastic in the filtered blends.Example 7: Removal of Undesirable Material from Waste Plastic / VGO Blends

[0062] Four recycled waste plastic samples, Plastic M through Plastic P, were obtained from several waste plastic feedstock suppliers. The plastic samples contained mainly PE or PP. They also contained substantial amounts of non-volatile materials (not hydrocarbon), ranging from 7.9 wt. % to 9.6 wt. % measured by Thermal Gravimetric Analysis (TGA). A blend of each waste plastic and VGO from Example 1 was prepared using the procedure described in Example 4. Again, the blend sample was analyzed before the filtration as well as after the filtration to determine the impact of the process in producing clean waste plastic / VGO blend for catalytic conversion processes. The results are summarized in Table 8.TABLE 8Impurity Removal from Waste Plastic / VGO Blend By Our Blend Preparation ProcessExample NumberExample 7-1Example 7-2Example 7-3Example 7-4Waste PlasticPlastic MPlastic NPlastic OPlastic PWaste Plastic PropertiesMain plastic componentsLDPE / PP mixMostly PPHDPEPP / HDPE mixNon-Volatile Residual, wt %9.68.58.37.9Blend Preparation ProcedureWt % plastic in blend5 wt %5 wt %5 wt %5 wt %Blend preparation temp, ° F.400450400350Filtration temp, ° F.400400400400Properties of Blend Before FiltrationChloride, ppm4——49Heptane Insolubles, wt %4.3———Metals, ppmAl<11<112240Ca609497108558Fe<8<81921Mg1728<887Na72<67<9Si204150169Ti61134789Total metals detected, ppm778589254964Properties of Filtered BlendChloride, ppm<1317Heptane Insolubles, wt %3.95.25.63.4Metals, ppmAl<11<11<11<11Ca1617144<25Fe<8<8<8<8Mg<8<8<8<8Na<4<4<4<4Si<131616<13Ti17<1321<13Total metals detected, ppm20987810Non-Volatile Residual, wt %00——% Reduction in chlorides>75%—— 86%% Reduction in metals 73%85%68%~100%

[0063] These results clearly show that melting and dissolution of waste plastic in hot VGO followed by hot filtration is very effective in reducing the contamination by undesirable inorganic filler materials as well as unwanted plastic. Substantial reduction of chloride and metals contents is observed. The present process can produce a cleaner plastic / VGO blend that is adequate for the subsequent catalytic conversion processes.

[0064] As used in this disclosure the word “comprises” or “comprising” is intended as an open-ended transition meaning the inclusion of the named elements, but not necessarily excluding other unnamed elements. The phrase “consists essentially of” or “consisting essentially of” is intended to mean the exclusion of other elements of any essential significance to the composition. The phrase “consisting of” or “consists of” is intended as a transition meaning the exclusion of all but the recited elements except for only minor traces of impurities.

[0065] As those skilled in the art will appreciate, numerous modifications and variations of the present invention are possible considering these teachings, and all such are contemplated hereby. For example, in addition to the embodiments described herein, the present invention contemplates and claims those inventions resulting from the combination of features of the invention cited herein and those of the cited prior art references which complement the features of the present invention. Similarly, it will be appreciated that any described material, feature, or article may be used in combination with any other material, feature, or article, and such combinations are considered within the scope of this invention.

[0066] All of the publications cited in this disclosure are incorporated by reference herein in their entireties for all purposes.

Claims

1. A process for converting waste plastic in a refinery comprising:(a) selecting waste plastics comprising polyethylene and / or polypropylene;(b) preparing a blend of petroleum based feed and selected waste plastic by mixing and blending the selected waste plastic with the petroleum based feed at a temperature in the range of from 300-450° F., with the blend comprising less than 20 wt. % of the selected waste plastic;(c) filtering the blend at a temperature ranging from 300-450° F.; and(d) passing the filtered blend to a refinery conversion unit for conversion of the blend.

2. The process of claim 1, wherein mixing and blending is conducted at a temperature in the range of from 300-400° F.

3. The process of claim 2, wherein the mixing and blending is conducted at a temperature in the range of from 350-400° F.

4. The process of claim 1, wherein the filtering is conducted at a temperature in the range of from 300-400° F.

5. The process of claim 4, wherein the filtering is conducted at a temperature in the range of from 350-400° F.

6. The process of claim 1, wherein the selected plastics comprise polypropylene, high-density polyethylene, and low-density polyethylene.

7. The process of claim 1, wherein the waste plastics selected in (a) comprise less than 5 wt. % plastics from the classification groups 1, 3, and 7.

8. The process of claim 7, wherein the plastics selected in (a) comprise less than 0.1 wt. % of plastics from classification groups 1, 3, and 7.

9. The process of claim 1, wherein the blend in (b) comprises from 1-10 wt. % of the selected waste plastic.

10. The process of claim 1, wherein the blend in (b) comprises from 1-5 wt. % of the selected waste plastic.

11. The process of claim 1, wherein the petroleum based feed comprises vacuum gas oil, atmospheric gas oil, or vacuum resid.

12. The process of claim 1, wherein the amount of high-density PP added to the refinery feedstock in the blend preparation unit is in the range of from 1-10 wt. % of the blend product.

13. The process of claim 1, wherein the refinery conversion unit is a fluid catalytic cracker.

14. The process of claim 1, wherein the refinery conversion unit is a high-performance compact reactor for hydrocarbon conversion.

15. The process of claim 1, wherein the refinery conversion unit is a coker.

16. The process of claim 1, wherein the refinery conversion unit is a hydrocracking unit.

17. The process of claim 13, wherein the mixed blend is filtered via continuous slurry removal, filter press, or centrifuge.

18. The process of claim 17, wherein solids are removed as a filter cake.

19. The process of claim 17, wherein solids are removed in a slurry steam.

20. The process of claim 19, wherein the slurry stream is supplied to a coker.

21. The process of claim 1, wherein a filter is used which comprises a 20-25-micron average pore opening.

22. The process of claim 1, wherein a naphtha fraction is recovered from the refinery conversion unit.

23. The process of claim 22, wherein a portion of the naphtha stream recovered is further processed in the refinery to clean gasoline, diesel, base oil, and / or jet fuel.

24. The process of claim 1, wherein a gasoline fraction is recovered from the refinery conversion unit and is sent to a gasoline blending pool.

25. The process of claim 1, wherein the filtered blend in (d) is passed to the refinery conversion unit at a temperature above the melting point of the highest melting plastic in the blend.

26. The process of claim 1, wherein the volume flow of the blend to the refinery conversion unit in (d) comprises up to 100 volume % of the total hydrocarbon flow to the conversion unit.

27. The process of claim 1, wherein the volume flow of the blend to the refinery conversion unit in (d) comprises up to 50 volume % of the total hydrocarbon flow to the conversion unit.

28. The process of claim 26, wherein the blend flow comprises up to 25 volume % of the total hydrocarbon flow to the conversion unit.

29. A process for converting waste plastic comprising:(a) selecting waste plastics comprising polyethylene and / or polypropylene;(b) preparing a blend of hydrocarbon feed and selected waste plastic by mixing and blending the selected waste plastic with the hydrocarbon feed at a temperature in the range of from 300-450° F., with the blend comprising less than 20 wt. % of the selected waste plastic;(c) filtering the blend at a temperature ranging from 300-450° F.; and(d) passing the filtered blend to a hydrocarbon conversion unit for conversion of the blend.

30. The process of claim 29, wherein the hydrocarbon feed comprises a hydrocarbon feed derived from bio feedstock, coal, natural gas or from plastic pyrolysis.

31. The process of claim 30, wherein the hydrocarbon feed is derived from plastic pyrolysis.

32. The process of claim 30, wherein mixing and blending is conducted at a temperature in the range of from 300-400° F.

33. The process of claim 32, wherein the mixing and blending is conducted at a temperature in the range of from 350-400° F.

34. The process of claim 30, wherein the filtering is conducted at a temperature in the range of from 300-400° F.

35. The process of claim 34, wherein the filtering is conducted at a temperature in the range of from 350-400° F.

36. The process of claim 30, wherein the selected plastics comprise polypropylene, high-density polyethylene, and low-density polyethylene.

37. The process of claim 30, wherein the waste plastics selected in (a) comprise less than 5 wt. % plastics from the classification groups 1, 3, and 7.

38. The process of claim 37, wherein the plastics selected in (a) comprise less than 0.1 wt. % of plastics from classification groups 1, 3, and 7.

39. The process of claim 30, wherein the blend in (b) comprises from 1-10 wt. % of the selected waste plastic.

40. The process of claim 30, wherein the blend in (b) comprises from 1-5 wt. % of the selected waste plastic.

41. The process of claim 30, wherein the hydrocarbon conversion unit is a fluid catalytic cracker.

42. The process of claim 30 wherein the hydrocarbon conversion unit is a high-performance compact reactor for hydrocarbon conversion.

43. The process of claim 30, wherein the hydrocarbon conversion unit is a coker.

44. The process of claim 30, wherein the hydrocarbon conversion unit is a hydrocracking unit.

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