Conversion of pyoil to olefins using acid catalysts

Abstract

A process for conversion of a plastic waste to an olefin product comprising thermally decomposing the plastic waste in the absence of oxygen to produce a pyoil and contacting the pyoil with an acid catalyst to produce the olefin product of C2 olefin, C3 olefin, and C4 olefin. The C3 olefin yield and C4 olefin yield increased more than two-fold in comparison with thermal cracking of the pyoil without the acid catalyst. Use of the acid catalysts improve light olefin yield without an increase in aromatics.

Description

CONVERSION OF PYOIL TO OLEFINS USING ACID CATALYSTSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to US Provisional Application No. 63 / 733809 filed December 13, 2024, the disclosure of which is incorporated herein by reference.FIELD

[0002] The present disclosure relates to the combination of pyrolysis processes followed by catalytic cracking of plastic waste to produce an olefin product having a high yield of light olefins.BACKGROUND

[0003] There is increasing demand from society and associated policy / regulatory drivers for more circular plastics. Converting difficult-to-recycle and highly heterogeneous waste plastics into building blocks from which virgin polymers can be made is an attractive approach. One technology includes converting plastic waste to pyrolysis oil (“pyoil”) via mild pyrolysis to minimize gas and often followed by thermal cracking to make olefins. However, thermal cracking of pyoil is challenged with significant bottoms such as tar formation and lower yield of light olefins.SUMMARY

[0004] Provided herein are catalytic pyrolysis processes for conversion of a plastic waste to an olefin product comprising the steps of thermally pyrolyzing the plastic waste in a first reactor in the absence of oxygen to produce a pyoil and contacting the pyoil with an acid catalyst in a second reactor to produce the olefin product comprising at least 60 wt.% C2-C4 olefins.

[0005] Further provided are processes for converting a plastic waste to an olefin product comprising the steps of providing a plastic waste comprising one or more polyolefins, pyrolyzing the plastic waste to produce a pyoil, contacting the pyoil with an acid catalyst to provide a mixture; and pyrolyzing the mixture to a temperature 550°C or less wherein the pyoil is catalytically decomposed to yield the olefin product comprising greater than 60 wt.% C2-C4 olefin, greater than 30 wt.% of propylene, and less than 40 wt.% C5+ olefin.

[0006] Moreover, the present processes for conversion of a plastic waste to an olefin product comprising the steps of thermally converting the plastic waste in the absence of oxygen to produce a pyoil, and contacting the pyoil with an acid catalyst to produce an increased olefinproduct yield of C3 olefin and C4 olefin by at least two-fold in comparison with the yield of C3 olefin and C4 olefin after thermal cracking of the pyoil without the acid catalyst.

[0007] In the present processes, the acid catalyst is a microporous material comprising a pore opening between 0.3 nm and less than 0.45 nm in diameter.

[0008] These and other features and attributes of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.DESCRIPTION OF THE DRAWINGS

[0009] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:

[0010] FIG. 1 is a chart that provides a comparative of olefin product yield for a flash pyrolysis process to olefin product yield where a mild pyrolysis to pyoil is followed by catalytic cracking with an acid catalyst as described in Example 1.

[0011] FIG. 2 is a chart that provides a comparative olefin product yield for 1) a flash pyrolysis process, 2) a mild pyrolysis followed by thermal cracking, and 3) a mild pyrolysis to pyoil followed by catalytic cracking with an acid catalyst as described in Example 2.DETAILED DESCRIPTION

[0012] Before the present compounds, components, compositions, and / or methods are disclosed and described, it is to be understood that unless otherwise indicated this disclosure is not limited to specific compounds, components, compositions, reactants, reaction conditions, ligands, catalyst structures, or the like, as such may vary, unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing different embodiments and is not intended to be limiting.

[0013] All numerical values within this detailed description and claims should be considered modified by “about” or “approximately” the indicated value to account for experimental error and variations.

[0014] For the purposes of this disclosure, the following definitions will apply.

[0015] As used herein, the terms “a” and “the” as used herein are understood to encompass the plural as well as the singular.

[0016] As provided herein, a reference to a “Cx” fraction, stream, portion, feed, or other quantity is defined as a fraction (or other quantity) where 50 wt.% or more of the fraction corresponds to hydrocarbons having “x” number of carbons. When a range is specified, such as “Cx-Cy,” 50 wt.% or more of the fraction corresponds to hydrocarbons having a number of carbons between “x” and “y”. A specification of “Cx+” (or “Cx-”) corresponds to a fractionwhere 50 wt.% or more of the fraction corresponds to hydrocarbons having the specified number of carbons or more (or the specified number of carbons or less).

[0017] The term “plastic waste” means and includes any classification of consumer waste plastics, post-consumer wastes and post-industrial wastes.

[0018] As described herein, the terms “olefin” and “polyolefin” are sometimes used interchangeably and refer to and include high-density polyethylene (“HDPE”), low-density polyethylene (“LDPE”), linear low-density polyethylene (“LLDPE”), polyethylene (“PE”), polyethylene terephthalate (“PET”), polypropylene (“PP”), polystyrene (“PS”) or mixtures thereof. Olefin and polyolefin further include co-polymers of various olefins, such as butene, hexenes, and / or any other olefins suitable for polymerization.

[0019] The term “pyoil” means and includes liquids derived from HDPE, LDPE, LLDPE, PE or a mixture thereof.

[0020] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited and ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.Pyrolysis Processing of Plastic Waste

[0021] Consumer waste plastics or “plastic waste” are classified and include polyethylene terephthalate waste (plastics recycle classification type 1), high density polyethylene waste (plastics recycle classification type 2), polyvinyl chloride waste (plastics recycle classification type 3), low density polyethylene waste (plastics recycle classification type 4), polypropylene waste (plastics recycle classification type 5), polystyrene waste (plastics recycle classification type 6) and other polymer waste (plastics recycle classification type 7).

[0022] In recycling plastic waste, polyethylene waste and polypropylene waste are often individually sorted from the plastic waste and sometimes sorted together from the plastic waste. See e.g., US Pub. No. 2021 / 0332299,

[0042] , Undesirable plastic materials such as multilayer films or composites and / or compounded wastes such as rubber tires can be mechanically sorted from the feed stream with near infrared spectroscopy (NIR), laser or x-ray technologies. Other undesirable materials can include stones, metals and other non-combustible hard materialswhich can be removed by mechanical means. For example, ferrous metals can be removed by a magnet.

[0023] To prepare solids, the solid polymers / polyolefins can be crushed, chopped, ground, or otherwise physically processed to reduce the median particle size to 3.0 cm or less, or 2.5 cm or less, or 2.0 cm or less, or 1.0 cm or less, such as down to 0.01 cm or possibly still smaller. For determining a median particle size, the particle size is defined as the diameter of the smallest bounding sphere that contains the particle.

[0024] In the present processes, a feed stream of a plastic waste (sometimes referred to as “plastic feedstock”) is heated to a temperature that pyrolyzes the plastic feedstock under thermal pyrolysis and produces a pyrolysis plastics effluent stream. The plastic feedstock is pyrolyzed (heated in the absence of oxygen) using one or more of various pyrolysis methods including fast pyrolysis and other pyrolysis methods such as vacuum pyrolysis, slow pyrolysis, and the like. Fast pyrolysis is an intense, short duration process that can be carried out in a variety of pyrolysis reactors such as fixed bed pyrolysis reactors, fluidized bed pyrolysis reactors, circulating fluidized bed reactors, or other pyrolysis reactors capable of fast pyrolysis. Fast pyrolysis includes rapidly imparting a relatively high temperature to feedstocks for a very short residence time, typically about 0.5 seconds to about 0.5 minutes, and then rapidly reducing the temperature of the pyrolysis effluent before chemical equilibrium can occur. By this approach, the structures of polymers are broken into reactive chemical fragments that are initially formed by depolymerization and volatilization reactions, but do not persist for any significant length of time.

[0025] The heating and cooling of products produced in a pyrolysis plastic waste reactor (a reactor sometimes referred as a “pyrolyzer” or a “pyrolysis unit”) can be performed in any convenient manner. For example, at least a portion of the heating of the plastic waste feedstock to the pyrolysis temperature can be performed at a heating rate of 100°C per second or more, or 200°C per second or more, such as up to l,000°C per second or possibly still faster. WO2020 / 252228 Al at

[0033] ,

[0034] ,

[0035] and

[0038] incorporated by reference; US Pub. No. 2021 / 0130700 Al,

[0171] -

[0177] .

[0026] Both operating temperature of the pyrolysis plastic waste reactor and reaction time depend in part on the desired products. Higher temperatures increase selectivity for ethylene, while lower temperatures increase selectivity for propylene. Shorter reaction times (at or above 500°C) reduce or minimize formation of coke. In an embodiment, the reaction time can correspond to 0.1 seconds to 6.0 seconds, or 0.1 seconds to 5.0 seconds, or 0.1 seconds to 1.0 seconds, or 1.0 seconds to 6.0 seconds, or 1.0 seconds to 5.0 seconds.

[0027] To control olefin partial pressure and to improve ethylene and propylene yields, a diluent steam is fed into the reactor. Steam also serves as a fluidizing gas. The weight ratio of steam to plastic feedstock can be between 0.3 : 1 to 10: 1.

[0028] Pyrolyzed plastic (the pyoil) is then optionally cooled to below 500°C at the end of the reaction time. An effluent stream from the pyrolysis plastic waste reactor typically includes the heat carrier particles, the diluent gas stream, a pyrolyzed product, and other products such as olefin and oil. Most notably, simpler lighter hydrocarbon molecules, including ethylene and propylene, are often generated at varying fractions within the effluent stream.

[0029] In an embodiment, the plastic feedstock is fed into a thermal pyrolyzer and heated to a temperature between 500°C and 900°C for a given reaction time. The pyrolysis plastics waste reactor melts plastic waste in a fluidized flow, or in a transport or pneumatic conveyance flow, with a dilute phase of heat carrier particles. A quasi-dense bed of plastic and heat carrier particles undergo pyrolysis at the bottom of the pyrolysis waste plastics reactor. Gaseous pyrolyzed plastic and heat carrier particles flow upwardly upon size reduction due to pyrolysis. Alternatively, the pyrolysis plastic waste reactor can be a continuous stirred tank reactor, a rotary kiln, or an auger reactor. In an embodiment, the pyrolysis plastic waste reactor employs an agitator.

[0030] In an embodiment, the pyrolysis waste plastics reactor is a fluidized bed where the plastic feedstock is mixed with heated fluidizing particles. Sand is an example of a suitable type of fluidizing particle for the fluidized bed. During operation, sand (or another type of heat transfer particle) can be passed into a regenerator to burn off coke and heat the particles. Often additional heat is supplied in the regenerator to compensate for the coke in the process. Typically, the heated particles are mixed with the plastic waste feedstock prior to entering the reactor. By heating the heat transfer particles to a temperature above the desired pyrolysis temperature, the heat transfer particles can provide at least a portion of the heat needed to achieve the pyrolysis temperature. For example, the heat transfer particles can be heated to a temperature that is greater than the desired pyrolysis temperature by 100°C or more. Optionally, if the plastic feedstock, sand, and fluidizing steam do not provide sufficient material to form a fluidized bed, additional fluidizing gas can be added, such as additional nitrogen. However, this might cause a corresponding increase in the volume of gas flow that needs to be handled during product recovery.

[0031] Upon exiting from the pyrolysis plastic wastes reactor, the heat transfer particles are separated from the vapor portions of the effluent using a cyclone or another solid / vapor separator. Such a separator can also remove any other solids present after pyrolysis. It is notedthat separation using a cyclone separator can result in an increase in N2 in the steam cracker effluent, which can make product recovery more challenging. Optionally, in addition to a cyclone or other primary solid / vapor separator, one or more filters can be included at a location downstream from the cyclone to allow for removal of fine particles that become entrained. As provided herein, the production of polymer-grade olefin fractions is most desirable. US Pub. No. 2022 / 0195309.

[0032] The present processes are performed in two steps. In a first step, a plastic waste is subject to thermal pyrolysis to produce a pyoil. In the second step, the pyoil is catalytically cracked using one or more acid catalysts where the pyoil is contacted with an acid catalyst to produce an olefin product comprising at least 60 wt.% C2-C4 olefins (referred to herein sometimes as “light olefin.”). In an embodiment, the olefin product comprises at least 25 wt.% of C3 and at least 25 wt.% of C4 and / or an improvement in yield of at least two times (twofold) the amount of C2 - C3 olefins when compared to a flash pyrolysis process at the same temperature without subsequent cracking of the pyoil over an acid catalyst. In the present processes, the one or more acid catalysts are microporous material comprising a pore opening between 0.3 nm and less than 0.45 nm in diameter and include small pore high silicate alumina zeolites such as SSZ-13 chabazite, silicoaluminophosphate such as SAPO-34, SAPO-18, or a mixture thereof to improve light olefin (C2-C3) yield over additional thermal cracking and without significant increase in aromatics.Step 1 - Thermal Pyrolysis - Production of Pyoil

[0033] As described above, in the present catalytic pyrolysis processes for conversion of a plastic waste to an olefin product, the plastic waste is thermally pyrolyzed in a first reactor in the absence of oxygen to produce the pyoil. The plastic waste contains one or more polyolefins. In the present processes, as described below, the acid catalyst is a microporous material comprising a pore opening between 0.3 nm and less than 0.45 nm in diameter. This first step of thermal pyrolysis is operated at a temperature of 550°C or less and at a pressure between 15 psig and 75 psig. Steam can be co-fed with the plastic waste into the first reactor. In an embodiment, the amount of steam co-fed with the plastic waste is 30 wt.% steam.

[0034] Thermal pyrolysis is performed by known methods and in known systems (e.g., at temperatures between 400°C to 550°C, or 550°C or less), including those described above. See

[0041] through

[0046] , incorporated by reference; see also, US Pat. No. 10,442,997.

[0035] In this first step, the plastic feedstock comprises the plastic waste such as a postconsumer waste and / or a post-industrial waste. Post-consumer waste includes waste plastic,waste rubber, textile, modified cellulose, wet-laid products and / or combination thereof. In an embodiment, at least 50 wt.% of the pyoil is derived from a plastic source wherein the pyrolysis feedstock comprises at least 50 wt.% plastic. In an embodiment, the plastic feedstock comprises olefin at 50 wt.% to 100 wt.% (or 65 wt.% to 80 wt.%, or 75 wt.% to 90 wt.%, or 80 wt.% to 100 wt.%) with a balance of one or more other polymers.

[0036] In this step, the plastic waste feedstock includes one or more polymers including, but not limited to, olefins (e.g., homopolymer and copolymers of ethylene, propylene, butene, hexene, butadiene, isoprene, isobutylene, and other olefins), polystyrene, polyvinylchloride, polyamide (e.g., nylon), polyethylene terephthalate, polyurethane, ethylene vinyl acetate, and the like. Examples of plastic sources include, but are not limited to, plastic waste (e.g., plastic straws, plastic utensils, plastic bags, food containers, and the like), composite materials (e.g., composite packaging, artificial turf, artificial turf components, etc.), and the like, and any combination thereof. Other materials may be used in combination with the plastic source to produce the pyoil, for example, paper, cardboard, textiles, tires, tissues, and the like, and any combination thereof.

[0037] Additionally, or alternately, a solvent or carrier can be added. For introduction into the pyrolysis reactor, it can be convenient for the olefin / polymer produced from the plastic feedstock to be in the form of a solution, slurry, or other fluid-type phase. If a solvent is used to at least partially solvate the olefins, any convenient solvent can be used. Examples of suitable solvents can include (but are not limited to) a wide range of petroleum or petrochemical products. For example, some suitable solvents include crude oil, naphtha, kerosene, diesel, and oils. Other potential solvents can correspond to naphthenic and / or aromatics solvents, such as toluene, benzene, methylnaphthalene, cyclohexane, methylcyclohexane, and mineral oil. Still other solvents can correspond to refinery fractions, such as a gas oil fraction or naphtha fraction from a steam cracker product. If a carrier is used, the carrier can correspond to a liquid or gas phase carrier, such as steam.

[0038] In an embodiment, the effluent of the pyrolysis step is distilled (or separated) into one or more cuts including a pyoil cut comprising the pyoil. In an embodiment, the pyoil comprises a C5+ stream or a C5-C30 stream, or a C5-C25 stream, or a C5-C20 stream. The pyoil comprises 50 wt.% or more of C5+ hydrocarbons, or 50 wt.% to 100 wt.%, or 50 wt.% to 75 wt.%, or 70 wt.% to 90 wt.%, or 80 wt.% to 100 wt.% of C5+ hydrocarbons, and less than 50 wt.%, or 0 wt.% to less than 50 wt.% of C4 hydrocarbons, or 25 wt.% to 50 wt.%, or 10 wt.% to 30 wt.%, or 0 wt.% to 20 wt.%, or 0 wt.% to 5 wt.%, or 0 wt.% to 2 wt.% of C4 hydrocarbons.

[0039] The pyoil has a specific gravity of 0.5 to 1.0 (or 0.5 to 0.7, or 0.6 to 0.9, or 0.7 to 1.0). The pyoil has an initial boiling point of 30°C or greater, 100°C or greater, 200°C or greater, 300°C or greater, 400°C or greater, 450°C or greater, 500°C or greater, or 600°C or greater. For example, the pyoil may have an initial boiling point of 30°C to 200°C, 30°C to 70°C, 50°C to 150°C, or 100°C to 200°C. The pyoil has a final boiling point of 850°C or less, 700°C or less, 600°C or less. For example, the pyoil has a final boiling of 150°C to 850°C, 150°C to 600°C, 250°C to 400°C, 300°C to 500°C, 400°C to 600°C, 600°C to 700°C, or 700°C to 800°C.

[0040] The pyoil can have properties like a naphtha, a distillate, a wax, an atmospheric resid, and the like. Pyoil quality, however, can vary widely and depends on several factors, including quality of the plastic waste, conversion technology (e.g., thermal pyrolysis, catalytic pyrolysis, etc.) and pre- or post-contaminant clean up within a pyrolysis unit.

[0041] In an embodiment, the pyoil comprises at least one of polyethylene and / or polypropylene. In an embodiment, the polyethylene and polypropylene are present in the mixture as a co-polymer of ethylene and propylene. Polyethylene can be any type of polyethylene of HDPE or LDPE. In addition to polyethylene and / or polypropylene, the pyoil can optionally include one or more of polystyrene, polyvinylchloride, polyamide (e.g., nylon), polyethylene terephthalate, and ethylene vinyl acetate. Still other polyolefins can correspond to polymers (including co-polymers) of butadiene, isoprene, and isobutylene.

[0042] Unless otherwise specified, weight of polyolefin polymer in the pyoil corresponds to weights relative to the total polymer content in the feedstock. Any additives, modifiers, or other components included in a formulated polymer are included in this weight. However, the weight percentages described herein exclude any solvents or carriers used so that the pyoil corresponds to a solution or slurry of polymers. For compatibility with introducing the pyrolysis product (pyoil) in a steam cracking process train, the pyoil can include limited amounts of polymers different from polyethylene and / or polypropylene. In various aspects, the pyoil for pyrolysis can include 55 wt.% to 100 wt.% of polyethylene, polypropylene, copolymer of ethylene and propylene, other C4-C6 olefins and / or dienes, or a combination thereof. In embodiments where the pyoil corresponds to 95 wt.% or more of polymers derived from ethylene and propylene, the pyoil can include 10 wt.% or more of ethylene monomers and 10 wt.% or more of propylene monomers.

[0043] The pyoil can include polyvinyl chloride (“PVC”) or polyvinylidenechloride (“PVDC”). PVDC is used, for example, in blister packaging. In a further embodiment, the pyoil does not include more than five percent PVC or PVDC. In a further embodiment, thepyoil does not include more than about three percent PVC or PVDC. In a further embodiment, the pyoil is no more than about two percent PVC or PVDC. In another embodiment, the pyoil can include no more than ten percent of a condensation polymer such as a polyester, a polyamide, polyethylene terephthalate, polyamide or polyurethane.

[0044] In an embodiment, the pyoil can optionally include 0.1 wt.% to 1 wt.%, of polyvinyl chloride, polyvinylidene chloride, or a combination thereof, and / or 0.1 wt.% to 1.0 wt.% polyamide. Polyvinyl chloride is roughly 65% chlorine by weight. As a result, pyrolysis of polyvinyl chloride (and / or polyvinylidene chloride) can result in formation of substantial amounts of hydrochloric acid relative to the initial weight of the polyvinyl chloride.

[0045] In limited amounts, the hydrochloric acid that results from pyrolysis of polyvinyl chloride and / or polyvinylidene chloride can be removed using guard beds prior to allowing the pyrolysis product (the pyoil) to enter a steam cracking process train.

[0046] Similarly, with regards to polyamide, pyrolysis results in the formation of NON. Limited amounts of NON can be handled by the steam cracking process train. In other aspects, from 0.1 wt.% to 10 wt.% of polyvinyl chloride and / or polyvinylidene chloride can optionally be included in the feed by including additional chlorine removal stages prior to combining the polyolefin pyrolysis product with the steam cracking processing train.

[0047] The present processes can include reducing the particle size of the olefins and mixing the olefins with a solvent or carrier. Where the plastic waste / olefins are introduced into a reactor at least partially as solids, having a small particle size can facilitate transport of the solids. Smaller particle size can potentially also contribute to achieving a desired level of conversion of the polymers / olefms under the short residence time conditions of the pyrolysis.

[0048] In an embodiment, the pyoil further comprises additives, modifiers, packaging dyes, and / or other components typically added to a polymer during and / or after formulation. The pyoil further includes components typically found in the plastic waste. Finally, the feedstock can include one or more solvents or carriers so that the pyoil corresponds to a solution or slurry of the olefms / polymers.Step 2- Catalytic Cracking of Pyoil - Improved C2 to C4 Olefin Yield

[0049] In a second step, the pyoil is then processed using catalytic pyrolysis in a second reactor. The pyoil is contacted with one or more acid catalysts and cracked under conditions using one more or acid catalyst to form an olefin product that includes C2 to C4 olefin.

[0050] In an embodiment of the second step, a cracking step, the acid catalyst is mixed with the pyoil in a second reactor and in an amount of less than or equal to 5 wt.% or less thanor equal to 10 wt.%, less than or equal to 15 wt.%, less than or equal to 25 wt.%, or less than or equal to 50 wt.%.

[0051] A diluent gas stream is optionally fed to the second reactor and is typically inert. Steam can be a diluent gas stream. The diluent gas stream can be a hydrocarbon gas. The diluent gas stream separates reactive olefin products from each other to preserve the selectivity to light olefins thus avoiding oligomerization of light olefins to higher olefins or over cracking to light gas. The absence of oxygen, however, is critical. The pyoil is optionally preheated to high temperature before it is fed to a second reactor or heated to pyrolysis temperature after entering the second reactor.

[0052] Cracking is the process where compounds such as heavy (high molecular weight and / or high boiling) hydrocarbons are broken down into smaller molecules such as light hydrocarbons. This is accomplished by breaking carbon-carbon bonds to form smaller molecules. The composition of the product of a cracking unit is strongly dependent on the temperature the unit is operated at and presence of catalysts. Steam cracking is described in US Patent No. 10,442,997 B2. Steam crackers and fluid crackers are commonly used crackers. Typically, fluid catalytic crackers (FCC) are used to produce gasoline and liquefied petroleum gas (“LPG”), while hydrocracking is a major source of jet fuel, diesel fuel, naphtha, and LPG. Steam crackers are primarily used to produce ethylene. Operation of these different types of crackers is known to those skilled in the art. The process utilizes microporous acidic material having a pore opening in the range of 0.3 nm to less than 0.45 nm as a catalyst composition to facilitate the conversion of the pyoil to C2-C4 olefin with high selectivity. The cracking conditions include a temperature of less than 550°C and pressure between 15 psig and 75 psig.

[0053] In an embodiment, the pyoil is fed from a first reactor (a pyrolysis unit) to a second reactor (i.e., a steam cracker). The second reactor optionally includes a recovery unit capable of catalytic cracking without causing process safety, environmental, reliability, or product quality issues. For example, the pyoil might contain small fractions of high boiling point hydrocarbon components that are not compatible for processing through a typical liquid steam cracker (e.g., naphtha cracker, gas oil cracker, etc.). Additionally, the pyoil might contain high levels of certain contaminants (e.g., metals, salts, total acid number, etc.) that certain liquid steam crackers are not designed to handle. Further, processing the pyoil can result in deposition of non-volatile materials (e.g., asphaltenes) in the convection section of the steam cracking furnace that cannot be removed through decoking or other on-line cleaning methods. Some of these contaminants might react with or otherwise interact with the metallurgy of the furnaceradiant or convection sections and decrease the operational life of these components in a variety of ways (e.g., causing corrosion or otherwise degrading the metallurgy).

[0054] In the present processes, the pyoil optionally comprises high boiling point hydrocarbons. For example, pyoil can include one or more heavy petroleum compounds, such as those commonly present in crude oil, resids, residuum, pitch, atmospheric resid, and vacuum resid. The pyoil might further include high levels of certain contaminants, such as metals and salts. Metals may include, for example, mercury, aluminum, vanadium, nickel, lead, chromium, iron, arsenic, sodium, potassium, magnesium, beryllium, antimony, barium, cadmium, calcium, cobalt, copper, manganese, molybdenum, selenium, silver, tin, titanium, zinc, lithium, and / or combinations thereof. Other non-metallic contaminants may include, for example, bromine, fluorine, phosphorus, and boron. The pyoil may have a total chlorides content of 160 wppm or greater. For example, pyoil might have a total chlorides content of 170 wppm to 1,000 wppm, 170 wppm to 500 wppm, 170 wppm to 275 wppm, 170 wppm to 250 wppm, 200 wppm to 300 wppm, or 200 wppm to 250 wppm. As used herein, the total chlorides content is the sum of measure of the total chlorides (organic and inorganic) in the recycle pyoil, as determined in accordance with ASTM D7359.

[0055] In addition to specific concentrations of contaminants, certain contaminants can cause pyoil to have a high acidity that can be problematic for further processing. The total acid number, as determined in accordance with ASTM D664, is a measurement that can be used to quantify the acidity of the pyoil. The pyoil has a total acid number of 1.7 mg KOH / g or greater. In an embodiment, pyoil has a total acid number of 0 mg KOH / g to 1.7 mg KOH / g, 1.7 mg KOH / g to 4 mg KOH / g, 1.7 mg KOH / g to 3 mg KOH / g, 1.7 mg KOH / g to 2.5 mg KOH / g, 2 mg KOH / g to 4 mg KOH / g, 2 mg KOH / g to 3 mg KOH / g, or 2 mg KOH / g to 2.5 mg KOH / g. Acid Catalysts

[0056] In the present processes, to catalytically crack pyoil, less than or equal to 50 percent acid catalysts are used. In an embodiment, the acid catalyst is a small pore size zeolite comprising between 0.3 nm and less than 0.45 nm micropores and rich in silicon (having a Si / Al ratio of greater than 5).

[0057] In an embodiment, the acid catalyst is an 8-ring microporous material. In an embodiment, the acid catalyst is an 8-ring silicoaluminophosphate (SAPO) such as SAPO-34, SAPO-18 or combinations thereof.

[0058] As provided herein, the acid catalyst is a microporous material. In an embodiment, the zeolite is an 8-ring zeolite or zeolitic material. In an embodiment, the acid catalyst is a small pore size zeolite (8R) comprising between 0.3 nm and less than 0.45 nm micropores. Inan embodiment, the acid catalyst is a Si-rich aluminosilicate zeolite having a Si / Al ratio greater than 5. In an embodiment, the acid catalyst is an aluminosilicate zeolite comprising 0.38 nm micropores.

[0059] In an embodiment, the acid catalyst is chabazite (CHA), as defined by the International Zeolite Associate (IZA). According to the IZA structure database, the poreopening of CHA is ~ 0.38 nm. More specifically, in an embodiment, the acid catalyst is SSZ- 13, a Si-rich (Si / Al > 5) small pore zeolite (chabazite topology). This zeolite is described in US Pat. No. 4,544,538 (the ‘538 patent). In US Pat. No. 4,544,538, the SSZ-13 molecular sieve is prepared in the presence of N,N,N-trimethyl-l-adamantammonium cation which serves as a structure directing agent (“SDA”), also known as on organic template. See US Pat. No. 4,544,538 at Col. 2, 1. 42 through Col. 4, 1. 25, incorporated by reference. Tables 1 and 2 of the '538 patent provide the X-ray powder diffraction patterns before and after calcination, respectively. Further, methods of preparing the SSZ-13 zeolite are provided. See, US Pat. No. 4,544,538 at Col. 4, 1. 26 through Col. 5, 1. 38, incorporated by reference. The CHA catalyst is substantially proton exchanged and calcined to convert it to the proton form, having a residual alkali amount (expressed in A2O wt.%, where A is the alkali metal such as Na, K, or a combination thereof) of less than 5000 ppm, less than 1000 ppm, and less than 500 ppm. The BET surface area of the CHA catalyst is greater than 200 m2 / g, greater than 300 m2 / g, and greater than 500 m2 / g. The Si / Al ratio is greater than 5, greater than 10, and greater than 20. The CHA catalyst can be in the form of neat zeolite, or optionally formulated with a binder to form extrudates or spray dried into spherical particles. The amount of binder is in the range of 5 wt.% to 60 wt.%, or 20 wt.% to 50 wt.%, or 30 wt.% to 40 wt.%.

[0060] In another embodiment, the acid catalyst is an 8-ring silicoaluminophosphate (SAPO) having the structure code CHA as defined by the International Zeolite Associate (IZA). According to the IZA structure database, the pore-opening of CHA is ~ 0.38 nm. In an embodiment, the acid catalyst is SAPO-34. The silicoaluminophosphate SAPO molecular sieves contain a three-dimensional microporous crystalline framework structure of [SiOz], [AIO2] and [PO2] corner sharing tetrahedral units; which are generally synthesized by the hydrothermal crystallization of a reaction mixture of silicon-, aluminum- and phosphorus- sources and at least one templating agent. For example, the synthesis of silicoaluminophosphate SAPO-34 is described in US Pat. No. 4,440,871, Col. 4. 1. 50 to Col. 8, 1. 58 & Examples 32-38, incorporated by reference. Conveniently, the silicoaluminophosphate molecular sieve has a silica to alumina molar ratio from about 0.15 to about 0.22, from about 0.17 to about 0.21, and from about 0.18 to about 0.19. The SAPO-34 catalyst is substantiallyproton exchanged and calcined to convert it to the proton form, having a residual alkali amount (expressed in A2O wt.%, where A is the alkali metal such as Na, K, or a combination thereof) of less than 5000 ppm, less than 1,000 ppm, and less than 500 ppm. The BET surface area of the SAPO-34 catalyst is greater than 200 m2 / g, greater than 300 m2 / g, and greater than 500 m2 / g. The SAPO-34 catalyst can be in the form of neat molecular sieve, or optionally formulated with a binder to form extrudates or spray dried into spherical particles. The amount of binder is in the range of 5 wt.% to 60 wt.%, or 20 wt.% to 50 wt.%, or 30 wt.% to 40 wt.%.

[0061] In another embodiment, the acid catalyst is an 8-ring silicoaluminophosphate (SAPO) having the structure code AEI as defined by the International Zeolite Associate (IZA). According to the IZA structure database, the pore-opening of AEI is ~ 0.38 nm. In an embodiment, the acid catalyst is SAPO-18. The silicoaluminophosphate SAPO molecular sieves contain a three-dimensional microporous crystalline framework structure of [SiO ], [AIO2] and [PO2] corner sharing tetrahedral units; which are generally synthesized by the hydrothermal crystallization of a reaction mixture of silicon-, aluminum- and phosphorus- sources and at least one templating agent. For example, the synthesis of silicoaluminophosphate SAPO-18 has been reported in several publications, including J. Chen et al. in Catalysis Letters , v.28, pp. 241-248 (1994) and US Pat. No. 5,609,843, Col. 1, 1. 4 to Col. 6, 1. 40, incorporated by reference. Conveniently, the silicoaluminophosphate molecular sieve has a silica to alumina molar ratio from about 0.15 to about 0.22, from about 0.17 to about 0.21, and from about 0.18 to about 0.19. The SAPO-18 catalyst is substantially proton exchanged and calcined to convert it to the proton form, having a residual alkali amount (expressed in A2O wt.%, where A is the alkali metal such as Na, K, or a combination thereof) of less than 5,000 ppm, less than 1,000 ppm, and less than 500 ppm. The BET surface area of the SAPO-18 catalyst is greater than 200 m2 / g, greater than 300 m2 / g, and greater than 500 m2 / g. The SAPO-18 catalyst can be in the form of neat molecular sieve, or optionally formulated with a binder to form extrudates or spray dried into spherical particles. The amount of binder is in the range of 5 wt.% to 60 wt.%, or 20 wt.% to 50 wt.%, or 30 wt.% to 40 wt.%.

[0062] In another embodiment, the acid catalyst is a combination of 8-ring silicoaluminophosphates (SAPO) having the structure code CHA and AEI as defined by the International Zeolite Associate (IZA). In an embodiment, the acid catalyst is a combination of SAPO-34 and SAPO-18, either by physical mixture or intergrowth. The mixture or intergrowth of CHA / AEI has the weight ratio of 5 / 95 to 95 / 5, or 30 / 70 to 70 / 30. The synthesis of CHA / AEI intergrowth is disclosed in US Pat. No. 7,622,624, Col. 5, 11 to Col. 5, 1. 52, incorporated by reference. Conveniently, the silicoaluminophosphate molecular sieve has a silica to aluminamolar ratio from about 0.15 to about 0.22, from about 0.17 to about 0.21, such as from about 0.18 to about 0.19. The combination of SAPO-34 / SAPO-18 catalyst is substantially proton exchanged and calcined to convert it to the proton form, having a residual alkali amount (expressed in A2O wt.%, where A is the alkali metal such as Na, K, or a combination thereof) of less than 5,000 ppm, less than 1,000 ppm, and less than 500 ppm. The BET surface area of the SAPO-34 / SAPO-18 catalyst is greater than 200 m2 / g, greater than 300 m2 / g, and greater than 500 m2 / g. The SAPO-34 / SAPO-18 catalyst can be in the form of neat molecular sieve, or optionally formulated with a binder to form extrudates or spray dried into spherical particles. The amount of binder is in the range of 5 wt.% to 60 wt.%, 20 wt.% to 50 wt.%, and 30 wt.% to 40 wt.%.

[0063] Generally, zeolites and their isotypes are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, framework type zeolites and other crystalline microporous molecular sieves, for which a structure has been established, are assigned a three-letter code and are described in the “Atlas of Zeolite Framework Types”, eds. Ch. Baerlocher, L.B. McCusker, and D.H. Olson, Elsevier, Sixth Edition, 2007, which is hereby incorporated by reference.

[0064] Certain zeolites comprise an inorganic framework type where the silicon tetrahedral atoms are connected by oxygen atoms with the four next-nearest tetrahedral atoms. The term “silicate”, as used herein, refers to a substance comprising silicon and oxygen atoms alternately bonded to each other (i.e., -O-Si-O-Si-), and optionally comprise other types of atoms within the inorganic framework type, including boron, gallium, aluminum, or other metals (e.g., transition metals, such as titanium, vanadium, or zinc). Atoms other than silicon and oxygen in the framework occupy a portion of the lattice sites that would be otherwise occupied by silicon atoms in an ‘all-silica’ framework (also referred to as “silicate”). Thus, the term “framework silicate” or “zeolite framework silicate” refers to an atomic lattice comprising silicate, borosilicate, gallosilicate, ferrisilicate, aluminosilicate, titanosilicate, zincosilicate, vanadosilicate, and the like. As noted above, the framework structure within a zeolite determines the size of the pores or channels. Currently, there are more than 200 known zeolite framework silicates recognized by the Structure Commission of the International Zeolite Association, providing a range of pore geometries and orientations defined.

[0065] The zeolite framework silicate is commonly characterized in terms of ring size, wherein the ring size refers to the number of silicon atoms (or alternative atoms, such as those listed above) that are tetrahedrally coordinated with oxygen atoms in a loop to define a pore orchannel within the interior of the zeolite. For example, an “8-ring” zeolite refers to a zeolite having pores or channels defined by 8 alternating tetrahedral atoms and 8 oxygen atoms in a loop. The pores or channels defined within a given zeolite are symmetrical or asymmetrical dependent upon various structural constraints that are present in the framework silicate.

[0066] Zeolites can be classified as having small, medium, large, and extra-large pore structures for pore windows delimited by 8, 10, 12, and more than 12 T-atoms, respectively. Extra-large pore zeolites (>12R) include, for example, AET (14R, e.g., ALPO-8), SFN (14R, e.g., SSZ-59), VFI (18R, e.g., VPI-5), CLO (20R, e.g., cloverite), and ITV (30R, e.g., ITQ-37) framework type zeolites. Extra-large pore zeolites generally have a free pore diameter of larger than about 0.8 nm. Large pore zeolites (12R) include, for example, LTL, MAZ, FAU, EMT, OFF, MTW, *BEA, MOR, and SFS framework type zeolites, e.g., mazzite, offretite, zeolite L, zeolite Y, zeolite X, omega, ZSM-2, ZSM-12, zeolite T, Beta, and SSZ-56. Large pore zeolites generally have a free pore diameter of 0.6 nm to 0.8 nm. Medium (or intermediate) pore size zeolites (10R) include, for example, MFI, MEL, *MRE, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON framework type zeolites, e.g., ZSM-5, ZSM-11, ZSM-48, ZSM-22, ZSM-23, ZSM-35, MCM-22, MCM-49, silicalite- 1 , and silicalite-2. Medium pore size zeolites generally have a free pore diameter of 0.45 nm to 0.6 nm. Small pore size zeolites (8R) include, for example, CHA, SSZ-13, RTH, ERI, KFI, LEV, and LTA framework type zeolites, e.g., ZK- 4, SAPO-34, SAPO-18, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, chabazite, and A1PO-17. Small pore size zeolites have a free pore diameter of about 0.3 nm to less than 0.45 nm.

[0067] Molecular sieve materials, both natural and synthetic, can be used as adsorbents and have catalytic properties for hydrocarbon conversion reactions. Certain molecular sieves, such as zeolites, AlPOs, and mesoporous materials, are ordered, porous crystalline materials having a definite crystalline structure as determined by X-ray diffraction (“XRD”). Molecular sieves can be ordered and produce specific identifiable XRD patterns. Within certain molecular sieve materials are cavities interconnected by channels or pores. Within a particular type of molecular sieve, the pores are generally uniform in size. Pore size determines whether a molecule can travel within the molecular sieve and be adsorbed or rejected.

[0068] Molecular sieves are utilized in a variety of industrial processes, e.g., cracking, hydrocracking, disproportionation, alkylation, oligomerization, and isomerization. Molecular sieves, including naturally occurring or the synthetic crystalline molecular sieves, can find application in catalysis and adsorption.

[0069] Synthesis of molecular sieve materials (which include zeolites) typically involves hydrothermal crystallization from a synthesis mixture comprising sources of all the elements present in the molecular sieve (or zeolite) such as sources of silica but also of alumina etc. In many cases a structure directing agent (“SDA”) is also present. Structure directing agents are compounds which are believed to promote the formation of a molecular sieve, and which are thought to act as templates around which certain molecular sieve structures can form and which thereby promote the formation of the desired molecular sieve. Various compounds have been used as structure directing agents including various types of quaternary ammonium cations. Typically, molecular sieve (zeolite) crystals form around structure directing agents with the structure directing agent occupying pores in the molecular sieve once crystallization is complete. The “as-synthesized” (or “as-made”) molecular sieve will therefore contain the structure directing agent in its pores so that, following crystallization, the “as-synthesized” molecular sieve is subjected to a treatment step such as a calcination step to remove the structure directing agent.

[0070] For instance, US 3,308,069 and J.B. Higgins et al., Zeolites, v.8, pp. 446-448 (1988) disclose the preparation and characterization of zeolite Beta, a large pore zeolite of *BEA framework type, which exhibits a three-dimensional pore system formed by 12-membered ring channels. Zeolite Beta was first crystallized from a reaction mixture containing the tetraethylammonium ion (US 3,308,069). US 11,180,430 B2 discloses the preparation of zeolite Beta, in particular zeolite Beta having a high external specific surface area, using 1,1’ -(pentane- 1, 5 -diyl)bis(l-pentylpiperidinium), and their use in olefin oligomerization processes.

[0071] Beta zeolite (also “P-zeolite”) is an aluminosilicate that consists of two distinct polymorph structures consisting of a three-dimensional network of 12-ring pores. The polymorphs grow as two-dimensional sheets, and the structure randomly alternates between the two types of sheets. As taught in the prior art, P-zeolite has been found to increase gas fractions and reduce liquid oil, however strong secondary reactions can occur to form high quantities of residue and wax, dependent on the plastic feedstock. See Mark, L. et al., “The Use of Heterogenous Catalysis in the Chemical Valorization of Plastic Waste” ChemSusChem, v.13, pp. 5808-5826 (2020) citing K. Li, S. et al., Energies 2016, v.9, pg. 431 & C. Ma, et al., Fuel Process. Technol. 2017, v.155, pp. 32-41. For example, P-zeolite could somewhat improve selectivity towards gaseous products while drastically reducing liquid olefin products for the pyrolysis of HIPS. However, most of the cracked products underwent severe cross-linking reactions following cracking to produce yellowish brown wax that coated the reactor walls. Id.

[0072] SSZ-13 (framework type code CHA) is a high-silica aluminosilicate zeolite possessing 0.38 x 0.38 nm micropores. It belongs to the ABC-6 family of zeolites as well as offretite, cancrinite, erionite and other related small-pore zeolites. The framework topology is the same as that of chabazite but SSZ-13 has a high silica composition with Si / Al > 5, which leads to low cation exchange capacity. The typical chemical formula of the unit cell can be described as Q.-.Naj Ak^Siss.eC^’zH?!) (1.4 <x<27)(0.7 <y< 4.3)(1 < z <7), where Q is N,N,N- 1-trimethyladamantammonium. US 4,544,538.

[0073] Another class of zeolites that are useful for plastic conversion are ZSM-5 catalysts. These zeolites are MFI (silicalite- 1) structured porous aluminosilicate zeolites that have been reported to have increased cracking activity for olefins in particular polyethylene that results in a decrease in the heavy oil fraction, reduction in wax production, minimization in char production, and an increase in light hydrocarbon content in the liquid and gas produced. Mark, L. et al., “The Use of Heterogenous Catalysis in the Chemical Valorization of Plastic Waste” ChemSusChem, v.13, pp. 5808-5826 (2020) at 5822. Other types of zeolitic materials that can be used in plastic conversion include amorphous (non-zeolite) solid acids (such as used in amorphous silica-alumina). See e.g., Busca, G., Silica-Alumina Catalytic Materials: A Critical Review, v.357, pp. 621-629 (2020).

[0074] For example, the present process that utilizes a zeolite having small pore size and rich in silicon to produce olefin product such as a mixture of C2-C4 (“C2-C4”) olefins, a mixture including C2-C3 olefins, or a mixture including C2 olefins, C3 olefins and optionally C4 olefins. The C2-C4 olefins produced are primarily in a gas phase. Further, as described herein, the present processes further produce C5 to C20+ (“C5 to C20+”) olefins. The olefin products of Cs to C20+ olefins are produced in a liquid phase. The olefin products in the liquid phase can be less than or equal to 80 wt.%, 75 wt.%, 70 wt.%, 60 wt.%, 50 wt.% or 45 wt.% of the total weight of olefin product produced. Similarly, the olefin products in the gas phase can be less than or equal to 50 wt.%, 45 wt.%, 40 wt.%, 35 wt.%, 30 wt.%, 25 wt.% or 20 wt.% of the total weight of the olefin products produced.Olefin Product - Polyethylene and / or Other Polyolefins

[0075] Polyolefin polymers are commonly used in a wide variety of industrial and consumer applications. In some instances, substantial quantities of plastic waste are available that correspond to a single type of polyolefin, but more typically polyolefin waste correspondsto a mixture of polyethylene, polypropylene, and / or other polymer chains based on small olefins.

[0076] Polyethylene is used widely in various consumer and industrial products including bags, films, geomembranes, and bottles. Polyethylene can be produced as high-density polyethylene (HDPE, approximately 0.940 to approximately 0.965 g / cm3), linear low-density polyethylene (LLDPE, approximately 0.915 to approximately 0.940 g / cm3) and low-density polyethylene (LDPE, <0.930 g / cm3), each having a chemical formula of (C2H4)n where n is a number one or greater, but with different molecular structure. HDPE has a low degree of branching with short side chains while LDPE has a very high degree of branching with long side chains. LLDPE is a substantially linear polymer with significant numbers of short branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins. US Pub. App. No. 2021 / 0332299

[0021] ,

[0077] Low density polyethylene (“LDPE”) is produced via radical polymerization at a temperature between 150°C and 300°C and pressure of 1,000-3,000 atm (101-304 MPa). The process uses a small amount of oxygen and / or organic peroxide initiator to produce polymer with about 4,000-40,000 carbon atoms per the average polymer molecule, and with many branches. High density polyethylene (“HDPE”) is manufactured at relatively low pressure (10- 80 atm, 1-8 MPa) and 80-150°C temperature in the presence of a catalyst. Id. at

[0023] , Present Process in Combination with Other Recycling Processes

[0078] The present processes are not limited to producing a type of polyolefin, a polymer or group of polymers. However, to optimize melting of plastic wastes and depending on the type of polymers in the plastic wastes, separate flows can be required for different polymers. For example, the condensation polymers PET are mechanically recycled and are removed from the plastic material prior to pyrolysis, or chemically recycled by an alternative process such as hydrolysis. In another example, because PVC generates HC1 at pyrolysis, PVC is typically removed from the plastic material. However, a small presence of PVC in the plastic material is acceptable. Alternative processes include chemical recycling by different processes (z.e., hydrolysis) of other polymers such as polyesters and polyamides.

[0079] In an embodiment, the present process includes a step of selecting plastic waste containing polyolefins such as polyethylene and / or polypropylene. Plastic waste is passed through the pyrolysis plastic wastes reactor to thermally crack at least a portion of the plastic waste and produce a pyrolyzed effluent. The pyrolyzed effluent can be separated into off gas, pyrolysis product, (z.e., comprising olefin, naphtha, diesel, and heavy fractions) and char. In an embodiment, the pyrolyzed effluent is a pyrolysis feedstock to a pyrolysis unit.

[0080] In an embodiment, the present process is integrated as a continuous process for converting plastic wastes comprising polyethylene into a recycle stream used in polyethylene polymerization. This process comprises the step of selecting plastic wastes containing polyethylene and / or polypropylene and then passing the plastic wastes through the pyrolysis plastic wastes reactor to thermally crack at least a portion of the plastic wastes and produce the pyrolyzed effluent which is further processed.

[0081] In an embodiment, the present processes can be incorporated into an oil refinery where a single use waste plastic such as polyethylene or polypropylene is in fluidic communication with a steam cracker for ethylene production allowing for a “cyclical economy.” Also, in an integrated process, the pyrolysis product in the form of a naphtha stream can be used as a steam cracker feedstock for ethylene generation and subsequent polyethylene production.

[0082] Aspects of the disclosure are described in greater detail by way of specific examples. The following examples are offered for illustrative purposes and are not intended to limit the disclosure in any manner. Those of skill in the relevant art will readily recognize a variety of parameters can be changed or modified to yield essentially the same results.ADDITIONAL EMBODIMENTS

[0083] Embodiment 1. A catalytic pyrolysis process for conversion of a plastic waste to an olefin product comprising the steps of: thermally pyrolyzing the plastic waste in a first reactor in the absence of oxygen to produce a pyrolysis oil (pyoil); and contacting the pyoil with an acid catalyst in a second reactor to produce the olefin product comprising at least 60 wt.% C2-C4 olefins, wherein the acid catalyst is a microporous material comprising a pore opening between 0.3 nm and less than 0.45 nm in diameter.

[0084] Embodiment 2. The process of embodiment 1, further comprising the step of separating the C2 olefin, the C3 olefin and / or the C4 olefin from the olefin product.

[0085] Embodiment 3. The process of embodiment 1, wherein the first reactor and / or the second reactor is operated at a temperature of 550°C or less.

[0086] Embodiment 4. The process of embodiment 1, wherein the first and / or the second reactor is operated at a pressure of between 15 psig and 75 psig.

[0087] Embodiment 5. The process of embodiment 1, wherein the plastic waste is co-fed with less than 30 wt.% steam into the first reactor.

[0088] Embodiment 6. The process of embodiment 5, further comprising the step of separating water produced from the steam co-fed into the first reactor.

[0089] Embodiment 7. The process of embodiment 1, wherein the plastic waste is a postconsumer waste and / or a post-industrial waste.

[0090] Embodiment 8. The process of embodiment 7, wherein the post-consumer waste comprises a waste plastic, a waste rubber, a textile, modified cellulose, wet-laid products, or combinations thereof.

[0091] Embodiment 9. A process for converting a plastic waste to an olefin product comprising the steps of: providing a plastic waste comprising one or more polyolefins; pyrolyzing the plastic waste to produce a pyoil; contacting the pyoil with an acid catalyst to provide a mixture; and pyrolyzing the mixture to a temperature of 550C or less, wherein the pyoil is catalytically decomposed to yield the olefin product comprising greater than 60 wt.% C2-C4 olefin, greater than 30 wt.% of propylene, and less than 40 wt.% C5+ olefin.

[0092] Embodiment 10. The process of embodiment 9, wherein the C2-C4 olefins are separated from the C5+ olefins.

[0093] Embodiment 11. The process of embodiment 9, wherein the acid catalyst is a microporous material comprising a micropore opening between 0.3 nm and less than 0.45 nm in diameter.

[0094] Embodiment 12. A process for conversion of a plastic waste to an olefin product comprising the steps of: thermally converting the plastic waste in the absence of oxygen to produce a pyoil; and contacting the pyoil with an acid catalyst to produce the olefin product comprising C2 olefin, C3 olefin, and C4 olefin, wherein a yield of C3 olefin and C4 olefin in the olefin product is increased by at least two-fold in comparison with the yield of C3 olefin and C4 olefin after thermal cracking of the pyoil without the acid catalyst.

[0095] Embodiment 13. The process of embodiment 12, wherein the plastic waste is heated at 550°C or less in the absence of oxygen.

[0096] Embodiment 14. The process of any one of the proceeding embodiments, wherein the acid catalyst is an 8-ring zeolite.

[0097] Embodiment 15. The process of embodiment 14, wherein the acid catalyst is CHA.

[0098] Embodiment 16. The process of any one of the proceeding embodiments, wherein the acid catalyst is an 8-ring silicoaluminophosphate (SAPO).

[0099] Embodiment 17. The process of embodiment 16, wherein the acidic catalyst is selected from SAPO-34, SAPO- 18, or a combination thereof.

[0100] Embodiment 18. The process of any one of the proceeding embodiments, wherein the plastic waste comprises at least 30 wt.% of polyethylene and / or polypropylene.

[0101] Embodiment 19. The process of any one of the proceeding embodiments, wherein the olefin product further comprises C5-C8 olefin, C9-C21 olefin, C21-C29 olefin, C29-C31 and C32-C35 olefin.

[0102] Embodiment 20. The process of embodiment 19, wherein an amount of C9-C21 olefin, C21-C29 olefin, C29-C31 olefin and C32-C35 olefin is reduced by at least 40 wt.% in comparison with the amount of C9-C21 olefin, C21-C29 olefin, C29-C31 olefin and C32-C35 olefin after thermal cracking of the pyoil without the acid catalyst.EXAMPLESExperimental Methods

[0103] Pyrolysis and cracking experiments were performed in a modified tandem pyrolyzer-catalytic reactor unit (Frontier Lab, flab-us.com). The unit has two reactors, a first reactor and a second reactor, connected in tandem, sitting on top of a GC / MSD / FID instrument (Agilent). The first reactor, a micro-pyrolyzer and the second reactor, a thermal or catalytic reactor, were independently temperature controlled, allowing for evaluation of pyrolysis and subsequent cracking at different temperatures. Approximately 0.5 mg of plastic sample is loaded in a stainless (“SS”) metal cup, which is dropped in the pyrolyzer at a pre-set temperature, pyrolysis products (pyoil) are swept by helium (50 seem) and sent to the second reactor. The effluent from the second reactor is trapped (at -195°C) via a micro-jet cooled with liquid nitrogen. After a pre-determined sample trapping period of 5 minutes, the trapped reaction sample is warmed up and travels through the GC column for separation. The effluent from the GC column is split 3 / 1 (v / v) and sent to a flame ionization detector (FID, for quantification) and mass spec detector (MSD, for identification), respectively.

[0104] A 30 m x 0.25 mm x 0.1 pm DB-5HT column (Agilent J&W) was used for separation. GC conditions included: helium carrier gas, 1.4 cc / min column flow; 25 / 1 split ratio; temperature: 35°C initial 5 minute hold; ramping to 200°C at 7.5 °C / min; and then heating to 325°C at 20°C / min with a hold for 10 minutes. H2, if formed, cannot be trapped using the micro-jet and therefore was not detected using this technique. The GC oven temperature was optimized for heavy product separation, thereby resolution for the light end was comprised but only minimally: methane / ethane / ethylene co-elude, and similarly, propylene / propane, butenes / butanes also co-elude. However, based on the mass spectra, the amounts of alkane formed from the examples are low.Example 1Flash Pyrolysis (“FP”) ofLLDPE (Exceed 1018) & Flash Pyrolysis Stream Cracking Using Acid Catalysts Chabazite (“CHA ”)

[0105] FIG. 1 provides a comparison of the olefin product yield for: 1) flash pyrolysis (“FP”) at 700°C where the second reactor was packed with quartz chips and held at 250°C, and 2) 700°C FP followed by cracking using acid catalysts in the temperature range of 500°C to 550°C. ZSM-5 (MFI) and an FCC equilibrium catalyst (eCat) are used as comparative examples. The acid catalyst is the CHA (SSZ-13). The SSZ-13 chabazite catalyst used in this example is in the proton-exchanged form, having a silica to alumina (SiCh / AhCh) molar ratio in the range of 13-15 (Si / Al ratio of 26-30), a BET surface area of greater than 600 m2 / g, crystallize sizes in the range of 0.5 micron - 1 micron, and a Na?O level of less than 500 ppm. As is seen in Figure 1, for the comparative examples using acid catalysts having pore opening of 0.45 nm or greater, the yield of C2 / C3 / C4 increases modestly relative to flash pyrolysis only: 32 wt.% C2 / C3 / C4 for flash pyrolysis, 53 wt.% for MFI, and 65 wt.% for FCC eCat. The magnitude of increase in C2 / C3 / C4 yield (predominantly olefins) is significantly higher when the acid catalyst CHA is used: 72 wt.% C2 / C3 / C4; and at the same time, yield to C5+ was reduced: 28 wt.% vs. 68 wt.% for flash pyrolysis.Example 2Mild Pyrolysis (MP) ofLLDPE (Exceed 1018) and Pyoil Cracking Using Chabazite (“CHA ”)

[0106] The SSZ-13 chabazite catalyst used in this example is in the proton-exchanged form, having a silica to alumina (SiCh / AhCh) molar ratio in the range of 13-15 (Si / Al ratio of 26-30), a BET surface area of greater than 600 m2 / g, crystallize sizes in the range of 0.5 micron to 1 micron, and a Na?O level of less than 500 ppm. The SAPO-34 (having the chabazite structure) catalyst used in this example is in the proton-exchanged form, having Si / Al / P atomic ratio of 0.15 / 0.78 / 0.63, a BET surface area of greater than 550 m2 / g, a mean particle size of ~ 2 micron, and an alkali level (Na2O+K2O) of less than 200 ppm. As shown in FIG. 2, when LLDPE is pyrolyzed at 500°C, total C2 / C3 / C4 yield is only 7 wt.% (balance C5+). When the LLPDE pyoil oil is generated at 500°C medium pyrolysis (“MP”), followed by acid catalyzed cracking using CHA and SAPO-34 catalysts at 500°C, yield to C2 / C3 / C4 (predominantly olefins) was enhanced for the MP+CHA and MP+SAPO-34 examples: 89 wt.% for CHA and 88 wt.% for SAPO-34. The 500°C MP simulates pyoil generation where the C2-C4 gas makeup is low, and liquids (C9+) is high. Acid cracking using the chabazite (CHA) or SAPO-34 provided higher C2-C4 olefin yield versus thermal cracking (on quartz) or FP at 700°C.

[0107] Many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure and that when numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated.

Claims

CLAIMS:We Claim:

1. A catalytic pyrolysis process for conversion of a plastic waste to an olefin product comprising the steps of: thermally pyrolyzing the plastic waste in a first reactor in the absence of oxygen to produce a pyrolysis oil (pyoil); and contacting the pyoil with an acid catalyst in a second reactor to produce the olefin product comprising at least 60 wt.% C2-C4 olefins, wherein the acid catalyst is a microporous material comprising a pore opening between 0.3 nm and less than 0.45 nm in diameter.

2. The process of claim 1, further comprising the step of separating the C2 olefin, the C3 olefin and / or the C4 olefin from the olefin product.

3. The process of claim 1, wherein the first reactor and / or the second reactor is operated at a temperature of 550°C or less.

4. The process of claim 1, wherein the first and / or the second reactor is operated at a pressure of between 15 psig and 75 psig.

5. The process of claim 1, wherein the plastic waste is co-fed with less than 30 wt.% steam into the first reactor.

6. The process of claim 5, further comprising the step of separating water produced from the steam co-fed into the first reactor.

7. The process of claim 1, wherein the plastic waste is a post-consumer waste and / or a post-industrial waste.

8. The process of claim 7, wherein the post-consumer waste comprises a waste plastic, a waste rubber, a textile, modified cellulose, wet-laid products, or combinations thereof.

9. A process for converting a plastic waste to an olefin product comprising the steps of: providing a plastic waste comprising one or more polyolefins; pyrolyzing the plastic waste to produce a pyoil; contacting the pyoil with an acid catalyst to provide a mixture; andpyrolyzing the mixture to a temperature of 550°C or less, wherein the pyoil is catalytically decomposed to yield the olefin product comprising greater than 60 wt.% C2-C4 olefin, greater than 30 wt.% of propylene, and less than 40 wt.% C5+ olefin.

10. The process of claim 9, wherein the C2-C4 olefins are separated from the C5+ olefins.

11. The process of claim 9, wherein the acid catalyst is a microporous material comprising a micropore opening between 0.3 nm and less than 0.45 nm in diameter.

12. A process for conversion of a plastic waste to an olefin product comprising the steps of: thermally converting the plastic waste in the absence of oxygen to produce a pyoil; and contacting the pyoil with an acid catalyst to produce the olefin product comprising C2 olefin, C3 olefin, and C4 olefin, wherein a yield of C3 olefin and C4 olefin in the olefin product is increased by at least two-fold in comparison with the yield of C3 olefin and C4 olefin after thermal cracking of the pyoil without the acid catalyst.

13. The process of claim 12, wherein the plastic waste is heated at 550°C or less in the absence of oxygen.

14. The process of any one of the proceeding claims, wherein the acid catalyst is an 8-ring zeolite.

15. The process of claim 14, wherein the acid catalyst is CHA.

16. The process of any one of the proceeding claims, wherein the acid catalyst is an 8-ring silicoaluminophosphate (SAPO).

17. The process of claim 16, wherein the acidic catalyst is selected from SAPO-34, SAPO-18. or a combination thereof.

18. The process of any one of the proceeding claims, wherein the plastic waste comprises at least 30 wt.% of polyethylene and / or polypropylene.

19. The process of any one of the proceeding claims, wherein the olefin product further comprises C5-C8 olefin, C9-C21 olefin, C21-C29 olefin, C29-C31 and C32-C35 olefin.

20. The process of claim 19, wherein an amount of C9-C21 olefin, C21-C29 olefin, C29- C31 olefin and C32-C35 olefin is reduced by at least 40 wt.% in comparison with the amountof C9-C21 olefin, C21-C29 olefin, C29-C31 olefin and C32-C35 olefin after thermal cracking of the pyoil without the acid catalyst.

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