Molten salt catalyst composition and method for the decomposition of carbon-containing feedstocks - Patents.com

Abstract

The catalyst composition comprises a metal catalyst dispersed in a molten eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. The process for catalytic cracking of hydrocarbons comprises, in a reactor system: contacting a carbon-containing feedstock with at least one catalyst in the presence of oxygen to produce olefinic and / or aromatic compounds; and recovering olefinic and / or aromatic compounds; The present invention relates to a method for catalytically cracking hydrocarbons, the method comprising: preparing a catalyst in a catalytic cracking process using a catalytic cracking catalyst; and a catalytic cracking process using a catalytic cracking catalyst; wherein the catalytic cracking process uses a catalytic catalyst dispersed in a molten eutectic mixture of an alkali metal or alkaline earth metal carbonate or hydroxide; and a catalyst preparation process comprising mixing and heating a metal catalyst precursor selected from a transition metal compound and a rare earth metal compound with the eutectic mixture of an alkali metal or alkaline earth metal carbonate or hydroxide.

Description

[Technical field]

[0001] CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 032,210, filed May 29, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] The present technology relates generally to catalysts for the decomposition of carbon-containing feedstocks. More specifically, the decomposition of carbon-containing feedstocks in the presence of an oxidizing agent to form olefinic and aromatic monomers. Summary of the Invention

[0003] Oxygen cracking is an attractive route for the direct conversion of carbon-containing feedstocks (e.g., waste plastics, bio-based complex compositions, light alkanes, and municipal waste) into value-added basic chemical building blocks (e.g., olefins, oxo compounds, and aromatics). Direct conversion of carbon-containing feedstocks can reduce the carbon dioxide emissions typically associated with the production of high-value basic chemicals. One method for performing oxygen cracking relies on the use of molten salt catalysts, and the inventors have found that molten salt catalysts can improve process efficiency.

[0004] In one aspect, a heterogeneous catalyst composition is provided that includes a metal catalyst dispersed in a molten salt matrix that includes a eutectic mixture of alkali or alkaline earth metal carbonates or hydroxides. In some embodiments, the metal catalyst includes a transition metal compound, a rare earth metal compound, or a mixture of transition metal compounds and rare earth metal compounds. In some embodiments, the eutectic mixture is a mixture of alkali or alkaline earth metal carbonates or hydroxides that has a melting point less than about 750° C.

[0005] In another embodiment, a process for catalytic cracking of hydrocarbons is provided, comprising contacting a carbon-containing feedstock with at least one heterogeneous catalyst in the presence of an oxidant in a reactor system to produce olefinic and / or aromatic compounds; and recovering the olefinic and / or aromatic compounds; wherein the at least one heterogeneous catalyst comprises metal compounds dispersed in a molten salt matrix of a eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides. The process may be an autothermal process.

[0006] In another aspect, a process for preparing a heterogeneous catalyst is provided, the process comprising: combining alkali or alkaline earth metal carbonates or hydroxides to form a salt matrix comprising a eutectic salt mixture; adding at least one metal catalyst precursor to the salt matrix to form a catalyst precursor mixture; heating the catalyst precursor mixture to a temperature between about 250° C. and about 750° C. to form a heterogeneous catalyst comprising a metal catalyst dispersed in the molten salt matrix; wherein the metal catalyst precursor comprises at least one transition metal compound, rare earth metal compound, or a combination of any two or more thereof. [Brief description of the drawings]

[0007] Figure 1 shows the ternary phase diagram of lithium, sodium, and potassium carbonates, reproduced from Chen et al., J. Sol. Energy Eng. 136(3):031017 (Aug. 2014).

[0008] FIG. 2 is a flow chart of one embodiment of a cracking method using the heterogeneous catalyst composition described herein.

[0009] FIG. 3 is a flow chart for another embodiment of a cracking process using the heterogeneous catalyst composition described herein and including a catalyst regeneration loop.

[0010] FIG. 4 is a general schematic diagram of a reactor system for treating polymer waste.

[0011] FIG. 5 is a schematic diagram of a batch reactor setup according to an embodiment.

[0012] FIG. 6 is a differential scanning calorimetry (DSC) trace for forming a eutectic melt from a mixture of Li2CO3, Na2CO3, and K2CO3 powders, according to an embodiment.

[0013] Figure 7 is a representative GC-MS (gas chromatography-mass spectrometry) trace showing peak assignments based on mass spectral signature matches with the NIST-MS database for experiments of direct oxygen degradation of botanicals (olive oil) over Li2CO3-Na2CO3-K2CO3 (43.5-31.5-25 mol%) eutectic mixtures in a mini-batch reactor. The experimental conditions are listed in the insert box at the top right.

[0014] FIG. 8 contains GC-MS traces of products recovered from direct oxygenation of olive oil in a mini-batch reactor without catalyst, and with Cat. E and Cat. F, according to an embodiment.

[0015] FIG. 9 includes GC-MS traces of products recovered from the direct oxygen decomposition of n-hexane in the presence of Li2CO3-Na2CO3-K2CO3 (43.5-31.5-25 mol%) eutectic mixture and Cat. A' in a mini-batch reactor, according to an embodiment.

[0016] FIG. 10 includes GC-MS traces of products recovered from a two-stage oxygen decomposition of HDPE in the presence of Cat. A, Cat. B, Cat. C, and Cat. D in a mini-batch reactor, according to an embodiment.

[0017] FIG. 11 includes GC-MS traces of products recovered from the two-stage enzymatic decomposition of various feedstocks in the presence of Cat. A in a mini-batch reactor, according to an embodiment.

[0018] FIG. 12 includes GC-MS traces of liquid products recovered from a two-stage oxygen decomposition process carried out in a stirred tank reactor in the presence of Cat. A′, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Various embodiments are described below. It should be noted that the specific embodiments are not intended as exhaustive descriptions or limitations on the broader aspects discussed herein. An aspect described in connection with a specific embodiment is not necessarily limited to that embodiment and can be implemented in any other embodiment(s).

[0020] As used herein, "about" is understood by those of ordinary skill in the art and will vary to some extent depending on the context in which it is used. If there is a use that is not clear to a person of ordinary skill in the art from the context in which the term is used, "about" will mean up to plus or minus 10% of the particular term.

[0021] The use of the terms "a" and "an" and "the" and similar reference words in the context of describing an element shall be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values ​​herein is merely intended to serve as a shorthand method for individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if set forth individually. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims, unless otherwise specified. No language in this specification should be construed as indicating any non-claimed element as required.

[0022] As used herein, the term "dispersion" refers to a system in which particles of one material are dispersed in a continuous phase of another material. The two phases can be in the same or different states, such as a solid metal catalyst dispersed in a molten alkali metal or alkaline earth metal carbonate eutectic melt. Dispersions are classified in several ways, including the size of the dispersed particles relative to the particles of the continuous phase, and whether or not there is spontaneous precipitation (sedimentation). Generally, dispersions of particles large enough to cause precipitation are called suspensions, smaller particles are called colloids, and smaller particles are called solutions. For the purposes of this invention, the metal catalyst dispersed in the molten matrix can be a suspension, a colloid, or a solution. The boundary between the bulk and dispersed metal catalyst cases is an average particle size of 10 mm (cross-sectional distance from one side to the other for the particles). Bulk metal catalysts can be said to have an average particle size of more than 10 mm, and dispersed metal catalysts have an average particle size of 10 mm or less. Another common descriptor in the boundary case is the geometric surface area of ​​the dispersed material. In this case, a bulk metal catalyst has a geometric surface area of ​​less than 0.01 square meters per gram of metal catalyst material, whereas a dispersed metal catalyst has a geometric surface area of ​​0.01 square meters or more per gram of metal catalyst material.

[0023] As used herein, the term "cracking" refers to a chemical process in which feedstocks, i.e., complex organic molecules such as long chain hydrocarbons, carbohydrates, etc., are broken down into simpler molecules such as light hydrocarbons, oxygenates, or oxides of carbon by scission of chemical bonds in the feedstock.

[0024] As used herein, the term "thermolysis" refers to a decomposition process in which the conversion of feedstocks to products is accomplished by thermal energy transfer, i.e., heating, and therefore requires operation at high temperatures in order to proceed.

[0025] As used herein, the term "oxycracking" refers to a cracking process that utilizes a combination of pyrolysis and oxidation processes and is generally applied to the processing of heavy carbon-containing feedstocks, resulting in the formation of amounts of organic oxygenates, CO, CO2, and HO as by-products in addition to light hydrocarbon products.

[0026] As used herein, the term "reactor system" refers to the location where the catalytic cracking reaction(s) take place. The process for catalytic cracking of hydrocarbons can occur in a single reactor or in at least two reactors in series.

[0027] As used herein, the term "at least one heterogeneous catalyst" refers to the possibility of introducing two or more heterogeneous catalysts into the reactor system of the process for catalytic cracking of hydrocarbons. Thus, one or more heterogeneous catalysts may be contacted with the carbon-containing feedstock in a single reactor or may be separated in at least two reactors in series. The at least one heterogeneous catalyst may be equal to or different from each other.

[0028] As used herein, the term "carbon-containing feedstock" meets the definition to include not only pure hydrocarbon materials as typically associated with the term, but also plastics (i.e., polymers) or carbon-containing segments within biomass or biowaste that are decomposable with the catalyst compositions provided herein. For example, carbon-containing feedstocks may contain oxygen in the material, as well as other heteroatoms (N, P, S, Cl, etc.), and other materials typically associated with polymers, such as loading agents (including silica, zinc oxide, titanium oxide, calcium carbonate, etc.), colorants, plasticizers, etc.

[0029] As used herein, the term "eutectic" or "eutectic mixture" refers to a homogenous mixture of substances that melts or solidifies at a single temperature below the melting point of any of the components. It does not necessarily refer to the lowest melting point achievable for a particular mixture of substances, which may be the eutectic point of that substance and part of a eutectic mixture. As long as a mixture of substances melts and forms a single continuous phase at a temperature below the melting point of any of its constituent pure substances, for the purposes of this disclosure, it is a "eutectic" or "eutectic mixture". As used herein, the phrase "eutectic mixture of alkali metal or alkaline earth metal carbonates or hydroxides" may instead be written as "eutectic mixture of alkali metal carbonates, alkali metal hydroxides, alkaline earth metal carbonates, alkaline earth hydroxides, or mixtures of any two or more thereof."

[0030] It has now been found that the cracking of carbon-containing feedstocks can be carried out in the presence of oxygen as the oxidant (either free oxygen gas (O2) or oxygen bound to a catalyst) and a molten salt catalyst to form a product stream containing olefinic and / or aromatic compounds. The method can be applied to carbon-containing feedstocks, including recycling olefinic polymers and biopolymers alike. The method can be applied to pure hydrocarbon feedstreams as well as mixed streams, especially when the hydrocarbon stream is from a mixed waste recycling operation. The described method and catalysts may improve performance over industry accepted methods such as pyrolysis, thermal steam cracking, fluid catalytic cracking, and supercritical fluid cracking. The cracking of hydrocarbons over a molten salt catalyst is a heterogeneous process and is therefore referred to as a "heterogeneous catalyst" or "heterogeneous catalytic process". When free oxygen gas (O2) is used in the process, the process is referred to as "direct oxygen cracking". When catalyst-bound oxygen is used in the process, the process is referred to as "two-stage oxycracking". In two-stage oxycracking, stage 1 is the reaction of the hydrocarbon feed with catalyst-bound oxygen (i.e., metal oxide lattice oxygen or surface-adsorbed oxygen) resulting in loss of bound oxygen to the reaction products and the formation of oxygen-deficient (e.g., spent) catalyst. Stage 2 is the catalyst regeneration reaction in which the oxygen-deficient form of the catalyst reacts with free oxygen gas to return the catalyst to its original oxidized form. The catalyst in such a two-stage process also functions as an oxygen carrier.

[0031] The method described herein utilizes an autothermal decomposition process whereby the thermal requirements for the process are met in whole or in part by internally generated heat, whereas other processes accepted in the industry rely entirely on externally generated heat to achieve the desired conversion and are therefore more energy and capital intensive.

[0032] The present method is also a high rate cracking process, allowing for lower processing temperatures (i.e., less than 750° C.) due to the presence of both oxygen and molten catalyst. Alternative cracking processes, such as pyrolysis and thermal steam cracking, require much higher temperatures, typically greater than about 850° C., to achieve similar productivity output per unit volume of reactor. Furthermore, the method of the present invention requires only moderate pressures in the reactor, i.e., less than about 20 atmospheres ("atm"). Alternative cracking processes, such as supercritical fluid cracking and high pressure catalytic cracking, utilize much higher processing pressures and are therefore more energy and capital intensive processes.

[0033] The process described herein also tolerates the presence of acid impurities in the feed, such as those containing chloride, bromide, sulfide, sulfate, and phosphate groups. The process also tolerates the presence of plastic filler components, such as silica, titania, zinc oxide, calcium carbonate, etc. It is believed that removal of such acid impurities and plastic filler components is accomplished by absorbing such materials into a eutectic mixture, purifying, and removing the impurities. Thus, the process is feedstock flexible and can be used to treat mixed plastic waste. Also, the process can be operated as a continuous, semi-continuous, or batch process. Thus, the process offers high flexibility in the design and operation of its end user applications.

[0034] Without being bound by theory, it is believed that the reaction proceeds according to the following eight equations, summarized in equation (9): Equation (1) describes catalytic oxygen decomposition of a polyolefin feed reacting with oxygen in the presence of a catalyst at a temperature below about 750° C., or below about 650° C. The catalyst is a molten salt mixture of an alkali metal or alkaline earth metal carbonate or hydroxide and a metal catalyst. The product of the reaction is an aldehyde. JPEG0007600270000001.jpg21165

[0035] When sufficient oxygen is present, the aldehyde product from equation (1) can undergo further oxidation to form a carboxylic acid according to equation (2). JPEG0007600270000002.jpg19151

[0036] Several other reactions are also likely occurring in the same reactor, as described by equations (3-4): Equation (3) is the deoxygenation reaction by catalytic conversion of aldehydes to olefins over a catalyst, with carbon monoxide and hydrogen being formed as by-products. JPEG0007600270000003.jpg20140

[0037] Equation (4) is the deoxygenation reaction by catalytic conversion of carboxylic acids to olefins over a catalyst, with carbon dioxide and hydrogen as by-products. JPEG0007600270000004.jpg18143

[0038] A catalyst which is a molten salt mixture of an alkali metal or alkaline earth metal carbonate or hydroxide and a metal compound can be a bifunctional catalyst since it simultaneously promotes the oxygen decomposition reaction and the deoxygenation reaction.

[0039] Several side reactions may also occur in the same reactor, as described in equations (5-8). These reactions may proceed on their own or may be accelerated by the presence of a catalyst. Equation (5) is the hydrogenation reaction via the conversion of olefins and hydrogen to alkanes. JPEG0007600270000005.jpg15133

[0040] Equation (6) is the reverse water gas shift reaction via the conversion of carbon dioxide and hydrogen to carbon monoxide and water. JPEG0007600270000006.jpg13113

[0041] Equation (7) is the disproportionation reaction via the conversion of two equivalents of carbon monoxide to one equivalent of carbon dioxide and one equivalent of free carbon (i.e., coke), also known as the Boudouard reaction. JPEG0007600270000007.jpg15107

[0042] Finally, in the presence of some excess oxygen, equation (8) is an oxidation reaction via the conversion of one equivalent of free carbon and two equivalents of oxygen to one equivalent of carbon dioxide. JPEG0007600270000008.jpg1598

[0043] The catalyst can be selected so that the overall reaction is shown in equation (9). JPEG0007600270000009.jpg16162

[0044] As provided in equation (9), the overall reaction is exothermic and provides heat to sustain itself. The standard reaction enthalpy of equation (9) is estimated to be about -97 kcal / mol. Thermal decomposition of polyethylene in the absence of a catalyst system and oxygen (-(CH2CH2) n It is noted that the reaction is endothermic with an estimated enthalpy of reaction of +25.4 kcal / mol.

[0045] In a first aspect, a heterogeneous catalyst composition is provided that includes a metal catalyst dispersed in a molten salt matrix of a eutectic mixture of alkali or alkaline earth metal carbonates or hydroxides. The metal catalyst may include at least one metal compound selected from the group of transition metal compounds, rare earth metal compounds, or combinations of any two or more thereof. The eutectic mixture is the basis of the molten salt matrix, and melts at a lower temperature than its constituent materials, and melts at a temperature at which catalytic reactions can be carried out to form desired materials from raw materials.

[0046] The eutectic mixture of alkali metal carbonates and hydroxides may be a mixture of Li, Na, and K carbonates or hydroxides. In some embodiments, the eutectic mixture is one of Li2CO3, Na2CO3, and K2CO3. FIG. 1 is a phase diagram illustrating the melting points of a wide variety of Li, Na, and K carbonate mixtures, reproduced from Chunlin Chen, Ty Tran, Rene Olivares, Steven Wright, Shouyi Sun; J. Sol. Energy Eng. Aug 2014, 136(3):031017. In some embodiments, the eutectic mixture of alkali metal carbonates or hydroxides has a melting point less than about 750° C., or less than about 650° C., including melting points of about 250° C. to about 650° C., about 350° C. to about 550° C., or about 400° C. Other exemplary eutectic mixtures of alkali metal carbonates include those in Table 1, reproduced from Mutch et al., J. Mater. Chem. A 7, 12951-12973 (2019). [Table 1] JPEG0007600270000010.jpg73168

[0047] It should be noted that if the eutectic mixture contains hydroxides of Li, Na, and / or K at the start of the process employing such a mixture, the process described herein will produce CO2 as a by-product. Thus, any alkali or alkaline earth metal hydroxide is readily converted to the corresponding carbonate by the production of CO2 at the operating temperatures of the molten salt.

[0048] In one embodiment, the transition metal compound included in the metal catalyst may include a transition metal having catalytic properties, and its incorporation into the catalyst composition may be as a transition metal carbonate, a transition metal salt of an organic acid, or a transition metal oxide. The transition metal may be based on a Group 4-12 metal. Exemplary transition metals may include, but are not limited to, one or more of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, and W. In an embodiment, the transition metal is one or more of Mn, Fe, Ni, Cu, Co, and W, and in an embodiment, the transition metal compound may include one or more carbonates of Mn, Fe, Co, Ni, and Cu. In other embodiments, the transition metal compound may include one or more salts of an organic acid of Cr, Mn, Fe, Co, Ni, Cu, and Zn, and the organic acid is derived from formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, oxalic acid, tartaric acid, lactic acid, and oleic acid. And in further embodiments, the transition metal compound may include an oxide of one or more of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, and W.

[0049] In one embodiment, the rare earth metal compound included in the catalyst may be introduced as a rare earth metal carbonate, a rare earth metal salt of an organic acid, or a rare earth metal oxide. Exemplary rare earth metals include, but are not limited to, one or more of La, Ce, Pr, and Nd. In some embodiments, the rare earth metal compound is a rare earth metal carbonate that is a carbonate of one or more of La, Ce, Pr, and Nd. In some embodiments, the rare earth metal carbonate is a carbonate of Ce. In other embodiments, the rare earth metal compound may include a salt of one or more of La, Ce, Pr, and Nd of an organic acid, where the organic acid is derived from formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, lactic acid, and oleic acid. And in further embodiments, the rare earth metal compound may include an oxide of one or more of La, Ce, Pr, and Nd. It should be noted that under the conditions of eutectic formation and reaction described herein, the transition metal or rare earth metal compound, if other than a carbonate or oxide, is susceptible to being converted to a carbonate or oxide during the course of the reaction. Thus, the transition metal or rare earth metal compound added to the salt mixture may be a precursor to a carbonate or oxide catalyst.

[0050] In any of the embodiments herein, the mixture of transition metal compounds and rare earth metal compounds may include a mixture of Cu and Ce, and the eutectic mixture of alkali metal carbonates or hydroxides includes a mixture of Li, Na, and K. As an illustrative example, in one embodiment, the transition metal compound includes a mixture of CuCO3, and Ce(CO3)2. In some such embodiments, the eutectic mixture of alkali metal carbonates or hydroxides may include a mixture of Li2CO3, Na2CO3, and K2CO3. In other embodiments, the transition metal compound includes a mixture of Cu2(OH)2CO3, and Ce2(CO3) 3·xH2O, and a molten salt matrix comprising a mixture of Li2CO3, Na2CO3, and K2CO3. When such compounds are present, the mixture of transition metal and rare earth compounds may include Cu and Ce in a mol% ratio of about 0.10-0.20:1.00, respectively. The molten salt may include Li, Na, and K in a mol% ratio of about 43:32:25.

[0051] In any embodiment herein, the mixture of transition metal compounds may include a mixture of La and Fe, and the eutectic mixture of alkali metal carbonates or hydroxides may include a mixture of Li, Na, and K. As an illustrative example, in some embodiments, the transition metal compounds may include a mixture of La(OH)3, Ba(CO3)2, and FeCO3. In some such embodiments, the eutectic mixture of alkali metal carbonates or hydroxides may include a mixture of Li2CO3, Na2CO3, and K2CO3. When such compounds are present, the mixture of transition metal compounds and rare earth metal compounds may include La, Ba, and Fe in a mol% ratio of about 0.03-0.04:0.03-0.04:1.00, respectively. The molten salt may include Li, Na, and K in a mol% ratio of about 43:32:25.

[0052] Before describing the process as well as the reactor in more detail, it should be noted that, overall, the process described herein is an oxygen cracking process. In other words, it is an oxygen-assisted pyrolysis of hydrocarbons. As with conventional pyrolysis, the method can produce light olefins and aromatic hydrocarbons as its main output, but at relatively low process temperatures, which can provide economic benefits to those skilled in the art. The use of an oxidant as a process co-feed is necessary to make the cracking reaction inside the volume net exothermic, i.e. self-heating. This allows for a comparable product yield at a lower temperature due to a higher thermal efficiency. However, the price of this advantage is that a portion of the hydrocarbon feedstock is consumed as internal fuel to generate the required heat. In the processing of certain feeds, this feed loss is economically disadvantageous, but in the processing of waste plastics, biowastes, and other low-quality feeds, the economic benefits can be greater. This economic benefit can be further enhanced when the oxygen cracking process is applied with catalysts that are specifically designed to maximize the yield of light olefins and aromatic products, minimize the yield of reaction by-products such as alkanes, organic oxygenates and heavy compounds, and overcome technical hurdles unique to the processing of waste plastics, including the presence of heteroatom functional groups, loadings, modifiers, etc. in the process feed.

[0053] In the oxygen cracking process, a carbon-containing feedstock is injected into a reaction system where it is contacted with oxygen (either free oxygen gas (O2), catalyst-bound oxygen, or both, and a catalyst). The upper temperature limit in the reactor is defined by the need to preserve a significant portion of the carbon-carbon bonds of the feed from pyrolysis. For example, for a polyethylene feed, the ceiling temperature is about 610°C. To those skilled in the art, commercial processes designed for the pyrolysis of polyethylene can be operated at temperatures 50-150°C above the ceiling temperature to achieve economically practical feed-to-monomer conversion rates. For other feeds, the ceiling temperature is a function of the ceiling temperature of the corresponding monomer, such as the values ​​in Table 2, reproduced from Stevens, MP Polymer Chemistry an Introduction (3rd ed.) New York: Oxford University Press. pp.193-194 (1999), with the addition of 50-150°C to achieve practical rates. [Table 2] JPEG0007600270000011.jpg70168

[0054] The lower temperature limit is defined by the need to maintain the catalyst in a liquid state. As an example, this is about 397°C for the Li2CO3-Na2CO3-K2CO3 (43.5-31.5-25 mol%) eutectic mixture, about 283°C for the NaOH-Na2CO3 (90-10 mol%) eutectic, about 360°C for the KOH-K2CO3 (90-10 mol%) eutectic, about 170°C for the NaOH-KOH (57-43 mol%) eutectic, and about 226°C for the LiOH-KOH (30-70 mol%) eutectic. Since the chemical reaction is essentially a partial oxidation, the higher the oxygen gas pressure in the feed, the better the reaction rate. In practice, the oxygen decomposition process can be carried out at sub-atmospheric to moderately high pressure ranges (20 atm) for the oxygen gas (e.g., air) feed to minimize the risk of thermal runaway for safety reasons.

[0055] In another aspect, a process for catalytic cracking of hydrocarbons is provided incorporating any of the described catalytic compositions. The process may include contacting a carbon-containing feedstock with at least one catalytic composition in the presence of oxygen in a reactor to produce olefinic and / or aromatic compounds. The process further includes recovering the olefinic and / or aromatic compounds. As described above, the at least one catalyst may be any of those described herein and may include a metal catalyst dispersed in a molten salt matrix including a eutectic mixture of alkali metal or alkaline earth metal carbonates. In some embodiments, this may include a mixture of transition metal compounds and rare earth metal compounds and a eutectic mixture of alkali metal carbonates or hydroxides. O2 gas may be introduced into the reactor / reaction as a purified O2 stream, air, or a mixture of O2 or air and a diluent gas, where the diluent is methane, carbon dioxide, nitrogen, argon, helium, or a combination of any two or more thereof.

[0056] The process provides for the production of olefinic and / or aromatic compounds from a carbon-containing feedstock. The carbon-containing feedstock may be selected from the processing of a wide variety of process materials, including recycled plastics, biomass, biowaste, mixed plastics, biomass, and / or biowaste, such that the olefinic and / or aromatic compounds produced may include a variety of unsaturated compounds, including, but not limited to, light olefins, α-olefins, terminal dienes, substituted and unsubstituted aromatic compounds containing a single aromatic ring or several aromatic ring compounds, and the like.

[0057] Exemplary olefinic and / or aromatic compounds are selected from a wide range of materials. In some embodiments, the olefinic compounds are C2-C 20 Olefins, C2-C 16 Olefin or C2-C 12 In some embodiments, the aromatic compound may be selected from a C6-C olefin, an olefin, or any subrange thereof. 18Aromatic, or C6-C 12 Exemplary olefinic and / or aromatic compounds include, but are not limited to, ethene, propene, 1-butene, 2-methyl-but-1-ene, 1-n-pentene, 2-methyl-penten-1-ene, 3-methyl-penten-1-ene, 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, benzene, toluene, ethylbenzene, xylene, styrene, α-methylstyrene, naphthalene, and anthracene.

[0058] As discussed herein, the carbon-containing feedstock may include, but is not limited to, any one or more of refinery range hydrocarbons, polymers, biopolymers, biomass, or biowaste. When the feedstock includes a polymer, exemplary polymers include, but are not limited to, polymers such as polyethylene, polypropylene, polyisobutylene, polybutadiene, polystyrene, poly-α-methylstyrene, polyacrylates, poly(meth)acrylates, polyvinyl acetate, and polyvinyl chloride. When the feedstock includes a biopolymer or other bio-based material, it may include materials such as fatty acids, triglyceride esters of fatty acids, cellulose, lignin, sugars, animal fats, tissues, and waste.

[0059] Refinery range hydrocarbons are usually defined by their boiling range fractions. For example, light naphtha has an approximate boiling range of 25-85°C, heavy naphtha has an approximate boiling range of 85-200°C, kerosene has an approximate boiling range of 170-265°C, gas oil has an approximate boiling range of 175-345°C, and heavy residue has an approximate boiling range of 345-656°C. All of these may serve as feedstocks for refinery range hydrocarbons. In some embodiments where the feedstock comprises refinery range hydrocarbons, it may include asphalt, vacuum residue, heavy residue, paraffin wax, lubricating oil, diesel, kerosene, naphtha, or gasoline. In some embodiments, the feedstock may include n-hexane, n-hexadecane, or white mineral oil.

[0060] The processes described herein may be generally illustrated by reference to Figures 2 and 3. As shown, the process 200, 300 includes introducing a carbon-containing feedstock 210 into a reactor. Oxygen gas (as O2, air, or other gas mixtures containing O2) 220 may be co-fed to a reactor 230 containing a catalyst including metal compounds dispersed in a molten salt matrix of a eutectic mixture of carbonates or hydroxides of alkali metals or alkaline earth metals, and the carbon-containing feedstock undergoes catalytic cracking with the oxygen to generate reaction products 240. Products of the reaction include light olefins, other hydrocarbons such as alkanes and oxygenates, hydrogen, carbon monoxide, carbon dioxide, water, and the like. The products are then separated 250 as appropriate, either by distillation, membrane separation, pressure swing adsorption, or a combination of any two or more thereof. As part of the separation, each of the products may be separated into three product streams, shown in Figure 2 as H2, CO, CO2 plus H2O 260, olefins 270, and alkanes and oxygenated organic compounds 280. Of course, the olefins can be recovered to prepare virgin polymers or for use in other applications. The alkane by-products, along with the oxygenates, which mostly contain low carbon atom aldehydes such as acetaldehyde and ketones such as acetone, can be used industrially in appropriate applications; or hydrogenated to alcohols; or recycled back to the cracking step with an optional recycle loop 290 for additional conversion to desired olefins.

[0061] 3, the process may also include a catalyst regeneration loop in which the spent molten salt catalyst 223 is transferred to a catalyst regeneration reactor 221 where oxygen (as O2, air, or other gas mixtures containing O2) is reacted with the spent molten salt catalyst. Gases 224 that do not react with the spent molten salt catalyst, such as nitrogen gas from the air, or gases that are a result of the regeneration of the catalyst, may be vented and the regenerated molten salt catalyst 222 is then returned to the reactor 230.

[0062] In the process, the temperature within the reactor system depends on the composition of the catalyst, the feed, and the desired reaction products. Thus, the temperature may be from the melting point of the eutectic mixture of alkali carbonates and / or hydroxides to about 750° C. This may include temperatures from about 250° C. to about 750° C.

[0063] In this step, the pressure in the reaction system may be lower than that in other similar steps. For example, it may be about 20 atm or less. In some embodiments, it is less than 1 atm to about 20 atm, about 1 atm to about 15 atm, or about 2 atm to about 10 atm.

[0064] In the process, at least one heterogeneous catalyst is prepared outside the reaction system; it can then be loaded into the reaction system to carry out the catalytic cracking of hydrocarbons.

[0065] In another embodiment of the process, at least one heterogeneous catalyst is prepared within the reaction system by loading a catalyst precursor mixture into the reaction system volume and internally heating at a process temperature. The catalyst precursor mixture comprises a salt matrix that includes a metal catalyst precursor, which comprises a eutectic mixture of a mixture of alkali or alkaline earth metal carbonates or hydroxides and at least one metal compound selected from a transition metal compound, a rare earth metal compound, or a combination of any two or more thereof.

[0066] Also provided is a process for preparing a heterogeneous catalyst. The process includes combining carbonates or hydroxides of alkali or alkaline earth metals to form a salt matrix comprising a eutectic salt mixture, adding at least one metal catalyst precursor to the salt matrix to form a catalyst precursor mixture, and heating the catalyst precursor mixture to a temperature of about 250°C to about 750°C to form a heterogeneous catalyst comprising a metal catalyst dispersed in a molten salt matrix. In this process, the metal catalyst precursor comprises at least one metal compound selected from a transition metal compound, a rare earth metal compound, or a combination of any two or more thereof, and the molten salt may also be in the form of a precursor, i.e., hydroxide, as described above. As described above, the metal catalyst may comprise a carbonate or oxide, or may comprise other oxide structures of metals such as perovskites and spinels.

[0067] Heterogeneous catalysts produced by the above process are useful in catalytic cracking processes for hydrocarbons. The step of forming such catalysts may be carried out either separately from the step of cracking the hydrocarbon feedstock (ex-situ) or in the reaction system in which the cracking takes place (in-situ). For batch reactions an in-situ process may be convenient, but for continuous processes an ex-situ process is more convenient.

[0068] The reactor systems for the proof of concept were batch and stirred tank reactors, however, other suitable reactor configurations are contemplated, such as falling film column reactors, packed column reactors, plate column reactors, spray tower reactors, and various gas-liquid stirred vessel reactors.

[0069] Referring now to FIG. 4, there is shown a schematic diagram of a reactor system 400 for the treatment of polymer waste. The reactor vessel 405, surrounded by insulation 406, includes a motor and agitation system 410, O2 gas enters the reactor via an inlet and feed manifold 420, and includes a catalyst loading port 425 and a catalyst offloading port 430. The catalyst composition is loaded into the reactor tank 405 via port 425. The polymer waste is chopped and loaded into a feed system including a heated auger screw extruder 415, through which the polymer is introduced into the reactor tank 405. The reactor is maintained at a temperature sufficient to maintain the catalyst system as a molten salt. Solid waste that is not catalytically converted, and solid impurities from the polymer, exit the reactor along with the aged catalyst via port 430 into a holding drum 435. The gaseous product stream exits the reactor 405 and enters a separator 440. A condensed liquid stream of heavy products 445 (eg, compounds with a dew point above 120° C.) is returned from the separator to the reactor, and a gas stream 450 is directed for further separation.

[0070] The invention thus broadly described will be more readily understood by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the invention.

[0071] Working Example Example 1. The catalyst used in the tests was prepared according to the following procedure.

[0072] Catalyst synthesis for mini-batch reactor screening testing: Li2CO3 (25.68 g), Na2CO3 (26.72 g), and K2CO3 (27.60 g) were added to a 2-liter mixing vessel and mixed thoroughly. This mixture is compositionally similar to a eutectic mixture of materials in the phase diagram (Figure 1) that melts at approximately 397 °C and has the chemical formula Li 0.86 Na 0.64 K 0.50The melting temperature can be described as 0.05°C, which can be described as 0.05°C. This melting temperature was confirmed by differential scanning calorimetry (DSC) analysis. Figure 6 shows the DSC trace of a 25 mg sample of the carbonate mixture of Li, Na, and K when heated at a heating rate of 20°C per minute. At about 160-165°C, water of hydration is released, and the three groups of peaks (397°C, 408°C, and 420°C) represent the three stages of melting of the precursor salts, a process that is kinetically limited starting from a mixture of the individual precursor salt powders, resulting in the formation of a single-phase eutectic melt above 420°C. The molten salt catalyst was used to melt 80.00 g of this carbonate eutectic mixture with 0.05 g of Li, Na, and K. 0.86 Na 0.64 K 0.50 The CO3 eutectic composition is further prepared by combining 0.40-18.00 g of each of the active metal precursor compounds intended for the formulation in a mini-batch reactor; this mixture of catalytic metal precursor compounds is calcined at 600 °C in air for 2 hours before mixing with the eutectic composition (due to off-gassing, believed to be primarily steam from crystalline hydride dehydration and CO2 from the transition or conversion of rare earth metal carbonate precursors to metal oxide forms in the final catalyst state). For example, one molten salt catalyst formulation contained approximately 80.00 g of a eutectic mixture of alkali carbonates and 1.00 g of barium (II) carbonate powder (BaCO3), as well as approximately 1.00 g of copper (II) carbonate powder (CuCO3·Cu(OH)2) and 17.00 g of cerium (III) carbonate powder (Ce2(CO3)3). Another molten salt catalyst formulation contained about 80.00 g of a eutectic mixture of alkali carbonates and 0.40 g of BaCO3, plus about 0.40 g of La2(CO3)3, and 6.80 g of FeCO3. Yet another catalyst formulation contained about 80.00 g of a eutectic mixture of alkali carbonates and 0.40 g of BaCO3, plus about 7.20 g of MnCO3. Table 3 shows the formulations of the catalysts prepared in the screening test.

[0073] Catalyst synthesis for continuous stirred tank reactor studies. First, Li2CO3 (642.0 g), Na2CO3 (668.0 g), and K2CO3 (690.0 g) were added to a 2-liter mixing vessel and mixed thoroughly to form the alkali-carbonate mixture. Next, 25.0 g of Cu2(OH)2CO3, 25.0 g of the alkali-carbonate eutectic mixture, and 425.0 g of Ce2(CO3)3·xH2O precursor powder were weighed into a 1-liter mixing vessel where they were mixed thoroughly to form the metal catalyst precursor mixture. The contents of the vessel were poured into two porcelain crucibles of 500 ml volume. The crucibles were placed in a calcination furnace and calcined at 600 °C for 2 hours ("hr") using a heating-cooling ramp of 5 °C / min. This calcination resulted in a weight loss of 18.7 wt% of the original metal catalyst precursor mixture due to decomposition of carbonates to oxides and loss of crystalline hydrogenation water. Finally, 386.0 g of the resulting metal catalyst powder was mixed with 1930.0 g of the alkali-carbonate eutectic powder mixture in a continuous stirred tank reactor immediately prior to reaction testing. [Table 3] JPEG0007600270000012.jpg222168

[0074] Example 2. Mini-batch reactor screening study: This example demonstrates that use of the catalyst of the present invention in the direct oxygen cracking of various carbon-containing feedstocks increases the extent of cracking, thereby increasing the yield to desirable light olefins and aromatics.

[0075] Description of the experimental setup: Reference is now made to FIG. 5. A round-bottomed, clear borosilicate glass vial 520 (Ace Glass), 23 mm in diameter, 75 mm in height, and 20 ml in volume, can be used as a mini-batch reactor suitable for screening both catalysts and substrates in oxygen decomposition in molten salts. After loading the desired amount of catalyst and reaction substrate 522, the vial is inserted into a PTFE-lined silicone septum 521 (Thermo Scientific TM SUN-SRi TMThe vials were sealed with a 20 mm diameter crimped cap with a 5 mm diameter thermal barrier. The reaction screening assembly consisted of a 50 mm diameter deep grooved 6 parallel 25 mm aluminum alloy block 505 (Corning LSE Digital Dry Bath Accessory) insulated with a glass wool insulation layer 510 and affixed on top of a compact ceramic hotplate 515 (Corning Electron Microscopy Sciences with Pyroceram heating element, Model Pc220, 25-550 °C range). The setup was placed inside a vent hood behind a blast shield for increased operator safety. The temperature of the aluminum block 505 was controlled by powering the hotplate through an external temperature controller (not shown in Figure 5) (Chemglass Life Sciences J-Kem Temperature Controller, Model 210 / T) with a metal jacketed 1 / 8 inch diameter K-type thermocouple 530 whose tip was inserted into the thermocouple channel of the aluminum block. To ensure good thermal contact between the vials and the block, 3 grams of 40 grit SiC powder was added to each of the six channels of the aluminum alloy block. Li in glass vial 525 0.86 Na 0.64 K 0.50 A eutectic salt mixture of CO3 was placed in one of the channels at the corner of the block, filling the vial to about 1 / 4 of its volume. A K-type thermocouple 535 was inserted into the vial with its tip immersed in the eutectic material at the bottom. The thermocouple was connected to a digital readout which showed the temperature of the reaction mixture in the vial.

[0076] Description of experimental procedure: A new glass vial is weighed; then 10-20 mg of raw material and 1100-1250 mg of molten salt catalyst powder are loaded; then the reactor is sealed using a crimping tool in air for direct oxygen decomposition or in a glove box under an inert nitrogen atmosphere for two-step oxygen decomposition. The vials are lined up in pairs and loaded using forceps into an aluminum block kept at 420 °C for direct oxygen decomposition or 500 °C for two-step oxygen decomposition. The vials are heated in the alloy block for 15 min, then removed and placed horizontally on a glass wool blanket to cool. Once the vials are near room temperature, they are placed in a vial holder array plate and stored until analysis. The analysis is performed with a GC instrument, and as part of the analysis, each vial is heated to 180 °C for 10 min before the gas phase is sampled and analyzed. Also, for some parallel reactors, analysis is performed using a separate GC-MS instrument.

[0077] Description of product analysis Product composition was analyzed using an Agilent 8890 gas chromatograph equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID). Identification of compounds was based on mass spectral match with the NIST-MS database on a separate GC-MS instrument for all compounds in a refinery gas standard (Restek Refinery Gas Standard #2, Manufacturer #34442) or by elution order following the boiling points of solutes / compounds (FID) and thermal conductivity difference (TCD). Quantification of hydrocarbon compounds (FID signal) and permanent gases (TCD signal) was performed using peak areas obtained by integrating the peaks on the gas chromatogram. Specifically, the peak areas were converted to molar concentrations using the molar response factors (TCD and FID) of various alkanes and alkenes estimated from GC calibration using refinery gas standard samples, and the molar or relative response factors (FID) of various aromatics were estimated from the theoretical effective carbon number approach (Journal of Chromatographic Science, Vol. 23, August, 1985). The yield (wt%) of a given compound was calculated using the following equation (10): TIFF0007600270000013.tif13169

[0078] The products obtained during the direct oxygen cracking using Cat.A (from Table 3) were analyzed using GC and the results are reported in Table 4. The product stream contained various alkanes, olefins, aromatics and oxygenates, namely hydrogen, methane, ethane, ethylene, propane, propylene, butane, butene, pentane, hexane, carbon oxides and others. The use of the catalyst resulted in high conversions of all feedstocks and improved overall yields to the desired light olefins and aromatics, albeit with slightly reduced selectivity. Furthermore, the products obtained from the parallel reactor operation were analyzed using GC-MS to capture a broader range of products. Figures 8 and 9 contain the GC-MS traces of the products recovered from the direct oxygen cracking of olive oil using Cat.E and Cat.F and from the direct oxygen cracking of n-hexane using Cat.A, respectively. [Table 4] JPEG0007600270000014.jpg109169 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0079] Example 3. Mini-batch reactor screening study: This example demonstrates that use of the catalyst of the present invention in the two-stage oxygen cracking of various carbon-containing feedstocks increases the extent of cracking, thereby increasing the yield to desirable light olefins and aromatics.

[0080] Using the same experimental setup as described in Example 2, products obtained from two-stage oxygen cracking of a wide range of feedstocks including high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate glycol (PETG), polystyrene (PS), polyvinyl chloride (PVC), asphalt, vegetable oil (Veg Oil), n-hexane, n-hexadecane, paper, rubber, polyurethane (PU) and potato chips using Cat. A (from Table 3) were analyzed using GC and the results are reported in Tables 5A-5G. The use of the catalyst resulted in high conversions of all feedstocks and improved overall yields to the desired light olefins and aromatics, albeit with a slight decrease in selectivity. Additionally, products obtained from parallel reactor operation were analyzed using GC-MS to capture a wider range of products. Figure 11 contains the GC-MS traces of products taken from two-stage oxygen cracking of n-hexane, n-hexadecane, PP, PETG and PVC using Cat. A. Feedstocks such as PETG and PVC contain heteroatoms such as O and Cl, but their oxygen decomposition products do not contain O and Cl, respectively (from Figure 11). This highlights a further important advantage of the melt-based catalysts of the present invention, where the melt phase retains the heteroatoms (such as O, Cl, etc.) during the reaction step, thereby eliminating or significantly reducing the emission of such heteroatom contaminants into the products or atmosphere. [Table 5A] JPEG0007600270000015.jpg102164 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0081] Thus, the two-stage oxygen cracking of HDPE and LDPE feedstocks using Cat. A succeeded in increasing the cracking conversion to gaseous products from 4.6% to 26.0% and from 6.1% to 20.3%, respectively, thereby increasing the overall yield to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity. [Table 5B] JPEG0007600270000016.jpg104166 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0082] Thus, the two-stage oxygen cracking of PP and PETG feedstocks using Cat. A increased the cracking conversion to gaseous products from 17.4% to 44.6% and 3.4% to 40.9%, respectively, thereby resulting in increased overall yields to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity. [Table 5C] JPEG0007600270000017.jpg108168 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0083] Thus, the two-stage oxygen cracking of PS and PVC feedstocks using Cat. A increased the cracking conversion to gaseous products from 6.9% to 38.1% and from 8.7% to 23.4%, respectively, thereby resulting in increased overall yields to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity. [Table 5D] JPEG0007600270000018.jpg106168a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0084] Thus, two-stage oxygen cracking of asphalt and vegetable oil feedstocks using Cat. A increased the cracking conversion (and selectivity) to gaseous products from 5.9% to 11.8% and from 28.9% to 32.4%, respectively, thereby leading to increased overall yields to light olefins (more specifically, ethylene and propylene) and aromatics. [Table 5E] JPEG0007600270000019.jpg105167 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0085] Thus, the two-stage oxygen cracking of n-hexane and n-hexadecane feedstocks using Cat. A increased the cracking conversion to gaseous products from 1.6% to 2.7% and from 6.4% to 16.8%, respectively, thereby leading to increased overall yields to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity in the case of the n-hexadecane feedstock. [Table 5F] JPEG0007600270000020.jpg108168 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0086] Thus, the two-stage oxygen cracking of paper and rubber stocks using Cat. A increased the cracking conversion to gaseous products from 3.1% to 31.7% and from 16.1% to 16.5%, respectively, thereby increasing the overall yield to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity in the case of the paper stock. [Table 5G] JPEG0007600270000021.jpg107168 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0087] Thus, the two-stage oxygen cracking of PU and potato chip feedstocks using Cat. A increased the cracking conversion to gaseous products from 6.5% to 15.5% and from 6.0% to 19.5%, respectively, thereby increasing the overall yield to light olefins (more specifically ethylene and propylene) and aromatics, albeit at the expense of slightly reduced selectivity.

[0088] Example 4. Mini-batch reactor screening study: This example demonstrates the use of various types of the inventive catalysts in a two-stage oxygen cracking to tailor the product flow / distribution towards light olefins and aromatics.

[0089] Using the same experimental setup as described in Example 2, the products obtained during the two-stage oxygen cracking of HDPE feedstock using Cat.A, Cat.B and Cat.C (from Table 3) were analyzed using GC and the results are reported in Table 6. The product distribution (more specifically, light olefins and aromatics) was found to be a strong function of catalyst type. In addition, the products obtained from the parallel reactor run were also analyzed using GC-MS to capture a wider range of products. Figure 10 contains the GC-MS traces of the products collected from the two-stage oxygen cracking of HDPE using Cat.A, Cat.B, Cat.C and Cat.D. [Table 6] JPEG0007600270000022.jpg100168 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene. b Conversion rate defined as the total amount of produced gas relative to the amount of feed.

[0090] The cracking conversion rate from the two-stage oxygen cracking of HDPE feedstock to gaseous products is Cat. A to Cat. B to Cat. C, whereas the selectivity to the desired light olefins (more specifically, ethylene and propylene) decreases from Cat. A to Cat. B to Cat. C, resulting in different overall yields to light olefins and aromatics for Cat. A, Cat. B and Cat. C.

[0091] Example 5. Bench-scale stirred tank reactor study: Liquid n-hexadecane feed was introduced via a syringe pump (Teledyne ISCO 1000D) at a rate of 0.77 grams per minute along with a flow of 400 standard cubic centimeters per minute (sccm) N2 diluent through a 0.95 centimeter diameter stainless steel dip tube. The dip tube terminated near the bottom of a 10.0 centimeter diameter, 62.2 centimeter high stainless steel stirred tank reactor. The reactor contained 2316 grams of molten catalyst, Cat. A', operated at 200 revolutions per minute under constant agitation by a 5 centimeter diameter, three-blade hydrofoil impeller located at the bottom of the molten catalyst bath. The height of the molten catalyst bath was approximately 14 centimeters, and the total height of the reactor heated to reaction temperature was approximately 28 centimeters. The molten salt catalyst was prepared inside the reactor prior to the experiment by first loading 1930 grams of alkali-carbonate eutectic precursor mixed powder into the reactor and heating it to 450 °C to melt the powder into a molten eutectic, then adding 386 grams of metal catalyst precursor powder into the molten salt eutectic under stirring and N2 diluent purge. The catalyst was conditioned prior to the oxygen decomposition reactor experiment by heating the reactor to 750 °C under 2000 sccm air flow and maintaining it at that temperature for 2 hours. The gas supply was then switched to N2 diluent with a flow rate of 400 sccm, and the reactor was allowed to cool to the desired reaction temperature. The temperature of the molten salt catalyst was monitored with a K-type thermocouple inserted through an access port located at the bottom of the reactor, just below the stirring impeller. The effluent gas stream first passed through a stainless steel condenser maintained at 5–15 °C, then through the sampling port zone of an online process GC (Agilent 8890) and an in-line process mass spectrometer (MS, Pfeiffer Vacuum ThermoStar), and was vented to the atmosphere through a mineral oil bubbler. The process GC was an identical instrument to that used in the mini-batch reactor screening study. The instrument was calibrated using a similar gas standard (Restek Refinery Gas Standard #2) that was also used to calibrate the process MS instrument.The content of residual coke in the catalyst was determined by integrating the 14 amu / z and 44 amu / z signals, which correspond to the N2 and CO2 ionized species concentrations in the signal obtained from the process MS output. The amount of liquid product accumulated in the condenser was measured by weight. The duration of the oxygen decomposition reaction step was 20 min, after which the liquid feed was stopped and the reactor was purged with N2 diluent at 400 sccm for 15 min. The flow rate of N2 was then increased to 2000 sccm for another 10 min to remove residual volatiles from the inner volume of the reactor. After the end of the purge, air was pumped into the reactor through the dip tube at 900 sccm for 20-30 min to reoxidize the molten catalyst and burn off the residual coke to perform the catalyst regeneration step. The furnace temperature was kept the same during the oxygen decomposition and catalyst regeneration reactions. [Table 7] JPEG0007600270000023.jpg114166 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene.

[0092] A summary of the results of the two-stage oxygen cracking of n-hexadecane using a molten salt catalyst comprising a copper-cerium metal catalyst composition is shown in Table 7. The results demonstrate the high yields of light olefins and high conversion of the feedstock obtained using the molten salt composition and process when the process is carried out at temperatures above 600° C. and below 700° C.

[0093] Example 6. Bench-scale stirred tank reactor study: Solid polymer feedstocks were introduced through a generic 3D printer head feeder as 1.75 mm diameter filaments at rates ranging from 0.75 to 1.4 grams per minute along with a 400 sccm flow of N2 diluent, which were either co-fed through a dip tube or fed separately: the diluent through a dip tube, and the polymer filament fed from the head space above the molten catalyst bath. The plastic feedstocks used in the experiments were high density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate glycol (PETG), and acrylonitrile butadiene styrene (ABS). [Table 8] JPEG0007600270000024.jpg124168 a Aromatics is the sum of the content of benzene, ethylbenzene, toluene, styrene, and xylene.

[0094] The products obtained during the two-stage oxygen cracking were analyzed using GC and the results are reported in Table 8. The liquid product composition of selected experiments was analyzed using headspace GC-MS analysis (Figure 12). The use of the oxygen cracking process with molten salt catalysts allows high conversion to gas phase products mainly consisting of light olefins and aromatics. For example, the two-stage oxygen cracking of polyolefin-based feedstocks (HDPE and PP) produced high yields of light olefins. The processing of styrene-containing copolymers mainly produced light aromatics including styrene monomer, and the processing of PETG also produced mainly aromatics, with small amounts of actophenone and not high amounts of other oxygenated organic products.

[0095] While particular embodiments have been illustrated and described, it is to be understood that changes and modifications can be made therein in accordance with the ordinary skill of those skilled in the art without departing from the technology in its broader aspects as defined in the appended claims.

[0096] The embodiments illustratively described herein may be suitably implemented in the absence of any element or elements, limitations or restrictions not specifically disclosed herein. Thus, for example, the terms "comprising", "including", "containing", etc., are intended to be interpreted expansively and without limitation. Furthermore, the terms and expressions employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Furthermore, the term "consisting essentially of" will be understood to include the elements specifically mentioned and additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The term "consisting of" excludes elements not specified.

[0097] The present disclosure is not limited in terms of the specific embodiments described herein. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope thereof. In addition to those enumerated herein, functionally equivalent methods and compositions within the scope of the present disclosure will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is understood that the present disclosure is not limited to specific methods, reagents, compounds, compositions, or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0098] Furthermore, when features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual species or subgroups of species of the Markush group.

[0099] As will be understood by those skilled in the art, for all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any possible subranges and combinations of subranges thereof. Any recited range can be easily recognized as fully descriptive and allowing the range to be broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be easily broken down into a lower third, middle third, upper third, etc. Also, as will be understood by those skilled in the art, all language such as "up to," "at least," "greater than," "less than," etc. refers to a range that includes the number recited and can then be broken down into subranges as described above. Finally, as will be understood by those skilled in the art, a range includes each individual species.

[0100] All publications, patent applications, issued patents, and other documents mentioned herein are incorporated by reference herein as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions contained in the texts incorporated by reference are excluded to the extent they conflict with definitions in this disclosure.

[0101] Other embodiments are within the scope of the following claims.

Claims

1. 1. A process for catalytic cracking of a carbon-containing feedstock, the process comprising: contacting a carbon-containing feedstock with a heterogeneous catalyst composition in a reactor system, the contacting occurring in the presence of an oxidant to produce a product compound; and recovering the product compound; Including, Where: The heterogeneous catalyst composition comprises a metal catalyst dispersed in a molten salt matrix comprising a eutectic mixture of an alkali metal or alkaline earth metal carbonate or hydroxide; The process wherein the metal catalyst comprises a transition metal compound and a rare earth metal compound.

2. 10. The process of claim 1 which is an autothermal process.

3. 3. The process of claim 1 or 2, wherein the contacting is carried out at a temperature of about 750° C. or less.

4. The process of any one of claims 1 to 3, wherein the contacting is carried out at a temperature of about 650°C or less.

5. The process of any one of claims 1 to 4, which is a continuous, semi-continuous or batch process.

6. 6. The process of any one of claims 1 to 5, wherein the product compounds include light olefins, α-olefins, terminal dienes, substituted and unsubstituted aromatic compounds, aldehydes, oxygenates, or a combination of any two or more thereof.

7. 7. The process of any one of claims 1 to 6, wherein the product compounds comprise ethene, propene, 1-butene, 2-methyl-but-1-ene, 1-n-pentene, 1-n-hexene, 2-methyl-pent-1-ene, 3-methyl-pent-1-ene, 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, benzene, toluene, ethylbenzene, xylene, styrene, alpha-methylstyrene, naphthalene, anthracene, or a combination of two or more thereof.

8. 8. The process of claim 7, wherein the carbon-containing feedstock comprises a polymer comprising polyethylene, polypropylene, polyisobutylene, polybutadiene, polystyrene, poly-α-methylstyrene, polaacrylate, poly(meth)acrylate, polyvinyl chloride, polyethylene terephthalate, or a combination of any two or more thereof.

9. 10. The process of claim 8, wherein the carbon-containing feedstock comprises refinery range hydrocarbons including asphalt, vacuum residue, heavy residual oil, paraffin wax, pyrolysis wax, lubricating oil, diesel, kerosene, naphtha, gasoline, or a combination of any two or more thereof.

10. 10. The process of claim 9, wherein the refinery range hydrocarbons comprise n-hexane.

11. 10. The process of claim 9, wherein the refinery range hydrocarbons comprise n-hexadecane.

12. 2. The process of claim 1, wherein the carbon-containing feedstock comprises lignin, fatty acids, vegetable oils, municipal waste, and paper waste, or a combination of any two or more thereof.

13. The oxidizing agent is O ２ , NO ｘ , S.O. ｘ 13. The process of any one of claims 1 to 12, comprising at least one selected from the group consisting of: nitrates, hydrogen peroxide, organic peroxides, and non-metal element oxides such as boron oxides, nitrogen oxides, phosphorus oxides, sulfur oxides, chlorine oxides, and bromine oxides.

14. The oxidizing agent is oxygen, and purified O ２ Flow, air, or O ２ or a mixture of air and a diluent is introduced into the reactor, the diluent being methane, carbon dioxide, nitrogen, argon, helium, or a combination of any two or more thereof.

15. The process of any one of claims 1 to 14, wherein the reactor system comprises a single reactor or at least a first reactor and a second reactor in series.

16. The process of any one of claims 1 to 15, wherein the reactor system comprises a single reactor and a heterogeneous catalyst is contacted with the carbon-containing feedstock.

17. 17. The process of any one of claims 1 to 16, wherein the reactor system comprises a first reactor and a second reactor connected in series, and the heterogeneous catalyst composition of the first reactor is the same or different from the heterogeneous catalyst composition of the second reactor.

18. A heterogeneous catalyst composition is prepared ex situ; and then loaded into the reaction system to carry out catalytic cracking of hydrocarbons, wherein the heterogeneous catalyst comprises: combining a mixture of alkali metal or alkaline earth metal carbonates or hydroxides to form a salt matrix comprising a eutectic salt mixture; adding a metal catalyst precursor to a salt matrix to form a catalyst precursor mixture; and heating the catalyst precursor mixture at a temperature of about 250° C. to about 750° C. to form a metal catalyst dispersed in the molten salt; The method is prepared by a process comprising the steps of: The metal catalyst precursor comprises a metal compound selected from the group consisting of a transition metal compound, a rare earth metal compound, and a combination of any two or more thereof; The process according to any one of claims 1 to 17.

19. A heterogeneous catalyst is prepared inside the reaction system by loading a catalyst precursor mixture into the reaction system volume and internally heating at a process temperature; 19. The process of any one of claims 1 to 18, wherein the catalyst precursor mixture comprises a salt matrix comprising a eutectic mixture of a mixture of alkali or alkaline earth metal carbonates or hydroxides, and a metal catalyst precursor comprising at least one metal compound selected from a transition metal compound, a rare earth metal compound, or a combination of any two or more thereof.

20. The process of claim 18 or 19, wherein the metal catalyst precursor comprises a carbonate of Ce.

21. The process of claim 18, wherein the metal catalyst precursor comprises Cu and Ce carbonates and the salt matrix comprises a mixture of Li, Na, and K carbonates or hydroxides.

22. The metal catalyst precursor is Cu ２ (OH) ２ CO ３ , and Ce ２ (CO ３ ) ３・ xH ２ O, and the salt matrix comprises a mixture of Li ２ CO ３ , Na ２ CO ３ , and K ２ CO ３ The process of any one of claims 18 to 21, comprising a mixture of:

23. The metal catalyst precursor is CuCO ３ , and Ce(CO ３ ) ２ and the salt matrix comprises a mixture of Li ２ CO ３ , Na ２ CO ３ , and K ２ CO ３ The process of any one of claims 18-22, comprising a mixture of:

24. The process of any one of claims 18 to 23, wherein the metal catalyst precursor comprises Cu and Ce in a mol% ratio of about 0.10-0.20:1.00, respectively.

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