Lewis acid-base pairs as highly active catalytic sites for hydrogenation and dehydrogenation processes

Abstract

Disclosed is a method of treating a reactant stream, the method comprising a catalyst composition comprising: a metal oxide (MOx) catalyst having a surface with M-O sites of Lewis type and having an equilibrium acid-base strength and a high surface area; and a trap. The trap can remove impurities from the reactant stream. The MOx catalyst includes a BET surface area of at least about 50 m2 / g.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 447,138, filed on February 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Disclosed herein is a method for treating a reactant stream using a catalyst composition comprising a metal oxide (MO x ) catalyst and a trap for removing impurities from the reactant stream. Specifically, the method includes treating the reactant stream with a trap, wherein the trap can remove impurities and the MOx promotes the chemical reaction. The impurities can include oxygen (O2), water (H2O), hydrogen sulfide (H2S), carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), sulfur-containing compounds, methanol or other alcohols, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. MO x The catalyst may have a surface with MO sites that are Lewis type and have balanced acid-base strength. x The catalyst may have a BET surface area of ​​at least about 75 m2 / g. Background Art

[0004] In the chemical industry, propylene is an important intermediate for the production of various chemical compounds. For example, propylene can be used to produce propylene oxide, acrylonitrile, cumene, acrylic acid, C3 and alcohols of greater carbon numbers, and polypropylene. Historically, propylene has been available as a co-product from steam crackers and as a waste gas product from the fluidized cracking catalytic unit in the refinery. It has been found that these technologies are not enough to meet the demand for propylene, thereby leading to the development of new technologies (such as dehydrogenation).

[0005] Consequently, dehydrogenation technologies and catalysts have been extensively developed and commercialized in recent years. Among these, propylene dehydrogenation (PDH) has become one of the most common alternative technologies due to its independent applicability. Non-limiting representative PDH technologies include those utilizing platinum group metal (PGM) catalysts (e.g., Linde-BASF, Oleflex, STAR, and FCDh (Dow) processes), or chromium-containing catalysts (e.g., Catofin and FDB-4 processes). In recent years, alternative catalytic materials have been explored to address the toxicity and environmental hostility of chromium-based systems and / or to reduce or replace the high costs associated with PGM catalysts.

[0006] Metal oxides such as ZrO2 are promising alternatives for use in catalyst compositions due to the presence of Lewis acid-base (LAB) pairs. The main limitation of using metal oxides for PDH is their rapid deactivation. During the dehydrogenation of hydrocarbons such as propane, the acid-base pairs of metal oxide dehydrogenation catalysts, including ZrO2, may be deactivated due to: (i) titration of H2O and / or CO2, which originate directly from the gas feed stream or are formed indirectly via the reaction of O2 or oxygenate impurities from the gas stream with propane and / or H2; and / or (ii) coke deposition caused by the adsorption of paraffin-derived molecules on the MO sites. In addition, due to the reducibility of some metal oxides, metal oxide dehydrogenation catalysts such as TiO2 and MoO2 are prone to deactivation. x ) may be reduced to a lower oxidation state or even a metallic state over time, potentially leading to deactivation or activation.

[0007] Efforts have been made to develop regeneration / reactivation methods for these catalysts. For example, high-temperature thermal regeneration processes can be used to activate and / or reactivate metal oxide catalysts that have been at least partially deactivated by bound CO and / or HO. However, the activity loss caused by sintering and annealing during thermal regeneration processes is irreversible.

[0008] Therefore, methods have been developed to clean MO x The surface of the catalyst (including acid-base sites) method, in which MO x Cleaning of the catalyst creates active sites on the surface without causing significant sintering or annealing as noted in high temperature thermal regeneration processes. It has been found that these surfaces can be re-titrated so that the surface, including acid and base sites, adsorbs and / or absorbs impurities and limits the reactivity time of such catalysts.

[0009] That is, chemical cleaning of these surfaces creates active surfaces, but these surfaces can be re-titrated by trace hydroxyl (from H2O) or carbonate / bicarbonate (from CO2) impurities in the reactant stream, or by molecules (such as O2) that can form such titrants during paraffin dehydrogenation. Preventing active sites from being titrated by impurities present in the inlet gas is a feasibility issue for practical processes involving LAB sites. Chemical treatment with dimethyl ether (DME) has enabled unprecedented and viable turnover of ZrO2 on materials previously considered unviable as PDH catalysts. However, maintaining this reactivity over time requires the removal of impurities from the reaction system during paraffin dehydrogenation and related process operations.

[0010] Therefore, there is a need for a method of pre-treating and / or treating the reactant streams to remove impurities and increase the life and performance of such catalysts used in dehydrogenation / hydrogenation reactions. Summary of the Invention

[0011] Disclosed herein is a method for treating a reactant stream using a catalyst composition comprising a metal oxide (MO x ) catalyst and a trap, wherein the reactant stream may contain hydrocarbons. The trap may remove impurities from the reactant stream. Impurities may include oxygen (O2), water (H2O), hydrogen sulfide (H2S), carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), sulfur-containing compounds, methanol or other organic alcohols, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. MO x The catalyst may have a surface with MO sites that are Lewis type and have balanced acid-base strength. x The catalyst may have a BET surface area of ​​at least about 75 m2 / g.

[0012] In some embodiments, impurities may be removed from the reactant stream during the hydrogenation or dehydrogenation process before the stream contacts the catalyst composition.

[0013] In some embodiments, MO x The surface of the catalyst can stabilize the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

[0014] In some embodiments, MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0015] In some embodiments, the method can be operated at an impurity level of less than about 2 ppm.

[0016] In some embodiments, the method can be operated at an impurity level of at most 100 ppm, at most 50 ppm, or at most 20 ppm.

[0017] In some embodiments, the reactant stream can have an oxygen content of about 5 ppm, about 1 ppm, or about 0.2 ppm.

[0018] In some embodiments, MO x The surface area of ​​the catalyst can be compared with that of MO x is proportional to the density of active sites of the catalyst.

[0019] In some embodiments, MO x The catalyst comprises a crystalline active component, wherein when the surface area of ​​the crystalline active component decreases, the MO x The density of active sites of the catalyst is reduced.

[0020] In some embodiments, MO xThe catalyst may be substantially free of hydroxyl groups.

[0021] In some embodiments, the treated MO x The catalyst does not contain hydroxyl groups.

[0022] In some embodiments, the trap can be an oxygen trap, a water trap, a carbon dioxide trap, an impurity trap, or a combination thereof.

[0023] In some embodiments, a surface having MO sites that are Lewis-type and have balanced acid-base strengths can be maintained during the dehydrogenation or hydrogenation process by avoiding titration with impurities.

[0024] In some embodiments, processing of the reactant stream may be performed at a temperature of about 500-900 K.

[0025] In some embodiments, processing of the reactant stream may be performed at temperatures up to 900 K.

[0026] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0027] In some embodiments, MO x The catalyst may comprise a metal oxide in which the cation is not reducible to a zero valence state.

[0028] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of zirconium (Zr), cobalt (Co), gallium (Ga), zinc (Zn), cerium (Ce), yttrium (Y), hafnium (Hf), and titanium (Ti).

[0029] In some embodiments, MO x The catalyst may include one or more of Mg, Ca, Sr, Ba and La on a zirconia support.

[0030] In some embodiments, MO x The catalyst may include ZrO2-silica, Zr-Al, Zr-Ti, or a combination thereof.

[0031] In some embodiments, MO x The catalyst may include ZrO2, tetragonal ZrO2 (t-ZrO2), monoclinic ZrO2 (m-ZrO2), Y-stabilized ZrO2, Ce-stabilized ZrO2, or Y2O3.

[0032] In some embodiments, the method may include cleaning the MO with a surface cleaning agent. x catalyst.

[0033] In some embodiments, the surface cleaning agent may include dimethyl ether, propylene, ethylene, methanol, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, anisole, dimethyl carbonate or a combination thereof. In another embodiment, the surface cleaning agent may include dimethyl ether. In another embodiment, the surface cleaning agent may include methanol. In some embodiments, the surface cleaning agent may include olefins. In another embodiment, the surface cleaning agent may include propylene.

[0034] In some embodiments, the method may further comprise cleaning the MO during the dehydrogenation or hydrogenation reaction by balancing water deposition and water removal via the olefin product at a temperature of about 800-900 K. x catalyst.

[0035] In some embodiments, cleaning may be performed at a temperature between approximately 323 K and 900 K.

[0036] In another embodiment of the present disclosure, a method for catalyzing a reaction using a catalyst composition as described herein is also provided. x Methods for catalyzing reactions of catalyst compositions comprising catalysts and traps include activating and / or reactivating the catalyst compositions using treatment methods as described herein. The reactions can be selected from the group consisting of alkane dehydrogenation, olefin hydrogenation, olefin-paraffin alkylation, reaction of CO / H2 mixtures without O-rejection such as H2O or CO2, formation of C-C bonds via olefin oligomerization or metathesis, dehydrocyclization (conversion of alkanes / olefins to aromatics), dehydrocyclization dimerization (conversion of alkanes / olefins to aromatics with a greater number of C atoms), transfer hydrogenation, hydroformylation / carbonylation, aromatization, dearomatization, reforming, isomerization, and bifunctional reactions in which one of the above functional groups can optionally be combined with a Bronsted acid functional group.

[0037] In some embodiments, the treating of the catalyst composition can be performed simultaneously with the catalytic reaction.

[0038] In some embodiments, the reaction can be an alkane dehydrogenation. In another embodiment, the reaction can be an alkene hydrogenation.

[0039] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0040] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0041] In some embodiments, MO xThe catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, Hf, and Ti.

[0042] In some embodiments, the catalyst composition can increase product yield by at least 2-fold compared to a comparable reaction using a catalyst composition that does not include a trap.

[0043] In some embodiments, the method can further include cycling between dehydrogenating the light alkane gas or hydrogenating the light olefin gas with the catalyst composition and reactivating the catalyst composition.

[0044] In another embodiment, a catalyst composition is provided. In an embodiment, the catalyst composition may include MO x Catalyst, the MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths and a BET surface area of ​​at least about 50 m2 / g, wherein the catalyst composition may be free of at least one of chromium or precious metals.

[0045] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0046] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0047] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, and Ti.

[0048] In some embodiments of the catalyst composition, MO x The catalyst may include ZrO 2 . In some embodiments, the catalyst composition may include at least about 25 wt % ZrO 2 based on the total weight of the catalyst composition.

[0049] In some embodiments, the catalyst composition may further comprise a rare earth metal, the rare earth metal comprising at least one lanthanide metal, an oxide thereof, or a combination thereof. In another embodiment, the catalyst composition may comprise a rare earth metal, the rare earth metal comprising at least one of Y, erbium (Er), Ce, dysprosium (Dy), gadolinium (Gd), lanthanum (La), neodymium (Nd), samarium (Sm), ytterbium (Yb), an oxide thereof, or a mixture thereof.

[0050] In some embodiments, the catalyst composition may comprise from about 0.5 wt% to about 50 wt% rare earth metal.

[0051] In some embodiments, the catalyst composition can be cleaned and can contain more surface active sites than before cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The surface area (circles, left axis) and particle size (triangles, right axis) of ZrO2 after treatment at different temperatures are depicted;

[0053] Figure 2 The effect of ZrO2 particle size on the propane dehydrogenation rate per catalyst mass (15 kPa C3H8, 5 kPa H2, 723 K) after thermal treatment and chemical cleaning is depicted.

[0054] Figure 3 The effect of ZrO2 particle size on the propane dehydrogenation rate per mass (15 kPaC3H8, 5 kPa H2, 723 K) for DME-treated ZrO2 samples is depicted.

[0055] Figure 4 Depicted are the active site titrations for H2O pulse injection during the dehydrogenation reaction (15 kPa C3H8, 5 kPa H2, 723 K) for ZrO2 thermally treated at different temperatures followed by DME treatment.

[0056] Figure 5 Depicts the relationship between ZrO2 particle size and the 2 The effect of the number of active sites;

[0057] Figure 6 , the graph shows that the rate of pure monoclinic and tetragonal ZrO2 decreases linearly with the amount of water injected, where the x-axis intersection defines the number of water molecules required to suppress the reactivity;

[0058] Figure 7 Dehydrogenation rates (per mass) of isobutane on ZrO2 treated in He for 30 min at different temperatures followed by subsequent DME treatment are plotted;

[0059] Figure 8 Depicted are the isobutane dehydrogenation rates (area) on ZrO2 treated in He for 30 min and subsequently treated with DME at different treatment temperatures.

[0060] Figure 9 The XRD patterns of the monoclinic ZrO2 sample synthesized according to Example 1 and treated at 573 K and 723 K, and the XRD pattern of the tetragonal Y-ZrO2 sample synthesized according to Example 2 and treated at 573 K are shown;

[0061] Figure 10Depicted are the alkane dehydrogenation rate constants for the C2-C7 alkanes of Example 1 after He (lower) and DME (upper) treatment at 723 K.

[0062] Figure 11 Depicts the active site titration of O2 and H2O during propane dehydrogenation catalysis of ZrO2 in Example 1 (15 kPa C3H8, 5 kPa H2, 723 K);

[0063] Figure 12 The area rate of propane dehydrogenation (in μmol m) of DME-treated m-ZrO2 at 723 K for Example 1 is plotted. -2 h -1 ) versus run time (in ks) and average lifetime of active sites where the reactant stream bypasses or flows through the oxygen trap;

[0064] Figure 13 Plotted are the area rates (in μmol m) of propane dehydrogenation of ZrO2 from Example 1 after He (lower) and DME (upper) treatment at 723 K. -2 h -1 The reaction flow is passed through the trap;

[0065] Figure 14 Plotted are the area rates (in μmol m) of propane dehydrogenation of Y-ZrO2 from Example 2 after He (lower) and DME (upper) treatment at 723 K. -2 h -1 The reaction flow is passed through the trap;

[0066] Figure 15 Plotted are the forward rates (in mol kg) for propane dehydrogenation at 723 K (lower) and 873 K (upper). -1 h -1 (in ks) versus run time (in ks) with an oxygen trap at 873 K and a short trap bypass;

[0067] Figure 16 The propane dehydrogenation rate (in mol kg) on ​​ZrO2 during propane dehydrogenation is plotted as the temperature is increased from 723 K to 873 K and then decreased back to 723 K. -1 h -1 ) and the run time (in ks), where the reactant stream passes through the trap under the following reaction conditions: 15 kPa C3H8, 5 kPa H2;

[0068] Figure 17 depicts the results of Example 18;

[0069] Figure 18 The area rates (in μmol m) of propane dehydrogenation after treatment with DME, He, and H2 are plotted under the following conditions: -2 h -1 Meter): 13.7 kPa propane, 723 K;

[0070] Figure 19 The area rate of propane dehydrogenation at 723 K (in μmol m) is plotted. -2 h -1 ) as a function of propane and hydrogen pressure on the sample of Example 1;

[0071] Figure 20 The area rate of propylene hydrogenation at 723 K (in μmol m -2 h -1 ) as a function of propylene and H2 pressure on the sample of Example 1; and

[0072] Figure 21 Plotted are the extraction rate constants (in mol Kg) for propane dehydrogenation (triangles) and propylene hydrogenation (circles). -1 bar -1 or bar -2 10 3 K / T and activation barrier. The propylene hydrogenation rate constant is compared to the predicted hydrogenation rate constant using the relationship between gas-phase thermodynamics and the dehydrogenation rate constant (triangle).

[0073] definition:

[0074] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0075] As used herein, "a" or "an" entity refers to one or more of that entity, e.g., "a compound" refers to one or more compounds or at least one compound, unless otherwise indicated. Thus, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein.

[0076] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Additionally, as used herein, "or" means "and / or."

[0077] As used herein, the term "alkyl" refers to a saturated straight (i.e., linear or unbranched) or branched hydrocarbon chain containing carbon atoms, such as, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. Unless otherwise indicated, an alkyl group contains 1-20 carbon atoms. In some embodiments, an alkyl group contains 1-10 carbon atoms (represented herein as C 1-10 In some embodiments, the alkyl group contains 1-8 carbon atoms (denoted herein as C 1-8 In some embodiments, the alkyl group contains 1-6 carbon atoms (denoted herein as C 1-6 In some embodiments, the alkyl group contains 1-4 carbon atoms (denoted herein as C 1-4 In some embodiments, the alkyl group contains 1-3 carbon atoms (denoted herein as C 1-3 Non-limiting examples of "alkyl" include methyl, ethyl, propyl, isopropyl, isobutyl, tert-butyl, sec-butyl, and the like.

[0078] As used herein, the term "alkenyl" means a straight (i.e., straight or unbranched) or branched hydrocarbon chain containing at least one carbon-carbon double bond. Unless otherwise indicated, alkenyl contains 2-20 (e.g., such as 2-12, 2-6, or 2-4) carbon atoms. Non-limiting examples of "alkenyl" include vinyl, allyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, 2-ethylhexenyl, cyclopent-1-ene-1-yl, etc.

[0079] As used herein, the term "alkynyl" means a straight (i.e., straight or unbranched) or branched hydrocarbon chain containing at least one carbon-carbon triple bond. Unless otherwise indicated, an alkynyl group contains 2-20 (e.g., such as 2-12, 2-6, or 2-4) carbon atoms. Non-limiting examples of "alkynyl" include ethynyl, propynyl, butynyl, pentynyl, hexynyl, etc.

[0080] The term "aryl" refers to monocyclic, bicyclic, and tricyclic ring systems having a total of five to fourteen ring members, wherein at least one ring in the system is aromatic and wherein each ring in the system contains 3 to 7 ring members. As used herein, the term "aryl" also refers to heteroaryl ring systems as defined below.

[0081] As used herein, the term "catalyst composition" refers to a composition comprising a material that promotes a chemical reaction.

[0082] As used herein, the term "heteroatom" refers to oxygen, sulfur, nitrogen, phosphorus, or silicon (including any oxidized form of nitrogen, sulfur, phosphorus, or silicon; the quaternized form of any basic nitrogen; or a substitutable nitrogen of a heterocyclic ring, such as N (as in 3,4-dihydro-2H-pyrrolyl), NH (as in pyrrolidinyl), or NR + (as in N-substituted pyrrolidinyl)) atom.

[0083] As used herein, the term "heteroaryl" refers to monocyclic, bicyclic, and tricyclic ring systems, including fused or bridged ring systems, having a total of five to fourteen ring members, wherein at least one ring in the system is aromatic, at least one ring in the system contains one or more heteroatoms, and wherein each ring in the system contains 3 to 7 ring members. Non-limiting examples of "heteroaryl" include azepinyl, acridinyl, benzimidazolyl, benzothiazolyl, benzindolyl, cinnolinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, isothiazolyl, imidazolyl, indazolyl, indolyl, isoindolyl, indolinyl, isoquinolinyl, indolizinyl, isoxazolyl, naphthyridinyl, oxadiazolyl, oxazolyl, pyrrolyl, phenazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and thiophenyl (i.e., thienyl).

[0084] As used herein, the term "increase" refers to a positive change, including but not limited to a positive change of 1%, a positive change of 5%, a positive change of 10%, a positive change of 25%, a positive change of 30%, a positive change of 50%, a positive change of 75%, a positive change of 100%, a positive change of 200%, etc.

[0085] As used herein, the term "reduce" refers to a negative change, including but not limited to a negative change of 1%, a negative change of 5%, a negative change of 10%, a negative change of 25%, a negative change of 30%, a negative change of 50%, a negative change of 75%, or a negative change of 100%.

[0086] As used herein, the term "pretreatment" refers to any process in which a catalyst is contacted with a chemical, a combination of chemicals, or a series of chemicals to remove impurities from the surface of the catalyst. As used herein, the term "cleaning" refers to any process in which a catalyst is contacted with a chemical, a combination of chemicals, or a series of chemicals to activate or reactivate the catalyst to a more active and / or selective state before the catalyst is used in the intended chemical process or at an intermediate time point during the use of the catalyst. In some embodiments, pretreatment is carried out in a chemical reactor. In some embodiments, pretreatment is carried out outside a chemical reactor. In some embodiments, when used at an intermediate point during the use of the catalyst, pretreatment recovers all or part of the activity and / or selectivity of the catalyst, a scheme of which may be referred to as catalyst regeneration treatment by those skilled in the art.

[0087] As used herein, the term "free of impurities" or "substantially free" refers to a stream that contains less than about 1 wt%, less than about 0.5 wt%, less than about 0.25 wt%, less than about 0.1 wt%, less than about 0.05 wt%, less than about 0.01 wt%, or 0 wt% of a component (e.g., an impurity). DETAILED DESCRIPTION

[0088] In an embodiment of the present disclosure, a method for treating a reactant stream using a catalyst composition comprising MO x Catalyst and trap. The method may include treating the reactant stream with a trap, wherein the trap can remove impurities. The impurities may include O2, H2O, H2S, CO2, CO, N2, sulfur-containing compounds, methanol or other alcohols, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. MO x The catalyst may have a surface with MO sites that are Lewis type and have balanced acid-base strength. xThe catalyst may have a BET surface area of ​​at least about 75 m2 / g. In some embodiments, the BET surface area may be about 50 m2 / g, about 55 m2 / g, about 60 m2 / g, about 65 m2 / g, about 70 m2 / g, about 75 m2 / g, about 80 m2 / g, about 85 m2 / g, about 90 m2 / g, about 95 m2 / g, about 100 m2 / g, about 105 m2 / g, about 110 m2 / g, about 115 m2 / g, about 120 m2 / g, about 12 5 m2 / g, about 130 m2 / g, about 135 m2 / g, about 140 m2 / g, about 145 m2 / g, about 150 m2 / g, about 155 m2 / g, about 160 m2 / g, about 165 m2 / g, about 170 m2 / g, about 175 m2 / g, about 180 m2 / g, about 185 m2 / g, about 190 m2 / g, about 195 m2 / g, about 200 m2 / g, or more.

[0089] In some embodiments, impurities can be removed from the reactant stream during the dehydrogenation or hydrogenation process before the reactant stream contacts the catalyst composition. The impurity can be any substance that can form HO, NH3, or HS during the dehydrogenation reaction. The impurity can be, for example, but not limited to, O2, CO, N2, oxygen-containing compounds, organic nitrogen compounds, or organic sulfur compounds, as these molecules can react with the reactants and form titrants.

[0090] In some embodiments, MO x The surface of the catalyst can stabilize the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

[0091] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths; MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic cleavage process of forming and breaking C—H bonds; and MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0092] In some embodiments, MO x The M of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0093] In some embodiments, the method of the present disclosure can be operated at an impurity level of less than about 2 ppm. In some embodiments, the impurity level can be from about 0.0001 ppm to about 2 ppm, from about 0.001 ppm to about 1.5 ppm, from about 0.05 ppm to about 1 ppm, from about 0.1 ppm to about 0.9 ppm, from about 0.2 ppm to about 0.8 ppm, from about 0.3 ppm to about 0.7 ppm, or from about 0.4 ppm to about 0.6 ppm. In other embodiments, the method can be operated at an impurity level of less than about 0.5 ppm, about 0.4 ppm, about 0.3 ppm, about 0.2 ppm, about 0.1 ppm, or about 0.05 ppm.

[0094] In some embodiments, the method can be operated at an impurity level of at most 100 ppm, at most 50 ppm, or at most 20 ppm. In other embodiments, the method can be operated at an impurity level of at most about 100 ppm, at most about 90 ppm, at most about 80 ppm, at most about 70 ppm, at most about 60 ppm, at most about 50 ppm, at most about 40 ppm, at most about 30 ppm, or at most about 20 ppm. In some embodiments, the impurity level can be from about 0.0001 ppm to about 100 ppm, from about 0.001 ppm to about 95 ppm, from about 0.01 ppm to about 90 ppm, from about 0.1 ppm to about 85 ppm, from about 1 ppm to about 80 ppm, from about 5 ppm to about 75 ppm, from about 10 ppm to about 70 ppm, from about 15 ppm to about 65 ppm, from about 20 ppm to about 60 ppm, from about 25 ppm to about 55 ppm, from about 30 ppm to about 50 ppm, or from about 35 ppm to about 45 ppm.

[0095] In some embodiments, the reactant stream can have an oxygen content of about 5 ppm, about 4.5 ppm, about 4 ppm, about 3.5 ppm, about 3 ppm, about 2.5 ppm, about 2 ppm, about 1.5 ppm, about 1 ppm. In other embodiments, the reactant stream can have an oxygen content of about 0.5 ppm, about 0.45 ppm, about 0.4 ppm, about 0.35 ppm, about 0.3 ppm, about 0.25 ppm, about 0.2 ppm, about 0.15 ppm, or about 0.1 ppm. In yet another embodiment, the reactant stream can have an oxygen content of about 0.1 ppm to about 2 ppm, about 0.15 ppm to about 1.75 ppm, about 0.2 ppm to about 1.5 ppm, about 0.25 ppm to about 1.25 ppm, about 0.3 ppm to about 1 ppm, about 0.35 ppm to about 0.75 ppm, or about 0.4 ppm to about 0.5 ppm.

[0096] In some embodiments, the density of active sites can be related to the MO x It has been found that in order to maintain a large number of active sites per catalyst mass in the catalyst composition, sintering of the catalyst composition should be avoided as this results in both a loss of surface area and a reduction in the area density of active sites, the latter due to annealing of the active sites by specific LABs.

[0097] In some embodiments, when the surface area decreases, then MO x The density of active sites of the catalyst may decrease.

[0098] In some embodiments, MO x The catalyst may be substantially free of hydroxyl groups.

[0099] In some embodiments, MO x The catalyst does not contain hydroxyl groups.

[0100] In some embodiments, the contacting agent comprises MO x After contacting the catalyst composition comprising MO x After the catalyst and the catalyst composition are removed from the catalyst trap, the reactant stream is free of oxygen.

[0101] In some embodiments, the trap can be an oxygen trap, a water trap, a carbon dioxide trap, or a combination thereof.

[0102] In some embodiments, a surface having MO sites that are Lewis acid-base pairs with balanced acid-base strengths can be maintained during the dehydrogenation or hydrogenation process by avoiding titration with impurities.

[0103] In some embodiments, the processing of the reactant stream may be performed at a temperature of about 500-900 K. In some embodiments, the processing of the reactant stream may be performed at a temperature of about 500 K to about 900 K, about 550 K to about 850 K, about 600 K to about 800 K, or about 650 K to about 750 K.

[0104] In some embodiments, the processing of the reactant stream can be carried out at a temperature up to 900 K. In some embodiments, the processing can be carried out at a temperature of about 500 K, about 550 K, about 600 K, about 650 K, 700 K, about 750 K, about 800 K, about 850 K, or about 900 K.

[0105] In some embodiments, MO x The catalyst may include a metal oxide having a metal center in the form of a cation. In some embodiments, MO x The catalyst may include at least one of ZrO2, Y2O3, CeO2, and CoO.

[0106] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0107] In some embodiments, MO x The catalyst may comprise a metal (M) selected from the group consisting of Zr, Co, Ga, Zr, Ce, Y, Hf, and Ti. In other embodiments, MO x The catalyst may include oxides of Y, Ce and Ti.

[0108] In some embodiments, MO x The catalyst may include one or more of Mg, Ca, Sr, Ba and La on a zirconia support.

[0109] In some embodiments, MO x The catalyst may include ZrO2-silica, Zr-alumina, Zr-titania, or a combination thereof.

[0110] In some embodiments, MO x The catalyst may include ZrO2, t-ZrO2, m-ZrO2, Y-stabilized ZrO2, Ce-stabilized ZrO2, or Y2O3.

[0111] In some embodiments, the method may further comprise cleaning the MO with a surface cleaning agent. x catalyst.

[0112] In some embodiments, the surface cleaning agent has all of the following characteristics:

[0113] reactive with one or more binding substances derived from CO2 and / or H2O via a stoichiometric reaction;

[0114] one or more reactions of the surface titrant that do not result in the formation of a Lewis acid-base pair; and / or

[0115] can be desorbed from the surface of porous metal oxide catalysts without leaving behind potentially irreversibly titrating MO x Surface fragmentation of the MO active sites of the catalyst.

[0116] In some embodiments, the surface cleaning agent is selected from alcohols, ketones, carboxylates, acids, esters, ethers, hemiacetals, hemiketals, acetals, ketals, orthoesters, orthocarbonates, organic anhydrides, and combinations thereof.

[0117] In some embodiments, the surface cleaning agent comprises at least one compound selected from the group consisting of ROH, RCOR', RCHO, ROCOOR', RCOOH, RCOOR', R2CH(OR1)(OH), RC(ORʺ)(OH)R', RCH(OR')(OR"), RC(OR")(OR‴)R', RC(OR')(OR")(OR‴), C(OR)(OR')(OR")(OR‴), and R1(CO)O(CO)R2, wherein R, R', R", R‴, R1, and R2 are each independently selected from alkyl, alkenyl, alkynyl, and aryl (e.g., C1-C6 alkyl; C1-C4 alkyl; C6-C 10 aryl).

[0118] In some embodiments, R, R', R", R‴, R1, and R2 are each selected from methyl, phenyl, and tert-butyl.

[0119] In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 group. In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 side group. In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 terminal group.

[0120] In some embodiments, the surface cleaning agent may include dimethyl ether, propylene, methanol, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, anisole, dimethyl carbonate or a combination thereof. In another embodiment, the surface cleaning agent may include dimethyl ether. In another embodiment, the surface cleaning agent may include methanol. In some embodiments, the surface cleaning agent may include olefins. In another embodiment, the surface cleaning agent may include propylene.

[0121] In some embodiments, the method may further comprise cleaning the MO during the dehydrogenation or hydrogenation reaction by balancing water deposition and water removal via the olefin product at a temperature of about 800-900 K. x catalyst.

[0122] In some embodiments, cleaning can be performed at a temperature between about 323 K and 900 K. In some embodiments, cleaning can be performed at a temperature of about 323 K, about 373 K, about 423 K, about 473 K, about 523 K, about 573 K, about 623 K, about 673 K, about 723 K, about 773 K, about 823 K, about 873 K, or about 900 K.

[0123] In some embodiments, the surface cleaning agent can be desorbed from the surface of the metal oxide catalyst without leaving behind the potentially irreversible titration of the MO. x Surface fragmentation of the MO active sites of the catalyst.

[0124] In some embodiments, the surface cleaning reagent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction; and the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0125] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O through a stoichiometric reaction; and the surface cleaning agent and / or its reaction product can be obtained from MO x The surface desorption of the catalyst without leaving behind the possible irreversible titration of MO x Surface fragmentation of MO active sites in catalysts.

[0126] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction.

[0127] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0128] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair; and the surface cleaning reagent can be obtained from MO x The surface desorption of the catalyst without leaving behind the possible irreversible titration of MO x Surface fragmentation of the MO active sites of the catalyst.

[0129] In some embodiments, the method further comprises subjecting the catalyst composition to an additional pretreatment in an oxidizing environment in the presence of oxygen, either before or after cleaning with the surface cleaning agent.

[0130] In some embodiments, the method further comprises additionally pre-treating the catalyst composition in an oxidizing environment in the presence of oxygen prior to cleaning with the surface cleaning agent.

[0131] In some embodiments, the method further comprises subjecting the catalyst composition to an additional treatment in an oxidizing environment with oxygen or in an oxygen-deficient environment after cleaning with the surface cleaning agent.

[0132] In another embodiment of the present disclosure, a method for catalyzing a reaction using a catalyst composition as described herein is also provided. x The method of catalyzing the reaction of the catalyst composition of the catalyst comprises activating and / or reactivating the catalyst composition using the pretreatment method described herein. The reaction can be selected from the group consisting of: alkane dehydrogenation, olefin hydrogenation, olefin-paraffin alkylation, from CO / H2 mixture without O-rejection such as H2O or CO2, C-C bond formation via olefin oligomerization or metathesis, dehydrocyclization (conversion of alkanes / olefins to aromatics), dehydrocyclization dimerization (conversion of alkanes / olefins to aromatics with a larger number of C atoms), transfer hydrogenation, hydroformylation / carbonylation, aromatization, dearomatization, reforming, isomerization, and bifunctional reactions in which one of the above functional groups can optionally be combined with a Bronsted acid functional group.

[0133] In some embodiments, treating the reactant stream with a trap can be performed simultaneously with the catalytic reaction. In some embodiments, treating the reactant stream with a trap can be performed in the same reactor system where the reaction occurs.

[0134] In some embodiments, the method further comprises activating and / or reactivating more than once using the methods described herein. In some embodiments, the method may further comprise co-feeding a surface cleaning reagent as described herein.

[0135] In some embodiments, the bifunctional reaction performed when the aforementioned functional groups are optionally combined with Bronsted acid functional groups is selected from catalytic reforming for octane enhancement, alkane hydroisomerization, and hydrocracking.

[0136] In some embodiments, the bifunctional reaction is selected from hydroisomerization, hydrocracking, fluid catalytic cracking, and a reaction for converting C2-C4 alkanes to aromatic compounds.

[0137] In some embodiments, the reaction is alkane dehydrogenation. In some embodiments, the method further includes cycling the active dehydrogenation of the light alkane gas or light olefin gas with the catalyst composition and reactivating the catalyst composition. In some embodiments, the method further includes cycling the active dehydrogenation of the light alkane gas or light olefin gas with the catalyst composition and reactivating the catalyst composition. In some embodiments, the method is performed using multiple reactors, with the reaction and activation and / or reactivation of the catalysts performed alternately in the reactors.

[0138] In some embodiments, the reaction is propane dehydrogenation.

[0139] In some embodiments, the reaction occurs in a reactor. In some embodiments, the reactor is selected from a U-shaped quartz reactor, a packed tubular reactor, a fluidized bed reactor, a circulating fluidized bed reactor, a fixed bed reactor, a circulating fixed bed reactor, a multitubular reactor, a multitubular reactor circulation group and a moving bed reactor, and a reactor system comprising a combination thereof.

[0140] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis type and have balanced acid-base strengths.

[0141] In some embodiments, MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

[0142] In some embodiments, MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0143] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths; the surface of the porous metal oxide catalyst stabilizes anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking C-H bonds; and the MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0144] In some embodiments, the catalyst composition increases product yield compared to a comparable reaction without reactivation.

[0145] In some embodiments, the catalyst composition increases the rate of formation, yield, or selectivity of one or more desired products relative to the same reaction performed with the catalyst composition without activation and / or reactivation.

[0146] In some embodiments, the reaction can be an alkane dehydrogenation. In another embodiment, the reaction can be an alkene hydrogenation.

[0147] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0148] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0149] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, Hf, and Ti.

[0150] In some embodiments, compared to a comparable reaction using a catalyst composition that does not include a trap, the MO x The catalyst composition of the catalyst and the trap as described herein can increase the product yield by at least 2 times. In some embodiments, the catalyst composition can increase the product yield by at least 2 times, at least 5 times, at least 10 times, at least 15 times, at least 20 times, at least 25 times, at least 30 times, at least 35 times, at least 40 times, at least 45 times, at least 50 times, at least 55 times, at least 60 times, at least 65 times, at least 70 times, at least 75 times, at least 80 times, at least 85 times, at least 90 times, at least 95 times, at least 100 times, at least 110 times, at least 120 times, at least 130 times, at least 140 times, or at least 150 times compared to a comparable reaction using a catalyst composition that does not include the trap of the present disclosure. That is, the catalyst composition of the present disclosure having a high surface and active site density as described herein can have an improved product yield.

[0151] In some embodiments, the method may further include cycling between dehydrogenating the light alkane gas or hydrogenating the light olefin gas with the catalyst composition and reactivating the catalyst.

[0152] In another embodiment, a catalyst composition is provided. In an embodiment, the catalyst composition may include MO x Catalyst, the MO xThe catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths and a BET surface area of ​​at least about 50 m2 / g, wherein the catalyst composition may be free of at least one of chromium or a precious metal. In some embodiments, the BET surface area may be at least about 50 m2 / g, at least about 60 m2 / g, at least about 70 m2 / g, at least about 80 m2 / g, at least about 90 m2 / g, or at least about 100 m2 / g.

[0153] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0154] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0155] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, Hf, and Ti.

[0156] In some embodiments of the catalyst composition, MO x The catalyst may include ZrO2. In some embodiments, the catalyst composition may include at least about 25 wt% ZrO2 based on the total weight of the catalyst composition. In some embodiments, the catalyst composition may include about 25 wt% ZrO2, about 30 wt% ZrO2, about 35 wt% ZrO2, about 40 wt% ZrO2, about 45 wt% ZrO2, about 50 wt% ZrO2, about 55 wt% ZrO2, or about 60 wt% ZrO2, or more.

[0157] In some embodiments, the catalyst composition may further comprise a rare earth metal comprising at least one lanthanide metal, an oxide thereof, or a combination thereof. In another embodiment, the catalyst composition may comprise a rare earth metal comprising at least one of Y, Er, Ce, Dy, Gd, La, Nd, Sm, Yb, an oxide thereof, or a mixture thereof.

[0158] In some embodiments, the catalyst composition may comprise from about 0.5 wt% to about 50 wt% of a rare earth metal. In some embodiments, the catalyst composition may comprise from about 0.5 wt%, about 1 wt%, about 5 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, or about 50 wt% of a rare earth metal.

[0159] In some embodiments, the catalyst composition may be pretreated and may contain more surface active sites than before pretreatment.

[0160] In some embodiments, the pretreatment of the reactants may include a trap, wherein the trap removes impurities. Impurities may include O2, H2O, H2S, CO2, CO, N2, sulfur-containing compounds, methanol, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. In some embodiments, when the reactant stream is treated with the trap of the present disclosure, the reactant stream may be free of impurities. In another embodiment, when the reactant stream is treated with the trap of the present disclosure, the reactant stream may be substantially free of impurities.

[0161] Some embodiments of the present disclosure relate to activating and / or reactivating MO x A method for cleaning a catalyst composition of a catalyst, the method comprising cleaning the catalyst composition with a surface cleaning agent, wherein:

[0162] The surface cleaning agent is selected from the group consisting of alcohols, ketones, carboxylates, acids, esters, ethers, hemiacetals, hemiketals, acetals, ketals, orthoesters, orthocarbonates, organic anhydrides, and combinations thereof; and further wherein:

[0163] If MO x The catalyst is ZrO2, then the surface cleaning agent is not dimethyl ether or propylene; and

[0164] Treating MO with a trap x The catalyst, wherein the trap can remove impurities. The impurities can include O2, H2O, H2S, CO2, CO, N2, sulfur compounds, methanol, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. x The catalyst may have a surface with MO sites that are Lewis type and have balanced acid-base strength. x The catalyst may have a BET surface area of ​​at least about 100 m2 / g.

[0165] In some embodiments, if MO x The catalyst is ZrO2, so the surface cleaning agent is not methanol.

[0166] In some embodiments, MO x The catalyst is deactivated by bound H2O and / or CO2. In some embodiments, MO x The catalyst is deactivated by strongly bound H2O and / or CO2.

[0167] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction.

[0168] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0169] In some embodiments, the surface cleaning agent can be desorbed from the surface of the porous metal oxide catalyst without leaving surface debris that could irreversibly titrate the MO active sites of the porous metal oxide catalyst.

[0170] In some embodiments, the surface cleaning reagent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction; and the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0171] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O through a stoichiometric reaction; and the surface cleaning agent can be derived from MO x The surface of the catalyst desorbs without leaving behind surface fragments that could irreversibly titrate the MO active sites of the porous metal oxide catalyst.

[0172] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair; and the surface cleaning reagent can be obtained from MO x The surface of the catalyst desorbs without leaving behind surface fragments that could irreversibly titrate the MO active sites of the porous metal oxide catalyst.

[0173] In some embodiments, the surface cleaning agent is selected from dimethyl ether, propylene, olefins, methanol, anisole, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, dimethyl carbonate, and combinations thereof.

[0174] In some embodiments, the surface cleaning agent is selected from dimethyl ether, propylene, and methanol.

[0175] In some embodiments, the surface cleaning agent is dimethyl ether.

[0176] In some embodiments, the surface cleaning agent is acrylic.

[0177] In some embodiments, the surface cleaning reagent is methanol.

[0178] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis type and have balanced acid-base strengths.

[0179] In some embodiments, MO xThe surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

[0180] In some embodiments, MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0181] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths; MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic cleavage process of forming and breaking C—H bonds; and MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0182] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0183] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0184] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, and Ti.

[0185] In some embodiments of the catalyst composition, MO x The catalyst may include ZrO 2 . In some embodiments, the catalyst composition may include at least about 50 wt % ZrO 2 based on the total weight of the catalyst composition.

[0186] In some embodiments, MO x The catalyst may include Y-stabilized ZrO2. In some embodiments, MO x The catalyst is Y-stabilized ZrO2.

[0187] In some embodiments, MO x The catalyst may include Y2O3. In some embodiments, MO x The catalyst is Y2O3.

[0188] In some embodiments, cleaning can be performed at a temperature up to 900 K. In some embodiments, cleaning can be performed at a temperature up to 873 K. In some embodiments, cleaning can be performed at a temperature up to 823 K. In some embodiments, cleaning can be performed at a temperature up to 723 K.

[0189] In some embodiments, cleaning can be performed at a temperature between 323 K and 900 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 873 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 823 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 723 K.

[0190] In some embodiments, the method may further comprise subjecting the catalyst composition to an additional pretreatment in an oxidizing environment in the presence of oxygen, either before or after pretreatment with the surface cleaning agent.

[0191] In some embodiments, the method may further comprise pre-treating the catalyst composition in an oxidizing environment in the presence of oxygen prior to pre-treating with the surface cleaning agent.

[0192] In some embodiments, the method may further comprise pretreating the catalyst composition in an oxidizing environment in the presence of oxygen after pretreating with the surface cleaning agent.

[0193] Some embodiments of the present disclosure relate to activating and / or reactivating MO x A method for cleaning a catalyst composition comprising cleaning the catalyst composition with a surface cleaning agent, wherein:

[0194] The surface cleaning agent comprises at least one compound selected from the group consisting of ROH, RCOR', RCHO, ROCOOR', RCOOH, RCOOR', R2CH(OR1)(OH), RC(ORʺ)(OH)R', RCH(OR')(OR"), RC(OR") (OR‴)R', RC(OR')(OR")(OR‴), C(OR)(OR')(OR")(OR‴), and R1(CO)O(CO)R2, wherein R, R', R", R‴, R1, and R2 are each independently selected from alkyl, alkenyl, alkynyl, and aryl (e.g., C1-C6 alkyl; C1-C4 alkyl; C6-C 10 aryl); and further, wherein:

[0195] If MO x The catalyst is ZrO2, then the surface cleaning agent is not dimethyl ether or propylene; and

[0196] The reactant stream is treated with a trap, wherein the trap can remove impurities. Impurities can include O2, H2O, H2S, CO2, CO, N2, sulfur compounds, methanol, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof. The treated MO x The catalyst may have a surface with MO sites that are Lewis type and have balanced acid-base strength. x The catalyst may have a BET surface area of ​​at least about 75 m2 / g.

[0197] In some embodiments, if MO x The catalyst is ZrO2, so the surface cleaning agent is not methanol.

[0198] In some embodiments, MO x The catalyst is deactivated by bound H2O and / or CO2. In some embodiments, MO x The catalyst is deactivated by strongly bound H2O and / or CO2.

[0199] In some embodiments, R, R', R", R‴, R1, and R2 are each selected from methyl, phenyl, and tert-butyl.

[0200] In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 group. In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 side group. In some embodiments, R, R', R", R‴, R1, and / or R2 do not have a -CH2CH3 terminal group.

[0201] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction.

[0202] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0203] In some embodiments, the surface cleaning agent can be desorbed from the surface of the porous metal oxide catalyst without leaving behind potentially irreversibly titrating the MO. x Surface fragmentation of the MO active sites of the catalyst.

[0204] In some embodiments, the surface cleaning reagent is reactive with one or more binding species derived from CO2 and / or H2O via a stoichiometric reaction; and the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair.

[0205] In some embodiments, the surface cleaning agent is reactive with one or more binding species derived from CO2 and / or H2O through a stoichiometric reaction; and the surface cleaning agent can be derived from MO x The surface desorption of the catalyst without leaving behind the possible irreversible titration of MO x Surface fragmentation of the MO active sites of the catalyst.

[0206] In some embodiments, the surface cleaning reagent does not result in one or more reactions of the surface titrant that form a Lewis acid-base pair; and the surface cleaning reagent can be obtained from MO x The surface desorption of the catalyst without leaving behind the possible irreversible titration of MO x Surface fragmentation of the MO active sites of the catalyst.

[0207] In some embodiments, the surface cleaning agent is selected from dimethyl ether, propylene, methanol, anisole, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, dimethyl carbonate, and combinations thereof.

[0208] In some embodiments, the surface cleaning agent is selected from dimethyl ether, propylene, and methanol.

[0209] In some embodiments, the surface cleaning agent is dimethyl ether.

[0210] In some embodiments, the surface cleaning agent is acrylic.

[0211] In some embodiments, the surface cleaning reagent is methanol.

[0212] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis type and have balanced acid-base strengths.

[0213] In some embodiments, MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

[0214] In some embodiments, MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0215] In some embodiments, MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths; MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic cleavage process of forming and breaking C—H bonds; and MO xThe metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

[0216] In some embodiments, MO x The catalyst may comprise a metal oxide having a metal center in the form of a cation.

[0217] In some embodiments, MO x The catalyst may include a metal oxide that is not reducible to a zero valent state.

[0218] In some embodiments, MO x The catalyst may include a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, and Ti.

[0219] In some embodiments of the catalyst composition, MO x The catalyst may include ZrO 2 . In some embodiments, the catalyst composition may include at least about 25 wt % ZrO 2 based on the total weight of the catalyst composition.

[0220] In some embodiments, MO x The catalyst may include Y-stabilized ZrO2. In some embodiments, MO x The catalyst is Y-stabilized ZrO2.

[0221] In some embodiments, MO x The catalyst may include Y2O3. In some embodiments, MO x The catalyst is Y2O3.

[0222] In some embodiments, cleaning can be performed at a temperature up to 900 K. In some embodiments, cleaning can be performed at a temperature up to 873 K. In some embodiments, cleaning can be performed at a temperature up to 823 K. In some embodiments, cleaning can be performed at a temperature up to 723 K.

[0223] In some embodiments, cleaning can be performed at a temperature between 323 K and 900 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 873 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 823 K. In some embodiments, cleaning can be performed at a temperature between 323 K and 723 K.

[0224] In some embodiments, the method can further include pre-treating the catalyst composition in an oxidizing environment in the presence of oxygen, either before or after cleaning with a surface cleaning agent and treating the reactants with a trap.

[0225] In some embodiments, the method can further include pre-treating the catalyst composition in an oxidizing environment in the presence of oxygen prior to cleaning with a surface cleaning agent and treating the reactants with a trap.

[0226] In some embodiments, the method may further include pre-treating the catalyst composition in an oxidizing environment in the presence of oxygen after cleaning with a surface cleaning agent and treating the reactants with a trap.

[0227] If one, more than one, or all of the members of a group are present in, used in, or otherwise relevant to a given product or method, a claim or description that includes "or" or "and / or" between at least one member of the group is considered satisfied, unless stated to the contrary or otherwise clear from the context. The present disclosure includes embodiments in which exactly one member of the group is present in, used in, or otherwise relevant to a given product or method. The present disclosure includes embodiments in which more than one or all of the members of the group are present in, used in, or otherwise relevant to a given product or method.

[0228] In addition, this disclosure encompasses all variations, combinations, and permutations in which at least one limitation, element, clause, and descriptive term from at least one listed claim is incorporated into another claim. For example, any claim dependent on another claim can be amended to include at least one limitation found in any other claim dependent on the same base claim. Where elements are presented as a list (e.g., as in Markush group format), each subgroup of elements is also disclosed, and any element may be removed from that group. It should be understood that, generally, where this disclosure or aspects of this disclosure are referred to as including specific elements and / or features, embodiments of this disclosure or aspects of this disclosure consist of or consist essentially of such elements and / or features. For the sake of brevity, these embodiments are not specifically recited herein. When a range is given (e.g., as from [X] to [Y]), the endpoints (e.g., as in the phrase "from [X] to [Y]") are included unless otherwise indicated. Furthermore, unless otherwise stated or otherwise apparent from the context and understanding of one of ordinary skill in the art, values ​​expressed as ranges in the various embodiments of the present disclosure may take any specific value or sub-range within the stated range, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise.

[0229] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments disclosed herein. Such equivalents are intended to be encompassed by the following claims.

[0230] Examples

[0231] The following examples are intended to be illustrative and are not meant to limit the scope of the present disclosure in any way.

[0232] Several tests were conducted to test various materials for dehydrogenation reactions that could benefit from thermal or chemical treatments to remove impurities from the surface of the stream and catalyst. Tests were also conducted to measure reaction rates as a means of evaluating the benefits of such treatments.

[0233] Example 1a: Monoclinic ZrO2 (m-ZrO2)

[0234] Monoclinic ZrO2 (m-ZrO2) was prepared using a hydrothermal synthesis method using the decomposition of urea to gradually increase the solution pH and induce precipitation, as described in Li, W. et al. "Facile Synthesis of Pure Monoclinic and Tetragonal Zirconia Nanoparticles and Their Phase Effects on the Behavior of Supported Molybdena Catalysts for Methanol Selective Oxidation," Langmuir 2008, 8358-8366. ZrO(NO3)2·xH2O (12.7 g; Sigma-Aldrich) and CO(NH2)2 (21.6 g; Sigma-Aldrich) were each dissolved in deionized water (≥ 17.6 MΩ-cm resistivity; 30 g) at 323 K. The two solutions were heated in a Teflon-lined autoclave (Parr, 125 cm 3 ) and kept at 393 K for 20 h. The resulting powder was rinsed with deionized water (250 g) and centrifuged four times, followed by treatment at 393 K for 12 h in ambient air. These samples were then heated in flowing He (Praxair, 99.999%, 1.6 cm 3 g -1 s -1 ) and treated at 723 K for 5 h.

[0235] Example 1b: Tetragonal ZrO2 (t-ZrO2)

[0236] Tetragonal ZrO2 (t-ZrO2) was prepared using a methanol thermal synthesis method as described in Li, W. et al., “Facile Synthesis of Pure Monoclinic and Tetragonal Zirconia Nanoparticles and Their Phase Effects on the Behavior of Supported Molybdena Catalysts for Methanol Selective Oxidation,” Langmuir 2008, 8358–8366. ZrO(NO3)2·xH2O (6.35 g; Sigma-Aldrich) and CO(NH2)2 (10.8 g; Sigma-Aldrich) were each dissolved in methanol (Fisher Scientific, 99.9%, 30 g) at 323 K. The two solutions were placed in a Teflon-lined autoclave (Parr, 125 cm 3 ) and kept at 393 K for 20 h. The resulting powder was washed with methanol (100 g) and then treated at 393 K for 12 h in ambient air. These samples were then heated in flowing air (Praxair, 99.999%, 1.6 cm3 g -1 s -1 ) and treated at 723 K for 5 h.

[0237] Example 2: Y-ZrO2

[0238] Y-ZrO2 was prepared by dissolving ZrOCl2·8H2O (Sigma-Aldrich) and Y(NO3)3·6H2O starting materials in deionized water (≥ 17.6 ΜΩ-cm resistivity) to form 125 ml of solution (C Zr = 0.2 mol L -1 )(where Y 3+ and ZrO 2+The precipitant was prepared using a precipitant (concentration corresponding to a 1:9 molar ratio) as described in Huang et al., "The Effects of Precipitants on Co-Precipitation Synthesis of Yttria-Stabilized Zirconia Nanocrystalline Powders," J. Sol-Gel Sci. Tech., 2019, 90, 359-368. NH4OH (13 ml, 25-28 wt% in water) was added to an ethanol-water solution (200 ml ethanol and 800 ml water) to form a precipitant solution. The main solution was then added dropwise to the precipitant solution at room temperature and stirred with a magnetic stirrer for 1 hour, followed by aging for 6 hours. The resulting powder was rinsed with deionized water (250 g) and ethanol (250 g) and centrifuged four times before being treated at 333 K in ambient air for 1 hour. These samples were then heated in flowing He (Praxair, 99.999%, 1.6 cm3 g -1 s -1 ) and treated at 723 K for 2 h.

[0239] Example 3: Supported CoO material

[0240] Silica-supported cobalt catalysts are known active materials for alkane dehydrogenation reactions. The support can be tailored to accommodate better dispersion of CoO domains by introducing additional anchoring sites (e.g., hydroxyl groups). x (OH) 4-2x Carrier (301 m 2 g -1 ) is obtained by converting SiO2 (293 m 2 g -1 ) (about 10 g) was further hydroxylated in a stirred aqueous solution at pH 2-5 (set by adding 2 NHNO3) at 373 K for 18 h. x (OH) 4-2x The aqueous slurry (about 12 g) was passed through distilled water (100 cm 3 g -1 ) was thoroughly washed and then dried at 393 K for 12 h before subsequent treatment to prepare the catalyst. The supported CoOx catalyst was prepared by coating SiOx(OH) with droplets of an aqueous solution of cobalt(II) acetate tetrahydrate (about 0.25 cm3 H2O per g of support). 4-2x (301 m 2 g -1The samples were dried in a tray at 393 K in ambient air for 9 h and in flowing dry air (1.67 cm 3 s -1 ) for 3 h to obtain 5.0-7.5 wt.% and 0.3-20 wt.% co-catalysts.

[0241] Example 4: Representative Reaction Rate Measurements

[0242] Propane (Praxair, 49.7% ± 2%, balance Ar) dehydrogenation (PDH) rates were measured in the presence of H2 (Praxair, 99.999%) and He (Praxair, 99.999%) on sized catalyst particles (177-250 μm) held in a U-shaped quartz reactor (10 mmi.d.). The catalyst particles were diluted with quartz sand (Sigma-Aldrich, 210-297 μm, treated in air at 1073 K for 8 h) at a 1:50 mass ratio to avoid potential rate corruption caused by bed-scale temperature gradients. Prior to PDH rate measurements, the catalyst bed was heated in flowing He (Praxair, 99.999%, 0.83 cm 3 g -1 s -1 ) at 723 K (heating rate 0.4 K s -1 ) for 3.6 ks. A dimethyl ether (DME) treatment is optionally performed to clean the surface sites. Such a treatment involves flowing about 1 to about 5 kPa of DME through the sample for 15 minutes, followed by a He purge for a period of time (e.g., 25 minutes), and then measuring the rate.

[0243] Additional experiments were performed in a similar manner for ethane, n-butane, and isobutane.

[0244] The inlet flow rate was set via an electronic mass flow controller (Porter). The desired mixture of propane, H2, and He was introduced using regulated flow rates of each gas. The reactant stream optionally passed through an oxygen trap (Agilent 5182-9401, 5 ppb) installed before the catalytic reactor.

[0245] The catalyst bed temperature was measured using a K-type thermocouple and maintained constant using resistance heating and an electronic temperature controller (Watlow 96). Reactant and product concentrations were determined by online gas chromatography (Agilent 6890A, GS-GASPRO capillary column, 15 μm, 0.32 mm diameter) using a flame ionization detector (FID). The forward propylene formation rate (r) per mass of catalyst was m ) is calculated by correcting the measured rate for the equilibrium approach value (ƞ) using Equations 1a and 1b.

[0246] (Equation 1a)

[0247] (Equation 1b)

[0248] in 、 and denote the molar flow rate of propylene in the reactor effluent, the mass of ZrO2, and the equilibrium approximation for the nonoxidative dehydrogenation of propane (Eq. 1a), respectively; 、 and are the pressure of species i (i = C3H8, H2, C3H6) in bar and the equilibrium constant for the nonoxidative dehydrogenation of propane. a In Equation 1c it is defined as:

[0249] (Equation 1c)

[0250] in Dehydrogenation selectivity is reported on a carbon basis as the ratio of the rate of propane conversion leading to propylene formation to the rate of propane conversion leading to the formation of smaller molecules (methane, ethane, and ethylene).

[0251] To evaluate the stability and deactivation of the catalyst, the first-order deactivation rate constant (k d ) to perform regression:

[0252] (Equation 1d)

[0253] in and represents the PDH rate at the initial t0 and at a given time t.

[0254] Product selectivity and dehydrogenation rate are determined by subtracting the contribution of any gas-phase homogeneous reactions that may have occurred in the absence of active catalyst material. Typical product selectivities over the catalyst are reported to be above 99%.

[0255] Example 5: Testing shows that small crystals provide the necessary combination of high surface area and high areal site density for dehydrogenation and hydrogenation reactions

[0256] Thermal treatment can negatively affect the surface area and cause sintering and annealing of the crystallites, thereby reducing the surface area and the area density of active sites. It has been found that thermal treatment can also partially activate the material via incomplete dehydroxylation when the treatment is not performed at high temperatures of 700 to 750 K.

[0257] The ZrO2 samples prepared as in Example 1a were heated in flowing He (Praxair, 99.999%, 1.6 cm 3 g -1 s -1 ) with a 0.16 K s -1 The samples were heated at a rate of 1.8 ks and held at the target temperature for 1.8 ks. The surface area of ​​the samples was measured by nitrogen absorption at its normal boiling point (3Flex, Micromeritics). The crystal structure and crystallite size of ZrO2 were determined by X-ray diffraction (Rigaku Miniflex, Cu-Kα radiation) at 20-80 o The 2θ range is 0.01 o The particle size of the ZrO2 sample was determined from the X-ray diffraction pattern using Rietveld refinement and the Scherrer equation and from the surface area value using the ZrO2 density at a given temperature and the Sauter mean diameter formula (d 32 = 6V p / A p , where V p and A p is calculated based on the volume and surface area of ​​the particles.

[0258] After measuring the dehydrogenation rate on heat-treated ZrO2, the ZrO2 samples were treated with 1-5 kPa dimethyl ether (DME) (Praxair, 5.07 ± 0.2% DME, 5.07 ± 0.2% Ar, balance He) in the temperature range of 523-723 K for 0.3-1.8 ks, followed by treatment in flowing He at 723 K for 1.8 ks to completely dehydroxylate the surface and expose Lewis acid-base (LAB) active sites.

[0259] The results of these treatments are shown in Figure 1-3 As shown in the chart presented in Figure 1 It can be seen that with the increase of heat treatment temperature, the surface area decreases and the crystallite diameter increases. Figure 2In , the results show that heat treatment leads to an initial increase in rate (per mass) with increasing temperature, which is due to the offsetting effects of partial dehydroxylation and sintering / annealing. In contrast, when treated with DME to dehydroxylate the surface, heat treatment (before DME cleaning) leads to a decrease in rate due to a simultaneous decrease in surface area and areal site density without any additional dehydroxylation, as such hydroxyl groups are eventually removed by the DME cleaning. Figure 3 , the graph shows the rate per surface area after heat treatment and DME cleaning, demonstrating that heat treatment reduces the rate even after correcting for surface area loss because the number of sites per surface area also decreases due to particle growth and loss of undercoordinated sites that provide the most catalytically competent LAB pairs.

[0260] Example 6: Site Titration Method and Density of Active Centers on Oxide Materials

[0261] As previously demonstrated, DME treatment removes hydroxyl groups that block active sites. This can be seen in WO 2022 / 132843 and International Application No. PCT / US2022 / 077002. The clean active sites exposed by such treatment can then be counted using water as a titrant, which restores the hydroxyl groups, making the active sites inaccessible to reactants. To determine the number of active sites, a 1 cm 2 tungsten (100 nm) ... 3 The loop injects pulses of 0.61 kPa H2O or 0.5 kPa O2 (the latter resulting in H2O formation via reaction with H2 under reaction conditions) into the reactant stream to perform H2O and O2 titrations. The results of these protocols and measurements are shown in Figure 4 and 5 It should be understood that these are intended as illustrative examples.

[0262] exist Figure 4 In , the graph shows that the rate decreases linearly with the amount of water injected, where the x-axis intersection defines the number of water molecules required to suppress the reactivity, which gives the number of active sites. Figure 5 , the graph shows that the number of active sites decreases with increasing crystallite diameter. Therefore, the inventors have concluded that this demonstrates that crystallite growth caused by heat treatment reduces the surface density of sites due to annealing. Therefore, small crystallites are required to provide not only a high surface area, but also a high area density of active sites, the product of which ultimately determines the number of active sites per mass of catalyst and, therefore, the mass-based productivity of the reaction catalyzed by such sites.

[0263] Example 7. Beneficial Use of Monoclinic ZrO2 for High Dehydrogenation Rates

[0264] exist Figure 6In the graph, the rate of pure monoclinic and tetragonal ZrO2 decreases linearly with the amount of water injected, where the intersection of the x-axis defines the number of water molecules required to suppress the reactivity, which provides the number of active sites. Figure 6 In Figure 2, the graph shows that both m-ZrO2 and t-ZrO2 catalysts have a similar number of active sites per surface area. However, the dehydrogenation rate for t-ZrO2 is approximately 1 / 7 of the rate measured for m-ZrO2. Therefore, it can be concluded that the number of active sites is not the only important characteristic, but that the structure of ZrO2 itself (i.e., the Zr-O coordination environment) is also important for site-based reactivity. Therefore, for high dehydrogenation rates, monoclinic structures are preferred.

[0265] Example 8: The support of Example 5 also shows the beneficial effect of small crystallites for isobutane dehydrogenation

[0266] exist Figure 7 and 8 In , the plotted graphs show that similar requirements for small crystallites to provide both high surface area and site density also apply to isobutane dehydrogenation, not just propane dehydrogenation, which requires activation of primary and tertiary C-H bonds rather than the primary and secondary C-H bonds in propane. Similar to the above examples, m-ZrO2 samples prepared as in Example 1a were treated at different temperatures. The present results show that as the material is sintered and annealed, both the mass normalized rate and the areal rate decrease with higher temperature, resulting in a decrease in both surface area and areal site density at higher temperature heat treatments. In Figure 7 and 8 The isobutane dehydrogenation data at the temperatures shown in represent initial dehydrogenation rates, extrapolated to the point of feed introduction, and are shown for a single batch of catalyst that was subsequently exposed to each treatment in sequence rather than for a fresh sample for each data point.

[0267] Example 9: Changes in crystallite size, surface area, and active site density at different thermal treatment temperatures

[0268] Table 1 lists the changes in crystallite size, surface area, and active site density at various heat treatment temperatures. Table 1 lists the catalyst nomenclature and their physicochemical characteristics. Samples A to D were prepared following the procedure described in Example 1a. The treatment temperatures for Samples A to D are specified in Table 1. Samples E and F were prepared following the same procedure described in Example 2. The treatment temperatures for Samples E and F are also specified in Table 1.

[0269] Table 1. Surface area, crystallite size, and active site density after heat treatment

[0270]

[0271] Example 10: Catalyst structural characteristics from XRD patterns in He and after different heat treatment temperatures with the addition of yttria as a stabilizer for the tetragonal phase of zirconia

[0272] The catalyst structural characteristics of the samples of Examples 1a and 2 were determined as in Figure 9 The sample of Example 1a was treated at 573 K and 723 K, while the sample of Example 2 was treated at 573 K. The heat treatment was carried out in the presence of He and with the addition of yttria as a stabilizer for the tetragonal phase of zirconia.

[0273] Example 11: Method for Removing Titrant Impurities and Precursors of Titrant Molecules from an Inlet Stream to Achieve and Maintain High Alkane Dehydrogenation Rates

[0274] Given that the areal dehydrogenation rates of other alkanes also decrease with increasing heat treatment temperature as the samples sinter and site anneal, this suggests that removing impurities from the reactant stream and thermal treatment and chemical cleaning produce similar effects and trends on the dehydrogenation of other molecules. This is believed to be because free Lewis acid-base pairs acting as active sites can also be exposed through DME treatment and feed cleaning protocols for such reactions of other alkanes. Figure 10 The data shown in represent the initial first-order dehydrogenation rate constants (where all rates are proportional to alkane pressure and insensitive to alkene or H2 pressure) and are then extrapolated to the point of initial alkane feed introduction after He or DME treatment at 723 K.

[0275] As in Figure 10 As can be seen in Figure 2, the effect of DME treatment is observed for all alkanes. Therefore, removing the titrant from the surface and preventing its reintroduction with the reactant stream is necessary to obtain and maintain high rates for all reactants. It should be further noted that Figure 10 represents the alkane dehydrogenation rate constants for C2-C7 alkanes on the sample of Example 1a after He and DME treatment at 723 K. Figure 10 The 2,4-DMP in the formula represents 2,4-dimethylpentane. Figure 10 The double-headed arrows and "x numbers" in the ' indicate the rate increase of the catalyst measured after DME treatment. For example, the first double-headed arrow and "x70" indicate that the activity after DME treatment is 70 times that of the catalyst when subjected to only heat treatment at the same temperature.

[0276] Example 12: Removal of impurities and their precursors in the titration of Lewis acid-base pairs

[0277] Water and O2-derived species act as titrants to cover the catalytically active sites. During the reaction, oxygen is converted to water via reaction with added or generated H2. Oxygen and water are also competent molecules for measuring active site density, with the factor of 2 being determined by the fact that two H2O molecules are produced per O2 molecule. Both H2O and CO2 molecules can also be formed by reaction with propane reactant or propylene co-produced with H2.

[0278] Figure 11 Active site titration of O2 and H2O during propane dehydrogenation catalysis of ZrO2 of Example 1a (723 K, 15 kPa C3H8, 5 kPa H2) is shown. Figure 11 It is demonstrated that both O2 and water are strong irreversible titrants of the dehydrogenation-hydrogenation active sites, and that each O2 molecule titrates two active sites as it reacts with H2 in the inlet stream to form two H2O molecules. Figure 11 It also demonstrates the need to remove not only water but also any precursors of water (or any other acid or base molecule that strictly titrates a Lewis acid-base pair). It also follows from these data that not only should other molecules that act as titrants due to their acid-base properties (e.g., CO2, NH3, oxygenates) be removed from the feed, but also any molecules that can form such molecules via reaction with H2, alkanes, alkenes, contact with the catalyst, or thermal decomposition should be removed before any stream contacts the catalyst.

[0279] Example 13: Use of a trap to remove impurities to promote stable dehydrogenation rates and demonstrate that deactivation and / or lower rates are prevalent in the absence of a clean reactant stream

[0280] For the DME-treated monoclinic ZrO2 material prepared in Example 1a, the propane dehydrogenation (PDH) rate at 723 K decreased with run time. The decrease in rate reflects the presence of trace titrant molecules present as impurities in the feed stream (see Example 12 above). Figure 12 The first three panels in the figure show the first-order catalyst deactivation caused by such impurities in the reactant stream, with an average lifetime of the active sites of 0.2 h (defined as the first-order deactivation rate constant k d The inverse of the deactivation rate). It has been found that the use of an oxygen trap (Agilent 5182-9401, 5 ppb specification) to remove impurities from the reactant stream is advantageous. When such molecules are present in the reactant gas, the inclusion of an oxygen trap to capture such molecules before such gas can contact the catalyst reduces the slope of the deactivation curve and increases the average active site lifetime to 2.2 hours ( Figure 12The two right panels). Use of an oxygen trap prolongs the high rates provided by thermochemical catalyst treatment by removing molecules from the feed stream that would deactivate catalyst sites for alkane dehydrogenation. Intermediate DME treatment can restore rates, indicating that the role of impurities removed from the catalyst by DME (and from the stream by the trap) is the cause of the observed deactivation.

[0281] Figure 12 The propane dehydrogenation rate and average lifetime of active sites for DME-treated ZrO2 at 723 K are shown for Example 1a, where the reactant stream bypasses or flows through the trap. Figure 12 In the present invention, the use of oxygen or water traps results in slower deactivation, the extent of which is inversely proportional to the concentration level of impurities in the inlet stream.

[0282] Impurity concentrations were also estimated from the deactivation rate constants.The deactivation rate constants typically observed in these examples and the corresponding concentrations of oxygen fed to the reactor will be described.

[0283] Equation 2 is used to calculate the rate of the first-order deactivation process:

[0284] (Equation 2)

[0285] where r is the reaction rate, k d is the deactivation rate constant, and t is the time. Since the deactivation rate constant represents the characteristic time (ns) for the site to decay, the concentration of the stoichiometric titrant is given by Equation 3:

[0286] (Equation 3)

[0287] Where t is the time since the start of deactivation, dt is the decay interval, and F0 is the flow rate of the gas through the catalyst bed. For the above reaction conditions, this provides an estimate of the titrant molecule concentration shown in Table 2 below. The data in Table 2 illustrate the purity levels required to maintain extremely high rates in the reactant stream, which are achieved by using chemical treatments and by using high surface area catalysts with a high area density of active sites (exposed by such chemical cleaning treatments). It should be noted that the purity levels required in the present disclosure are sensitive and should be controlled to maintain low oxygen concentrations.

[0288] Table 2: Estimated concentrations of titrant molecules

[0289]

[0290] Example 14: Activation-deactivation of ZrO2 (Example 1a) and Y-ZrO2 (Example 2) materials in the presence of a trap based on initial processing conditions

[0291] He treatment (at 723 K) resulted in lower propane dehydrogenation rates than the same sample treated with DME (at 723 K) prior to the reaction. The rate after He treatment was found to increase with run time because product propylene molecules partially exposed titration sites from bound species that could not be removed by the inert He at the same temperatures used for propane dehydrogenation. The rate stabilized with time as a steady-state was reached between site cleaning by reaction products and site titration by residual O₂ or HO (at sub-ppm levels) in the feed stream. In other words, the rate at which HO entered and titrated to the site matched the rate at which such titrants could be removed via chemical reactions for any given propylene concentration (defined by propane conversion). In contrast, material initially treated with DME (at 723 K) exhibited a dehydrogenation rate that decreased with run time because residual O₂ or HO (at sub-ppm levels) in the feed stream titrated to the site, until the same steady-state was reached between site cleaning (activation) and titration (deactivation). For identical experimental conditions, the steady-state rates are equivalent after each treatment and for each material, but the pathways to this steady state start at higher or lower rates, depending on the initial extent of dehydroxylation caused by the initial treatment in He or DME. These steady-state rates are lower at higher inlet HO levels than at lower inlet HO levels, demonstrating the need to control purity levels in the reactant streams. This demonstrates the requirement for rigorous removal of the titrant or its precursors to achieve higher steady-state reaction rates, as well as the benefit of the DME treatment, which allows for a greater amount of catalytic turnover before both samples reach steady-state rates (as indicated by the integrated area between the two curves). These are seen in Figure 13 and 14 , which shows that this is the case for both YZr and Zr oxides.

[0292] Example 15: Effect of Oxygen Trap on Catalyst Self-Activation and Deactivation at 723 K and 873 K

[0293] The presence of an oxygen trap enables self-activation at both 723 K and 873 K. Bypassing the oxygen trap reduces the reaction rate because the concentration of titrant in the feed stream increases, suppressing the dehydrogenation reaction. After cleaning the reactant stream, the rate increases because the reaction products act as cleaning agents. This reflects the new steady-state degree of dehydroxylation imposed by the higher impurity levels when the inlet stream bypasses the trap and can be explained in Figure 15 In Figure 15 In the example, the oxygen trap was bypassed at the indicated location, which showed a lower dehydrogenation rate. Figure 15It is further shown that due to the lower titrant / impurity introduction rate, a higher steady-state rate of impurity removal is achieved. This equilibrium is achieved by the removal of impurities by propylene during the reaction at a temperature at which propylene becomes competent, making propylene an inherent chemical dehydroxylation agent formed during propane dehydrogenation.

[0294] Example 16: Effect of Oxygen Trap on Propane Dehydrogenation Rate When Reaction Temperature Increases from 723 K to 873 K

[0295] exist Figure 16 In , the propane dehydrogenation rate over ZrO2 was measured during propane dehydrogenation at an increasing temperature from 723 K to 873 K, where the reactant stream passed through an oxygen trap under the following reaction conditions: 15 kPa C3H8, 5 kPa H2. With increasing dehydrogenation reaction temperature, the reaction rate has been found to increase, as Figure 16 This study combines the effect of temperature on reaction rate with catalyst self-activation of the reaction products, which becomes more effective as temperature increases. Lowering the temperature back to 723 K resulted in higher dehydrogenation rates than those measured at 723 K before the experiment at 873 K, indicating that the propylene reaction products act as competent dehydroxylation agents at these higher temperatures. The presence of an oxygen trap prevents catalyst deactivation and enables the catalyst to achieve higher steady-state dehydrogenation rates.

[0296] Example 17: Representative Propane Dehydrogenation Rates with and without Oxygen Traps According to Embodiments of the Disclosure at Different Temperatures and for Different Catalysts

[0297] Table 3 shows a comparison of propane dehydrogenation rates.

[0298] Table 3: Comparison of propane dehydrogenation rates

[0299]

[0300] Sample E1 is a sample prepared according to Example 1a;

[0301] Sample E2 is a sample prepared according to Example 2;

[0302] Sample E3 is a sample prepared according to Example 3;

[0303] Sample E4 is a commercially available Al2O3 material: Catalox SBa-200 from Sasol

[0304] S1, S2, and S4 are samples prepared as according to Pan et al. (US 2009 / 0325784);

[0305] S5 is a sample prepared according to Zhang et al., “Control of Coordinatively Unsaturated Zr Sites in ZrO2 for Efficient C—H Bond Activation.”

[0306] Example 18: Pre-reduction using a reducible oxide

[0307] For reducible oxides such as Ce-ZrO2 (Ce-Zr ratio 1:6), a reduction pretreatment (e.g. with H2 at 723 K) is required before DME treatment of the clean sites, otherwise the reduction of the reducible components of the catalyst under the dehydrogenation reaction conditions leads to the formation of H2O during alkane dehydrogenation, which titrates the active LAB sites and deactivates the catalyst. The results of this study are presented in Figure 17 After the first DME treatment, the catalyst rapidly deactivated due to the reduction of CeO₂ during dehydrogenation, resulting in water formation and active site titration. After the titration sites were cleaned by a second DME treatment, the deactivation rate decreased because Ce had been reduced and no additional water formation was present. The same effect was observed when the catalyst was oxidized and then subsequently treated with DME (panels 3 and 4 compared to panels 1 and 2). However, if a reduction treatment (CeO₂ is reduced and the formed water is removed by the DME treatment) was performed after oxidation but before DME treatment, the deactivation rate was even lower (panel 5) because all CeO₂ had already been reduced during the reduction treatment and no water was formed during dehydrogenation.

[0308] Example 19: Increased reaction rate by chemical cleaning is not caused by reduction of the oxide catalyst

[0309] The test was performed in the absence of an oxygen trap during the purge period. It was found that the rate increase by DME treatment could not be increased by He or H2 treatment. This test was performed to compare the chemical treatments proposed so far in the literature, namely, reduction treatment of the surface with dehydroxylation methods.

[0310] As in Figure 18 It can be seen that surface reduction treatment is not beneficial for cleaning metal oxides. Figure 18, shows the propane dehydrogenation rates after treatment with DME, He, and H2 under the following conditions: 13.7 kPa propane, 723 K. The sample according to Example 1a of the present application, along with S5 as described in Table 3 above, was treated with H2. After treatment, the material's activity was less than that after treatment with DME or He. Therefore, the inventors believe this indicates that the material's activity is not due to reduced metal centers, but rather to exposed Lewis acid-base pairs on the surface. Oxygen traps in the catalyst keep the surface clean.

[0311] The inventors estimated the activity of the comparative examples based on literature thermodynamic data, which confirmed that the metal cations of the metal oxide materials were unlikely to be reduced.

[0312] Under the conditions of the present dehydrogenation reaction, the formation of oxygen vacancies by reaction with hydrogen to form water is unlikely. The required reduction potentials for these oxides (described as the ratio of H2 to HO) were calculated by extracting DFT-derived oxygen vacancy formation energies from the literature. The remaining energy required to form water from molecular H2 and diatomic O was calculated from a tabulated thermochemical database. Combining these values ​​enabled the prediction of the free energy of the reaction at 873 K and the subsequent equilibrium constant, which was used to derive the ratio of H2 to HO required for O removal. Calculations were performed using Equations 4 to 7 presented below.

[0313] M (Equation 4)

[0314] (Equation 5)

[0315] (Equation 6)

[0316] Among them, the National Institute of Standards and Technology (NIST) and Stull, Westrum, and Sinke “The chemicalthermodynamics of organic compounds” (Stull) give:

[0317] (Equation 7)

[0318] The resulting H2 to H2O ratios required to facilitate oxygen removal from the lattice to form active sites are shown in Table 4. Thus, it can be confirmed that oxygen removal from the lattice to form vacancies is unlikely under the dehydrogenation reaction or pretreatment conditions. As can be seen in Table 4, the ratios are very high and cannot be achieved using any of the available water removal protocols. In fact, for at least the first four samples in Table 2, this ratio requires less than one molecule of water (10-27 of the order of magnitude).

[0319] Table 4: Oxygen vacancy generation energy and H2 / H2O ratio required for vacancy generation

[0320]

[0321] 5 Refers to Puigdollers et al. “Increasing Oxide Reducibility: The Role of Metal / Oxide Interfaces in the Formation of Oxygen Vacancies.” Acs Catal 2017, 7, 6493-6513

[0322] 6 Refers to Zheng et al. “Native Point Defects in Yttria and Relevance to Its Use as a High-Dielectric-Constant Gate Oxide Material: First Principles Study” Physical Review B 2006, 73

[0323] 8 Lawler et al. "CeO2 (111) Surface with Oxygen Vacancy for Radical Scavenging: A Density Functional Theory Apprach." J. Phys. Chem C 2020, 124, 20950-20959

[0324] E f is the DFT-derived electron energy required to remove each O atom from a stoichiometric oxide in its highest oxidation state.

[0325] Example 20: Hydrogenation of unsaturated hydrocarbons

[0326] As described herein, the present application involves avoiding contact with impurities to prevent deactivation of Lewis acid-base active sites by titrating the most competent active centers of the dehydrogenation process. It has been surprisingly discovered that these considerations can also be applied to the reverse reaction. This is believed to be possible because both processes involve the same rate-limiting step and transition state, but traverse the reaction coordinate in opposite directions. (Gounder et al. "Catalytic Hydrogenation of Alkenes on Acidic Zeolites: Mechanistic Connections to Monomolecular Alkane Dehydrogenation Reactions," J Catalyst 2011, 277, 36-45). This extension applies to the following systems:

[0327] • The metal oxide Lewis acid-base pairs that dehydrogenate alkanes can also dehydrogenate unsaturated hydrocarbons (such as alkenes and alkynes, Figure 19-21 The two reactions are thermodynamically linked because they meet the strict criteria for hydrogenation and dehydrogenation chemistry of Lewis acid-base pairs.

[0328] • For each given hydrogenation-dehydrogenation pair (e.g., an alkane-alkene pair), the rates of dehydrogenation to hydrogenation (and their pressure dependence) reflect the gas-phase thermodynamics of their interconversion reaction, thus enabling prediction of the rate of the reverse reaction.

[0329] • Competent thermochemical treatments (e.g., DME, 723 K) and stream cleaning schemes that increase the reaction rate of dehydrogenation reactions also increase the rate of hydrogenation reactions, but may be less necessary if the reactant is also a chemical activator (e.g., an olefin).

[0330] For example, a representative reaction is the hydrogenation of propylene over a monoclinic ZrO2 catalyst. The rate is first order with respect to both propylene and hydrogen pressure ( Figure 19 and 20 ), which is consistent with the reaction rate equation:

[0331] (Equation 8)

[0332] Using the above knowledge about the reversibility of the mechanism requiring essentially bare sites and proceeding through the same kinetically related transition state, the rates of hydrogenation and dehydrogenation can be related to the reverse reaction through the gas-phase reaction equilibrium constant according to Equation 9:

[0333] (Equation 9)

[0334] The Lewis acid-base pair shown here as an example meets this stringent requirement, and thus the propylene hydrogenation rate can be predicted from the propane dehydrogenation rate ( Figure 21 ), and are in good agreement with the hydrogenation rates measured for ZrO2 catalysts (circles). The measured barriers for each reaction (84 and −48 kJ mol -1 ) and the heat of reaction (130 kJ mol -1 ) are consistent.

Claims

1. A method for treating a reactant stream, the method comprising: Use MO x a catalyst and a trap to treat the reactant stream, wherein the trap removes impurities from the reactant stream, the impurities comprising oxygen (O2), water (H2O), hydrogen sulfide (H2S), carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), sulfur-containing compounds, methanol, ketones, inorganic nitrogen compounds, organic nitrogen compounds, oxygen-containing compounds, or combinations thereof; Among them, the MO x The catalyst has a surface with MO sites that are Lewis-type and have balanced acid-base strengths, and Among them, the MO x The catalyst has a BET surface area of ​​at least about 75 m2 / g.

2. The method according to claim 1, wherein This impurity is removed from the reactant stream prior to contacting the catalyst composition during the hydrogenation or dehydrogenation process.

3. The method according to claim 1 or 2, wherein The MO x The surface of the catalyst stabilizes the anionic and / or cationic moieties formed in the transition state of the heterolytic process of forming and breaking CH bonds.

4. The method according to any one of claims 1 to 3, wherein The MO x The metal (M) of the catalyst does not undergo reduction to a lower oxidation state in the reducing environment of typical hydrogenation-dehydrogenation catalysis.

5. A method as claimed in any one of the preceding claims, wherein The process operates at impurity levels of less than about 2 ppm.

6. The method according to any one of claims 1 to 4, wherein The method operates at no more than 100 ppm, no more than 50 ppm, or no more than 20 ppm of impurities.

7. A method as claimed in any one of the preceding claims, wherein The reactant stream has an oxygen content of at most 5 ppm, at most 1 ppm, or at most 0.2 ppm.

8. A method as claimed in any one of the preceding claims, wherein The MO x The surface area of ​​the catalyst is related to the MO x Proportional to the amount of active material of the catalyst.

9. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst comprises a crystalline active component, wherein when the surface area of ​​the crystalline active component decreases, the MO x The density of active sites of the catalyst is reduced.

10. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst is substantially free of hydroxyl groups.

11. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst does not contain hydroxyl groups.

12. A method as claimed in any one of the preceding claims, wherein The trap is an oxygen trap, a water trap, a carbon dioxide trap, or a combination thereof.

13. A method as claimed in any one of the preceding claims, wherein The surface with Lewis-type MO sites having balanced acid-base strengths is maintained during the dehydrogenation or hydrogenation process by avoiding titration with the impurities.

14. A method as claimed in any one of the preceding claims, wherein The treatment is carried out at a temperature of approximately 500-900 K.

15. A method as claimed in any one of the preceding claims, wherein The treatment is carried out at temperatures up to 900 K.

16. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst comprises a metal oxide having a metal center in the form of a cation.

17. The method according to any one of claims 1 to 15, wherein The MO x The catalyst comprises a metal oxide comprising a cation that is not reducible to a zero valence state.

18. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst includes a metal selected from the group consisting of zirconium (Zr), cobalt (Co), gallium (Ga), zinc (Zn), cerium (Ce), yttrium (Y), and titanium (Ti).

19. A method as claimed in any one of the preceding claims, wherein The MO x The catalyst includes one or more of Mg, Ca, Sr, Ba and La on a zirconia support.

20. The method of any one of claims 1 to 15, wherein The MO x The catalyst includes ZrO2-silica, Zr-Al, Zr-Ti, or a combination thereof.

21. The method of any one of claims 1 to 15, wherein The MO x The catalyst includes ZrO2, t-ZrO2, m-ZrO2, Y-stabilized ZrO2, or Y2O3.

22. The method of any one of claims 1 to 21, further comprising cleaning the MO with a surface cleaning agent. x catalyst.

23. The method of claim 22, wherein: The surface cleaning agent includes dimethyl ether, propylene, ethylene, methanol, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, anisole, dimethyl carbonate, or a combination thereof.

24. The method of claim 22, wherein: The surface cleaning agent includes dimethyl ether.

25. The method of claim 22, wherein: The surface cleaning reagent includes methanol.

26. The method of claim 22, wherein: The surface cleaning agent includes an olefin.

27. The method of claim 22, wherein: The surface cleaning agent includes acrylic.

28. The method of claim 22, wherein: The surface cleaning reagent is a product stream.

29. The method of any one of claims 1 to 21, further comprising cleaning the MO during the dehydrogenation or hydrogenation reaction by balancing water deposition and water removal via the olefin product at a temperature of about 800-900 K. x catalyst.

30. The method of any one of claims 22 to 27, wherein The cleaning is performed at a temperature between approximately 323 K and 900 K.

31. A method of using MO x A method for catalyzing a reaction using a catalyst composition comprising a catalyst and a trap, the method comprising activating and / or reactivating the catalyst composition using the method of any one of claims 1 to 30, wherein the reaction is selected from the group consisting of: alkane dehydrogenation, olefin hydrogenation, olefin-paraffin alkylation, from a CO / H2 mixture without O-rejection such as H2O or CO2, C-C bond formation via olefin oligomerization or metathesis, dehydrocyclization (conversion of alkanes / olefins to aromatics), dehydrocyclization dimerization (conversion of alkanes / olefins to aromatics with a larger number of C atoms), transfer hydrogenation, hydroformylation / carbonylation, aromatization, dearomatization, reforming, isomerization, and bifunctional reactions in which one of the above functional groups can be combined with a Bronsted acid functional group.

32. The method of claim 31, wherein The reactant stream is treated with the trap concurrently with the catalytic reaction.

33. The method of claim 31 or 32, wherein: This reaction is the dehydrogenation of an alkane.

34. The method of claim 31 or 32, wherein: The reaction is the hydrogenation of olefins.

35. The method of any one of claims 31 to 34, wherein The MO x The catalyst comprises a metal oxide having a metal center in the form of a cation.

36. The method of any one of claims 31 to 34, wherein The MO x The catalyst comprises a metal oxide that is not reducible to a zero valent state.

37. The method of any one of claims 31 to 34, wherein The MO x The catalyst includes a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, and Ti.

38. The method of any one of claims 31 to 37, wherein The catalyst composition increases product yield by at least 2-fold compared to a comparable reaction using a catalyst composition that does not include a trap.

39. The method of any one of claims 31 to 37, wherein The method further comprises cycling between actively dehydrogenating light alkane gas or hydrogenating light olefin gas using the catalyst composition and reactivating the catalyst composition.

40. A catalyst composition comprising: MO having a surface with MO sites and a BET surface area of ​​at least about 50 m2 / g x catalyst, the MO site is Lewis type and has balanced acid-base strength, The catalyst composition does not contain at least one of chromium or precious metals.

41. The catalyst composition of claim 40, wherein The MO x The catalyst comprises a metal oxide having a metal center in the form of a cation.

42. The catalyst composition of claim 40, wherein The MO x The catalyst comprises a metal oxide that is not reducible to a zero valent state.

43. The catalyst composition of claim 40, wherein The MO x The catalyst includes a metal selected from the group consisting of Zr, Co, Ga, Zn, Ce, Y, and Ti.

44. The catalyst composition of claim 40, wherein The MO x The catalyst includes ZrO2.

45. The catalyst composition of claim 44, comprising at least about 25 wt% ZrO2 based on the total weight of the catalyst composition.

46. ​​The catalyst composition of claim 40, further comprising a rare earth metal comprising at least one lanthanide metal, an oxide thereof, or a combination thereof.

47. The catalyst composition of claim 40, further comprising a rare earth metal, the rare earth metal comprising at least one of Y, erbium (Er), Ce, dysprosium (Dy), gadolinium (Gd), lanthanum (La), neodymium (Nd), samarium (Sm), ytterbium (Yb), oxides thereof, or mixtures thereof.

48. The catalyst composition of claim 46 or 47, comprising from about 0.5 wt% to about 50 wt% of the rare earth metal.

49. The catalyst composition of claim 40, further comprising a trap.

50. The catalyst composition of claim 49, wherein The trap is an oxygen trap, a water trap, a carbon dioxide trap, or a combination thereof.

51. The catalyst composition of claim 40, wherein The catalyst composition has been cleaned and contains more surface active sites than before cleaning.

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