Process for producing carboxylic acids or alkyl esters

Abstract

The present invention generally relates to a gas phase process for producing carboxylic acids or alkyl esters. In one embodiment, the gas phase process for producing carboxylic acids or alkyl esters includes: (a) providing a catalyst support, the catalyst support comprising a deposit of cobalt thiocyanate on at least a portion of the catalyst support; (b) heating the catalyst support to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst; and (c) reacting an alkene gas, steam or an alkanol gas, and a carbon-containing gas in a reactor in the presence of the supported cobalt sulfide catalyst to form a product stream, the carbon-containing gas comprising carbon monoxide or a mixture of carbon monoxide and carbon dioxide, where when steam is used as a reactant, the product stream comprises carboxylic acids, and when alkanol gas is used as a reactant, the product stream comprises alkyl esters.

Description

[[Technical Field]]

[0001] The present invention generally relates to a gas phase process for producing carboxylic acids or alkyl esters. [[Background Art]]

[0002] Carboxylic acids such as propionic acid are important intermediates for the synthesis of many oxygenates that find use in herbicides, food preservatives, plastics, plasticizers, and cosmetics.

[0003] Various methods for producing carboxylic acids are known. Taking propionic acid as an example, one commercial process relies on liquid-phase hydrocarboxylation of ethylene. In this process, ethylene, carbon monoxide (CO) and water are directly converted into propionic acid under harsh reaction conditions (e.g., 250 to 320°C and 100 to 300 bar) in the presence of a highly toxic Ni(CO)4 catalyst.

[0004] A second liquid-phase process for producing carboxylic acids uses olefin hydroformylation followed by oxidation of the aldehyde to produce the carboxylic acid. In this commercially practiced two-step reaction process for producing propionic acid, propanal is produced via hydroformylation of ethylene in the first step, and propanal is oxidized to propionic acid in the second step ("Ullmann's Encyclopedia of Industrial Chemistry" Vol. 30, pp. 295-311 (2012)).

[0005] Another route for producing carboxylic acids is the direct oxidation of hydrocarbons ("Ullmann's Encyclopedia of Industrial Chemistry" Vol.30, pp.295-311 (2012)). Direct oxidation of hydrocarbons can also be used to produce propionic acid as a byproduct during acetic acid synthesis from naphtha ("Ullmann's Encyclopedia of Industrial Chemistry" Vol.30, pp.295-311 (2012)).

[0006] One-step liquid-phase hydrocarboxylation of ethylene offers advantages in ethylene yield compared to the two-step hydroformylation / oxidation pathway. However, its industrial use is limited due to the costs and risks associated with operating high-pressure reactors using corrosive and toxic nickel carbonyl catalysts.

[0007] The processes described above relate to reactions in the liquid phase. Published literature on gas-phase hydrocarboxylation is limited. Early studies described the formation of carboxylic acids by mixing water vapor with CO and olefins. Examples of catalysts include charcoal (see U.S. Patent No. 2,089,903), ZnCl (see U.S. Patent No. 1,924,767), and tungsten oxide (see U.S. Patent No. 2,008,348), and in all cases, the catalyst was used in combination with a metal halide. These studies cover a pressure range of 25–900 atmospheres, but the examples have been carried out at 600–700 atmospheres.

[0008] U.S. Patent No. 3,501,518 discloses that carbonylation reactions can be activated by palladium sulfide. The reaction is carried out in a liquid phase, at a temperature range of 30 to 180°C and a pressure of 5 to 100 MPa (49 to 987 atm), and requires the addition of a halide or co-catalyst, such as an acid and an organophosphine or nitrile.

[0009] Recently disclosed U.S. Patent No. 10,144,693 disclosed an improved gas-phase hydrocarboxylation process using a group VIII metal sulfide catalyst. This included bulk and supported catalysts that enabled high propionic acid selectivity. U.S. Patent No. 10,144,693 also described a method for preparing a cobalt sulfide catalyst.

[0010] Alkyl esters such as methyl propionate, n-propyl propionate, n-butyl propionate, and n-pentyl propionate are important solvents, among many other applications, found in lacquers, inks, paints, coatings, films, and fragrances.

[0011] Various methods are known for producing alkyl esters of aliphatic carboxylic acids, such as methyl methacrylate (MMA). One commercial method relies solely on the acetone cyanohydrin (ACH) technology, which involves reacting acetone with hydrogen cyanide to form ACH, followed by acid-assisted hydrolysis and methanol esterification to produce approximately 400 kilotons of MMA per year. While the ACH route has traditionally been the core technology used in the United States and other parts of the world, lower-cost alternative technologies are being considered for future capacity increases. Some of these alternative technologies are ethylene-based. One such method involves the hydroformylation of ethylene to propionaldehyde, followed by condensation to form methacrolein (MA), and then oxidation and esterification to form MMA. Another route is the alpha process, a two-step liquid-phase process in which methyl propionate is produced using a homogeneous palladium-based catalyst, and then condensed with formaldehyde in a second step to produce MMA. This process is described in International Publication No. 1999 / 021820. Other reports of homogeneous catalysts for liquid-phase carbonylation of ethylene to methyl propionate include U.S. Patent No. 3,507,891 (cobalt-pyridine catalyst), Chem. Commun., 2001, 47-48 (rhodium / β-ketophosphine catalyst), and J. Molecular Catalysis 40 (1987) 243-254, Hidai et al. (ruthenium-iodide catalyst).

[0012] One report of a heterogeneous catalyst operating in the gas phase is by Bhattacharyya, S.K. and Nag, S.N., Brennstoff-Chemie, Vol. 43, pp. 114-118 (1962). This study describes the use of metal iodides supported on silica gel to synthesize methyl propionate from ethylene, CO, and methanol in the gas phase. This process generates large amounts of undesirable by-products, oxygenated and hydrocarbon compounds, and operates at a pressure of 253 bar (25.3 MPa).

[0013] Recently, U.S. Patent No. 9,938,226 disclosed a gas-phase carbonylation process for producing alkylalkanoates using a group VIII metal sulfide catalyst. U.S. Patent No. 9,938,226 also described a method for preparing a cobalt sulfide catalyst.

[0014] In addition to the methods for preparing cobalt sulfide catalysts described in U.S. Patents 9,938,226 and 10,144,693, there are alternative approaches to preparing cobalt sulfide catalysts using additional organic ligands and / or air oxidation, as described in European Patent No. 0065028(A1) and Thermochimica Acta 425 (2005), pp. 13-21. However, such approaches may result in undesirable Co oxides. Russian Patent No. 2677285 attempts to use CoO and convert the oxide to a sulfide with hydrogen gas.

[0015] It is desirable to have alternative gas-phase processes for producing carboxylic acids and / or alkyl esters. [Overview of the project]

[0016] Embodiments of the present invention advantageously provide alternative gas-phase processes for producing carboxylic acids and / or alkyl esters. Such processes utilize supported cobalt sulfide catalysts prepared in a manner that offers numerous advantages. For example, the processes are versatile, and in some embodiments, catalysts can be prepared using various supports such as Al2O3, SiO2, carbon, and SiC. In some embodiments, carbonylation reactions can proceed using cobalt sulfide catalysts without the need for halides or other co-catalysts, and can proceed at moderate pressures. In some embodiments, cobalt sulfide catalysts can demonstrate promising performance in direct propionic acid synthesis, achieving high selectivity exceeding 98% and productivity comparable to or exceeding that of conventional bulk cobalt sulfide catalysts.

[0017] In one embodiment, a gas-phase process for producing a carboxylic acid or alkyl ester is (a) To provide a catalyst support wherein the catalyst support comprises a deposit of cobalt thiocyanate on at least a portion of the catalyst support, and the catalyst support comprises 5 m 2 To provide a material having a surface area exceeding / g (b) Heating the catalyst support to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst, (c) Reacting an alkene gas, water vapor or alkanol gas and a carbon-containing gas in a reactor in the presence of a supported cobalt sulfide catalyst to form a product stream, wherein the carbon-containing gas includes carbon monoxide or a mixture of carbon monoxide and carbon dioxide. When water vapor is used as a reactant, the product stream contains a carboxylic acid; when alkanol gas is used as a reactant, the product stream contains an alkyl ester.

[0018] These and other embodiments are described in more detail in “Modes for Carrying Out the Invention.” [Modes for carrying out the invention]

[0019] This disclosure relates, in general, to a gas-phase process for producing carboxylic acids or alkyl esters. The process utilizes supported cobalt sulfide prepared in a manner that offers many advantages. Generally, a catalyst support is provided with a deposit of cobalt thiocyanate on at least a portion thereof, and is then heated to convert the cobalt thiocyanate on the support to cobalt sulfide, forming a supported cobalt sulfide catalyst. As further described herein, such supported cobalt sulfide catalysts function well in the synthesis of carboxylic acids and alkyl esters, achieving high selectivity and productivity, particularly compared to conventional bulk cobalt sulfide catalysts.

[0020] All references to the periodic table of elements can be found in the CRC Handbook of Chemistry and Physics, 71. st This refers to the periodic table of elements published on pages 1-10 of Ed. (1990-1991). Any reference to a group refers to the group as it appears in the periodic table of that element using the IUPAC system for numbering groups. Unless otherwise stated, implied in the context, or customary in the art, all parts and percentages are based on weight, and all test methods are current as of the filing date of this disclosure. Due to U.S. patent practice, any referenced patent, patent application, or publication is incorporated by reference (or the entirety of its U.S. equivalent) particularly with respect to synthetic techniques, product and processing designs, polymers, catalysts, definitions (to the extent that they do not conflict with any definitions specifically provided in this disclosure), and general knowledge in the art.

[0021] Numerical ranges in this disclosure are approximations and, unless otherwise indicated, may include values ​​outside the range. Numerical ranges include all values, including lower and upper limits, in increments of one unit, provided that there is at least two units of separation between any lower and upper limit. For example, if a compositional, physical, or other property such as molecular weight or weight percentage is in the range of 100 to 1,000, it is intended that all individual values ​​such as 100, 101, 102, and sub-ranges such as 100 to 144, 155 to 170, and 197 to 200 be explicitly listed. For ranges that include values ​​less than 1 or fractions greater than 1 (e.g., 1.1, 1.5, etc.), one unit is considered to be 0.0001, 0.001, 0.01, or 0.1, where appropriate. For ranges that include single-digit numbers with fewer than 10 digits (e.g., 1 to 5), one unit is typically considered to be 0.1. These are merely examples of what is specifically intended, and all possible numerical combinations between the listed minimum and maximum values ​​should be considered expressly described in this disclosure. Numerical ranges are provided in this disclosure, in particular, with respect to the amounts of various reactants in the process of the present invention and the operating conditions of the process of the present invention.

[0022] As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are interchangeable. The terms “comprise,” “include,” and their variations are not restrictive when they appear in the specification and claims. Thus, for example, an aqueous composition containing “one” hydrophobic polymer particles may be interpreted as meaning that the composition contains “one or more” hydrophobic polymer particles.

[0023] As used herein, the term "ppmw" means parts per million by weight. When used to assess the concentration of a weakly basic amine, the phrase "ppmw (nitrogen basis)" is based on the weight of amine nitrogen divided by the total weight of the mixture. This separates the analysis from the molecular weight of the amine and focuses on the active group on the weakly basic amine. Amine nitrogen does not include nitrogen moieties that cannot react with acids, such as quaternary amines.

[0024] "Composition" and similar terms mean a mixture or blend of two or more constituent components.

[0025] "Hydroxycarbonylation conditions" and similar terms refer to the temperature, pressure, and other conditions required for an alkene, carbon monoxide, and water (one or more of these in at least partially gaseous form) to react with each other on and in contact with a solid sulfide-containing catalyst to form a carboxylic acid. In one embodiment, each of the alkene, CO, and water is in at least partially gaseous form. In another embodiment, each of the alkene, CO, and water is in fully or almost fully gaseous form.

[0026] The terms “halogen-free hydroxycarbonylation conditions” and similar terms mean hydroxycarbonylation conditions in which no form of halogen is present, or is essentially absent, in the space where alkene, CO, and water come into contact on a sulfide-containing catalyst to form a carboxylic acid. “Essentially absent” means, in the context of halogens, that any halogen present in the reaction space is present in an amount that does not substantially affect the conversion rate or selectivity of the reactants to the desired carboxylic acid. Such halogen sources may be, for example, from one or more of the feeds to the reaction or catalyst (e.g., as contaminants), or from the surface of a part of the apparatus. In one embodiment, “halogen-free” means less than 1,000 parts per million (ppm), preferably less than 10 ppm, and more preferably less than 1 ppm, based on the total weight of the reactants.

[0027] "Carbonylation conditions" and similar terms refer to the temperature, pressure, and other conditions required for alkenes, carbon monoxide, and alkanols (one or more of these being in at least partially gaseous form) to react with each other on and in contact with a solid sulfide-containing catalyst to form alkyl alkanoates. In one embodiment, each of the alkene, CO, and alkanol is in at least partially gaseous form. In one embodiment, each of the alkene, CO, and alkanol is in completely or almost completely gaseous form.

[0028] The terms “halogen-free carbonylation conditions” and similar terms mean carbonylation conditions in which no form of halogen is present, or is essentially absent, in the space where alkenes, CO, and alkanols come into contact on a sulfide-containing catalyst to form alkylalkanoates. “Essentially absent” means that any halogen present in the reaction space is present in an amount that does not substantially affect the conversion rate or selectivity of the reactants to the desired alkylalkanoate. Such halogen sources may be, for example, from one or more of the feeds to the reaction or catalyst (e.g., as contaminants), or from the surface of a part of the apparatus. In one embodiment, “halogen-free” means less than 1,000 parts per million (ppm), preferably less than 10 ppm, and more preferably less than 1 ppm, based on the total weight of the reactants.

[0029] "Condensation conditions" and similar terms refer to the temperature, pressure, and other conditions required for alkylalkanoates and aldehydes in gaseous form to react with each other on and in contact with a solid condensation catalyst to form alkyl esters of aliphatic carboxylic acids.

[0030] In one embodiment, a gas-phase process for producing a carboxylic acid or alkyl ester comprises (a) a catalyst support comprising a catalyst support comprising a deposit of cobalt thiocyanate on at least a portion of the catalyst support, and the catalyst support comprising 5 m 2A process comprising: (b) providing a catalyst having a surface area greater than / g, (c) heating a catalyst support to convert cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst, and (d) reacting an alkene gas, water vapor or an alkanol gas and a carbon-containing gas in a reactor in the presence of the supported cobalt sulfide catalyst to form a product stream, wherein the carbon-containing gas includes carbon monoxide or a mixture of carbon monoxide and carbon dioxide, wherein when water vapor is used as a reactant, the product stream contains a carboxylic acid, and when an alkanol gas is used as a reactant, the product stream contains an alkyl ester.

[0031] In some embodiments, a catalyst support containing a deposit of cobalt thiocyanate on at least a portion of the catalyst support is formed by contacting an aqueous solution of a cobalt(II) salt with the catalyst support in the presence of a thiocyanate anion, thereby depositing the aqueous solution on at least a portion of the catalyst support. Thus, in some embodiments, the process further includes contacting an aqueous solution of a cobalt(II) salt with the catalyst support in the presence of a thiocyanate anion, thereby depositing the aqueous solution on at least a portion of the catalyst support, thereby forming a catalyst support containing a deposit of cobalt thiocyanate. In some embodiments, the cobalt(II) salt in the presence of a thiocyanate anion is provided by first dissolving cobalt thiosulfate in water. In such embodiments, the process further includes dissolving cobalt thiosulfate in water to provide an aqueous solution of the cobalt(II) salt in the presence of a thiocyanate anion. This is particularly advantageous than providing cobalt to one compound and thiocyanate to another, because such an approach requires the removal of the anion associated with cobalt and the cation associated with thiocyanate. In some embodiments, the aqueous solution does not contain cations other than cobalt(II) in amounts exceeding 0.1 molar equivalents relative to cobalt, and the aqueous solution does not contain anions other than thiocyanate anions in amounts exceeding 0.1 molar equivalents relative to thiocyanate.

[0032] In some embodiments, when a catalyst support is heated to convert cobalt thiocyanate on the support to cobalt sulfide and form a supported cobalt sulfide catalyst, the catalyst support is heated to a temperature of 200°C to 550°C.

[0033] In some embodiments, the process of the present invention further includes heating the catalyst support to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst, and drying the catalyst support containing the cobalt thiocyanate deposit on at least a portion of the catalyst support at a temperature of 150°C or less under inert conditions.

[0034] In some embodiments, the catalyst support is heated to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst outside the reactor, and the process further includes adding the supported cobalt sulfide catalyst to the reactor. In other embodiments, the catalyst support is heated inside the reactor to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst.

[0035] In some embodiments, the process of the present invention further includes passivating the supported cobalt sulfide catalyst with a diluted oxygen stream containing up to 2 volume percent of O2 at a temperature of 25°C or below. In some embodiments, for example, if the supported cobalt sulfide catalyst is formed in the reactor, the passivation step may not be necessary.

[0036] In some embodiments, the alkene gas is ethylene.

[0037] In some embodiments, the film of the present invention is continuous.

[0038] In some embodiments where the product stream contains a carboxylic acid, the carboxylic acid selectivity is 80 mol% or more. In some embodiments where the product stream contains an alkyl ester, the alkyl ester selectivity is 80 mol% or more.

[0039] In some embodiments, the reaction for forming a carboxylic acid or an alkyl ester, for example, reacting an alkene gas, water vapor or alkanol gas, and a carbon-containing gas in the presence of a supported cobalt sulfide catalyst to form a product stream, occurs in a reactor at a pressure of 0.1 MPa to 10 MPa.

[0040] Supported cobalt sulfide catalyst The catalyst used in the gas phase process of the present invention is a supported metal sulfide catalyst.

[0041] The supported cobalt sulfide catalyst used in embodiments of the present invention can be advantageously prepared by first forming a catalyst support comprising a deposit of cobalt thiocyanate on at least a portion of the catalyst support. In various embodiments, different catalyst supports can be used. In general, the catalyst support should have sufficient mechanical strength and surface properties for use under the reaction conditions described herein. With respect to mechanical strength, in some embodiments, the catalyst support has a crushing strength of greater than 2 pounds per millimeter. With respect to surface area, the catalyst support has a surface area of 5 m 2 per gram or more. In some embodiments, the catalyst support has a surface area of 10 m 2 per gram or more, in a preferred embodiment 50 m 2 per gram or more, in a more preferred embodiment 100 m 2 per gram or more. In some embodiments, the surface area of the catalyst support is more than 10 m 2 per gram up to a maximum of 800 m 2 per gram. As used herein, the surface area of a catalyst support is measured by nitrogen adsorption at 77.4 K using conventional techniques on a Micromeritics ASAP 2420 instrument. Prior to adsorption measurement, the sample is degassed in vacuum at 300°C for at least 3 hours. The surface area is calculated using the BET method known to a person skilled in the art.

[0042] In some embodiments, the catalyst support can be alumina, carbon, silicon carbide, silica, silica-alumina, hafnia, zirconia, titania, and mixtures thereof.

[0043] Next, the catalyst support is brought into contact with an aqueous solution of cobalt(II) salt in the presence of thiocyanate anions to deposit the aqueous solution onto at least a portion of the catalyst support. In some embodiments, cobalt thiosulfate is first dissolved in water to provide an aqueous solution of cobalt(II) salt in the presence of thiocyanate anions, which is then brought into contact with the catalyst support.

[0044] The cobalt(II) salt in the presence of the thiocyanate anion is first provided by dissolving cobalt thiosulfate in water. In such embodiments, the process further comprises dissolving cobalt thiosulfate in water to provide an aqueous solution of the cobalt(II) salt in the presence of the thiocyanate anion. This is particularly advantageous than providing cobalt to one compound and thiocyanate to another, because such an approach requires the removal of the anion associated with cobalt and the cation associated with thiocyanate.

[0045] When the coated catalyst support is brought into contact with an aqueous solution of cobalt(II) salt in the presence of a thiocyanate anion, it can be dried to remove substantially all of the water. For example, in some embodiments, the coated catalyst support can be dried under inert conditions for 2 to 5 hours at a temperature below 150°C. Once dried, the catalyst support contains a deposit of cobalt thiocyanate on at least a portion of the catalyst support.

[0046] Next, the catalyst support containing the cobalt thiocyanate deposit is heated to convert the cobalt thiocyanate on the support to cobalt sulfide, thereby forming a supported cobalt sulfide catalyst. In some embodiments, the catalyst support is heated at a temperature of 200°C to 550°C to convert the cobalt thiocyanate to cobalt sulfide. In some embodiments, the catalyst support is heated in an inert gas stream at a temperature of 200°C to 550°C to convert the cobalt thiocyanate on the support to cobalt sulfide. In some embodiments, the catalyst support can be heated in a reactor (where a carboxylic acid or alkyl ester is formed) to convert the cobalt thiocyanate on the support to cobalt sulfide. In other embodiments, the catalyst support may be heated outside the reactor and then supplied to the reactor at an appropriate time for use in the reaction.

[0047] In some embodiments, the process of the present invention further includes passivating the supported cobalt sulfide catalyst with a diluted oxygen stream containing up to 2 volume percent of O2 at a temperature of 25°C or below. Passivating the supported cobalt sulfide catalyst can help avoid over-oxidation of cobalt sulfide particles and protect the catalyst before use. In some embodiments, for example, if the supported cobalt sulfide catalyst is formed in the reactor, the passivation step may not be necessary.

[0048] Cobalt sulfide can contain numerous phases. In some embodiments, cobalt sulfide is CoS2, Co4S3, Co3S4, CoS, Co7S8, Co9S8, Co 1-x The formula includes S (wherein x is 0.2 or less), or a combination thereof. Much of the cobalt sulfide on the catalyst support may be crystalline, but in some embodiments, at least a portion of the cobalt sulfide may be amorphous.

[0049] In some embodiments, the catalyst support includes alumina, carbon, silicon carbide, silica, silica-alumina, halfnia, zirconia, titania, or mixtures thereof.

[0050] In some embodiments, the bulk sulfur to cobalt atom ratio in cobalt sulfide is 0.3 or higher. In some embodiments, the bulk sulfur to cobalt atom ratio in cobalt sulfide is 0.75 or higher. In some embodiments, the bulk sulfur to cobalt atom ratio in cobalt sulfide is up to 2.0.

[0051] In some embodiments, the cobalt content in the supported cobalt sulfide catalyst is 5% to 50% by weight, based on the total weight of the supported cobalt sulfide catalyst.

[0052] In some embodiments, the cobalt oxide content in the supported cobalt sulfide catalyst is less than 5% by weight, based on the total content of cobalt oxide and cobalt sulfide.

[0053] Production of carboxylic acids Reactants In the production of carboxylic acids according to some embodiments of the gas-phase process of the present invention, the reactants are an alkene gas, water vapor (i.e., gaseous water), and a carbon-containing gas, the carbon-containing gas comprising carbon monoxide or a mixture of carbon monoxide and carbon dioxide. The alkene gas may contain either a monoolefin or a polyolefin, i.e., two or more double bonds. Monoolefin alkenes are of formula C n H 2n The formula is such that n is an integer greater than 1, typically 2 to 8, more typically 2 to 6. In some embodiments, n is 2 (i.e., the alkene is ethylene). In some embodiments, mixtures of alkenes can be used. For example, commercially available alpha-olefins containing four or more carbon atoms may contain small amounts of the corresponding internal olefin and / or their corresponding saturated hydrocarbons, and such commercially available alkenes do not necessarily need to be purified from them before use.

[0054] The carbon-containing gas may be carbon monoxide or a mixture of carbon monoxide and carbon dioxide. In some embodiments, the carbon-containing gas is carbon monoxide. In such embodiments, carbon monoxide can be used as is or in combination with one or more other gases that are inert to the reaction reagents, products, and by-products under the reaction conditions. Such other gases include, but are not limited to, nitrogen and noble gases.

[0055] The terms "alkene" and "olefin" are used interchangeably herein. Exemplary alpha and internal olefins include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 2-butene, 2-methylpropene (isobutylene), 2-methylbutene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, cyclohexene, butadiene, styrene, 1,4-hexadiene, 1,7-octadiene, as well as alkyl alkenoates, alkenyl alkanoates, alkenyl alkyl ethers, alkenols, and alkenal. Like carbon monoxide, alkenes may contain other compounds such as impurities and contaminants. In the case of alkenes, some of these compounds may be present as a result of the process by which the alkene was formed. For example, methane-containing sources such as shale gas or natural gas can be converted to alkenes by techniques well known to those skilled in the art. Depending on the alkene production process, by-products such as CO, H2, CO2, and / or others may be present in the alkene. Therefore, in some embodiments, the gas-phase process of the present invention involves producing a carboxylic acid by contacting an alkene gas, carbon monoxide gas, water vapor, and a supported cobalt sulfide catalyst at a temperature greater than 250°C to 400°C under halogen-free hydroxycarbonylation conditions, provided that the alkene, preferably ethylene, is derived from a methane-containing source such as shale gas or natural gas.

[0056] Water (liquid or gaseous) may be pure or diluted. In some embodiments, water may be provided at least partially by any precursor that provides water, including alcohols, acids, and other oxygenated substances.

[0057] catalyst The catalyst used in the reaction is the supported cobalt sulfide catalyst described above.

[0058] Process conditions and equipment The process of the present invention is carried out in the gas phase on a solid catalyst. Therefore, in one embodiment, an alkene, a carbon-containing gas (e.g., CO), and water are introduced as gases and come into contact with each other on and in contact with the solid catalyst bed. The reactants can be introduced in one or more feed streams. In embodiments in which the carbon-containing gas contains carbon monoxide, the molar ratio of CO to alkene is typically at least 1:1, typically at least 3:1, more typically 3:1 to 50:1, and even more typically 3:1 to 15:1. The molar ratio of alkene to vapor is typically at least 0.1:1, more typically at least 0.5:1, more typically 0.1:1 to 10:1, and even more typically 0.2:1 to 2:1.

[0059] This process can be operated in either continuous mode or batch mode, but it is preferably operated in continuous mode.

[0060] The process temperature may be between 250°C and 450°C, 260°C and 400°C, or 280°C and 350°C. The total process pressure may be between 0.1 and 30 MPa, or between 1.5 and 6 MPa. The gas space velocity per hour of the process is typically 100 to 1,000,000 liters of gas feed per liter of catalyst per hour (L / L*), more typically 500 to 5,000 L / L*.

[0061] In one embodiment, the reaction takes place in a fixed-bed reactor. In one embodiment, the reactor is a tubular reactor. In a typical protocol, the temperature and pressure are slowly increased to the reaction conditions. The catalyst can be exposed to a feed containing an inert gas (such as nitrogen or helium), carbon monoxide, alkenes, water, optionally a small amount of sulfur-containing gas such as H2S, and any combination of the above. Examples of other sulfur-containing gases include, but are not limited to, mercaptans, thiophenes, dimethyl sulfide, and dimethyl disulfide. The feed gas may also contain impurities or contaminants, such as hydrogen. The effluent gas from the reactor can be analyzed by gas chromatography (GC) to determine the product composition and the amount of converted CO.

[0062] Manufacturing of alkyl esters Reactants In the production of alkyl esters according to some embodiments of the gas-phase process of the present invention, the reactants are an alkene gas, an alkanol gas, and a carbon-containing gas, wherein the carbon-containing gas includes carbon monoxide or a mixture of carbon monoxide and carbon dioxide. The alkene gas is of formula C n H 2n The formula is such that n is an integer greater than 1 (>), typically between 2 and 8, more typically between 2 and 6. In some embodiments, n is 2 (i.e., the alkene is ethylene). In some embodiments, mixtures of alkenes can be used. For example, commercially available alpha-olefins containing four or more carbon atoms may contain small amounts of the corresponding internal olefin and / or their corresponding saturated hydrocarbons, and such commercially available alkenes do not necessarily need to be purified from them before use.

[0063] The carbon-containing gas may be carbon monoxide or a mixture of carbon monoxide and carbon dioxide. In some embodiments, the carbon-containing gas is carbon monoxide. In such embodiments, carbon monoxide can be used as is or in combination with one or more other gases that are inert to the reaction reagents, products, and by-products under the reaction conditions. Such other gases include, but are not limited to, nitrogen and noble gases.

[0064] Alkanol (i.e., alcohol) gases typically contain one or more substituents such as cyano, carbonyl, alkoxy, or aryl groups. 1~8 These are alkanols. Exemplary alkanols include, but are not limited to, methanol, ethanol, propanol, 2-propanol, 2-butanol, t-butyl alcohol, and caprylic alcohol. For the purposes of the present invention, polyhydroxyl compounds (e.g., diols and sugars) are considered alkanols that can be used in the implementation of the present invention. Methanol is a particularly useful alkanol in some embodiments.

[0065] catalyst The catalyst used in the reaction is the supported cobalt sulfide catalyst described above.

[0066] Process conditions and equipment The process of the present invention is carried out in the gas phase on a solid catalyst. Therefore, in one embodiment, an alkene, a carbon-containing gas (e.g., CO), and an alkanol are introduced as gases and come into contact with each other on and in contact with the solid catalyst bed. The reactants can be introduced in one or more feed streams. In embodiments in which the carbon-containing gas contains carbon monoxide, the molar ratio of CO to alkene is typically at least 1:1, typically at least 3:1, more typically 3:1 to 50:1, and even more typically 3:1 to 15:1. The molar ratio of alkene to alkanol is typically at least 0.1:1, more typically at least 0.5:1, more typically 0.1:1 to 10:1, and even more typically 0.2:1 to 2:1.

[0067] This process can be operated in either continuous or batch mode, but it is typically and preferably operated in continuous mode.

[0068] The process temperature is typically 120°C to 450°C, more typically 250°C to 380°C, and even more typically 280°C to 340°C. The total process pressure is typically 0.1 to 20 MPa, more typically 1.5 to 6 MPa. The space velocity of this process is typically 100 to 1,000,000 liters of gas feed per liter of catalyst per hour (L / L*), more typically 500 to 5,000 L / L*.

[0069] In one embodiment, the reaction takes place in a high-pressure fixed-bed reactor. In one embodiment, the reactor is a tubular reactor. In a typical protocol, the temperature and pressure are slowly increased to the reaction conditions. The catalyst can be exposed to a feed consisting of an inert gas (such as nitrogen or helium), hydrogen, a small amount of H2S, carbon monoxide, olefins, alkanols, and any combination of the above. The effluent gas from the reactor is analyzed by gas chromatography (GC) to determine the product composition and the amount of CO converted.

[0070] In one embodiment of the gas-phase process of the present invention, ethylene, CO, and methanol are brought into contact with a supported cobalt sulfide catalyst and with the supported cobalt sulfide catalyst under carbonylation conditions to form methyl propionate.

[0071] Production of alkyl esters of aliphatic carboxylic acids In one embodiment of the present invention, an alkyl ester produced by the gas-phase process described above is condensed with an aldehyde to form an alkyl ester of an aliphatic carboxylic acid. When the alkyl ester is methyl propionate and the aldehyde is formaldehyde, the product is methyl methacrylate (MMA). The apparatus, conditions, and protocol for this condensation reaction are well known to those skilled in the art.

[0072] Examples of the inventions of this application include the following: [1] A gas phase process for producing a carboxylic acid or alkyl ester, (a) To provide a catalyst support, wherein the catalyst support comprises a deposit of cobalt thiocyanate on at least a portion of the catalyst support, and the catalyst support comprises 5 m 2 To provide a product having a surface area exceeding / g (b) Heating the catalyst support to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst, (c) Reacting an alkene gas, water vapor or alkanol gas and a carbon-containing gas in a reactor in the presence of the supported cobalt sulfide catalyst to form a product stream, wherein the carbon-containing gas includes carbon monoxide or a mixture of carbon monoxide and carbon dioxide. A process wherein, when water vapor is used as a reactant, the product stream contains a carboxylic acid, and when alkanol gas is used as a reactant, the product stream contains an alkyl ester. [2] The process according to [1], wherein the catalyst support, which includes a deposit of cobalt thiocyanate on at least a portion thereof, is formed by contacting an aqueous solution of a cobalt(II) salt with the catalyst support in the presence of a thiocyanate anion, thereby depositing the aqueous solution on at least a portion thereof. [3] The process according to [1] or [2] above, further comprising dissolving cobalt thiosulfate in water to provide the aqueous solution of the cobalt(II) salt in the presence of a thiocyanate anion. [4] The process according to any one of the above [1] to [3], wherein the aqueous solution does not contain cations other than cobalt(II) in an amount of 0.1 molar equivalents relative to cobalt, and the aqueous solution does not contain anions other than thiocyanate anions in an amount of 0.1 molar equivalents relative to thiocyanate. [5] The process according to any one of the above [1] to [4], wherein the catalyst support is heated at a temperature of 200°C to 550°C. [6] The process according to any one of [1] to [5] above, further comprising drying the catalyst support, which includes a deposit of cobalt thiocyanate on at least a portion of the catalyst support, at a temperature of 150°C or less under inert conditions before heating the catalyst support in step (b). [7] Up to 2 volume percent of O at temperatures below 25°C 2 The process according to any one of the above [1] to [6], further comprising passivating the supported cobalt sulfide catalyst with a dilution oxygen stream containing the above. [8] The cobalt sulfide is CoS 2 Co 4 S 3 Co 3 S 4、 CoS, Co 7 S 8 Co 9 S 8 Co 1-x A process described in any one of the above [1] to [7], including S (wherein x is 0.2 or less), or any combination thereof. [9] The process described in any one of the above [1] to [8], wherein the bulk sulfur-to-cobalt atom ratio is 0.3 or greater.

[10] The process according to any one of the above [1] to [9], wherein the catalyst support comprises alumina, carbon, silicon carbide, silica, silica-alumina, halfnia, zirconia, titania, or a mixture thereof, or the cobalt content in the supported cobalt sulfide catalyst is 5% to 50% by weight based on the total weight of the supported cobalt sulfide catalyst.

[11] The surface area of ​​the catalyst support is 10 m 2 / g~maximum 800m 2 The process described in any one of the above items [1] to

[10] , wherein the process is / g.

[12] The process according to any one of [1] to

[11] above, wherein the catalyst support is heated to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst outside the reactor, and the process further comprises adding the supported cobalt sulfide catalyst to the reactor.

[13] The process according to any one of the above [1] to [9], wherein the catalyst support is heated in the reactor to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst.

[14] The process according to any one of the above [1] to

[13] , wherein the carboxylic acid selectivity or alkyl ester selectivity is 80 mol% or more.

[15] The process according to any one of the above [1] to

[14] , wherein the alkene gas is ethylene or the process is continuous. Some embodiments of the present invention will be described in more detail in the following examples. [Examples]

[0073] All parts and percentages in the following examples are given by weight unless otherwise indicated. Unless otherwise specified, pressures are given as absolute pressures.

[0074] Catalyst synthesis Many catalysts are synthesized as described. The catalysts described as examples of the present invention can be used in gas-phase processes according to some embodiments of the present invention.

[0075] Example 1 of the present invention Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method. An impregnation solution of cobalt(II) thiocyanate in deionized water is prepared at a concentration of 2 moles. Then, 7.86 grams of 40-80 mesh size Al2O3 carrier (NORPRO SA31132) is placed in a porcelain dish, and 7.86 milliliters of the impregnation solution are added dropwise while gently shaking. The characteristics of the carrier are shown in Tables 1a-1b.

[0076] Tables 1a-1b show that the surface area of ​​the support was measured by nitrogen adsorption at 77.4 K using a conventional technique with a Micromeritics ASAP2420 instrument. Before adsorption measurement, the sample was degassed in a vacuum at 300°C for at least 3 hours. The surface area was calculated using the BET method known to those skilled in the art.

[0077] A porcelain dish containing the impregnated catalyst is placed in a stainless steel drum, where the catalyst is dried and then self-reduced in a stream of pure N2 (overhead flow 5.5 L / min) using the following procedure: The N2 stream is run at room temperature for 30 minutes, then increased from room temperature to 120°C at a rate of 2°C / min, held at 120°C for 2 hours, then increased from 120°C to 550°C at a rate of 3°C / min, held at 550°C for 4 hours, and then cooled to room temperature 20-25°C (24-48 hours). The catalyst is then passedivated in a 1 vol% O2 / N2 stream at room temperature (20-25°C) for 2 hours, and then the oxygen concentration in the gas stream is gradually increased to 21 vol% O2 / N2. Before opening the stainless steel drum, the catalyst is purged in 21 vol% O2 / N2 for 1 hour. The result is a black substance. The catalyst composition was determined by X-ray fluorescence (XRF) and X-ray diffraction (XRD), and the results are reported in Tables 2a and 2b.

[0078] Example 2 of the present invention Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method. The support is Al2O3 (NORPRO SA6173; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 9.14 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 8.226 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0079] Example 3 of the present invention Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method. The support is Al2O3 (NORPRO SA6178; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 6.8 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5.916 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0080] Example 4 of the present invention Catalyst Co X S y Al2O3-SiO2 is prepared by an initial wet impregnation method. The support is Al2O3-SiO2 (SASOL Siralox 1.5 / 140 in powder form; support properties are reported in Tables 1a-1b). The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 9.5 milliliters. After preparation, the catalyst was pelletized, pulverized, and sieved to a mesh size of 40-80. The catalyst composition was determined by XRF and XRD and is reported in Tables 2a-2b.

[0081] Example 5 of the present invention Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method. The support is Al2O3 (NORPRO SA6176; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 11.5 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0082] Embodiment 6 of the present invention Catalyst Co X S y Al2O3 is prepared by an initial wet impregnation method. The support is basic Al2O3 doped with 4.5% CaO and 1% MgO (NORPRO SA65169; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 10.68 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0083] Example 7 of the present invention Catalyst Co X S y / C is prepared by the initial wet impregnation method. The support is activated carbon (Norit GAS 610; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 12 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0084] Example 8 of the present invention Catalyst Co XS y / C is prepared by the initial wet impregnation method. The support is activated carbon (Sicat Catalyst Meso-C; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5.2 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0085] Example 9 of the present invention Catalyst Co X S y / SiO2 is prepared by the initial wet impregnation method. The support is SiO2 (NORPRO SS61138, support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 5 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 6.1 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0086] Example 10 of the present invention Catalyst Co X S y / SiO2 is prepared by the initial wet impregnation method. The support is SiO2 (Fuji Sliysia Cariact Q20C; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 5 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5.1 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0087] Example 11 of the present invention The CoXSy / SiO2 catalyst is prepared by the initial wet impregnation method. The support is SiO2 (Fuji Sliysia Cariact Q30C; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 5 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 6.1 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0088] Example 12 of the present invention Catalyst Co X S y / SiO2 is prepared by the initial wet impregnation method. The support is SiO2 (Fuji Sliysia Cariact Q40C; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 5 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5.1 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0089] Example 13 of the present invention Catalyst Co X S y / SiO2 is prepared by the initial wet impregnation method. The support is SiO2 (Fuji Sliysia Cariact Q10; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 10.2 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 10.2 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0090] Example 14 of the present invention Catalyst Co X S y / SiO2 is prepared by the initial wet impregnation method. The support is SiO2 (Fuji Sliysia Cariact Q20C; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 10.2 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 8.0 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0091] Example 15 of the present invention Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method. The support is Al2O3 (NORPRO CA 08408, support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 11.8 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 10 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0092] Example 16 of the present invention Catalyst Co X S yThe SiC catalyst is prepared by an initial wet impregnation method. The support is SiC (made of SiCat Catalyst; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 10.6 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0093] Example 17 of the present invention Catalyst Co X S y / ZrO2 is prepared by the initial wet impregnation method. The support is ZrO2 (NORPRO SZ31164, support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 11.3 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 4 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0094] Example 18 of the present invention Catalyst Co X S y / C is prepared by the initial wet impregnation method. The support is activated carbon (Sicat Catalyst Meso-C, support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 10.22 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0095] Example 19 of the present invention Catalyst Co X S y / TiO2 is prepared by the initial wet impregnation method. The support is TiO2 (NORPRO ST31119, support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method as used in Example 1 of the present invention is used. The mass of the support used is 11.22 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 5 milliliters. Drying and self-reduction are carried out in the same manner as in Example 1, but the final calcination temperature is 400°C (4 hours) instead of 550°C. Catalyst passivation is carried out in the same manner as in Example 1. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0096] Comparative Example 1 (Bulk Cobalt Sulfide Catalyst) A bulk cobalt sulfide catalyst having Co9S8 as the main crystalline phase is prepared at 60°C by a coprecipitation method using an aqueous solution of cobalt(II) acetate tetrahydrate (440 g of Co(CH3COO)2·4H2O, purchased from Sigma Aldrich) and an aqueous solution of ammonium sulfide (531.7 g of (NH4)2S, 20%, purchased from Sigma Aldrich) in 3200 ml of H2O.

[0097] After precipitation, the sample is allowed to mature at 60°C for 15 minutes, then cooled to room temperature. The final pH of the slurry is approximately 6.9. The resulting precipitate is washed three times with deionized water (500 ml per wash) and centrifuged at 6000 rpm for 15 minutes. The sample is then dried overnight (18 hours) in a vacuum oven at 60°C, heat-treated in a tubular furnace at 550°C for 1 hour under a flow of 50 ml / min of N2, and subsequently passivated at room temperature for 2 hours using 1% O2 / Ar. The BET surface area of ​​this sample, measured by N2ads / des, is 10.7 m². 2 The value is / g. According to XRD, the catalyst is Co 1-x The catalyst contains S and Co9S8 phases. Before testing, the catalyst is tabletized, crushed, and sieved to a mesh size of 40-80. The catalyst composition is determined by XRF and XRD and reported in Tables 2a-2b.

[0098] Comparative Example 2 Catalyst Co X S y Al2O2 is prepared by the initial wet impregnation method. The support is Al2O3 (NORPRO SA51161; support properties are reported in Tables 1a-1b). The support is crushed and sieved to a mesh size of 40-80. The same catalyst preparation method used in Example 1 of the present invention is used. The mass of the support used is 9.2 grams. The volume of 2M cobalt(II) thiocyanate solution used for initial wet impregnation is 4.692 milliliters. The catalyst composition is determined by XRF and XRD and is reported in Tables 2a-2b.

[0099] Comparative Example 3 Catalyst Co X S y Al2O3 is prepared by the initial wet impregnation method.

[0100] OO x Preparation of Al2O3 First, a 1 mol (M) impregnation solution of cobalt(II) acetate in deionized water is prepared. Next, 5 grams of 40-80 mesh size Al2O3 support (NORPRO SA31132, support properties reported in Tables 1a-1b) is placed in a porcelain dish, and 5 ml of the impregnation solution is added dropwise while gently shaking. The impregnated catalyst is dried in a box oven in air at 120°C for 2 hours. The impregnation is repeated two more times, and the catalyst is dried in air after each impregnation. A total of three impregnations are performed. Total volume of 1 M cobalt(II) acetate solution used for the three initial wet impregnations: 15.0 ml. The impregnated catalyst is dried and calcined in air using the following program: the temperature is increased from room temperature to 120°C at a rate of 2°C / min, held at 120°C for 2 hours, the temperature is increased from 120°C to 400°C at a rate of 3°C / min, held at 400°C for 4 hours, and then cooled to room temperature to calcine the supported cobalt oxide material CoO x / Al2O3 is obtained.

[0101] OO x Sulfurization of Al2O3 CoO as prepared x / Al2O3 is sulfided in the liquid phase using an aqueous solution of ammonium sulfide. For this purpose, 25 ml of deionized water and 25 ml of 20 wt% aqueous solution of ammonium sulfide are added to a 250 ml glass beaker equipped with a magnetic stirring rod and a thermocouple. The solution is heated to 60°C, and then 5 g of CoO x Add the Al2O3 material to the solution and stir the slurry at 60°C (±5°C) for 20 minutes. Filter the cake through filter paper and collect it, then wash it with 500 ml of deionized water.

[0102] The cake is dried overnight in air at room temperature. The dried cake is then placed in a stainless steel drum for drying, auto-reduction, and passivation. Drying and auto-reduction are carried out in a flow of pure N2 (overhead flow of 5.5 liters / min) using the following program: The N2 flow is run at room temperature for 30 minutes, the temperature is increased from room temperature to 120°C at a rate of 2°C / min, the temperature is maintained at 120°C for 2 hours, the temperature is increased from 120°C to 550°C at a rate of 3°C / min, the temperature is maintained at 550°C for 4 hours, and the temperature is cooled to room temperature of 20-25°C (24-48 hours). The catalyst is then passedivated in a 1 vol% O2 / N2 flow at room temperature (20-25°C) for 2 hours. Next, the oxygen concentration in the gas flow is gradually increased to 21 vol% O2 / N2. Before opening the stainless steel drum, the catalyst is purged in 21 vol% O2 / N2 for 1 hour. A black supported cobalt sulfide catalyst is obtained. The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0103] Comparative Example 4 Catalyst Co X S y Al2O3 is prepared using the preparation method described in Comparative Example 3.

[0104] Preparation of CoOx / Al2O3 The same preparation method described in Comparative Example 3 is used for this comparative example. The carrier is Al2O3 (NORPRO SA6176; carrier properties are reported in Tables 1a-1b). The carrier is crushed and sieved to a mesh size of 40-80. The mass of the carrier used is 5 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wet impregnations is 17.25 milliliters.

[0105] Sulfurization of CoOx / Al2O3 The same sulfidation method described in Comparative Example 3 is used in this comparative example.

[0106] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0107] Comparative Example 5 Catalyst Co X S yAl2O3 is prepared using the preparation method described in Comparative Example 3.

[0108] Preparation of CoOx / Al2O3 The same preparation method described in Comparative Example 3 is used for this comparative example. The carrier is Al2O3 (NORPRO SA6178; carrier properties are reported in Tables 1a-1b). The carrier is crushed and sieved to a mesh size of 40-80. The mass of the carrier used is 5 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wet impregnations is 13.05 milliliters.

[0109] Sulfurization of CoOx / Al2O3 The same sulfidation method described in Comparative Example 3 is used in this comparative example.

[0110] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0111] Comparative Example 6 Catalyst Co X S y / SiO2 is prepared using the preparation method described in Comparative Example 3.

[0112] Preparation of CoOx / Si2O2 The same preparation method described in Comparative Example 3 is used for this comparative example. The carrier is SiO2 (NORPRO SS61138; carrier properties are reported in Tables 1a-1b). The carrier is crushed and sieved to a mesh size of 40-80. The mass of the carrier used is 5 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wet impregnations is 18 milliliters.

[0113] Sulfurization of CoOx / SiO2 The same sulfidation method described in Comparative Example 3 is used in this comparative example.

[0114] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0115] Comparative Example 7 Catalyst Co X S y / SiO2 is prepared using the preparation method described in Comparative Example 3.

[0116] Preparation of CoOx / Si2O2 The same preparation method described in Comparative Example 3 is used for this comparative example. The carrier is SiO2 (Fuji Sliysia Cariact Q10; carrier properties are reported in Tables 1a-1b). The carrier is crushed and sieved to a mesh size of 40-80. The mass of the carrier used is 5 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wetting impregnations is 12.9 milliliters.

[0117] Sulfurization of CoOx / SiO2 The same sulfidation method described in Comparative Example 3 is used in this comparative example.

[0118] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0119] Comparative Example 8 Catalyst Co X S y / SiO2 is prepared using the preparation method described in Comparative Example 3.

[0120] Preparation of CoOx / Si2O2 The same preparation method described in Comparative Example 3 is used for this comparative example. The carrier is SiO2 (Fuji Sliysia Cariact Q20C; carrier properties are reported in Tables 1a-1b). The carrier is crushed and sieved to a mesh size of 40-80. The mass of the carrier used is 5 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wetting impregnations is 15 milliliters.

[0121] Sulfurization of CoOx / SiO2 The same sulfidation method described in Comparative Example 3 is used in this comparative example.

[0122] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0123] Comparative Example 9 Using the preparation method described in Comparative Example 3, a cobalt oxide-supported catalyst CoO x Prepare Al2O3.

[0124] The support material is Al2O3 (NORPRO SA31132; support material properties are reported in Tables 1a-1b). The support material is crushed and sieved to a mesh size of 40-80. The mass of the support material used is 10 grams. The total volume of 1M cobalt(II) acetate solution used for the three initial wet impregnations is 20 milliliters.

[0125] The catalyst compositions determined by XRF and XRD are reported in Tables 2a and 2b.

[0126] Comparative Example 10 Using the preparation method described in Comparative Example 3, a cobalt oxide-supported catalyst CoO x Prepare Al2O3.

[0127] The support material is Al2O3 (NORPRO SA6176; support material properties are reported in Tables 1a-1b). The support material is crushed and sieved to a mesh size of 40-80. The mass of the support material used is 10 grams. The total volume of 1M cobalt(II) acetate solution used for the two initial wet impregnations is 23 milliliters.

[0128] The catalyst compositions determined by XRF and XRD are reported in Tables 2a and 2b.

[0129] Comparative Example 11 Using the preparation method described in Comparative Example 3, a cobalt oxide-supported catalyst CoO x Prepare Al2O3.

[0130] The support material is Al2O3 (NORPRO SA6178; support material properties are reported in Tables 1a-1b). The support material is crushed and sieved to a mesh size of 40-80. The mass of the support material used is 10 grams. The total volume of 1M cobalt(II) acetate solution used for the two initial wet impregnations is 17.4 milliliters.

[0131] The catalyst compositions determined by XRF and XRD are reported in Tables 2a and 2b.

[0132] Comparative Example 12 Using the preparation method described in Comparative Example 3, a cobalt oxide-supported catalyst CoO x Prepare Al2O3.

[0133] The support material was Al2O3-SiO2 in powder form (SASOL Siralox 1.5 / 140; support characteristics are reported in Tables 1a-1b). The mass of the support material used was 10 grams. The total volume of 1M cobalt(II) acetate solution used for the two initial wetting impregnations was 19 milliliters. After preparation, the catalyst was pelletized, pulverized, and sieved to a mesh size of 40-80.

[0134] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b.

[0135] Comparative Example 13 A cobalt oxide-supported catalyst CoOx / SiO2 is prepared using the preparation method described in Comparative Example 3.

[0136] The support material is SiO2 (NORPRO SS61138; support material properties are reported in Tables 1a-1b). The support material is crushed and sieved to a mesh size of 40-80. The mass of the support material used is 10 grams. The total volume of 1 M cobalt(II) acetate solution used for the two initial wet impregnations is 24 milliliters.

[0137] The catalyst composition was determined by XRF and XRD and reported in Tables 2a and 2b. [Table 1] *BJH adsorption average pore width (4V / A) na-unavailable [Table 2] *BJH adsorption average pore width (4V / A) **From the supplier nm - Not measured [Table 3] *Balancing - Carbon **Calculated from the amount of impregnated cobalt and the S / Co ratio determined by XRF.** ***Two phases of cobalt sulfide were detected by XRD. Co 1-x The ratio of S to Co9S8 is approximately 1:1 wt / wt. Sample composition derived from ^XRD. [Table 4] *Balancing - Carbon **Calculated from the amount of impregnated cobalt and the S / Co ratio determined by XRF.** ***Two phases of cobalt sulfide were detected by XRD. Co 1-x The ratio of S to Co9S8 is approximately 1:1 wt / wt. Sample composition derived from ^XRD.

[0138] Catalyst testing of Examples 1-19 and Comparative Examples 1-13 of the present invention Kinetic measurements The dynamics of the cobalt sulfide catalyst are evaluated using a fixed-bed reactor under the conditions specified in Table 3. The reactor is packed with 1 gram of catalyst (40-80 mesh), and the catalyst bed is sandwiched between layers of 20-40 mesh quartz chips. The reactor is leak-tested under N2 at 750 psig, and then started by flowing a dry reaction gas feed containing 8% ethylene, 56% CO, and 16% N2 at a flow rate of 50 standard cubic centimeters / min (sccm). A liquid water feed is introduced at a rate of 2.5 milligrams / min at >150°C, resulting in a feed composition of ethylene / CO / water / N2 (vol %) = approximately 7.5% / approximately 53.5% / approximately 5.9% / bal in the total gas flow. For conditions 1 and 2 in Table 3, the reaction is considered to have started when the reaction temperature reaches 270°C. The catalyst is first tested at 270°C for several hours (Condition 1), and then at 290°C (Condition 2). For conditions 3-5 in Table 3, the reaction is considered to have started when the reaction temperature reaches 250°C. The catalyst is first tested at 250°C for several hours (Condition 3), then at 270°C for several hours (Condition 4), and then at 290°C for several hours (Condition 5).

[0139] X-ray fluorescence (XRF) measurement X-ray fluorescence (XRF) data is collected at room temperature (RT) using a PANalytical PW4400 spectrometer with an X-ray tube equipped with a rhodium anode.

[0140] Powder X-ray Diffraction (XRD) P-XRD measurements are performed under ambient laboratory conditions using Cu Kα (λ=1.5406 Å) on a Bruker AXS diffractometer D8 Discover with a General Area Diffraction Detector System (GADDS). A 2-theta range of 9–70° is recorded with an integration step size of 0.05°. The XRD pattern is obtained after 2-theta calibration against a reference standard (Al2O3 corundum, PDF#00-046-1212).

[0141] The reference numbers used for the cobalt sulfide phase are as follows: Co 1-x S(“Co7S8”)-PDF#00-042-0826,04-022-8171 Co9S8-PDF#01-073-6395,04-004-4525 CoS-PDF#01-075-0605,03-065-3418 CoS2-PDF#04-004-6455 Co4S3-PDF#00-030-0458 (cubic crystal), 00-002-1458 (hexagonal crystal) Co3S4-PDF#04-006-5317 Co3O4-PDF#00-042-1467 CoO-PDF#01-076-3832 The results are shown in Tables 4-6.

[0142] Examples 1-19 of the present invention demonstrate that supported cobalt sulfide catalysts can be prepared by initial wetting impregnation followed by thermal decomposition of cobalt(II) thiocyanate under inert conditions. When used in some embodiments of the gas-phase process of the present invention, the as-prepared catalyst exhibits high selectivity for propionic acid. This preparation method is versatile and allows for the preparation of catalysts across different classes of supports, such as alumina, silica, and carbon.

[0143] Comparative Example 1 is a bulk cobalt sulfide catalyst. A comparison of the examples of the present invention with Comparative Example 1 demonstrates that comparable activity and selectivity performance of a supported catalyst can be achieved with a lower cobalt loading amount in the supported catalyst (<15 wt% Co) according to some embodiments of the present invention, compared to a bulk catalyst (67.4 wt% Co).

[0144] Comparative Example 2 demonstrates that not all supports are suitable for the preparation of cobalt sulfide catalysts according to some embodiments of the present invention. Comparative Example 2 shows that low surface area supports such as alpha-alumina (<5 m²) are not suitable. 2shows that an oxide support having / g) results in a low-activity catalyst, probably due to the formation of large cobalt sulfide crystallites.

[0145] Comparative Examples 3 to 8 show that supported cobalt sulfide catalysts prepared by sulfiding cobalt oxide and autoreduced at 550°C have lower activity compared to catalysts prepared according to some embodiments of the present invention.

[0146] Comparative Examples 9 to 13 show that another class of catalysts, i.e., supported cobalt oxide, is not active in the direct synthesis of propionic acid.

[0147] Calculation of Catalytic Performance for Examples of the Present Invention and Comparative Examples The carbon balance is defined and calculated as follows. [Formula] where n i is the number of carbon atoms in species V i and Vi represents the molar flow rate of species i. [Formula] wherein Cpi is the concentration of all products having 2 or more carbon atoms, and Cri is the reactant at the reactor outlet. [Formula] (All products having 2 or more carbon atoms are assumed to be derived from ethylene) where σ i is the stoichiometry with respect to C2, and for C4s, σ i = 2, for C6s, σ i = 3, and for all other products, such as aldehydes, alcohols and esters, σ i = 1. [Table 5] *Mass per hour of spatial velocity [Table 6] *The data is an average over 2-8 hours on the stream. [Table 7] *The data is an average over 2-8 hours on the stream. [Table 8] *The data is an average over 2-8 hours on the stream. [Table 9] [Table 10] [Table 11] [Table 12] [Table 13] [Table 14]

Claims

1. A gas-phase process for producing carboxylic acids or alkyl esters, (a) To provide a catalyst support, wherein the catalyst support comprises a deposit of cobalt thiocyanate on at least a portion of the catalyst support, and the catalyst support is 5 m ２ To provide a product having a surface area exceeding / g, (b) Heating the catalyst support to convert the cobalt thiocyanate on the support to cobalt sulfide to form a supported cobalt sulfide catalyst, (c) Reacting an alkene gas, water vapor or alkanol gas and a carbon-containing gas in a reactor in the presence of the supported cobalt sulfide catalyst to form a product stream, wherein the carbon-containing gas includes carbon monoxide or a mixture of carbon monoxide and carbon dioxide. A process wherein, when water vapor is used as a reactant, the product stream contains a carboxylic acid, and when alkanol gas is used as a reactant, the product stream contains an alkyl ester.

2. The process according to claim 1, wherein the catalyst support, which includes a deposit of cobalt thiocyanate on at least a portion thereof, is formed by contacting an aqueous solution of a cobalt(II) salt with the catalyst support in the presence of a thiocyanate anion, thereby depositing the aqueous solution on at least a portion thereof.

3. The process according to claim 2, further comprising dissolving cobalt thiosulfate in water to provide the aqueous solution of the cobalt(II) salt in the presence of a thiocyanate anion.

4. The process according to claim 2, wherein the aqueous solution does not contain cations other than cobalt(II) in an amount exceeding 0.1 molar equivalents relative to cobalt, and the aqueous solution does not contain anions other than thiocyanate anions in an amount exceeding 0.1 molar equivalents relative to thiocyanate.

5. The process according to claim 1 or 2, wherein the catalyst support is heated to a temperature of 200°C to 550°C.

6. The process according to claim 1 or 2, further comprising, before heating the catalyst support in step (b), drying the catalyst support, which includes a deposit of cobalt thiocyanate on at least a portion of the catalyst support, at a temperature of 150°C or less under inert conditions.

7. At temperatures below 25°C, up to 2 volume percent of O ２ The process according to claim 1 or 2, further comprising passivating the supported cobalt sulfide catalyst with a dilution oxygen stream containing the following:

8. The process according to claim 1 or 2, wherein the bulk sulfur-to-cobalt atom ratio is 0.3 or greater.

9. The process according to claim 1 or 2, wherein the catalyst support comprises alumina, carbon, silicon carbide, silica, silica-alumina, halfnia, zirconia, titania, or a mixture thereof, or the cobalt content in the supported cobalt sulfide catalyst is 5% to 50% by weight based on the total weight of the supported cobalt sulfide catalyst.

10. The surface area of ​​the catalyst support is 10 m² ２ / g and up to 800m ２ The process according to claim 1 or 2, wherein the value is / g.

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