Oxidative coupling catalyst, method for producing oxidative coupling catalyst, and method for producing hydrocarbons

Abstract

The purpose of the present invention is to provide an oxidative coupling catalyst, a method for producing an oxidative coupling catalyst, and a method for producing hydrocarbons that make it possible to manufacture C2 or higher hydrocarbons at high yield even at high temperature and high pressure and that enable a reduction in the size of equipment for carrying out an OCM reaction. One aspect of the present invention is an oxidative coupling catalyst by which C2 or higher hydrocarbons are produced from methane through a reaction for oxidative coupling of methane, the oxidative coupling catalyst being a sintered body of silica on which an alkali metal salt is supported.

Description

Oxidative coupling catalyst, method for producing oxidative coupling catalyst, and method for producing hydrocarbons

[0001] This disclosure relates to an oxidative coupling catalyst, a method for producing an oxidative coupling catalyst, and a method for producing hydrocarbons. This application claims priority to Japanese Patent Application No. 2023-010932, filed on January 27, 2023, the contents of which are incorporated herein by reference.

[0002] BACKGROUND ART There is known a technique for producing hydrocarbons such as olefins by an oxidative coupling reaction of methane (hereinafter also referred to as an "OCM reaction") using a gas containing methane such as natural gas.

[0003] For example, Patent Document 1 proposes a method for producing hydrocarbons having two or more carbon atoms from methane through an OCM reaction using a catalyst (oxidative coupling catalyst) in which an oxide of sodium, manganese, and tungsten or a composite oxide thereof is supported on an inorganic oxide. The invention of Patent Document 1 aims to carry out the OCM reaction with high efficiency and produce hydrocarbons having two or more carbon atoms in high yield.

[0004] Patent No. 5493928

[0005] However, the invention of Patent Document 1 targets the OCM reaction at atmospheric pressure, which may result in an enlarged reactor for the OCM reaction and increased power consumption for compressors and other devices that supply the downstream purification and separation processes of the reactor. To address this issue, it is conceivable to carry out the OCM reaction at high temperatures and under pressure (e.g., 750°C, 0.9 MPa). However, when the OCM reaction is carried out at high temperatures and pressures, the active components of the oxidative coupling catalyst may melt, volatilize, and decrease, resulting in a decrease in the yield of the resulting hydrocarbons. Another issue is that in the case of a catalyst using an inert silica support, if silica gel with a large particle size is used, the catalyst may crack during calcination.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an oxidative coupling catalyst that can produce hydrocarbons having two or more carbon atoms in high yield even under high temperature and pressure conditions, and that can reduce the size of equipment for performing the OCM reaction, a method for producing an oxidative coupling catalyst, and a method for producing hydrocarbons.

[0007] In order to solve the above problems, the oxidative coupling catalyst according to the present disclosure is an oxidative coupling catalyst that produces hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane, and is a calcined product of silica on which an alkali metal salt is supported.

[0008] The method for producing an oxidative coupling catalyst according to the present disclosure is a method for producing hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane, and includes the steps of: bringing silica or a calcined product of silica into contact with an aqueous solution containing an alkali metal salt to obtain a precursor in which the silica or the calcined product of silica is impregnated with the aqueous solution; and calcining the precursor at 800°C or higher to obtain the oxidative coupling catalyst.

[0009] The method for producing hydrocarbons according to the present disclosure uses the above-described oxidative coupling catalyst to produce hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane.

[0010] According to the present disclosure, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure conditions, and the equipment for performing the OCM reaction can be made smaller.

[0011] 1 is a flowchart showing a method for producing an oxidative coupling catalyst according to an embodiment of the present disclosure. FIG. 2 is a flowchart showing a method for producing hydrocarbons according to an embodiment of the present disclosure. FIG. 3 is a photograph showing silica gel particles after calcination. FIG. 4 is a photograph showing extruded silica after calcination. FIG. 5 is a graph showing the results of X-ray diffraction (XRD) of extruded silica after calcination. FIG. 6 is a graph showing the results of X-ray diffraction (XRD) of an oxidative coupling catalyst according to an embodiment of the present disclosure. FIG. 7 is a flowchart showing a method for producing an oxidative coupling catalyst according to Example 1. FIG. 8 is a flowchart showing a method for producing an oxidative coupling catalyst according to Example 2. FIG. 9 is a flowchart showing a method for producing an oxidative coupling catalyst according to Example 3. FIG. 10 is a photograph showing the oxidative coupling catalyst obtained in Example 3. FIG. 11 is a graph showing the yield of olefins having 2 to 4 carbon atoms in the product gas, the methane conversion rate, the selectivity for hydrocarbons having 2 to 4 carbon atoms, and the oxygen consumption rate relative to the partial pressure of methane in the feed gas when an oxidative coupling reaction is carried out using the oxidative coupling catalysts obtained in Examples 2, 4, and 5. FIG. 12 is a graph showing the methane conversion rate when an oxidative coupling reaction of methane is carried out using the oxidative coupling catalyst according to an embodiment of the present disclosure. FIG. 13 is a graph showing the oxygen consumption rate when an oxidative coupling reaction of methane is carried out using the oxidative coupling catalyst according to an embodiment of the present disclosure.

[0012] Oxidation Coupling Catalyst An oxidation coupling catalyst according to an embodiment of the present disclosure is a calcined product of silica carrying an alkali metal salt. In this specification, the term "calcined product" refers to a porous body obtained by kneading silica powder with a binder, molding the resulting silica by a method such as extrusion molding, and then heat-treating the resulting silica at 700°C or higher.

[0013] The particle size of the oxidative coupling catalyst of this embodiment is preferably 1 to 5 mm, more preferably 2 to 4 mm. A larger particle size of the oxidative coupling catalyst can further reduce the pressure loss in the catalyst layer when the OCM reaction is carried out under pressurized conditions, but the catalyst surface area per unit volume of the catalyst layer is smaller, requiring a larger amount of catalyst to achieve the desired performance. Conversely, a smaller particle size of the oxidative coupling catalyst increases the catalyst surface area per unit volume of the catalyst layer, allowing a smaller amount of catalyst to achieve the desired performance, but increasing the pressure loss in the catalyst layer. In equipment (OCM plants) where the OCM reaction is carried out, the process gas is pressurized downstream of the OCM reactor using a compressor or the like, and a decrease in gas pressure due to pressure loss in the catalyst layer significantly affects the power of the compressor or the like. Therefore, by setting the particle size of the oxidative coupling catalyst within the above numerical range, the catalyst amount and pressure loss can be optimized. The particle size can be measured, for example, by a sieving method using several types of sieves with different mesh sizes. When the particle size of the oxidation coupling catalyst varies, it is evaluated based on the average particle size. The average particle size of the oxidation coupling catalyst of this embodiment is preferably 1 to 5 mm, more preferably 2 to 4 mm. The average particle size is given by the median diameter (d50) of the results of measuring the particle sizes of multiple particles measured by a method such as image analysis.

[0014] The oxidation coupling catalyst of this embodiment preferably exhibits crystallinity from the viewpoint of further enhancing catalytic activity. Whether or not the oxidation coupling catalyst exhibits crystallinity can be confirmed by X-ray diffraction (XRD). When a peak is observed at a specific diffraction angle in XRD, i.e., when a diffraction phenomenon is observed, the oxidation coupling catalyst is determined to exhibit crystallinity.

[0015] Examples of the alkali metal salt that is the active component of the oxidation coupling catalyst of this embodiment include alkali metal salts of oxides containing at least tungsten or zirconium (hereinafter, also simply referred to as "oxides"). Examples of oxides containing at least tungsten or zirconium include tungsten (VI) oxide, tungstic acid, zirconia (ZrO ２ ), zircon (ZrSiO４ ) and the like. The oxide containing at least tungsten or zirconium may be a composite oxide of tungsten or zirconium with a metal element other than tungsten and zirconium. The metal element other than tungsten and zirconium is not particularly limited, and examples thereof include aluminum, magnesium, calcium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, palladium, silver, indium, tin, iridium, platinum, and gold. These metal elements may or may not form a composite oxide with tungsten or zirconium. Among these metal elements, manganese, indium, and tin are preferred because they can further increase the yield of hydrocarbons having 2 to 4 carbon atoms in the OCM reaction, and tin is more preferred because it can further increase the selectivity for hydrocarbons having 2 to 4 carbon atoms even under pressurized conditions.

[0016] Examples of alkali metals in the alkali metal salt include sodium, potassium, rubidium, and cesium. Among these alkali metals, potassium is preferred because it has high catalytic activity and excellent heat resistance. This is because sodium tungstate (Na ２ WO ４ , melting point 698°C) melts if the operating temperature of the reactor is too high and may have poor durability, whereas potassium tungstate (K ２ WO ４ , melting point 921°C) does not melt when the operating temperature of the reactor is set to less than 900°C, and has excellent durability.

[0017] When the oxidative coupling catalyst of this embodiment contains manganese and a potassium salt of an oxide, the mass ratio of manganese:potassium salt of an oxide:silica is preferably (0.01 to 5):(0.05 to 10):(85 to 99.9), more preferably (0.5 to 4):(1 to 8):(88 to 98.5), and even more preferably (1 to 3):(2 to 7):(90 to 97). The total mass of manganese, potassium salt of an oxide, and silica is defined as 100. When the mass ratio of manganese:potassium salt of an oxide:silica is within the above range, the selectivity to hydrocarbons having 2 to 4 carbon atoms can be further increased in the OCM reaction, even under pressurized conditions. The mass ratio (mass concentration) of manganese and potassium in the mass ratio of manganese:potassium salt of an oxide:silica can be determined by analyzing the oxidative coupling catalyst by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The mass ratio (mass concentration) of silica can be calculated by subtracting the mass ratio (mass concentration) of each active component (manganese and potassium) from the total mass of the oxidative coupling catalyst. The mass ratio expressed as manganese:potassium oxide salt:silica can be adjusted by adjusting the concentration and amount of each raw material aqueous solution, or a combination thereof.

[0018] When the oxidation coupling catalyst of this embodiment contains tin, manganese, and a potassium salt of an oxide, the mass ratio of tin:manganese:potassium salt of an oxide:silica is preferably (0.01 to 50):(0.01 to 5):(0.05 to 10):(35 to 99.9), more preferably (2 to 50):(0.5 to 4):(1 to 8):(38 to 96.5), and even more preferably (10 to 20):(1 to 3):(2 to 7):(70 to 87), where the total mass of tin, manganese, potassium salt of an oxide, and silica is taken as 100. When the mass ratio of tin:manganese:potassium salt of an oxide:silica is within the above range, the selectivity to hydrocarbons having 2 to 4 carbon atoms can be further increased in the OCM reaction even under pressurized conditions. In the mass ratio of tin:manganese:potassium oxide salt:silica, the mass ratios (mass concentrations) of tin, manganese, and potassium are determined by analyzing the oxidative coupling catalyst using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The mass ratio (mass concentration) of silica can be calculated by subtracting the mass ratios (mass concentrations) of each active component (tin, manganese, and potassium) from the total mass of the oxidative coupling catalyst. The mass ratio of tin:manganese:potassium oxide salt:silica can be adjusted by adjusting the concentrations and amounts of the aqueous solutions of each raw material, and by combining these.

[0019] The silica used as the carrier for the oxidation coupling catalyst of this embodiment is not particularly limited, and examples thereof include granular silica gel, silica powder, silica obtained by extruding a composition in which silica powder is dispersed in a binder to form pellets (hereinafter also referred to as "extruded silica"), and extruded calcined silica obtained by calcining extruded silica at 700°C or higher for 5 hours or more. Among these silicas, extruded silica and extruded calcined silica (calcined extruded silica) are preferred, with extruded calcined silica being more preferred, because the particle size can be easily adjusted by selecting a die and they do not break during high-temperature calcination even if the particle size is large. The specific surface area of ​​the silica is 200 to 500 m. ２ / g is preferred, and 250 to 450m ２ / g is more preferable, and 300 to 400m ２The pore volume of silica is preferably 0.25 to 0.60 cm3 / g. ３ / g is preferred, and 0.30 to 0.55 cm ３ / g is more preferable, and 0.40 to 0.50 cm ３ When the silica is extruded and pyrogenic silica, the specific surface area of ​​the extruded and pyrogenic silica is preferably 80 to 140 m / g. ２ / g is preferred, and 90 to 130m ２ / g is more preferable, and 100 to 120m ２ When the silica is extruded pyrogenic silica, the pore volume of the extruded pyrogenic silica is preferably 0.12 to 0.18 cm ３ / g is preferred, and 0.13 to 0.17 cm ３ / g is more preferable, and 0.14 to 0.16 cm ３ The specific surface area of ​​the oxidative coupling catalyst of the present disclosure is preferably 1.0 to 7.5 m / g. ２ / g is preferred, and 1.3 to 7.0 m ２ / g is more preferable, and 1.5 to 5.5m ２ The pore volume of the oxidative coupling catalyst of the present disclosure is preferably 0.0010 to 0.0100 cm 3 / g. ３ / g is preferred, and 0.0020 to 0.0080 cm ３ / g is more preferable, and 0.0030 to 0.0070 cm ３ In this specification, the specific surface area and pore volume can be measured by a gas adsorption method.

[0020] Examples of binders used in extruded silica include those containing methylcellulose derivatives, polyacrylic acid copolymers, polyurethane copolymers, etc., and among these, those containing methylcellulose derivatives are preferred. Examples of the binder include, but are not limited to, the Celander (registered trademark) YB series from HighChem Co., Ltd.

[0021] The silica used as a raw material for the oxidation coupling catalyst of this embodiment is preferably amorphous. Amorphous silica can be impregnated with an active component such as tin, manganese, potassium, or indium, and then calcined to exhibit crystallinity, thereby exhibiting catalytic function. The raw silica may be crystalline. Whether silica is amorphous or not can be confirmed by X-ray diffraction (XRD). When no peak is observed at a specific diffraction angle in XRD, i.e., when no diffraction phenomenon is observed, the silica is determined to be amorphous.

[0022] The oxidative coupling catalyst of this embodiment preferably has a methane conversion rate (%) defined by the following formula (1) of 13.0 to 25.0%, more preferably 15.0 to 23.0%, and even more preferably 17.9 to 20.0%. The oxidative coupling catalyst of this embodiment preferably has a selectivity (%) for hydrocarbons having 2 to 4 carbon atoms defined by the following formula (2) of 50 to 80%, more preferably 54 to 70%, and even more preferably 55 to 65%. The oxidative coupling catalyst of this embodiment preferably has a yield (%) for hydrocarbons having 2 to 4 carbon atoms defined by the following formula (3) of 7 to 30%, more preferably 9 to 20%, and even more preferably 10 to 15%.

[0023] <<Method for Producing Oxidation Coupling Catalyst>> As shown in Figure 1 , the method for producing an oxidation coupling catalyst according to the present disclosure includes the steps of: bringing silica or a calcined product of silica into contact with an aqueous solution containing an alkali metal salt to obtain a precursor in which the silica or the calcined product of silica is impregnated with the aqueous solution; and calcining the precursor at 800°C or higher to obtain an oxidation coupling catalyst. Each step will be described in more detail below.

[0024] The aqueous solution containing an alkali metal salt to be impregnated into silica or a calcined silica product can be obtained by dissolving an alkali metal salt of an oxide containing at least tungsten or zirconium in water. The aqueous solution containing a metal element other than tungsten and zirconium can be obtained by dissolving an inorganic compound such as a chloride, nitrate, sulfate, carbonate, bicarbonate, or ammonium salt of a metal element other than tungsten or zirconium, or an organic compound such as an acetate or oxalate, in water. Alternatively, a composite oxide such as potassium tungstate can be dissolved in water to obtain an aqueous solution. The molar concentration of the metal in the aqueous solution can be determined appropriately depending on the performance required of the oxidation coupling catalyst.

[0025] When an aqueous solution containing multiple metals is used in the precursor preparation step, aqueous solutions each containing one metal may be prepared and sequentially impregnated into silica (sequential impregnation method), or aqueous solutions containing multiple metals may be co-impregnated into silica (co-impregnation method). When an aqueous solution containing multiple metals is used, the co-impregnation method is preferred because it provides superior catalyst production efficiency. In the sequential impregnation method, the water content in the aqueous solution containing each metal is preferably 100 to 500 parts by mass per 100 parts by mass of the metal-containing compound. In the co-impregnation method, the water content in the aqueous solution containing multiple metals is preferably 100 to 500 parts by mass per 100 parts by mass of the metal-containing compound in total. In the sequential impregnation method, it is preferable to impregnate silica with an aqueous solution containing an alkali metal salt of an oxide containing at least tungsten or zirconium before impregnating the silica with the aqueous solution containing the other metal element. In the co-impregnation method, when the aqueous solution dissolving multiple types of metals contains manganese and a potassium salt of an oxide, the mass ratio of manganese:potassium salt of an oxide:silica is preferably (0.01-5):(0.05-10):(85-99.9), more preferably (0.5-4):(1-8):(88-98.5), and even more preferably (1-3):(2-7):(90-97), where the total mass of manganese, potassium salt of an oxide, and silica is taken as 100. In the co-impregnation method, when the aqueous solution dissolving multiple types of metals contains tin, manganese, and a potassium salt of an oxide, the mass ratio of tin:manganese:potassium salt of an oxide:silica is preferably (0.01-50):(0.01-5):(0.05-10):(35-99.9), more preferably (2-50):(0.5-4):(1-8):(38-96.5), and even more preferably (10-20):(1-3):(2-7):(70-87), where the total mass of tin, manganese, potassium salt of an oxide, and silica is taken as 100.

[0026] In the step of obtaining a calcined product of the precursor, the temperature (calcination temperature) when calcining the precursor is, for example, 800°C or higher, preferably 850°C or higher, and more preferably 850°C or higher but lower than 900°C. When the calcination temperature is equal to or higher than the lower limit, the alkali metal salt is converted to an oxide containing an alkali metal or a composite oxide thereof, and is supported on the calcined product of silica as a stable active component. In addition, the amorphous silica exhibits crystallinity, thereby further enhancing catalytic activity. When the calcination temperature is lower than the upper limit, melting and volatilization of the active component of the catalyst can be suppressed, and a decrease in the active component of the catalyst can be suppressed. In this specification, the "calcination temperature" is expressed as the set temperature of an oven or the like when calcining the precursor. When the sequential impregnation method is used, a calcined product of the precursor can be obtained by impregnating with an aqueous solution of a first metal, calcining the resulting impregnated product, subsequently impregnating with an aqueous solution of a second metal, calcining the resulting impregnated product, and subsequently impregnating with an aqueous solution of a third metal, and calcining the resulting impregnated product. In the sequential impregnation method, the first metal and the second metal are preferably metal elements other than tungsten and zirconium, and the third metal is preferably a metal element containing tungsten and zirconium.

[0027] The time for calcining the precursor (calcination time) is, for example, preferably 1 to 24 hours, more preferably 2 to 18 hours, and even more preferably 3 to 12 hours. When the calcination time is equal to or greater than the above-mentioned lower limit, the active component is sufficiently supported on the silica. From the viewpoint of productivity, the calcination time is preferably equal to or less than the above-mentioned upper limit. In this specification, the "calcination time" is expressed as the time for which heating in an oven or the like is maintained after the calcination temperature is reached.

[0028] The method for producing an oxidation coupling catalyst according to the present disclosure may further include a step of extruding a composition in which silica powder is dispersed in a binder to obtain silica. Using extruded silica as a support for the oxidation coupling catalyst facilitates adjustment of the particle size of the oxidation coupling catalyst, and even if the particle size is large, cracking during high-temperature firing can be suppressed. The shape of the extruded silica is not particularly limited, and examples include cylindrical, ring-shaped, spherical, lumpy, and fibrous shapes. The shape of the extruded silica can be adjusted by cutting or pulverizing the extruded noodle-shaped body into any desired shape.

[0029] The method for producing an oxidation coupling catalyst according to the present disclosure preferably further comprises a step of calcining a molded body obtained by extruding the composition at 700°C or higher to obtain a calcined product of the silica. By using a calcined body obtained by calcining the extruded silica (hereinafter also referred to as "extruded calcined silica") as a support, cracking of the silica support can be further suppressed in the subsequent calcination step to obtain the oxidation coupling catalyst. For example, during calcination, the specific surface area and pore volume rapidly decrease (sintering), which generates thermal stress inside the silica. Silica with low toughness may be unable to withstand the thermal stress and may crack. Extruded calcined silica has the toughness to withstand thermal stress, which can further suppress cracking of the silica support.

[0030] Indicators of the mechanical properties of a material related to cracking include, for example, strength, which indicates static robustness, and toughness, which indicates dynamic tenacity. It is generally known that there is a trade-off relationship between strength and toughness. During silica calcination, shrinkage deformation occurs as the specific surface area and pore area decrease, and it is therefore believed that dynamic tenacity (toughness) has a large effect on cracking. For this reason, in order to suppress the occurrence of cracking in the silica carrier, high toughness, i.e., low strength, is preferred. Strength can be evaluated, for example, by measuring the strength (crushing strength) when the silica carrier is crushed. The crushing strength of extrusion-molded calcined silica is, for example, 10 N / mm ２ Preferably, less than 8 N / mm ２ More preferably, 6 N / mm or less ２When the crushing strength of the extruded and calcined silica is equal to or less than the upper limit, the occurrence of cracks in the silica carrier can be further suppressed. The lower limit of the crushing strength of the extruded and calcined silica is not particularly limited, but is, for example, 2 N / mm ２ The crushing strength of the extruded and pyrogenic silica is given as the average value of the crushing strengths of, for example, five randomly selected silica carriers measured with a Kiya hardness tester. The crushing strength of the extruded and pyrogenic silica can be adjusted by the size, shape, and firing conditions of the extruded and pyrogenic silica.

[0031] The calcination temperature (hereinafter also referred to as "pre-calcination temperature") when obtaining extruded calcined silica is preferably, for example, 400°C or higher. When the pre-calcination temperature is equal to or higher than the above lower limit, sufficient strength can be imparted to the silica carrier. The upper limit of the pre-calcination temperature is not particularly limited, and is, for example, 1000°C. In this specification, the "pre-calcination temperature" is expressed as the set temperature of an oven or the like when calcining the extruded silica.

[0032] The calcination time when obtaining extruded calcined silica (hereinafter also referred to as "pre-calcination time") is, for example, preferably 1 to 24 hours, more preferably 5 to 10 hours. When the pre-calcination time is equal to or greater than the above-mentioned lower limit, sufficient strength and toughness can be imparted to the silica support, and the occurrence of cracks in the silica support can be further suppressed in the subsequent calcination step to obtain the oxidation coupling catalyst. When the pre-calcination time is equal to or less than the above-mentioned upper limit, the time required to obtain extruded calcined silica can be reduced, and the production efficiency of the oxidation coupling catalyst can be further improved. In this specification, the "pre-calcination time" is expressed as the time during which heating in an oven or the like is maintained after the pre-calcination temperature has been reached.

[0033] In the method for producing an oxidation coupling catalyst according to the present disclosure, the silica used in the step of obtaining silica is preferably amorphous. Amorphous silica can be impregnated with an active component such as tin, manganese, potassium, or indium, and then calcined to exhibit crystallinity, thereby exhibiting catalytic function. The raw silica may also be crystalline. Examples of amorphous silica include the above-mentioned granular silica gel, silica powder, extruded silica, and extruded calcined silica.

[0034] <<Hydrocarbon Production Method>> The hydrocarbon production method of the present disclosure is a method for producing hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane using the oxidative coupling catalyst of the present disclosure. The hydrocarbon production method of the present disclosure is capable of producing hydrocarbons having two or more carbon atoms in high yield by using the oxidative coupling catalyst of the present disclosure. In addition, because the hydrocarbon production method of the present disclosure uses the oxidative coupling catalyst of the present disclosure, it is possible to produce hydrocarbons having two or more carbon atoms in high yield even under high temperature and pressure, thereby enabling the downsizing of equipment for performing the OCM reaction. As shown in FIG. 2 , the hydrocarbon production method of this embodiment is a method for producing hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane. The hydrocarbon production method of this embodiment will be described in more detail below.

[0035] The methane used as the reaction raw material may be pure methane, or may be a methane-containing gas containing other components to the extent that they do not inhibit the OCM reaction. These methane and methane-containing gases can be obtained from natural gas, methane-containing gases obtained in high-temperature coal coke ovens, methane-containing gases obtained by the hydrogenation reaction of carbon monoxide and carbon dioxide produced from coal cracking gas, or methane-containing gases obtained by the decomposition of hydrocarbons derived from petroleum fractions. In addition, methane-containing gases obtained by fermentation or methane isolation or purification treatment from the methane-containing gases can be obtained as the reaction raw material.

[0036] The OCM reaction can be carried out in an atmosphere in which oxygen, carbon dioxide, nitrous oxide, etc. are present, but is preferably carried out in an atmosphere in which oxygen is present. Oxygen, air, oxygen-enriched air, and other oxygen-containing gases can be used as the oxygen source for the OCM reaction. Furthermore, the OCM reaction is more preferably carried out in an atmosphere in which oxygen and steam coexist. This is because hydroxyl radicals (OH radicals) are generated from steam and active oxygen on the catalyst surface. OH radicals react with methane to form methyl radicals (CH ３ In the oxidative coupling reaction of methane, CH ３ The reaction mechanism is thought to be that ethane and ethylene are produced from radicals.

[0037] As the steam source, water evaporated in a boiler or the like may be used, or steam in the exhaust gas from a boiler or various chemical plants may be used after being isolated or purified as necessary. In addition, steam is also produced by the OCM reaction, and this steam may also be used.

[0038] The ratio of methane, oxygen, and steam used in the OCM reaction is preferably in the range of 0.05 to 0.2 moles of oxygen and 0 to 0.1 moles of steam per mole of methane. When the ratios of oxygen and steam are within the above ranges, hydrocarbons having two or more carbon atoms can be produced safely and in a higher yield. In the OCM reaction, an inert gas such as nitrogen, helium, or argon may be present in the reaction atmosphere.

[0039] The temperature (reaction temperature) of the OCM reaction is, for example, preferably 500 to 1100°C, more preferably 600 to 1000°C, and even more preferably 700 to 900°C. When the reaction temperature is equal to or higher than the above lower limit, a practical reaction rate can be obtained. When the reaction temperature is equal to or lower than the above upper limit, side reactions such as steam reforming reactions, combustion reactions, and polymerization reactions can be suppressed, and the yield of hydrocarbons having two or more carbon atoms can be further increased. In addition, by suppressing the melting and volatilization of the active components of the catalyst, the durability of the catalyst can be further improved. In this specification, the "reaction temperature" refers to the temperature inside the catalyst layer of a reactor or the like during the OCM reaction.

[0040] The OCM reaction is preferably carried out under pressurized conditions. By carrying out the OCM reaction under pressurized conditions, the gas volume can be reduced, allowing for the miniaturization of the reactor in which the OCM reaction is carried out. Furthermore, the power required for compressors and the like that supply process gas to the purification and separation processes downstream of the reactor can be reduced. The pressure in the OCM reaction (reaction pressure) is, for example, preferably 0.4 to 1.2 MPa, more preferably 0.5 to 1.1 MPa, and even more preferably 0.6 to 1.0 MPa. When the reaction pressure is equal to or greater than the lower limit, the reactor in which the OCM reaction is carried out can be made more compact. When the reaction pressure is equal to or less than the upper limit, side reactions such as combustion reactions and polymerization reactions can be suppressed, and a decrease in the yield of hydrocarbons having two or more carbon atoms can be suppressed. In this specification, the "reaction pressure" refers to the total pressure of the raw material gas used in the reaction. In this specification, the pressure is measured using a pressure gauge equipped in the reaction vessel.

[0041] An example of equipment for carrying out the OCM reaction is a fixed-bed reactor in which a mixture of raw material methane or a methane-containing gas and atmospheric gas containing oxygen or an oxygen-containing gas, preferably further containing steam, is circulated through a reactor filled with a catalyst. The equipment for carrying out the OCM reaction may be a fluidized-bed reactor or a moving-bed reactor. Furthermore, a membrane reactor may be used to suppress combustion of raw material methane by using a high oxygen concentration at the inlet of the catalyst layer, or a reactor that enables a split-feed method in which oxygen is injected separately into each catalyst layer may be used.

[0042] The space velocity in the OCM reaction is, for example, preferably 1,000 to 5,000,000 / h, and more preferably 10,000 to 500,000 / h. When the space velocity in the OCM reaction is within the above-mentioned range, the yield of hydrocarbons having two or more carbon atoms can be further increased. Here, "space velocity" is also referred to as GHSV, and means the total volumetric flow rate per hour of the feed gas per unit volume of the catalyst layer (under conditions of 0°C and 1 atm). The catalyst layer volume means the volume including the catalyst packed in the reaction tube and the voids therein.

[0043] The reactor may be filled with a single catalyst, or multiple catalysts with different activities may be mixed or layered. If desired, multiple catalysts with different activities, or a single catalyst and an inert inorganic diluent, may be used, so that the activity varies from the inlet to the outlet of the reactor.

[0044] The reactor outlet gas, i.e., the gas containing hydrocarbons having two or more carbon atoms produced by the OCM reaction, has a composition that varies depending on the reaction raw materials. The hydrocarbons having two or more carbon atoms, which are the target products in the outlet gas, are introduced into a known separation and purification facility and are recovered, purified, recycled, or discharged according to the respective components, thereby obtaining the desired target products, such as ethylene, ethane, propane, propylene, and butane.

[0045] Although the embodiments of the present disclosure have been described in detail above, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present disclosure. Furthermore, the present disclosure is not limited to the embodiments, but is limited only by the scope of the claims.

[0046] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to these examples. The raw materials used in these examples are as follows.

[0047] [Raw materials used] ・Mn (NO ３ ) ２ ・6H ２ O: Manganese (II) nitrate hexahydrate. ・SnCl ４ ・5H ２ O: tin (IV) chloride pentahydrate. ２ WO ４ : Potassium tungstate. SiO ２ : Silica powder. In(NO ３ ) ２ ・3H ２ O: Indium(III) nitrate trihydrate.

[0048] <<Preparation of Extruded Silica>> When silica gel particles, which are conventionally selected as catalyst carrier materials, are calcined at temperatures above 900°C, the specific surface area (pore volume) is significantly reduced, causing stress on the particles, which can lead to cracking if the average particle diameter is 3 mm or greater (see Figure 3). Therefore, an experiment was conducted in which silica extruded into pellets, crushed to a uniform particle size (hereinafter also referred to as "extruded silica"), was calcined at 900°C for 8 hours. The results are shown in Figure 4.

[0049] As shown in Figure 4, the extruded silica did not crack even when the average particle size was 3 mm. This is thought to be because the extruded silica has high resistance (toughness) to stress.

[0050] <<Measurement of specific surface area and pore area>> Fresh extruded silica before calcination, extruded silica after calcination at 900°C for 8 hours (extruded calcined silica), and an oxidation coupling catalyst in which an alkali metal salt is supported on extruded calcined silica were prepared, and the specific surface area and pore area of ​​each were measured. The results are shown in Table 1.

[0051]

[0052] As shown in Table 1, it was confirmed that the specific surface area and pore area of ​​extruded silica were reduced by calcining the extruded silica. Furthermore, it was confirmed that the specific surface area and pore area were significantly reduced by supporting an alkali metal salt on the calcined extruded silica. This is thought to be due to sintering caused by the high-temperature calcination.

[0053] X-ray diffraction (XRD) was performed on the extruded calcined silica and the oxidative coupling catalyst in which an alkali metal salt was supported on the extruded calcined silica. The results are shown in Figures 5 and 6.

[0054] As shown in Figure 5, it was confirmed that the extruded calcined silica had an amorphous structure. In contrast, as shown in Figure 6, diffraction was observed in the oxidation coupling catalyst in which an alkali metal salt was supported on calcined extruded silica, confirming that the silica was crystallized. Thus, it was confirmed that the oxidation coupling catalyst of the present disclosure does not crack even when crystallized.

[0055] <<Measurement of Crushing Strength>> A cylindrical extruded calcined silica having a diameter of 5 mm and a height of 5 mm and a spherical silica gel having a diameter of 4 mm were prepared, and the compressive force (N) at the time of crushing was measured using a Kiya hardness tester (manufactured by Fujiwara Seisakusho Co., Ltd., 043019-D). Crushing strength (N / mm ２ ) is the compression force applied to the area of ​​the silica support (in the case of extruded pyrogenic silica, it is (5 / 2) ２ ×π (mm ２ ), and in the case of silica gel, (4 / 2) ２ ×π (mm ２ The crushing strength was measured for n=5 and the results are shown in Table 2.

[0056]

[0057] As shown in Table 2, the crushing strength of silica gel was more than twice as high as that of extruded pyrogenic silica. This indicates that extruded pyrogenic silica has sufficient toughness and is highly likely to not break during firing.

[0058] <<Production of Oxidative Coupling Catalyst>> [Example 1] Mn(NO ３ ) ２ ・6H ２ 6.27 mL of ultrapure water, three times the amount of 2.09 g of SiO raw material powder, was added and stirred to prepare a Mn raw material aqueous solution. ２ 54.6 mL of ultrapure water, three times the amount of powder, was added to 18.2 g of powder, and the Mn raw material aqueous solution was added, followed by SiO ２ The powder was impregnated with an aqueous Mn raw material solution to obtain Impregnated Material I. Impregnated Material I was heated in the air at 130°C for 5 hours and dried to evaporate the water. The dried Impregnated Material I was heated at a temperature increase rate of 2°C / min, fired at 900°C for 8 hours, and then cooled at a cooling rate of 20°C / min to obtain a fired product of Impregnated Material I (Fired Product I). Next, SnCl ４ ・5H ２3.54 mL of ultrapure water, three times the weight of the O raw powder, was added to 1.18 g of the O raw powder and stirred to prepare an Sn raw material aqueous solution. Ultrapure water, three times the weight of the fired material I, was added, and the Sn raw material aqueous solution was added and impregnated to obtain Impregnated Material II. Impregnated Material II was heated at 130°C for 5 hours in an air atmosphere and dried to evaporate the water. After drying, Impregnated Material II was heated at a heating rate of 2°C / min, fired at 900°C for 8 hours, and then cooled at a cooling rate of 20°C / min to obtain a fired product of Impregnated Material II (Fired Material II). Next, K ２ WO ４ To 1.00 g of the raw material powder, 3 mL of ultrapure water was added in an amount three times that of the raw material powder, and the mixture was stirred to prepare a potassium raw material aqueous solution. Ultrapure water in an amount three times that of the calcined material II was added, and the potassium raw material aqueous solution was added and impregnated to obtain an impregnated material III (precursor). The impregnated material III was heated at 130°C for 5 hours in an air atmosphere, dried, and the water evaporated. The dried impregnated material III was heated at a heating rate of 2°C / min, calcined at 900°C for 8 hours, and then cooled at a cooling rate of 20°C / min to obtain a calcined product of the impregnated material III (calcined product III). The resulting calcined product III was loaded into a hand press with a diameter of 20 mm, and compression-molded into a cylindrical pellet under a pressure of 40 MPa. The resulting pellets were crushed in a crusher and classified using sieves with openings of 250 μm and 500 μm to obtain oxidation coupling catalysts with particle sizes of 250 to 500 μm (sequential impregnation method, see FIG. 7).

[0059] [Example 2] Mn(NO ３ ) ２ ・6H ２ 2.09 g of raw material powder of O, SnCl ４ ・5H ２ 1.18 g of raw powder of O, and K ２ WO ４ 1.00 g of the raw material powder was added to 12.8 mL of ultrapure water, three times the amount of the raw material powder, and stirred to prepare a raw material aqueous solution. ２ The raw material aqueous solution was added to 14.6 g of powder, and 54.6 mL of ultrapure water was added, and SiO ２ The powder is brought into contact with the raw material aqueous solution to form SiO ２A precursor was obtained by impregnating the powder with the raw material aqueous solution. The obtained precursor was heated and dried at 130°C for 5 hours in an air atmosphere to evaporate the water. The dried precursor was heated at a temperature increase rate of 2°C / min, calcined at 900°C for 8 hours, and then cooled at a cooling rate of 20°C / min to obtain a calcined product of the precursor (calcined product IV). The obtained calcined product IV was loaded into a hand press with a diameter of 20 mm and compression-molded into cylindrical pellets under a pressure of 40 MPa. The obtained pellets were pulverized in a pulverizer and classified using sieves with 250 μm and 500 μm openings to obtain an oxidation coupling catalyst with particle sizes of 250 to 500 μm (co-impregnation method, see Figure 8).

[0060] [Example 3] Granular silica or extruded calcined silica was prepared and classified using sieves with 2 mm and 2.36 mm openings to obtain a silica support with a particle size of 2 to 2.36 mm. To 14.6 g of the obtained silica support, a raw material aqueous solution prepared in the same manner as in Example 2 was added, and 54.6 mL of ultrapure water was added. The raw material aqueous solution was brought into contact with the silica support to obtain a precursor in which the silica support was impregnated with the raw material aqueous solution. The obtained precursor was heated at 130°C for 5 hours in an air atmosphere and dried to evaporate the water. The dried precursor was heated at a heating rate of 2°C / min, calcined at 900°C for 8 hours, and then cooled at a cooling rate of 20°C / min to obtain a granular oxidation coupling catalyst as shown in Figure 10 (co-impregnation method, see Figure 9).

[0061] Example 4: SnCl ４ ・5H ２ Instead of 1.18 g of raw material powder of In(NO ３ ) ２ ・3H ２ An oxidation coupling catalyst having a particle size of 250 to 500 μm was obtained in the same manner as in Example 2, except that 1.237 g of the raw material powder of O was used.

[0062] Example 5: SnCl ４ ・5H ２ An oxidation coupling catalyst having a particle size of 250 to 500 μm was obtained in the same manner as in Example 2, except that the raw material powder of O was not added.

[0063] <Production of Hydrocarbons> The following three types of oxidation coupling catalysts were prepared in Examples 2, 4, and 5. In the following rational formulas, "wt%" represents the mass ratio of the metal element to the total mass of the oxidation coupling catalyst. Sn-Mn-KW: Sn (2 wt%) Mn (2 wt%) K ２ WO ４ (5wt%) / SiO ２ . ・In-Mn-KW: In (2wt%) Mn (2wt%) K ２ WO ４ (5wt%) / SiO ２ . ・Mn-KW: Mn (2wt%)K ２ WO ４ (5wt%) / SiO ２ .

[0064] A pressurizable reactor was filled with the above three types of oxidative coupling catalysts, and hydrocarbons were produced by a methane oxidative coupling reaction using methane-containing natural gas as a feedstock. An inert quartz tube with no catalytic activity was used as the reactor. The yield of hydrocarbons with 2 to 4 carbon atoms in the product gas, the methane conversion rate, the selectivity for hydrocarbons with 2 to 4 carbon atoms, and the oxygen consumption rate were measured relative to the partial pressure of methane in the feedstock gas. The results are shown in Figure 11.

[0065] Here, the methane conversion is defined by the following formula (1): Methane conversion (%) = (methane flow rate at reactor inlet - methane flow rate at reactor outlet) / methane flow rate at reactor inlet x 100 (1) The selectivity of hydrocarbons having 2 to 4 carbon atoms (C2-4 hydrocarbon selectivity) is defined by the following formula (2): C2-4 hydrocarbon selectivity (%) = (methane-equivalent C2-4 hydrocarbon flow rate) / (methane flow rate at reactor inlet - methane flow rate at reactor outlet) x 100 (2) Furthermore, the yield of hydrocarbons having 2 to 4 carbon atoms (C2-4 hydrocarbon yield) is defined by the following formula (3): C2-4 hydrocarbon yield (%) = (methane conversion) x (C2-4 hydrocarbon selectivity) x 100 (3)

[0066] The units of the flow rates in the above formulas are molar flow rates (for example, kgmol / h), and the "methane-equivalent C2-4 hydrocarbon flow rate" in formula (2) means the flow rate converted into methane by multiplying the flow rate of each compound of hydrocarbons having 2 to 4 carbon atoms, such as ethane, ethylene, propane, and propylene, by the number of carbon atoms in each compound.

[0067] As shown in Figure 11, when "Sn-Mn-KW" is used as the oxidative coupling catalyst, it was confirmed that the selectivity for hydrocarbons with 2 to 4 carbon atoms is improved at methane partial pressures of 500 kPa or higher compared to when other oxidative coupling catalysts are used. This means that when tin is added to the oxidative coupling catalyst, the selectivity for the target product, hydrocarbons with 2 to 4 carbon atoms, is improved under pressurized conditions (e.g., 500 kPa or higher). Therefore, the use of "Sn-Mn-KW" as the oxidative coupling catalyst is expected to lead to the downsizing of the equipment used to perform the OCM reaction, the purification of the downstream stream from the reactor, and a reduction in the power required for compressors and other equipment used in the separation process.

[0068] The oxidative coupling catalyst (Sn (20 wt%) Mn (2 wt%) K) supported on "Sn-Mn-KW" prepared by changing the concentration of the active component in the method shown in Example 3 was used. ２ WO ４ (5wt%) / SiO ２ The methane conversion rate and oxygen consumption rate were measured when an oxidative coupling reaction of methane was carried out using silica gel particles carrying "Mn-KW" and when an oxidative coupling reaction of methane was carried out using silica gel particles carrying "Mn-KW". The total pressure was 0.9 MPa, the gas supply temperature to the catalyst layer was 600 to 700°C, and the molar ratio of methane to oxygen (CH ４ / O ２ The performance was evaluated under the conditions of a 10 (mol / mol) catalyst, a raw material gas flow rate of 4000 Ncc / min, and a catalyst amount of 2.3 g. The results are shown in Figures 12 and 13.

[0069] As shown in Figure 12, it was confirmed that the methane conversion rate was improved by supporting "Sn-Mn-KW" on a silica carrier. As shown in Figure 13, by supporting "Sn-Mn-KW" on a silica carrier, the oxygen consumption rate was maintained at 100% even at 650°C, and it was confirmed that high catalytic activity was maintained even at relatively low temperatures (e.g., approximately 650°C).

[0070] Oxidative coupling catalysts with modified active component compositions were prepared in accordance with the methods of Examples 1 and 2 described above (Composition Examples 1 to 10). The BET specific surface area of ​​the resulting oxidative coupling catalysts was measured. Furthermore, the nine types of oxidative coupling catalysts (Composition Examples 1 and 2, Composition Examples 4 to 10) were packed into a pressurizable reactor, and hydrocarbons were produced by a methane oxidative coupling reaction using methane-containing natural gas as the feedstock. An inert quartz tube was used as the reactor. The yield of hydrocarbons with 2 to 4 carbon atoms in the product gas, the methane conversion rate, and the selectivity for hydrocarbons with 2 to 4 carbon atoms were measured relative to the partial pressure of methane in the feedstock gas. The total pressure was 0.9 MPa, the gas supply temperature to the catalyst layer was 750°C, and the molar ratio of methane to oxygen (CH ４ / O ２ The performance was evaluated under the conditions of 6 (mol / mol), a raw material gas flow rate of 240 Ncc / min, and a catalyst amount of 200 mg. The results are shown in Table 3.

[0071]

[0072] As shown in Table 3, regardless of which oxidative coupling catalyst was used, the selectivity for hydrocarbons having 2 to 4 carbon atoms was a high value of 50% or more. In addition, regardless of which oxidative coupling catalyst was used, the yield of hydrocarbons having 2 to 4 carbon atoms was a good value of 7% or more.

[0073] From the above results, it was confirmed that the oxidative coupling catalyst according to the present disclosure makes it possible to produce hydrocarbons having two or more carbon atoms in high yield even under high temperature and pressure conditions, and that it is possible to reduce the size of the equipment used to perform the OCM reaction.

[0074] <Additional Notes> The oxidation coupling catalyst, the method for producing an oxidation coupling catalyst, and the method for producing hydrocarbons described in the above-described embodiments can be understood, for example, as follows.

[0075] (1) The oxidative coupling catalyst according to a first aspect is an oxidative coupling catalyst that produces hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane, and is a calcined product of silica carrying an alkali metal salt.

[0076] According to the above configuration, cracking of the support of the oxidation coupling catalyst can be suppressed even when the OCM reaction is carried out under high temperature and pressure, which makes it possible to produce hydrocarbons having two or more carbon atoms in high yield even under high temperature and pressure, and to reduce the size of the equipment used to carry out the OCM reaction.

[0077] (2) The oxidation coupling catalyst according to a second aspect is the oxidation coupling catalyst according to (1), in which the calcined silica carrying the alkali metal salt exhibits crystallinity.

[0078] According to the above configuration, the catalytic activity can be further improved.

[0079] (3) The oxidation coupling catalyst according to a third aspect is the oxidation coupling catalyst according to (1) or (2), wherein the alkali metal salt is an alkali metal salt of an oxide containing at least one of tungsten and zirconium.

[0080] According to the above configuration, the yield of hydrocarbons having 2 to 4 carbon atoms in the OCM reaction can be further increased.

[0081] (4) The oxidation coupling catalyst according to a fourth aspect is the oxidation coupling catalyst according to (3), in which the alkali metal salt is a potassium salt of the oxide.

[0082] According to the above configuration, the catalyst has high catalytic activity and excellent heat resistance.

[0083] (5) The oxidation coupling catalyst according to the fifth aspect is the oxidation coupling catalyst according to (4), in which manganese is further supported.

[0084] According to the above configuration, the yield of hydrocarbons having 2 to 4 carbon atoms in the OCM reaction can be further increased.

[0085] (6) An oxidation coupling catalyst according to a sixth aspect is the oxidation coupling catalyst according to (5), wherein the mass ratio of the manganese : the potassium salt of the oxide : the silica is (0.01 to 5):(0.05 to 10):(85 to 99.9).

[0086] According to the above-mentioned configuration, the selectivity for hydrocarbons having 2 to 4 carbon atoms can be further increased in the OCM reaction even under pressurized conditions.

[0087] (7) The oxidation coupling catalyst according to the seventh aspect is the oxidation coupling catalyst according to (5), in which tin is further supported.

[0088] According to the above-mentioned method, the selectivity for hydrocarbons having 2 to 4 carbon atoms can be further increased even under pressurized conditions.

[0089] (8) An oxidation coupling catalyst according to an eighth aspect is the oxidation coupling catalyst according to (7), wherein the mass ratio of the tin:the manganese:the potassium salt of the oxide:the silica is (0.01 to 50):(0.01 to 5):(0.05 to 10):(35 to 99.9).

[0090] According to the above-mentioned configuration, the selectivity for hydrocarbons having 2 to 4 carbon atoms can be further increased in the OCM reaction even under pressurized conditions.

[0091] (9) The oxidation coupling catalyst according to a ninth aspect is any one of the oxidation coupling catalysts (1) to (8), and has an average particle size of 1 to 5 mm.

[0092] According to the above configuration, the yield of hydrocarbons having 2 to 4 carbon atoms in the OCM reaction can be further increased. In addition, the pressure loss when the OCM reaction is carried out under pressurized conditions can be further reduced, allowing for the downsizing of the equipment for carrying out the OCM reaction.

[0093] (10) A tenth aspect of the present invention provides a method for producing an oxidative coupling catalyst for producing hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane, the method comprising the steps of: bringing silica or a calcined product of silica into contact with an aqueous solution containing an alkali metal salt to obtain a precursor in which the silica or the calcined product of silica is impregnated with the aqueous solution; and calcining the precursor at 800°C or higher to obtain the oxidative coupling catalyst.

[0094] According to the above-described configuration, a calcined silica supporting an alkali metal salt can be obtained. Therefore, even when the OCM reaction is carried out under high temperature and pressure, cracking of the support of the oxidation coupling catalyst can be suppressed. As a result, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure, and the equipment for carrying out the OCM reaction can be made smaller.

[0095] (11) A method for producing an oxidation coupling catalyst according to an eleventh aspect is the method for producing an oxidation coupling catalyst according to (10), further comprising a step of extruding a composition in which silica powder is dispersed in a binder to obtain the silica.

[0096] According to the above-mentioned configuration, the particle size of the oxidation coupling catalyst can be easily adjusted, and the heat resistance is superior.

[0097] (12) A twelfth aspect of the present invention relates to a method for producing an oxidation coupling catalyst according to (11), which further comprises a step of calcining a molded product obtained by extruding the composition at 700°C or higher to obtain the calcined silica.

[0098] According to the above-mentioned configuration, the occurrence of cracks in the fired product can be further suppressed in the subsequent step of obtaining a fired product of the precursor.

[0099] (13) A thirteenth aspect of the present invention relates to a method for producing an oxidation coupling catalyst according to (12), further comprising the step of obtaining a calcined product of silica, wherein the calcined product of silica has a crushing strength of 10 N / mm ２ The following is the result.

[0100] According to the above-mentioned configuration, the occurrence of cracks in the fired product can be further suppressed in the subsequent step of obtaining a fired product of the precursor.

[0101] (14) A fourteenth aspect of the method for producing an oxidation coupling catalyst is the method for producing an oxidation coupling catalyst according to any one of (10) to (13), in which the silica is amorphous.

[0102] According to the above-mentioned configuration, the occurrence of cracks in the fired product can be further suppressed in the subsequent step of obtaining a fired product of the precursor.

[0103] (15) A fifteenth aspect of the present invention relates to a method for producing hydrocarbons, which uses any one of the oxidative coupling catalysts (1) to (9) to produce hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane.

[0104] According to the above configuration, hydrocarbons having two or more carbon atoms can be produced in high yield. In addition, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure, and the equipment for performing the OCM reaction can be made smaller.

[0105] (16) A sixteenth aspect of the hydrocarbon production method is the hydrocarbon production method according to (15), in which the oxidative coupling reaction is carried out under pressure conditions.

[0106] According to the above configuration, the equipment for performing the OCM reaction can be made smaller, and as a result, the power required for the equipment for performing the OCM reaction can be reduced.

[0107] (17) A seventeenth aspect of the hydrocarbon production method is the hydrocarbon production method according to (15) or (16), in which the pressure under the pressurized conditions is 0.9 MPa or more.

[0108] According to the above configuration, the equipment for performing the OCM reaction can be made smaller.

[0109] (18) A hydrocarbon production method according to an eighteenth aspect is any one of (15) to (17), in which the oxidative coupling reaction is carried out at 500° C. or higher.

[0110] According to the above configuration, the decrease in catalytic activity can be suppressed.

[0111] (19) Use of the calcined silica carrying an alkali metal salt according to the nineteenth aspect for producing an oxidative coupling catalyst, wherein the oxidative coupling catalyst is an oxidative coupling catalyst that produces hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane.

[0112] According to the above configuration, hydrocarbons having two or more carbon atoms can be produced in high yield. In addition, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure, and the equipment for performing the OCM reaction can be made smaller.

[0113] (20) Use of the calcined silica carrying an alkali metal salt according to the twentieth aspect as an oxidative coupling catalyst, wherein the oxidative coupling catalyst is an oxidative coupling catalyst that produces hydrocarbons having two or more carbon atoms from methane through an oxidative coupling reaction of methane.

[0114] According to the above configuration, hydrocarbons having two or more carbon atoms can be produced in high yield. In addition, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure, and the equipment for performing the OCM reaction can be made smaller.

[0115] According to the present disclosure, hydrocarbons having two or more carbon atoms can be produced in high yield even under high temperature and pressure conditions, and the equipment for performing the OCM reaction can be made smaller.

Claims

1. An oxidative coupling catalyst for producing hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane, comprising: It is a calcined product of silica carrying an alkali metal salt, An oxidative coupling catalyst having a particle size of 1 to 5 mm.

2. 2. The oxidative coupling catalyst according to claim 1, wherein the calcined product of the silica on which the alkali metal salt is supported exhibits crystallinity.

3. 3. The oxidative coupling catalyst according to claim 1, wherein the alkali metal salt is an alkali metal salt of an oxide containing at least one of tungsten and zirconium.

4. 4. The oxidative coupling catalyst of claim 3, wherein said alkali metal salt is a potassium salt of said oxide.

5. 5. The oxidative coupling catalyst according to claim 4, further comprising supported manganese.

6. 6. The oxidative coupling catalyst according to claim 5, wherein the mass ratio of the manganese: the potassium oxide salt: the silica is (0.01 to 5):(0.05 to 10):(85 to 99.9).

7. The oxidative coupling catalyst according to claim 5, further comprising supported tin.

8. 8. The oxidative coupling catalyst according to claim 7, wherein the mass ratio of the tin:the manganese:the potassium salt of the oxide:the silica is (0.01 to 50):(0.01 to 5):(0.05 to 10):(35 to 99.9).

9. 1. A method for producing an oxidative coupling catalyst for producing hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane, comprising: a step of contacting silica or a calcined product of silica with an aqueous solution containing an alkali metal salt to obtain a precursor in which the silica or the calcined product of silica is impregnated with the aqueous solution; calcining the precursor at 800°C or higher to obtain an oxidation coupling catalyst having a particle size of 1 to 5 mm; The method for producing an oxidative coupling catalyst comprising the steps of:

10. 10. The method for producing an oxidation coupling catalyst according to claim 9, further comprising the step of extruding a composition in which silica powder is dispersed in a binder to obtain the silica.

11. 11. The method for producing an oxidation coupling catalyst according to claim 10, further comprising the step of calcining a molded product obtained by extruding the composition at 700°C or higher to obtain the calcined product of silica.

12. 12. The method for producing an oxidative coupling catalyst according to claim 11, further comprising a step of obtaining a calcined product of the silica, wherein the calcined product of the silica has a crushing strength of 10 N / mm<2 >or less.

13. 11. The method for producing an oxidative coupling catalyst according to claim 9 or 10, wherein the silica is amorphous.

14. A method for producing hydrocarbons, comprising: generating hydrocarbons having two or more carbon atoms from methane by an oxidative coupling reaction of methane using the oxidative coupling catalyst according to claim 1 or 2.

15. The method for producing hydrocarbons according to claim 14, wherein the oxidative coupling reaction is carried out under pressure.

16. The method for producing hydrocarbons according to claim 15, wherein the pressure under the pressurized conditions is 0.9 MPa or more.

17. The method for producing hydrocarbons according to claim 16, wherein the oxidative coupling reaction is carried out at 500°C or higher.