Method for preparing methanol through hydrogenation of carbon dioxide

Abstract

The invention provides a method for preparing methanol by hydrogenating carbon dioxide, which comprises the following steps of: introducing raw material gas into the outer side of a membrane tube of a membrane reactor, and introducing purging gas into the inner side of the membrane tube of the membrane reactor; the membrane tube comprises a membrane support body and a membrane functional layer covering the outer surface of the membrane support body; the membrane functional layer comprises a CHA molecular sieve membrane and a catalyst loaded on the outer surface of the CHA molecular sieve membrane; wherein a catalyst in the catalyst layer comprises a metal oxide carrier and an active metal component loaded on the surface of the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium-zirconium composite oxide with a mesoporous structure. According to the method, water generated in the reaction process can be removed from a reaction system in time, thermodynamic equilibrium is broken, forward proceeding of the reaction is promoted, and the method has the advantages of excellent catalytic performance, high reaction activity, high target product selectivity, good reaction stability and low inactivation rate.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and in particular to a method for producing methanol by hydrogenating carbon dioxide. Background Art

[0002] Carbon emissions are currently considered one of the main causes of global warming. Effective measures are needed to reduce atmospheric CO2 concentrations by capturing and converting CO2. The primary source of carbon emissions is fossil fuels. Methanol, a key chemical raw material and a substitute for fossil fuels, can be produced by reacting CO2 with hydrogen from renewable energy, offering both an effective method for controlling greenhouse gases and a viable alternative to fossil fuels.

[0003] Due to the chemical stability of CO2 and its difficulty in activation, the conversion rate of this reaction is generally low. Methanol production is an exothermic reaction, and thermodynamically, low temperatures favor methanol production but hinder carbon dioxide activation. Furthermore, the CO2 hydrogenation reaction itself is subject to thermodynamic limitations, resulting in low CO2 conversion and methanol selectivity. Therefore, designing and developing more effective methods to overcome the thermodynamic limitations of CO2 hydrogenation and improve CO2 conversion is of great significance for its industrial application. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem in the prior art that CO2 hydrogenation catalysts are subject to thermodynamic limitations and have low catalytic activity.

[0005] In order to achieve the above object, the present invention provides a method for producing methanol by hydrogenating carbon dioxide, the method comprising:

[0006] The feed gas is introduced into the outer side of the membrane tube of the membrane reactor, and the purge gas is introduced into the inner side of the membrane tube of the membrane reactor; the membrane tube includes a membrane support and a membrane functional layer covering the outer surface of the membrane support; the membrane functional layer includes a CHA molecular sieve membrane and a catalyst layer supported on the outer surface of the CHA molecular sieve membrane;

[0007] The catalyst in the catalyst layer includes a metal oxide carrier and an active metal component supported on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium-zirconium composite oxide with a mesoporous structure.

[0008] Optionally, based on the total weight of the catalyst, the content of Pd is 0.1 to 6 weight %; based on the total weight of the metal oxide support, the content of indium oxide is 60 to 90 weight %, and the content of zirconium oxide is 10 to 40 weight %; preferably, based on the total weight of the catalyst, the content of Pd is 1 to 6 weight %; based on the total weight of the metal oxide support, the content of indium oxide is 75 to 90 weight %, and the content of zirconium oxide is 10 to 25 weight %.

[0009] Optionally, the method for preparing the membrane tube of the membrane reactor includes:

[0010] S1, mixing a solution containing a surfactant with an acid, an indium precursor, and a zirconium precursor, and performing a first drying treatment to obtain an indium zirconium composite oxide support precursor; dispersing the indium zirconium composite oxide support precursor in a first organic solvent to obtain a first material;

[0011] S2, ultrasonically mixing a solution containing a palladium salt and a solution containing a reducing agent, followed by centrifugal washing to obtain a palladium precursor; dispersing the palladium precursor in a second organic solvent to obtain a second material;

[0012] S3, mixing the first material and the second material to obtain a catalyst precursor solution;

[0013] S4, immersing the membrane support with the CHA molecular sieve membrane on its outer surface in the catalyst precursor solution to obtain a pretreated membrane tube; and performing a second drying treatment and a calcination treatment on the pretreated membrane tube.

[0014] Optionally, the surfactant is selected from at least one of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123), hexadecyltrimethylammonium bromide (CTAB), malic acid, sodium 2-ethylhexane sulfosuccinate and nonylphenol polyoxyethylene ether; the solvent in the solution containing the surfactant is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide; the acid is selected from at least one of nitric acid, hydrochloric acid and phosphoric acid; the indium precursor is selected from at least one of indium nitrate, indium chloride and indium sulfate; the zirconium precursor is selected from at least one of zirconium nitrate, zirconium chloride and zirconium sulfate; optionally, in the solution containing the surfactant, the molar concentration of the surfactant is 0.001 to 1 mol / L; H in the acid + The molar concentration of the surfactant is 3 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium oxide precursor and the zirconium oxide precursor is 0.005 to 0.05: 1 to 5: 60 to 90: 10 to 40; preferably, the molar concentration of the surfactant is 0.01 to 0.05 mol / L; the H +The molar concentration is 6 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium precursor and the zirconium precursor is 0.015 to 0.025:1.5 to 3:75 to 90:10 to 25.

[0015] Optionally, the palladium salt is selected from at least one of palladium nitrate, palladium chloride, palladium acetate, ammonium tetrachloropalladate, ammonium hexachloropalladate, dichlorodiammine palladium and dichlorotetrammine palladium; the reducing agent is selected from at least one of sodium borohydride (NaBH4), lithium borohydride (LiBH4), zinc borohydride (Zn BH3), lithium aluminum hydride (LiAlH4) and sodium cyanoborohydride; the solvent in the solution containing the reducing agent is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide; optionally, in the solution containing the palladium salt, the mass concentration of the palladium salt is 0.005-0.03 weight%; the volume ratio of the solution containing the palladium salt and the solution containing the reducing agent is 0.01-1:10-100.

[0016] Optionally, the first organic solvent and the second organic solvent are each independently selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetyl.

[0017] Optionally, in step S1, the mixing is carried out under stirring, and the mixing conditions include: mixing time of 3 to 9 hours, stirring speed of 100 to 300 r / min; the first drying conditions include: temperature of 50 to 100°C, time of 30 to 60 hours; in step S2, the ultrasonic mixing conditions include: frequency of 10 to 50 kHz, temperature of 20 to 35°C, time of 0.5 to 2 hours; in step S4, the impregnation includes using a pulling impregnation device to The membrane support body with a CHA molecular sieve membrane covered on the outer surface is subjected to an impregnation treatment; wherein, the pulling speed of the pulling and impregnation equipment is 500-1500 μm / s, the standing time of the pulling and impregnation equipment is 20-60 seconds, and the number of impregnations of the pulling and impregnation equipment is 10-60 times; the conditions for the second drying treatment include: a temperature of 90-150°C and a time of 1-5 hours; the conditions for the first calcination treatment include: a temperature of 300-400°C and a time of 3-6 hours.

[0018] Optionally, the method further comprises: before the impregnation in step S4, using K and / or Cs to modify the membrane support with the CHA molecular sieve membrane on the outer surface; the modification step comprises: immersing the membrane support with the CHA molecular sieve membrane on the outer surface in a solution containing K+ and / or a solution containing Cs+, and then performing a third drying treatment on the impregnation result; optionally, the K-containing solution + In the solution, K +The concentration of Cs + In the solution, Cs + The concentration is 0.5 to 2 mol / L; the immersion conditions include: a temperature of 20 to 40°C and a time of 12 to 48 hours; the third drying conditions include: a temperature of 50 to 80°C and a time of 12 to 48 hours.

[0019] Optionally, the membrane support body is selected from at least one of porous mullite, alumina, titanium oxide, cordierite and zirconium oxide, preferably porous mullite; the membrane support body is formed into a tubular shape; the thickness of the membrane support body is 1.5 to 2.5 mm, the thickness of the CHA molecular sieve membrane layer is 1 to 3 μm, and the thickness of the membrane functional layer is 5 to 50 μm.

[0020] Optionally, the raw gas consists of hydrogen, carbon dioxide and nitrogen; wherein the molar ratio of hydrogen, carbon dioxide and nitrogen is 1 to 6:1:1; and the purge gas is hydrogen.

[0021] Optionally, the reaction conditions outside the membrane tube of the membrane reactor include: reaction pressure of 2-4 MPa, reaction temperature of 200-350°C, volume space velocity of 1200-10800 h -1 ; The pressure difference on both sides of the membrane tube of the membrane reactor is 0.08~2.0MPa.

[0022] Through the above technical solution, the present invention uses a membrane reactor to strengthen the CO2 hydrogenation to methanol reaction, which can promptly remove the water produced during the reaction and effectively promote the occurrence of methanol catalytic reaction. The membrane tube filled in the membrane reaction cavity of the membrane reactor of the present invention includes a membrane support and a membrane functional layer covered on the outer surface of the membrane support; the membrane functional layer includes a CHA molecular sieve membrane inner layer and a catalyst outer layer loaded on the surface of the CHA molecular sieve membrane layer. Among them, the CHA molecular sieve membrane inner layer has the technical advantage of quickly removing water produced in the reaction; the catalyst in the catalyst outer layer includes an indium zirconium composite oxide carrier with a mesoporous structure and an active metal component Pd. The indium zirconium composite oxide carrier has an ordered mesoporous structure. The catalyst has high catalytic activity and selectivity, and can significantly improve the conversion rate of carbon dioxide and the content of methanol in the product.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1It is a process flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0027] The present invention provides a method for preparing methanol by hydrogenating carbon dioxide. Figure 1 As shown, the method includes:

[0028] The feed gas is introduced into the outer side of the membrane tube of the membrane reactor, and the purge gas is introduced into the inner side of the membrane tube of the membrane reactor; the membrane tube includes a membrane support and a membrane functional layer covering the outer surface of the membrane support; the membrane functional layer includes a CHA molecular sieve membrane and a catalyst layer supported on the outer surface of the CHA molecular sieve membrane;

[0029] The catalyst in the catalyst layer includes a metal oxide carrier and an active metal component supported on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium-zirconium composite oxide with a mesoporous structure.

[0030] During the reaction process of the present invention, a high-temperature graphite gasket can be used to seal the membrane tube to the membrane reactor. Carbon dioxide and hydrogen are introduced on the reaction side. The reaction products pass through the molecular sieve membrane into the inner side of the membrane tube and are carried out of the reactor by the purge gas, thereby promoting the forward progress of the CO2 hydrogenation to methanol reaction. The method of the present invention can promptly remove water generated during the reaction from the reaction system, breaking thermodynamic equilibrium and promoting the forward progress of the reaction. It has excellent catalytic performance, high reaction activity, high selectivity for the target product, good reaction stability, and low deactivation rate.

[0031] The membrane tube filled in the membrane reaction chamber of the membrane reactor of the present invention includes a membrane support and a membrane functional layer coated on the outer surface of the membrane support; the membrane functional layer includes a CHA molecular sieve membrane and a catalyst loaded on the outer surface of the CHA molecular sieve membrane layer. Among them, the inner layer of the CHA molecular sieve membrane has the technical advantage of quickly removing water produced in the reaction. The catalyst in the outer layer includes an indium zirconium composite oxide support with a mesoporous structure and an active metal component Pd. The indium zirconium composite oxide support of the present invention has an ordered mesoporous structure. The catalyst has high catalytic activity and selectivity, and can significantly improve the conversion rate of carbon dioxide and the content of methanol in the product.

[0032] According to the present invention, based on the total weight of the catalyst, the content of Pd can be 0.1 to 6 weight percent; based on the total weight of the metal oxide support, the content of indium oxide can be 60 to 90 weight percent, and the content of zirconium oxide can be 10 to 40 weight percent. Preferably, based on the total weight of the catalyst, the content of Pd can be 1 to 6 weight percent; based on the total weight of the metal oxide support, the content of indium oxide can be 75 to 90 weight percent, and the content of zirconium oxide can be 10 to 25 weight percent. The catalyst of the present invention has excellent catalytic performance, high reaction activity, and a deactivation rate that can meet high carbon dioxide conversion and methanol selectivity even during long-term reaction operation.

[0033] According to the present invention, the method for preparing the membrane tube of the membrane reactor may include:

[0034] S1, mixing a solution containing a surfactant with an acid, an indium precursor, and a zirconium precursor, and performing a first drying treatment to obtain an indium zirconium composite oxide support precursor; dispersing the indium zirconium composite oxide support precursor in a first organic solvent to obtain a first material;

[0035] S2, ultrasonically mixing a solution containing a palladium salt and a solution containing a reducing agent, followed by centrifugal washing to obtain a palladium precursor; dispersing the palladium precursor in a second organic solvent to obtain a second material;

[0036] S3, mixing the first material and the second material to obtain a catalyst precursor solution;

[0037] S4, immersing the membrane support with the CHA molecular sieve membrane on its outer surface in the catalyst precursor solution to obtain a pretreated membrane tube; and performing a second drying treatment and a calcination treatment on the pretreated membrane tube.

[0038] The membrane tube prepared using the method of the present invention comprises a membrane support and a membrane functional layer coated on the outer surface of the membrane support. The membrane functional layer comprises a CHA molecular sieve membrane and a catalyst layer supported on the outer surface of the CHA molecular sieve membrane layer. The catalyst in the catalyst layer comprises a mesoporous indium zirconium composite oxide and an active metal component, Pd, supported on the surface of the indium zirconium composite oxide. This catalyst exhibits high reactivity and excellent catalytic performance, capable of maintaining high carbon dioxide conversion and methanol selectivity even during long-term reaction operations.

[0039] According to the present invention, the surfactant can be selected from at least one of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123), hexadecyltrimethylammonium bromide (CTAB), malic acid, sodium 2-ethylhexane sulfosuccinate and nonylphenol polyoxyethylene ether; the solvent in the solution containing the surfactant can be selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide; the acid can be selected from at least one of nitric acid, hydrochloric acid and phosphoric acid; the indium precursor can be selected from at least one of indium nitrate, indium chloride and indium sulfate; the zirconium precursor can be selected from at least one of zirconium nitrate, zirconium chloride and zirconium sulfate; optionally, in the solution containing the surfactant, the molar concentration of the surfactant is 0.001 to 1 mol / L; the H in the acid + The molar concentration of the surfactant is 3 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium oxide precursor and the zirconium oxide precursor is 0.005 to 0.05: 1 to 5: 60 to 90: 10 to 40; preferably, the molar concentration of the surfactant is 0.01 to 0.05 mol / L; the H + The molar concentration is 6 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium precursor and the zirconium precursor is 0.015 to 0.025:1.5 to 3:75 to 90:10 to 25.

[0040] According to the present invention, the palladium salt can be selected from at least one of palladium nitrate, palladium chloride, palladium acetate, ammonium tetrachloropalladate, ammonium hexachloropalladate, dichlorodiammine palladium and dichlorotetrammine palladium; the reducing agent can be selected from at least one of sodium borohydride (NaBH4), lithium borohydride (LiBH4), zinc borohydride (Zn BH3), lithium aluminum hydride (LiAlH4) and sodium cyanoborohydride; the solvent in the solution containing the reducing agent can be selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide; optionally, in the solution containing the palladium salt, the mass concentration of the palladium salt is 0.005-0.03 weight%; the volume ratio of the solution containing the palladium salt and the solution containing the reducing agent is 0.01-1:10-100.

[0041] According to the present invention, the first organic solvent and the second organic solvent may be independently selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetyl.

[0042] According to the present invention, in step S1, the mixing is carried out under stirring, and the mixing conditions may include: a mixing time of 3 to 9 hours and a stirring speed of 100 to 300 r / min; the first drying conditions may include: a temperature of 50 to 100°C and a time of 30 to 60 hours; in step S2, the ultrasonic mixing conditions may include: a frequency of 10 to 50 KHZ, a temperature of 20 to 35°C, and a time of 0.5 to 2 hours; in step S4, the impregnation includes using a pulling impregnation The impregnation equipment performs an impregnation treatment on the membrane support body whose outer surface is covered with the CHA molecular sieve membrane; wherein, the pulling speed of the pulling impregnation equipment is 500-1500 μm / s, the standing time of the pulling impregnation equipment is 20-60s, and the number of impregnations of the pulling impregnation equipment is 10-60 times; the conditions for the second drying treatment include: temperature of 90-150°C, time of 1-5h; the conditions for the first calcination treatment include: temperature of 300-400°C, time of 3-6h.

[0043] The specific steps of the present invention using a pulling and impregnation device for impregnation treatment may include: fixing the upper end of a membrane support body with a CHA molecular sieve membrane on the outer surface on the pulling and impregnation device, sealing both ends of the membrane support body with polytetrafluoroethylene stoppers, vertically fixing the upper end of the tube on a pulling and impregnation coating machine, immersing it in a glass bottle filled with a catalyst precursor solution and letting it stand, then pulling it up vertically, repeating the dipping process multiple times, and then drying and calcining to obtain a membrane tube with a double functional layer.

[0044] According to the present invention, the membrane support with the CHA molecular sieve membrane on the outer surface is preferably a membrane tube modified with K and / or Cs. The modified membrane tube can more effectively remove water from the reaction system, thereby effectively promoting the occurrence of the methanol catalytic reaction. In an exemplary embodiment of the present invention, the method of the present invention further includes: before the impregnation in step S4, modifying the membrane support with the CHA molecular sieve membrane on the outer surface with K and / or Cs; the modification step includes: immersing the membrane support with the CHA molecular sieve membrane on the outer surface in a solution containing K. + Solutions and / or containing Cs + The impregnation result is then subjected to a third drying process; optionally, the K-containing + In the solution, K + The concentration of Cs + In the solution, Cs + The concentration is 0.5 to 2 mol / L; the conditions for the impregnation may include: a temperature of 20 to 40°C and a time of 12 to 48 hours; the conditions for the third drying treatment may include: a temperature of 50 to 80°C and a time of 12 to 48 hours.

[0045] According to the present invention, the membrane support can be selected from at least one of porous mullite, alumina, titanium oxide, cordierite, and zirconium oxide, preferably porous mullite; the membrane support is formed into a tubular shape. The use of porous mullite as the membrane support in the present invention offers the technical advantage of high-temperature stability. Preferably, the membrane support has a thickness of 1.5 to 2.5 mm, the CHA molecular sieve membrane layer has a thickness of 1 to 3 μm, and the membrane functional layer has a thickness of 5 to 50 μm.

[0046] The membrane tube involved in the present invention, including the membrane support and the membrane functional layer coated on the outer surface of the membrane support, can be obtained commercially or by synthesis. For example, the synthesis method of the membrane tube can be SSZ-13 seed coating method.

[0047] The porous mullite used in the present invention may be prepared by a common method in the art. For example, a pore-forming agent is added to the porous mullite production process, and the pore-forming agent is burned off during the sintering process of the mullite to leave pores.

[0048] In a preferred embodiment of the present invention, the raw gas consists of hydrogen, carbon dioxide and nitrogen; wherein the molar ratio of hydrogen, carbon dioxide and nitrogen can be 1 to 6:1:1; and the purge gas can be hydrogen.

[0049] In the present invention, the reaction conditions outside the membrane tube of the membrane reactor may include: reaction pressure of 2-4 MPa, reaction temperature of 200-350°C, volume space velocity of 1200-10800 h -1 ; The pressure difference on both sides of the membrane tube of the membrane reactor can be 0.08~2.0MPa.

[0050] The present invention is further described in detail below by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0051] The membrane tube used in the embodiment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The membrane tube is prepared according to the SSZ-13 seed coating method. The specific preparation steps include: pretreatment of the porous mullite support (polishing the outer surface of the support smooth with sandpaper and then pickling and drying), pre-coating the surface of the support with seeds by hot dipping, plugging both ends of the seed-coated support with polytetrafluoroethylene plugs, and then vertically placing it into the prepared SSZ-13 molecular sieve mother liquor to crystallize and synthesize the CHA type molecular sieve membrane.

[0052] The membrane tube used in the comparative example, which includes a tubular porous mullite support and an LTA molecular sieve membrane attached to the outer surface of the porous mullite, is prepared according to the NaA molecular sieve seed coating method. The specific preparation steps include: pretreatment of the porous mullite support (polishing the outer surface of the support smooth with sandpaper and then pickling and drying), pre-coating the surface of the support with seeds by hot dipping, plugging both ends of the seed-coated support with polytetrafluoroethylene plugs, and then vertically placing it into the prepared NaA molecular sieve mother liquor to crystallize and synthesize the NaA molecular sieve membrane.

[0053] Example 1

[0054] (1) Weigh 4.1 g of P123 and dissolve it in 40 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 4.2 g of In(NO3)3·4H2O, 0.7 g of Zr(NO3)2·5H2O, and 5.8 mL of H + Concentrated nitric acid with a concentration of 12 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 45°C for 4.5 hours to make it into a sol state, placed in a 50°C oven to dry for 48 hours, and placed in 100 mL of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0055] 0.7 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 40 ml of ethanol, and then 1 ml of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0056] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0057] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 2.2 mm, and the thickness of the CHA molecular sieve membrane is 22 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 20 h and dried at 65°C for 22 h.

[0058] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 1000μm / s, let it stand for 30s, and then pull it up vertically at a speed of 1000μm / s. Repeat the dipping 20 times, with an interval of 120s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 110℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 4 hours to obtain a membrane tube with a double functional layer.

[0059] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 5:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 280 ° C, the pressure on the reaction side was 3.05 MPa, the pressure on the purge side was 2.89 MPa, the pressure difference on both sides was maintained at 0.16 MPa, and the air velocity was set to 8000 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0060] Example 2

[0061] (1) Weigh 3.5 g of P123 and dissolve it in 60 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 4.2 g of In(NO3)3·4H2O, 2.1 g of Zr(NO3)2·5H2O, and 4.6 mL of H + Concentrated nitric acid with a concentration of 10 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 3 hours to make it into a sol state, placed in a 60°C oven to dry for 48 hours, and placed in 100 mL of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0062] 0.23 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 40 mL of ethanol, and then 4 mL of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0063] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0064] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 1.8 mm, and the thickness of the CHA molecular sieve membrane is 15 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 36 hours and dried at 55°C for 36 hours.

[0065] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 800μm / s, let it stand for 35s, and then pull it up vertically at a speed of 800μm / s. Repeat the dipping 20 times, with an interval of 100s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 120℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 3 hours to obtain a membrane tube with a double functional layer.

[0066] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 4:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 280 ° C, the pressure on the reaction side was 3.10 MPa, the pressure on the purge side was 3.00 MPa, the pressure difference on both sides was maintained at 0.10 MPa, and the air velocity was set to 8500 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0067] Example 3

[0068] (1) Weigh 3.8 g of P123 and dissolve it in 45 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 2.8 g of In(NO3)3·4H2O, 2.2 g of Zr(NO3)2·5H2O and 5.3 mL of H + Concentrated nitric acid with a concentration of 9 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 4 hours to make it into a sol state, placed in a 60°C oven to dry for 48 hours, and placed in 100 mL of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0069] 0.3 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 40 mL of ethanol, and then 6 mL of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0070] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0071] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 2.0 mm, and the thickness of the CHA molecular sieve membrane is 25 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 20 h and dried at 65°C for 35 h.

[0072] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 900μm / s, let it stand for 45s, and then pull it up vertically at a speed of 900μm / s. Repeat the dipping 30 times, with an interval of 110s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 120℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 4 hours to obtain a membrane tube with a double functional layer.

[0073] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 3:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 280 ° C, the pressure on the reaction side was 3.16 MPa, the pressure on the purge side was 3.02 MPa, the pressure difference on both sides was maintained at 0.14 MPa, and the air velocity was set to 9500 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0074] Example 4

[0075] (1) Weigh 6.9 g of P123 and dissolve it in 50 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 3.6 g of In(NO3)3·4H2O, 4.5 g of Zr(NO3)2·5H2O, and 11.5 mL of H + Concentrated nitric acid with a concentration of 11 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 4 hours to make it into a sol state, placed in a 60°C oven to dry for 48 hours, and placed in 100 mL of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0076] 0.02 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 50 mL of ethanol, and then 5 mL of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0077] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0078] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 2.3 mm, and the thickness of the CHA molecular sieve membrane is 34 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 30 h and dried at 65°C for 30 h.

[0079] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 1000μm / s, let it stand for 35 seconds, and then pull it up vertically at a speed of 1000μm / s. Repeat the dipping 35 times, with an interval of 120s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 120℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 3 hours to obtain a membrane tube with a double functional layer.

[0080] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 3:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 260 ° C, the pressure on the reaction side was 2.56 MPa, the pressure on the purge side was 2.42 MPa, the pressure difference on both sides was maintained at 0.14 MPa, and the air velocity was set to 11500 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0081] Example 5

[0082] (1) Weigh 2.6 g of P123 and dissolve it in 30 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 8.6 g of In(NO3)3·4H2O, 0.9 g of Zr(NO3)2·5H2O, and 6.4 mL of H + Concentrated nitric acid with a concentration of 10 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 4 hours to make it into a sol state, placed in a 60°C oven to dry for 48 hours, and placed in 100 mL of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0083] 0.03 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 30 mL of ethanol, and then 3 mL of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0084] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0085] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 2.3 mm, and the thickness of the CHA molecular sieve membrane is 29 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 30 h and dried at 65°C for 30 h.

[0086] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 1200μm / s, let it stand for 45s, and then pull it up vertically at a speed of 200μm / s. Repeat the dipping 30 times, with an interval of 110s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 120℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 3 hours to obtain a membrane tube with a double functional layer.

[0087] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 4:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 240 ° C, the pressure on the reaction side was 3.64 MPa, the pressure on the purge side was 3.51 MPa, the pressure difference on both sides was maintained at 0.13 MPa, and the air velocity was set to 4500 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0088] Comparative Example 1

[0089] (1) Weigh 4.1 g of P123 and dissolve it in 40 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 4 g of In(NO3)3·4H2O, 0.7 g of Zr(NO3)2·5H2O, and 5.8 mL of H +Concentrated nitric acid with a concentration of 12 mol / L was dissolved in an anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 4 hours to make it into a sol state, placed in a 60°C oven and dried for 48 hours, heated to 400°C at 1°C / min, and calcined for 5 hours to obtain an indium zirconium composite oxide support.

[0090] Weigh 0.112 g of palladium nitrate and dissolve it in 10 mL of deionized water to obtain a palladium salt solution. Then weigh 1.5 g of indium zirconium composite oxide support and put it into the palladium salt solution. Stir at 25°C for 1 hour, then rotary dry at 45°C, 20 ppm, and 0.1 MPa for 1.5 hours, and finally calcine at 350°C for 4 hours to obtain the catalyst, which is pressed into tablets and sieved into 40-60 mesh.

[0091] (2) The activity of the prepared catalyst was evaluated in a fixed bed reactor. The reaction conditions were the same as in Example 1. The test results are shown in Table 2.

[0092] Comparative Example 2

[0093] (1) Weigh 4.2 g In(NO3)3·4H2O, 0.7 g Zr(NO3)2·5H2O, and 5.8 mL H + Concentrated nitric acid with a concentration of 12 mol / L was dissolved in 40 mL of anhydrous ethanol solution, stirred in a constant temperature water bath at 45°C for 4.5 hours to make it into a sol state, placed in a 50°C oven to dry for 48 hours, and placed in 100 mL of ethanol to obtain an indium zirconium composite oxide precursor solution.

[0094] 0.7 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 40 ml of ethanol, and then 1 ml of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0095] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0096] (2) The membrane tube used in this comparative example before treatment includes a tubular porous mullite support and a CHA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 1.8 mm, and the thickness of the CHA molecular sieve membrane is 22 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 20 h and dried at 65°C for 22 h.

[0097] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 1000μm / s, let it stand for 30s, and then pull it up vertically at a speed of 1000μm / s. Repeat the dipping 20 times, with an interval of 120s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 110℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 4 hours to obtain a membrane tube with a double functional layer.

[0098] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 5:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 280 ° C, the pressure on the reaction side was 3.05 MPa, the pressure on the purge side was 2.89 MPa, the pressure difference on both sides was maintained at 0.16 MPa, and the air velocity was set to 8000 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0099] Comparative Example 3

[0100] (1) Weigh 4.1 g of P123 and dissolve it in 40 ml of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 4.2 g of In(NO3)3·4H2O, 0.7 g of Zr(NO3)2·5H2O and 5.8 ml of concentrated nitric acid and dissolve them in the anhydrous ethanol solution of P123. Stir in a constant temperature water bath at 45°C for 4.5 h to make it into a sol state. Place it in a 50°C oven and dry it for 48 h. Place it in 100 ml of ethanol to prepare an indium zirconium composite oxide precursor solution.

[0101] 0.7 ml of Na2PdCl4 (200 mg / mL) was weighed and added to 40 ml of ethanol, and then 1 ml of NaBH4 aqueous solution was added. The mixture was magnetically stirred at room temperature, centrifuged, and washed with ethanol to obtain a palladium precursor solution.

[0102] The indium zirconium composite oxide carrier precursor solution and the palladium precursor solution are mixed to obtain a catalyst precursor solution.

[0103] (2) The membrane tube used in this embodiment before treatment includes a tubular porous mullite support and a NaA type molecular sieve membrane attached to the outer surface of the porous mullite. The thickness of the porous mullite support is 1.8 mm, and the thickness of the molecular sieve membrane is 30 μm. The membrane tube is immersed in 1 mol / L potassium nitrate solvent for 20 h and dried at 65°C for 22 h.

[0104] (3) Fix the upper end of the molecular sieve membrane on the pulling and dipping equipment, and seal both ends with polytetrafluoroethylene stoppers. Fix the upper end of the tube vertically on the pulling and dipping coating machine, immerse it in a glass bottle containing the catalyst precursor solution at a speed of 1000μm / s, let it stand for 30s, and then pull it up vertically at a speed of 1000μm / s. Repeat the dipping 20 times, with an interval of 120s each time. After the impregnation is completed, the molecular sieve membrane loaded with the catalyst precursor is placed in an oven at 110℃ for 2 hours, and then placed in a micro box furnace and calcined at 350℃ for 4 hours to obtain a membrane tube with a double functional layer.

[0105] (4) The prepared membrane tube with a bifunctional molecular sieve membrane was sealed on the membrane reactor using a high-temperature graphite gasket. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 5:1:1) was introduced into the reaction side, and the purge gas hydrogen was introduced into the other side for purge. The reaction temperature was set to 280 ° C, the pressure on the reaction side was 3.05 MPa, the pressure on the purge side was 2.89 MPa, the pressure difference on both sides was maintained at 0.16 MPa, and the air velocity was set to 8000 h -1 The liquid products on the reaction side and the purge side were collected in an ice-water bath. The gas lines on both sides were respectively fed into gas chromatography to analyze the product composition and the flow rates were measured respectively. The evaluation results are shown in Table 2.

[0106] Table 1

[0107]

[0108] Table 2

[0109]

[0110]

[0111] The results in Table 2 show that the membrane tube with a dual functional layer prepared by the present invention is used in a membrane reactor, and has the advantages of excellent catalytic performance, high reaction activity, high selectivity for the target product, good reaction stability, and low deactivation rate in the reaction of producing methanol from carbon dioxide hydrogenation.

[0112] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0113] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0114] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing methanol by hydrogenating carbon dioxide, characterized in that: The method comprises: The feed gas is introduced into the outer side of the membrane tube of the membrane reactor, and the purge gas is introduced into the inner side of the membrane tube of the membrane reactor; the membrane tube includes a membrane support and a membrane functional layer covering the outer surface of the membrane support; the membrane functional layer includes a CHA molecular sieve membrane and a catalyst layer supported on the outer surface of the CHA molecular sieve membrane; The catalyst in the catalyst layer includes a metal oxide carrier and an active metal component supported on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium-zirconium composite oxide with a mesoporous structure.

2. The method according to claim 1, wherein Based on the total weight of the catalyst, the content of Pd is 0.1 to 6 weight percent; based on the total weight of the metal oxide support, the content of indium oxide is 60 to 90 weight percent, and the content of zirconium oxide is 10 to 40 weight percent; Preferably, based on the total weight of the catalyst, the content of Pd is 1 to 6 wt %; based on the total weight of the metal oxide support, the content of indium oxide is 75 to 90 wt %, and the content of zirconium oxide is 10 to 25 wt %.

3. The method according to claim 1 or 2, wherein: The method for preparing the membrane tube of the membrane reactor comprises: S1, mixing a solution containing a surfactant with an acid, an indium precursor, and a zirconium precursor, and performing a first drying treatment to obtain an indium zirconium composite oxide support precursor; dispersing the indium zirconium composite oxide support precursor in a first organic solvent to obtain a first material; S2, ultrasonically mixing a solution containing a palladium salt and a solution containing a reducing agent, followed by centrifugal washing to obtain a palladium precursor; dispersing the palladium precursor in a second organic solvent to obtain a second material; S3, mixing the first material and the second material to obtain a catalyst precursor solution; S4, immersing the membrane support with the CHA molecular sieve membrane on its outer surface in the catalyst precursor solution to obtain a pretreated membrane tube; and performing a second drying treatment and a calcination treatment on the pretreated membrane tube.

4. The method according to claim 3, wherein: The surfactant is selected from at least one of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, hexadecyltrimethylammonium bromide, malic acid, sodium 2-ethylhexane sulfosuccinate and nonylphenol polyoxyethylene ether; The solvent in the solution containing the surfactant is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide; The acid is selected from at least one of nitric acid, hydrochloric acid and phosphoric acid; The indium precursor is selected from at least one of indium nitrate, indium chloride and indium sulfate; The zirconium precursor is selected from at least one of zirconium nitrate, zirconium chloride and zirconium sulfate; Optionally, in the solution containing a surfactant, the molar concentration of the surfactant is 0.001 to 1 mol / L; + The molar concentration is 3 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium oxide precursor and the zirconium oxide precursor is 0.005 to 0.05: 1 to 5: 60 to 90: 10 to 40; Preferably, the molar concentration of the surfactant is 0.01 to 0.05 mol / L; + The molar concentration is 6 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium precursor and the zirconium precursor is 0.015 to 0.025:1.5 to 3:75 to 90:10 to 25.

5. The method according to claim 3, wherein: The palladium salt is selected from at least one of palladium nitrate, palladium chloride, palladium acetate, ammonium tetrachloropalladate, ammonium hexachloropalladate, dichlorodiamine palladium, and dichlorotetraamine palladium; the reducing agent is selected from at least one of sodium borohydride, lithium borohydride, zinc borohydride, lithium aluminum hydride, and sodium cyanoborohydride; and the solvent in the solution containing the reducing agent is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol, and N,N-dimethylacetamide; Optionally, in the solution containing palladium salt, the mass concentration of the palladium salt is 0.005-0.03 weight %; and the volume ratio of the solution containing palladium salt to the solution containing reducing agent is 0.01-1:10-100.

6. The method according to claim 3, wherein: The first organic solvent and the second organic solvent are each independently selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetyl.

7. The method according to claim 3, wherein: In step S1, the mixing is performed under stirring, and the mixing conditions include: a mixing time of 3 to 9 hours and a stirring speed of 100 to 300 r / min; the first drying conditions include: a temperature of 50 to 100° C. and a time of 30 to 60 hours; In step S2, the ultrasonic mixing conditions include: frequency of 10 to 50 kHz, temperature of 20 to 35°C, and time of 0.5 to 2 hours; In step S4, the impregnation includes using a pulling and impregnation device to impregnate the membrane support body whose outer surface is covered with a CHA molecular sieve membrane; wherein, the pulling speed of the pulling and impregnation device is 500-1500 μm / s, the standing time of the pulling and impregnation device is 20-60s, and the number of impregnations of the pulling and impregnation device is 10-60 times; the conditions for the second drying treatment include: a temperature of 90-150°C and a time of 1-5 hours; the conditions for the first calcination treatment include: a temperature of 300-400°C and a time of 3-6 hours.

8. The method according to claim 3, wherein: The method further comprises: before the impregnation in step S4, using K and / or Cs to modify the membrane support body with the CHA molecular sieve membrane on the outer surface; the modification step comprises: impregnating the membrane support body with the CHA molecular sieve membrane on the outer surface in a solution containing K and / or Cs; + Solutions and / or containing Cs + The impregnation result is then subjected to a third drying treatment; Optionally, the K + In the solution, K + The concentration of Cs + In the solution, Cs + The concentration is 0.5 to 2 mol / L; the immersion conditions include: a temperature of 20 to 40°C and a time of 12 to 48 hours; the third drying conditions include: a temperature of 50 to 80°C and a time of 12 to 48 hours.

9. The method according to claim 1, wherein The membrane support body is selected from at least one of porous mullite, alumina, titanium oxide, cordierite and zirconium oxide, preferably porous mullite; the membrane support body is formed into a tubular shape; the thickness of the membrane support body is 1.5 to 2.5 mm, the thickness of the CHA molecular sieve membrane layer is 1 to 3 μm, and the thickness of the membrane functional layer is 5 to 50 μm.

10. The method according to claim 1, wherein The raw gas consists of hydrogen, carbon dioxide and nitrogen; wherein the molar ratio of hydrogen, carbon dioxide and nitrogen is 1 to 6:1:1; and the purge gas is hydrogen.

11. The method according to claim 1, wherein The reaction conditions outside the membrane tube of the membrane reactor include: reaction pressure of 2-4 MPa, reaction temperature of 200-350°C, volume space velocity of 1200-10800 h -1 ; The pressure difference on both sides of the membrane tube of the membrane reactor is 0.08~2.0MPa.

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