Method for preparing methanol through hydrogenation of carbon dioxide

Abstract

The invention provides a method for preparing methanol by hydrogenating carbon dioxide, which is characterized by comprising 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; wherein the membrane tube of the membrane reactor comprises a membrane support body and a membrane functional layer covering the outer surface of the membrane support body; the membrane functional layer is a CHA molecular sieve membrane; the outer part of the membrane reaction cavity is filled with a catalyst; the catalyst comprises a metal oxide carrier and an active metal component loaded on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium-zirconium composite oxide with an ordered mesoporous structure. The membrane reactor is adopted to reinforce the CO2 hydrogenation methanol preparation reaction, so that water generated in the reaction process can be removed in time, and the methanol catalytic reaction is effectively promoted.

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] With the continuous increase in CO2 emissions, environmental issues such as the greenhouse effect and global warming are becoming increasingly prominent. Therefore, an effective method is needed to reduce atmospheric CO2 concentrations by capturing and converting CO2. Methanol, a key chemical raw material and a substitute for fossil fuels, can be produced by reacting CO2 with hydrogen from renewable energy sources, offering both an effective method for controlling greenhouse gases and a promising approach to replacing fossil fuels.

[0003] Due to the stable chemical properties of CO2 and its difficulty in activation, the conversion rate of CO2 hydrogenation to methanol is generally low. Furthermore, methanol production is an exothermic reaction. While low temperatures are thermodynamically favorable for methanol production, they are detrimental to the activation of carbon dioxide. Therefore, the CO2 hydrogenation to methanol reaction is subject to thermodynamic limitations. The low CO2 conversion rate also, to a certain extent, limits the further application of CO2 hydrogenation to methanol. Therefore, designing and developing more effective methods to overcome the thermodynamic limitations of CO2 hydrogenation to methanol and improve CO2 conversion rates is of great significance for the industrial application of CO2 hydrogenation to methanol. 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 passed into the outside of the membrane tube of the membrane reactor, and the sweep gas is passed into the inside of the membrane tube of the membrane reactor;

[0007] In which, the membrane tube includes a membrane support body and a membrane functional layer covered on the outer surface of the membrane support body; the membrane functional layer is a CHA molecular sieve membrane; the outside of the membrane tube is filled with a catalyst; the catalyst includes a metal oxide carrier and an active metal component loaded on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium zirconium composite oxide with an ordered mesoporous structure.

[0008] The method of the present invention can promptly remove the water generated during the reaction from the reaction system, break the thermodynamic equilibrium, and promote the forward progress of the reaction. It has excellent catalytic performance, high reaction activity, high selectivity of the target product, good reaction stability, and low deactivation rate.

[0009] Optionally, based on the total weight of the catalyst, the content of Pd is 0.1 to 5.5 weight %; based on the total weight of the metal oxide support, the content of indium oxide is 70 to 95 weight %, and the content of zirconium oxide is 5 to 30 weight %; preferably, based on the total weight of the catalyst, the content of Pd is 1.0 to 5.5 weight %; based on the total weight of the metal oxide support, the content of indium oxide is 80 to 90 weight %, and the content of zirconium oxide is 10 to 20 weight %.

[0010] Optionally, the preparation method of the catalyst comprises:

[0011] S11, mixing a solution containing a surfactant with an acid, an indium oxide precursor, and a zirconium oxide precursor to obtain a mixed material;

[0012] S12, performing a first drying and a first calcination on the mixed material to obtain an indium zirconium composite oxide support;

[0013] S13, impregnating the indium zirconium composite oxide support in a solution containing a palladium salt to obtain an impregnated material;

[0014] S14, performing a second roasting and a second drying on the impregnated material.

[0015] 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: 70 to 95: 5 to 30; preferably, the molar concentration of the surfactant is 0.001 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 oxide precursor and the zirconium oxide precursor is 0.005 to 0.025:1.5 to 3:80 to 90:10 to 20.

[0016] 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; optionally, in the solution containing the palladium salt, the mass concentration of the palladium salt is 0.005 to 0.03 weight %.

[0017] Optionally, in step S11, the mixing is carried out under stirring, and the mixing conditions include: mixing time of 3 to 9 hours, and stirring speed of 100 to 300 r / min; in step S12, the first drying conditions include: temperature of 50 to 100°C, and time of 30 to 60 hours; the first roasting conditions include: temperature of 600 to 1200°C, and time of 3 to 6 hours; in step S13, the impregnation is carried out under stirring, and the impregnation conditions include: temperature of 20 to 35°C, time of 0.5 to 2 hours, and stirring speed of 10 to 30 r / min; in step S14, the second drying is rotary evaporation drying, and the rotary evaporation drying conditions include: temperature of 45 to 72°C, rotation speed of 10 to 30 rpm, vacuum degree of 0.05 to 0.1 MPa, and rotary evaporation time of 1 to 3 hours; the second roasting conditions include: temperature of 300 to 500°C, and time of 1 to 5 hours.

[0018] Optionally, the membrane support is selected from at least one of porous mullite, alumina, titanium oxide, cordierite and zirconium oxide, preferably mullite; the membrane support is formed into a tubular shape; the thickness of the membrane support is 1.5 to 2.5 mm, and the thickness of the CHA molecular sieve membrane is 1 to 10 μm.

[0019] Optionally, the membrane tube of the membrane reactor is a membrane tube modified with K and / or Cs; the modification step comprises: immersing the membrane support having the membrane functional layer on the outer surface in a solution containing K. + Solutions and / or containing Cs + obtaining a first membrane tube from the solution, and subjecting the first membrane tube to a third drying process;

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 generated during the reaction and effectively promote the occurrence of methanol catalytic reaction. The membrane tube of the membrane reactor used in 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 is a CHA molecular sieve membrane, which has the technical advantage of quickly removing water produced in the reaction. The catalyst loaded on the outside of the membrane tube includes an indium zirconium composite oxide with a mesoporous structure and an active metal component Pd, wherein the indium zirconium composite oxide 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.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 It is a process flow chart of the method of the present invention.

[0027] Figure 2 This is a SEM image of the indium zirconium composite oxide support prepared in Example 1 of the present invention.

[0028] Figure 3 This is the XRD spectrum of the indium zirconium composite oxide support prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] The present invention provides a method for preparing methanol by hydrogenating carbon dioxide. Figure 1 As shown, the method includes:

[0031] The feed gas is introduced into the outer side of the membrane tube of the membrane reactor, and the sweep gas is introduced into the inner side of the membrane tube of the membrane reactor;

[0032] In which, the membrane tube includes a membrane support body and a membrane functional layer covered on the outer surface of the membrane support body; the membrane functional layer is a CHA molecular sieve membrane; the outside of the membrane tube is filled with a catalyst; the catalyst includes a metal oxide carrier and an active metal component loaded on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium zirconium composite oxide with an ordered mesoporous structure.

[0033] The material with ordered mesoporous structure involved in the present invention refers to a material with a regular, continuously adjustable pore structure. Figure 2 As shown, the indium zirconium composite oxide carrier with an ordered mesoporous structure of the present invention has regular pores.

[0034] During the reaction process of the present invention, a high-temperature graphite gasket can be used to seal the membrane tube on the membrane reactor, a catalyst can be loaded on the outside of the membrane tube, carbon dioxide and hydrogen are introduced to the outside of the membrane tube, and the reaction products pass through the molecular sieve membrane into the inner side of the membrane reaction chamber and are carried out of the reactor by the purge gas, thereby promoting the forward progress of the CO2 hydrogenation to methanol reaction reaction.

[0035] The present invention uses a membrane reactor to enhance the CO2 hydrogenation to methanol reaction, which can promptly remove the water generated during the reaction and effectively promote the occurrence of methanol catalytic reaction. In the present invention, the membrane tube of the membrane reactor includes a membrane support and a membrane functional layer coated on the outer surface of the membrane support. The membrane functional layer is a CHA molecular sieve membrane, which has the technical advantage of quickly removing water generated in the reaction. The catalyst loaded on the outside of the membrane tube includes an indium zirconium composite oxide with a mesoporous structure and an active metal component Pd, such as Figure 1 As shown, the indium zirconium composite oxide 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.

[0036] According to the present invention, based on the total weight of the catalyst, the content of Pd can be 0.1 to 5.5 weight percent; based on the total weight of the metal oxide support, the content of indium oxide can be 70 to 95 weight percent, and the content of zirconium oxide can be 5 to 30 weight percent. Preferably, based on the total weight of the catalyst, the content of Pd can be 1.0 to 5.5 weight percent; based on the total weight of the metal oxide support, the content of indium oxide can be 80 to 90 weight percent, and the content of zirconium oxide can be 10 to 20 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.

[0037] According to the present invention, the method for preparing the catalyst may include:

[0038] S11, mixing a solution containing a surfactant with an acid, an indium oxide precursor, and a zirconium oxide precursor to obtain a mixed material;

[0039] S12, performing a first drying and a first calcination on the mixed material to obtain an indium zirconium composite oxide support;

[0040] S13, impregnating the indium zirconium composite oxide support in a solution containing a palladium salt to obtain an impregnated material;

[0041] S14, performing a second roasting and a second drying on the impregnated material.

[0042] The catalyst prepared using the method of the present invention comprises an indium-zirconium composite oxide with an ordered mesoporous structure and an active metal component, Pd, supported on the surface of the indium-zirconium composite oxide. The catalyst exhibits high reactivity and excellent catalytic performance, capable of maintaining high carbon dioxide conversion and methanol selectivity even during long-term reaction operation.

[0043] 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 can be 0.001 to 1 mol / L; the H in the acid + The molar concentration of the surfactant can be 3 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium oxide precursor and the zirconium oxide precursor can be 0.005 to 0.05:1 to 5:70 to 95:5 to 30; preferably, the molar concentration of the surfactant is 0.001 to 0.05 mol / L; the H + The molar concentration of the surfactant may be 6 to 12 mol / L; the molar ratio of the surfactant, the acid, the indium oxide precursor, and the zirconium oxide precursor may be 0.005 to 0.025:1.5 to 3:80 to 90:10 to 20.

[0044] 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; optionally, in the solution containing the palladium salt, the mass concentration of the palladium salt is 0.005 to 0.03 weight %.

[0045] According to the present invention, in step S11, the mixing is preferably 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; in step S12, the first drying conditions may include: a temperature of 50 to 100°C and a time of 30 to 60 hours; the first roasting conditions may include: a temperature of 600 to 1200°C and a time of 3 to 6 hours; in step S13, the impregnation is preferably carried out under stirring, and the impregnation conditions may include: a temperature of 20 to 35°C, a time of 0.5 to 2 hours, and a stirring speed of 10 to 30 r / min; in step S14, the second drying is preferably rotary evaporation drying, and the rotary evaporation drying conditions may include: a temperature of 45 to 72°C, a rotation speed of 10 to 30 rpm, a vacuum degree of 0.05 to 0.1 MPa, and a rotary evaporation time of 1 to 3 hours; the second roasting conditions may include: a temperature of 300 to 500°C and a time of 1 to 5 hours.

[0046] 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 resistance and stability. Preferably, the membrane support has a thickness of 1.5 to 2.5 mm, and the CHA molecular sieve membrane has a thickness of 1 to 10 μm.

[0047] According to the present invention, the membrane tube of the membrane reactor 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 modification step comprises: immersing the membrane support having the membrane functional layer on the outer surface in a solution containing K. + Solutions and / or containing Cs + A first membrane tube is obtained from the solution containing K, and the first membrane tube is subjected to a third drying process; + In the solution, K + The concentration of Cs can be 0.5 to 2 mol / L; + In the solution, Cs +The concentration can be 0.5-2 mol / L; the conditions for the impregnation may include: a temperature of 20-40°C and a time of 12-48 hours; the conditions for the third drying treatment may include: a temperature of 50-80°C and a time of 12-48 hours.

[0048] The membrane tube involved in the present invention, including the membrane support and the membrane functional layer synthesized on the outer surface of the membrane support, can be obtained commercially or synthesized. For example, the membrane tube can be synthesized by SSZ-13 seed coating method.

[0049] 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.

[0050] In a preferred embodiment of the present invention, the feed gas may be composed of hydrogen, carbon dioxide and nitrogen; wherein the molar ratio of hydrogen, carbon dioxide and nitrogen may be 1 to 6:1:1; and the purge gas is preferably hydrogen.

[0051] According to the present invention, the reaction conditions outside the membrane tube of the membrane reactor may include: a reaction pressure of 2 to 4 MPa, a reaction temperature of 200 to 350°C, a volume space velocity of 1200 to 10800 h -1 ; The pressure difference on both sides of the membrane tube of the membrane reactor can be 0.08~2.0MPa.

[0052] The present invention is further described in detail below through examples. The raw materials used in the examples can be obtained through commercial channels. The membrane tube including the tubular porous mullite support and the CHA type molecular sieve membrane attached to the outer surface of the porous mullite used in the examples is prepared according to the SSZ-13 seed coating method, and 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 the two ends of the carrier coated with seeds 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.

[0053] 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.

[0054] Example 1

[0055] (1) Weigh 4.2 g of P123 and dissolve it in 80 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 8.4 g of In(NO3)3·4H2O, 0.6 g of Zr(NO3)2·5H2O, and 6.4 mL of H + Concentrated nitric acid with a concentration of 12 mol / L was dissolved in anhydrous ethanol solution of P123, stirred in a constant temperature water bath at 40°C for 4 hours to form a sol, placed in a 60°C oven to dry for 48 hours, heated to 400°C at 1°C / min, and calcined for 5 hours to obtain an indium zirconium composite oxide support. The composition of the support is listed in Table 1, and the SEM image is shown in Figure 1. Figure 2 As shown, the XRD spectrum is shown as Figure 3 As shown, it shows that the carrier contains an ordered mesoporous structure.

[0056] 0.03 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.5 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25° C. for 1 h, then rotary dried at 45° C., 20 ppm, and 0.1 MPa for 1.5 h, and finally calcined at 350° C. for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0057] (2) The membrane tube used in this example consisted of a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 1.8 mm, and the CHA molecular sieve membrane had a thickness of 1.1 μm. The membrane tube was soaked in a 1 mol / L potassium nitrate solvent for 24 h and dried at 60°C for 24 h to obtain the modified membrane tube of this example.

[0058] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 3:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 280°C, the pressure on the reaction side is 3.15 MPa, the pressure on the purge side is 3.0 MPa, the pressure difference on both sides is maintained at 0.15 MPa, and the air velocity is set to 9000 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.

[0059] Example 2

[0060] (1) Weigh 7.5 g of P123 and dissolve it in 120 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 9.2 g of In(NO3)3·4H2O, 5 g of Zr(NO3)2·5H2O, and 9.6 mL of H + Concentrated nitric acid (10 mol / L) was dissolved in an anhydrous ethanol solution of P123 and stirred in a constant-temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours. The temperature was then increased to 400°C at a rate of 1°C / min and calcined for 5 hours to produce an indium-zirconium composite oxide support. The composition of the support is listed in Table 1.

[0061] 0.23 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 3.2 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25° C. for 1 h, then rotary dried at 45° C., 20 ppm, and 0.1 MPa for 1 h, and finally calcined at 350° C. for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0062] (2) The membrane tube used in this example consisted of a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 2.1 mm, and the CHA molecular sieve membrane had a thickness of 1.2 μm. The membrane tube was soaked in a 1 mol / L potassium nitrate solvent for 36 h and dried at 55°C for 36 h to obtain the modified membrane tube of this example.

[0063] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 4:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 280°C, the pressure on the reaction side is 3.13 MPa, the pressure on the purge side is 3.02 MPa, the pressure difference on both sides is maintained at 0.11 MPa, and the air velocity is 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.

[0064] Example 3

[0065] (1) Weigh 6.8 g of P123 and dissolve it in 85 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 7.6 g of In(NO3)3·4H2O, 1.8 g of Zr(NO3)2·5H2O, and 8.3 mL of H +Concentrated nitric acid at a concentration of 11 mol / L was dissolved in an anhydrous ethanol solution of P123. The solution was stirred in a constant temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours. The temperature was then increased to 400°C at a rate of 1°C / min and calcined for 5 hours to produce an indium zirconium composite oxide support. The composition of the support is listed in Table 1.

[0066] 0.3 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.1 mL of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25°C for 1 h, then rotary dried at 45°C, 20 ppm, and 0.1 MPa for 1 h, and finally calcined at 350°C for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0067] (2) The membrane tube used in this example consisted of a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 2.2 mm, and the CHA molecular sieve membrane had a thickness of 1.6 μm. The membrane tube was soaked in a 1 mol / L potassium nitrate solvent for 30 h and dried at 65°C for 30 h to obtain the modified membrane tube of this example.

[0068] (3) The prepared membrane tube was sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment was loaded on the outside of the membrane tube of this embodiment. The raw gas (the raw gas consisted of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 was 3.5:1:1) was introduced into the outside of the membrane tube. The inside of the membrane tube was the purge side, and purge gas hydrogen was introduced. The reaction temperature was set to 280°C, the pressure on the reaction side was 3.14 MPa, the pressure on the purge side was 3.02 MPa, the pressure difference on both sides was maintained at 0.12 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.

[0069] Example 4

[0070] (1) Weigh 3.9 g of P123 and dissolve it in 50 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 2.0 g of In(NO3)3·4H2O, 3.0 g of Zr(NO3)2·5H2O and 10.5 mL of H + 9 mol / L concentrated nitric acid was dissolved in an anhydrous ethanol solution of P123 and stirred in a constant temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours, heated to 400°C at a rate of 1°C / min, and calcined for 5 hours to produce an indium zirconium composite oxide support. The composition of the support is listed in Table 1.

[0071] 0.002 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 1.2 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25°C for 1 h, then rotary dried at 45°C, 20 ppm, and 0.1 MPa for 1 h, and finally calcined at 350°C for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0072] (2) The membrane tube used in this example consisted of a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 1.9 mm, and the CHA molecular sieve membrane had a thickness of 1.8 μm. The membrane tube was soaked in 1 mol / L potassium nitrate for 30 h and dried at 65°C for 30 h to obtain the modified membrane tube of this example.

[0073] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 2:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 260°C, the pressure on the reaction side is 2.11 MPa, the pressure on the purge side is 2.02 MPa, the pressure difference on both sides is maintained at 0.09 MPa, and the air velocity is set to 10500 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 5

[0075] (1) Weigh 2.2 g of P123 and dissolve it in 30 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 9.0 g of In(NO3)3·4H2O, 0.1 g of Zr(NO3)2·5H2O, and 5.4 mL of H + Concentrated nitric acid (10 mol / L) was dissolved in an anhydrous ethanol solution of P123 and stirred in a constant-temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours. The temperature was then increased to 400°C at a rate of 1°C / min and calcined for 5 hours to produce an indium-zirconium composite oxide support. The composition of the support is listed in Table 1.

[0076] 0.003 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.6 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25°C for 1 h, then rotary dried at 45°C, 20 ppm, and 0.1 MPa for 1 h, and finally calcined at 350°C for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0077] (2) The membrane tube used in this example consisted of a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 2.0 mm, and the CHA molecular sieve membrane had a thickness of 1.1 μm. The membrane tube was soaked in a 1 mol / L potassium nitrate solvent for 30 h and dried at 65°C for 30 h to obtain the modified membrane tube of this example.

[0078] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 2.5:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 240°C, the pressure on the reaction side is 3.54 MPa, the pressure on the purge side is 3.42 MPa, the pressure difference on both sides is maintained at 0.12 MPa, and the air velocity is set to 1500 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.

[0079] Example 6

[0080] (1) Weigh 4.2 g of P123 and dissolve it in 80 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 8.4 g of In(NO3)3·4H2O, 0.6 g of Zr(NO3)2·5H2O, and 6.4 mL of H + Concentrated nitric acid at a concentration of 12 mol / L was dissolved in an anhydrous ethanol solution of P123. The solution was stirred in a constant temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours. The temperature was then increased to 400°C at a rate of 1°C / min and calcined for 5 hours to produce an indium zirconium composite oxide support. The composition of the support is listed in Table 1.

[0081] 0.03 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.5 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25° C. for 1 h, then rotary dried at 45° C., 20 ppm, and 0.1 MPa for 1.5 h, and finally calcined at 350° C. for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0082] (2) The membrane tube used in this embodiment includes a tubular porous mullite support and a CHA 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 1.4 μm.

[0083] (3) The prepared membrane tube membrane is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 3:1:1). The outside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 280°C, the pressure on the reaction side is 3.15 MPa, the pressure on the purge side is 3.0 MPa, the pressure difference on both sides is maintained at 0.15 MPa, and the air velocity is set to 9000 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.

[0084] Comparative Example 1

[0085] (1) The preparation of the catalyst is the same as in Example 1.

[0086] (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.

[0087] Comparative Example 2

[0088] (1) Weigh 8.4gIn(NO3)3·4H2O, 0.6gZr(NO3)2·5H2O, 6.4mL H + A 12 mol / L concentrated nitric acid solution in 80 mL of anhydrous ethanol was stirred in a constant temperature water bath at 40°C for 4 hours to form a sol. The solution was then dried in a 60°C oven for 48 hours. The temperature was then increased to 400°C at a rate of 1°C / min and calcined for 5 hours to produce an indium zirconium composite oxide support. The composition of the support is listed in Table 1.

[0089] 0.03 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.5 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25°C for 1 h, then rotary dried at 45°C, 20 ppm, and 0.1 MPa for 1 h, and finally calcined at 350°C for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0090] (2) The membrane tube used in this comparative example comprised a tubular porous mullite support and a CHA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 1.8 mm, and the CHA molecular sieve membrane had a thickness of 1.2 μm. The membrane tube was soaked in a 1 mol / L potassium nitrate solvent for 24 h and dried at 60°C for 24 h to obtain a modified membrane tube.

[0091] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 3:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 280°C, the pressure on the reaction side is 3.15 MPa, the pressure on the purge side is 3.0 MPa, the pressure difference on both sides is maintained at 0.15 MPa, and the air velocity is set to 9000 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.

[0092] Comparative Example 3

[0093] (1) Weigh 4.2 g of P123 and dissolve it in 80 mL of anhydrous ethanol. Ultrasonicate until P123 is completely dissolved. Weigh 8.4 g of In(NO3)3·4H2O, 0.6 g of Zr(NO3)2·5H2O, and 6.4 mL of H + Concentrated nitric acid with a concentration of 12 mol / L was dissolved in an anhydrous ethanol solution of P123 and stirred in a constant temperature water bath at 40°C for 4 hours to form a sol. The solution was then placed in a 60°C oven and dried for 48 hours. The temperature was then raised to 400°C at a rate of 1°C / min and calcined for 5 hours to obtain an indium zirconium composite oxide support. The composition of the support is listed in Table 1 and the XRD spectrum is shown below. Figure 1 As shown, it shows that the carrier contains an ordered mesoporous structure.

[0094] 0.03 g of palladium nitrate was weighed and dissolved in 10 mL of deionized water to obtain a palladium salt solution. 2.5 g of indium zirconium composite oxide support was then weighed and added to the palladium salt solution. The mixture was stirred at 25° C. for 1 h, then rotary dried at 45° C., 20 ppm, and 0.1 MPa for 1.5 h, and finally calcined at 350° C. for 4 h to obtain a catalyst. The catalyst was pressed into tablets and sieved into 40-60 mesh. The composition is shown in Table 1.

[0095] (2) The membrane tube used in this comparative example comprised a tubular porous mullite support and an LTA molecular sieve membrane attached to the outer surface of the porous mullite. The porous mullite support had a thickness of 2.0 mm, and the CHA molecular sieve membrane had a thickness of 2.1 μm. The membrane tube was soaked in 1 mol / L potassium nitrate for 24 h and dried at 60°C for 24 h to obtain a modified membrane tube.

[0096] (3) The prepared membrane tube is sealed on the membrane reactor using a high-temperature graphite gasket, and the catalyst prepared in this embodiment is loaded on the outside of the membrane tube of this embodiment. The raw gas is introduced into the outside of the membrane tube (the raw gas consists of H2, CO2 and N2, and the molar ratio of H2, CO2 and N2 is 3:1:1). The inside of the membrane tube is the purge side, and the purge gas hydrogen is introduced. The reaction temperature is set to 280°C, the pressure on the reaction side is 3.15 MPa, the pressure on the purge side is 3.0 MPa, the pressure difference on both sides is maintained at 0.15 MPa, and the air velocity is set to 9000 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.

[0097] Table 1

[0098]

[0099] Table 2

[0100]

[0101]

[0102] The results in Table 2 show that, in the reaction of preparing methanol by hydrogenating carbon dioxide, loading the catalyst prepared by the present invention onto the outside of the membrane tube of the membrane reactor can significantly improve the conversion rate of carbon dioxide and the content of methanol in the product.

[0103] 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.

[0104] 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.

[0105] 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 sweep gas is introduced into the inner side of the membrane tube of the membrane reactor; In which, the membrane tube includes a membrane support body and a membrane functional layer covered on the outer surface of the membrane support body; the membrane functional layer is a CHA molecular sieve membrane; the outside of the membrane tube is filled with a catalyst; the catalyst includes a metal oxide carrier and an active metal component loaded on the metal oxide carrier; the active metal component is Pd, and the metal oxide carrier is an indium zirconium composite oxide with an ordered 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 5.5 weight percent; based on the total weight of the metal oxide support, the content of indium oxide is 70 to 95 weight percent, and the content of zirconium oxide is 5 to 30 weight percent; Preferably, based on the total weight of the catalyst, the content of Pd is 1.0-5.5 wt %; based on the total weight of the metal oxide support, the content of indium oxide is 80-90 wt %, and the content of zirconium oxide is 10-20 wt %.

3. The method according to claim 1 or 2, wherein: The preparation method of the catalyst comprises: S11, mixing a solution containing a surfactant with an acid, an indium oxide precursor, and a zirconium oxide precursor to obtain a mixed material; S12, performing a first drying and a first calcination on the mixed material to obtain an indium zirconium composite oxide support; S13, impregnating the indium zirconium composite oxide support in a solution containing a palladium salt to obtain an impregnated material; S14, performing a second roasting and a second drying on the impregnated material.

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: 70 to 95: 5 to 30; Preferably, the molar concentration of the surfactant is 0.001 to 0.05 mol / L; + The molar concentration is 6 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 0.025:1.5 to 3:80 to 90:10 to 20.

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, dichlorodiammine palladium and dichlorotetrammine palladium; optionally, in the solution containing the palladium salt, the mass concentration of the palladium salt is 0.005-0.03 weight %.

6. The method according to claim 3, wherein: In step S11, 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; In step S12, the first drying conditions include: temperature of 50-100° C., time of 30-60 hours; the first calcination conditions include: temperature of 600-1200° C., time of 3-6 hours; In step S13, the immersion is carried out under stirring, and the immersion conditions include: temperature of 20 to 35° C., time of 0.5 to 2 hours, and stirring speed of 10 to 30 r / min; In step S14, the second drying is rotary evaporation drying, and the conditions of the rotary evaporation drying include: temperature of 45-72°C, rotation speed of 10-30rpm, vacuum degree of 0.05-0.1MPa, and rotary evaporation time of 1-3h; the conditions of the second roasting include: temperature of 300-500°C and time of 1-5h.

7. The method according to claim 1, wherein The membrane support is 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 thickness of the membrane support is 1.5 to 2.5 mm, and the thickness of the CHA molecular sieve membrane is 1 to 10 μm.

8. The method according to claim 1 or 7, wherein The membrane tube of the membrane reactor is a membrane tube modified with K and / or Cs; The modification treatment step comprises: immersing the membrane support having the membrane functional layer on its outer surface in a solution containing K + Solutions and / or containing Cs + obtaining a first membrane tube from the solution, and subjecting the first membrane tube to a third drying process; 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 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.

10. 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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