Noble Metal-Modified Catalyst and Its Preparation Method and Application

Abstract

The present invention relates to the technical field of catalysts, and discloses a noble metal modified catalyst, a preparation method thereof and an application thereof. The noble metal modified catalyst provided by the present invention contains an active component, a doped carrier and a noble metal component. The active component is indium oxide having a cubic structure, the doped carrier is a mixture of magnesium oxide and alumina, and the noble metal component is Pd. Among them, the content of the active component accounts for 40%-85% of the total mass of the active component and the doped carrier; the doped carrier accounts for 15%-60% of the total mass of the active component and the doped carrier; the noble metal component accounts for 0.01%-1.5% of the total mass of the catalyst. The present invention further provides a preparation method of the noble metal modified catalyst and its application in the reaction of hydrogenating carbon dioxide to prepare methanol. The catalyst provided by the present invention not only has excellent catalytic performance, high reaction activity and high selectivity of the target product, but also has a simple preparation process and low production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a noble metal modified catalyst, a preparation method thereof and an application thereof. Background Art

[0002] As an important raw material for chemicals and a substitute for fossil fuels, methanol reacts CO 2 with H from renewable energy 2 to produce methanol, which is not only an effective way to control greenhouse gases but also to solve the substitution of fossil fuels.

[0003] For the hydrogenation of CO 2 to produce methanol, among numerous catalysts, modified copper-based catalysts have been studied and applied for a long time. However, the methanol selectivity in its catalytic reaction process is only about 60%. Furthermore, there are disadvantages such as high activity of side reaction (RWGS), sintering of the active phase induced by H 2 O, and poor stability, which limit the further application of copper-based catalysts. In addition, other catalytic systems for the hydrogenation of CO 2 to produce methanol also have some defects. For example, the high cost problem of noble metal catalysts, the low activity and easy migration problems of ZnO catalysts, which all limit the further application of these catalysts in this field to a certain extent.

[0004] Indium oxide has moderate CO 2 and CO adsorption capacities, not only showing significantly better methanol selectivity than copper-based catalysts, cobalt-based catalysts, and noble metal catalysts, but also having higher catalytic activity compared to ZnO catalysts. Therefore, it has attracted wide attention of scientific researchers. Based on indium oxide, how to further promote the activation of CO 2 and H 2 and stabilize key intermediates to achieve high activity, high selectivity and stability is essential for the industrial application of CO2 hydrogenation to methanol, although it still faces great challenges to greatly improve its catalytic performance. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem that the catalytic performance of indium oxide in the prior art needs to be further improved, and to provide a noble metal modified catalyst, a preparation method thereof and an application thereof. The catalyst provided by the present invention not only has excellent catalytic performance, high reaction activity and high selectivity of the target product, but also has a simple preparation process and low production cost.

[0006] To achieve the above object, a first aspect of the present invention provides a noble metal modified catalyst, which catalyst contains an active component, a doped support and a noble metal component. The active component is indium oxide having a cubic structure, the doped support is a mixture of magnesium oxide and aluminum oxide, and the noble metal component is Pd. Among them, the content of the active component accounts for 40%-85% of the total mass of the active component and the doped support; the doped support accounts for 15%-60% of the total mass of the active component and the doped support; the noble metal component accounts for 0.01%-1.5% of the total mass of the catalyst.

[0007] A second aspect of the present invention provides a preparation method of the noble metal modified catalyst, which method includes:

[0008] (1) Mix a solution containing a metal indium salt, a precipitant solution and a doped support to obtain a precipitation mother liquor; the doped support is a mixture of magnesium oxide and aluminum oxide;

[0009] (2) Age the precipitation mother liquor to form a precipitate;

[0010] (3) Perform solid-liquid separation on the product obtained in step (2), and then perform drying and calcination to obtain a catalyst semi-finished product;

[0011] (4) Contact a solution containing a metal palladium salt with the catalyst semi-finished product, and then perform drying and calcination.

[0012] A third aspect of the present invention provides the noble metal modified catalyst prepared by the preparation method of the present invention.

[0013] A fourth aspect of the present invention provides the application of the noble metal modified catalyst of the present invention and the noble metal modified catalyst prepared by the preparation method of the present invention in the reaction of hydrogenating carbon dioxide to prepare methanol.

[0014] Through the above technical solution, the noble metal modified catalyst of the present invention uses a mixture of magnesium oxide and aluminum oxide as the doped support of indium oxide, and combines with the loaded noble metal palladium to jointly modify indium oxide, which not only improves the contact and catalytic effect between the catalyst and the catalytic substrate (such as carbon dioxide and H 2 ), but also makes the catalyst have high catalytic activity and high selectivity. Furthermore, the noble metal modified catalyst of the present invention can effectively improve the conversion rate of the catalytic substrate and the selectivity of the target product. In the reaction of hydrogenating carbon dioxide to prepare methanol, at 5 MPa and 7000 h -1 conditions, the selectivity of methanol on this catalyst can reach 95%;

[0015] The preparation method of the noble metal modified catalyst described in the present invention synthesizes indium oxide by aging precipitation treatment in the presence of a doped carrier, and further loads noble metal palladium on the catalyst semi-finished product by an impregnation method, realizing the modification effect of both the doped carrier and noble metal palladium on indium oxide. The prepared catalyst not only has excellent catalytic performance, high reaction activity, high selectivity of target products, etc., but also has simple production process steps, can effectively reduce its production cost, and can achieve mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD pattern of the doped carrier prepared in Example 1 of the present invention;

[0017] Figure 2 is the XRD pattern of the noble metal modified catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0019] The first aspect of the present invention provides a noble metal modified catalyst, which contains an active component, a doped carrier and a noble metal component. The active component is indium oxide with a cubic structure, the doped carrier is a mixture of magnesium oxide and aluminum oxide, and the noble metal component is Pd; wherein, the content of the active component accounts for 40%-85% of the total mass of the active component and the doped carrier; the doped carrier accounts for 15%-60% of the total mass of the active component and the doped carrier; the noble metal component accounts for 0.01%-1.5% of the total mass of the catalyst.

[0020] The content of each component in the catalyst of the present invention can be measured by the XRF method.

[0021] According to the present invention, the noble metal modified catalyst uses a mixture of magnesium oxide and aluminum oxide as the doped carrier of the indium oxide catalyst, and combines with noble metal palladium to jointly modify indium oxide, which not only improves the contact and catalytic effect between the catalyst and the catalytic substrate (such as carbon dioxide and H 2 )), but also makes the catalyst have high catalytic activity and high selectivity. Furthermore, the noble metal modified catalyst of the present invention can effectively improve the conversion rate of the catalytic substrate and the selectivity of the target product.

[0022] According to the present invention, in order to further improve the catalytic performance of the noble metal modified catalyst, preferably, the content of the active component accounts for 55-75% of the total mass of the active component and the doped carrier; the doped carrier accounts for 25-45% of the total mass of the active component and the doped carrier.

[0023] According to the present invention, in order to further improve the catalytic performance of the noble metal modified catalyst, preferably, the noble metal component accounts for 0.75-1.5% of the total mass of the catalyst;

[0024] According to the present invention, in order to further improve the catalytic performance of the noble metal modified catalyst and the selectivity to the target product, preferably, the mass ratio of the active component to the doped carrier is 1-6:1, and more preferably 1-3:1.

[0025] According to the present invention, in order to improve the modification effect on the active component and enhance the stability of the catalyst, preferably, magnesium oxide accounts for 2-18% of the total mass of the active component and the doped carrier, and more preferably 2.5-12.5%; alumina accounts for 14-54% of the total mass of the active component and the doped carrier, and more preferably 18.5-40.5%.

[0026] According to the present invention, the doped carrier can adopt magnesium oxide and alumina with a conventional structure. In order to further increase the contact area between the catalyst and the catalytic substrate while modifying the active component and enhance the catalytic effect, preferably, the doped carrier has an ordered mesoporous structure.

[0027] According to the present invention, the cubic structure of the indium oxide and the ordered mesoporous structure of the doped carrier can be determined by XRD method.

[0028] The second aspect of the present invention provides a preparation method of a noble metal modified catalyst, and the method includes:

[0029] (1) Mix a solution containing a metal indium salt, a precipitant solution and a doped carrier to obtain a precipitation mother liquor; the doped carrier is a mixture of magnesium oxide and alumina;

[0030] (2) Age the precipitation mother liquor to form a precipitate;

[0031] (3) Perform solid-liquid separation on the product obtained in step (2), and then perform drying and calcination to obtain a catalyst semi-finished product;

[0032] (4) Contact a solution containing a metal palladium salt with the catalyst semi-finished product, and then perform drying and calcination.

[0033] According to the present invention, there is no particular limitation on the specific operation methods of solid-liquid separation, drying and calcination, and they can be carried out according to the conventional operation means in the art.

[0034] According to the present invention, a method for preparing a noble metal modified catalyst comprises synthesizing indium oxide by aging precipitation treatment in the presence of a doped support, and further loading noble metal palladium on the catalyst semi-finished product by an impregnation method, so as to realize the modification effects of both the doped support and noble metal palladium on indium oxide. The prepared catalyst not only has advantages such as excellent catalytic performance, high reaction activity, high selectivity for target products, good reaction stability, and low catalyst deactivation rate, but also has a simple production process step, can effectively reduce its production cost, and can achieve mass production.

[0035] According to the present invention, in order to improve the catalytic performance of the noble metal modified catalyst, preferably, the amounts of the indium metal salt, the doped support, and the palladium metal salt are such that in the prepared catalyst, indium oxide accounts for 40%-85% of the total mass of indium oxide and the doped support; the doped support accounts for 15%-60% of the total mass of indium oxide and the doped support; and palladium element accounts for 0.01%-1.5% of the total mass of the catalyst.

[0036] Preferably, the amounts of the indium metal salt, the doped support, and the palladium metal salt are such that in the prepared catalyst, indium oxide accounts for 55-75% of the total mass of indium oxide and the doped support; the doped support accounts for 25-45% of the total mass of indium oxide and the doped support; and palladium element accounts for 0.75-1.5% of the total mass of the catalyst.

[0037] According to the present invention, in order to further improve the catalytic performance of the noble metal modified catalyst and the selectivity for target products, preferably, the mass ratio of the amounts of the indium metal salt and the doped support in terms of oxides is 1-6:1, and more preferably 1-3:1.

[0038] According to the present invention, when preparing the noble metal modified catalyst, the doped support can be commercially available magnesium oxide and aluminum oxide, or magnesium oxide and aluminum oxide prepared by existing methods. In order to further increase the contact area between the catalyst and the catalytic substrate while modifying the active components and improve the catalytic effect, preferably, the preparation method of the doped support enables the doped support to have an ordered mesoporous structure, and more preferably, the doped support is prepared by a solvent evaporation-induced self-assembly method.

[0039] According to a preferred embodiment of the present invention, the preparation method of the doped support includes: mixing an acid, an aluminum precursor, and a magnesium precursor in the presence of a surfactant and in the presence of a solvent, and then drying and calcining.

[0040] According to the present invention, in order to improve the stability of the noble metal modified catalyst, preferably, the amounts of the aluminum precursor and the magnesium precursor are such that in the prepared catalyst, magnesium oxide accounts for 2-18% of the total mass of indium oxide and the doped support, more preferably 2.5-12.5%; aluminum oxide accounts for 14-54% of the total mass of indium oxide and the doped support, more preferably 18.5-40.5%.

[0041] According to the present invention, preferably, the surfactant is selected from at least one of P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), CTAB (cetyltrimethylammonium bromide), malic acid, sodium 2-ethylhexane sulfosuccinate, and nonylphenol polyoxyethylene ether.

[0042] According to the present invention, preferably, the solvent is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol, and N,N-dimethylacetamide.

[0043] According to the present invention, preferably, the acid is selected from at least one of nitric acid, hydrochloric acid, and phosphoric acid.

[0044] According to the present invention, preferably, the aluminum source is at least one of aluminum isopropoxide, aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0045] In the present invention, there is no particular limitation on the type of the magnesium precursor, as long as it contains magnesium element. For example, it can be at least one of magnesium nitrate, magnesium chloride, and magnesium sulfate.

[0046] The above substances are all conventional selections in the art and can be obtained through commercial purchase.

[0047] Preferably, the method for preparing the doped support in the present invention includes: mixing P123 and absolute ethanol and dissolving them under ultrasound, then adding concentrated nitric acid, and after clarification, adding aluminum isopropoxide and magnesium nitrate, stirring and reacting, and then drying and calcining.

[0048] Preferably, the molar ratio of the surfactant, the organic solvent, the acid to the aluminum precursor is 0.01-0.05:10-80:1-10:1, preferably 0.01-0.03:20-60:3-7:1.

[0049] According to the present invention, preferably, in the method for preparing the doped support, the mixing time is 3-9 h, and more preferably the mixing is carried out under stirring conditions; wherein, the stirring speed can be 100 rpm-500 rpm.

[0050] According to the present invention, the drying conditions in the preparation method of the doped carrier preferably include: the temperature is 60-90°C, specifically it can be 60°C, 70°C, 80°C, 90°C, or any value within the range formed by any two of the above values; the time is 36-60h, specifically it can be 36h, 40h, 45h, 50h, 55h, 60h, or any value within the range formed by any two of the above values; the calcination conditions preferably include: the temperature is 600-1200°C, specifically it can be 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, or any value within the range formed by any two of the above values; the time is 3-6h, specifically it can be 3h, 4h, 5h, 6h, or any value within the range formed by any two of the above values.

[0051] According to the present invention, there is no particular limitation on the type of the indium metal salt, as long as it can form a corresponding salt solution form and react with a precipitant to form indium oxide. For example, it can be at least one of indium nitrate, indium chloride, and indium sulfate. The above substances are all conventional selections in the art and can be obtained through commercial purchase.

[0052] According to the present invention, preferably, the precipitant is urea. In this preferred embodiment, it is more conducive to enabling the precipitation mother liquor formed by mixing the precipitant with the indium metal salt and the doped carrier to form indium oxide with a cubic structure in the form of aging precipitation, and at the same time realizing the modification effect on indium oxide.

[0053] According to the present invention, preferably, the solvents in the solution containing the indium metal salt and the precipitant solution in step (1) are independently an organic solvent and / or water, preferably an organic solvent and water.

[0054] Preferably, the organic solvent is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol, and N,N-dimethylacetamide; exemplarily, the solution containing the indium metal salt is obtained by dissolving the indium metal salt in a mixed solution of ethanol and deionized water, and the precipitant solution is obtained by dissolving the precipitant in a mixed solution of ethanol and deionized water. Among them, the dosage ratio of ethanol to deionized water is not particularly limited as long as the indium metal salt or the precipitant can be effectively dissolved respectively.

[0055] According to the present invention, the concentrations of the indium metal salt solution and the precipitant solution are not particularly limited. To promote the sufficient reaction between the indium metal salt and the precipitant and improve the reaction efficiency, preferably, the concentration of the indium metal salt solution is 0.1 - 1 mol / L, specifically it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, or any value within the range formed by any two of the above values; preferably, the concentration of the precipitant solution is 1 - 3 mol / L, specifically it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, or any value within the range formed by any two of the above values.

[0056] According to the present invention, the dosage ratio of the indium metal salt and the precipitant is such that it can fully convert the indium metal salt into indium oxide. Under preferred conditions, the molar ratio of indium in the indium metal salt to the precipitant is 1:5 - 7. Research has shown that under this molar ratio condition, the carbon dioxide conversion rate and methanol yield can be significantly improved.

[0057] According to the present invention, in order to make the indium metal salt, precipitant, and doping carrier in the precipitation mother liquor fully mixed and uniform, and improve the efficiency of aging precipitation, preferably, the mixing in step (1) is carried out under stirring conditions, preferably for 1 - 10 h, where the stirring speed can be 100 rpm - 500 rpm.

[0058] According to the present invention, preferably, the mixing in step (1) includes first mixing the indium metal salt solution and the precipitant solution, and then adding the doping carrier. The first mixing can be carried out by conventional mixing methods, such as adding the indium metal salt solution to the precipitant solution for mixing. To optimize the mixing effect of the two, preferably, the process of the first mixing is: adding the precipitant solution dropwise to the indium metal salt solution.

[0059] According to the present invention, preferably, the aging conditions in step (2) include: the temperature is 80 - 180 °C, specifically it can be 80 °C, 100 °C, 120 °C, 140 °C, 160 °C, 180 °C, or any value within the range formed by any two of the above values, and more preferably 120 - 160 °C; the time is 12 - 22 h, specifically it can be 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, or any value within the range formed by any two of the above values, and more preferably 18 - 20 h. The aging reaction in step (2) is a hydrothermal reaction, and preferably the aging reaction is carried out under closed conditions. The aging of the precipitation mother liquor can be carried out in a hydrothermal synthesis reactor. Specifically, the precipitation mother liquor can be placed in a hydrothermal synthesis reactor, and the hydrothermal synthesis reactor can be placed in an oven for the aging.

[0060] According to a preferred embodiment of the present invention, the method further includes washing the product obtained in step (2), preferably washing until the pH value of the product obtained in step (2) is between 6 and 8. According to the present invention, the manner of the washing is not particularly limited and can be carried out according to the conventional technical means in the art. Preferably, a centrifugation method can be adopted, and centrifugation can simultaneously achieve the above-mentioned solid-liquid separation and washing.

[0061] According to the present invention, preferably, the conditions for drying in step (3) include: the temperature is 60-90°C, specifically it can be 60°C, 70°C, 80°C, 90°C, or any value within the range formed by any two of the above values; the time is 12-24 h, specifically it can be 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, or any value within the range formed by any two of the above values.

[0062] According to the present invention, preferably, the conditions for calcination in step (3) include: the temperature is 300-500°C, specifically it can be 300°C, 350°C, 400°C, 450°C, 500°C, or any value within the range formed by any two of the above values; the time is 3-6 h, specifically it can be 3 h, 4 h, 5 h, 6 h, or any value within the range formed by any two of the above values.

[0063] According to the present invention, the type of the metal palladium salt is not particularly limited as long as it can form a corresponding solution form and palladium can be loaded on the catalyst semi-finished product by the impregnation method. Preferably, the metal palladium salt is selected from at least one of palladium nitrate, palladium chloride, palladium acetate, ammonium tetrachloropalladate, ammonium hexachloropalladate, dichlorodiamminepalladium, and dichlorotetraamminepalladium; the above substances are all conventional selections in the art and can be obtained through commercial purchase.

[0064] According to the present invention, preferably, the conditions for the contact in step (4) include: carried out under stirring conditions, the temperature is 20-35°C, specifically it can be 20°C, 25°C, 30°C, 35°C, or any value within the range formed by any two of the above values; the time is 0.5-2 h, specifically it can be 0.5 h, 1 h, 1.5 h, 2 h, or any value within the range formed by any two of the above values. Among them, the stirring speed can be 100 rpm - 500 rpm.

[0065] According to the present invention, the concentration of the solution containing the metal palladium salt is not particularly limited. In order to promote the loading effect of precious metal palladium on the semi-finished catalyst, preferably, the concentration of the solution containing the metal palladium salt is 0.005-0.3% by weight.

[0066] According to the present invention, preferably, the drying is rotary evaporation drying. Further preferably, the conditions of the rotary evaporation drying include: the temperature is 45 - 72 °C, specifically it can be 45 °C, 55 °C, 65 °C, 72 °C, or any value within the range formed by any two of the above values; the rotation speed is 10 - 30 rpm, specifically it can be 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, or any value within the range formed by any two of the above values; the vacuum degree is 0.05 - 0.1 MPa, specifically it can be 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, or any value within the range formed by any two of the above values; the rotary evaporation time is 1 - 3 h, specifically it can be 1 h, 2 h, 3 h, or any value within the range formed by any two of the above values.

[0067] According to the present invention, preferably, the conditions of the calcination in step (4) include: the temperature is 300 - 500 °C, specifically it can be 300 °C, 400 °C, 500 °C, or any value within the range formed by any two of the above values; the time is 1 - 5 h, specifically it can be 1 h, 2 h, 3 h, 4 h, 5 h, or any value within the range formed by any two of the above values.

[0068] According to a particularly preferred embodiment of the present invention, the preparation method of the noble metal modified catalyst comprises the following steps:

[0069] (1) Mix the surfactant and the solvent, dissolve them under ultrasonic treatment, then add an acid. After clarification, add the aluminum precursor and the magnesium precursor, stir for 3 - 9 h, dry at 60 - 90 °C for 36 - 60 h, and then calcine at 600 - 1200 °C for 3 - 6 h to obtain a doped carrier;

[0070] (2) Dissolve the metal indium salt in a solvent to prepare a solution containing the metal indium salt, and dissolve the precipitating agent in a solvent to prepare a precipitating agent solution; dropwise add the precipitating agent solution to the solution containing the metal indium salt, then add the doped carrier obtained in step (1), and stir for 1 h - 10 h to obtain a precipitation mother liquor;

[0071] (3) Age the precipitation mother liquor obtained in step (2) at a temperature of 80 - 160 °C for 12 - 22 h to form a precipitate;

[0072] (4) After solid - liquid separation of the product obtained in step (3), wash it until the pH value is between 6 - 8, then dry at 60 - 90 °C for 12 - 24 h, and calcine at 300 - 500 °C for 3 - 6 h to obtain a catalyst semi - product;

[0073] (5) Contact the solution containing palladium metal salt with the catalyst semi-finished product obtained in step (4) at a temperature of 20 - 35 °C with stirring for 0.5 - 2 h, then perform rotary evaporation and drying for 1 - 3 h under the conditions of a temperature of 45 - 72 °C, a rotation speed of 10 - 30 rpm, and a vacuum degree of 0.05 - 0.1 MPa, and then calcine for 1 - 5 h under the condition of a temperature of 300 - 500 °C.

[0074] The third aspect of the present invention provides a noble metal modified catalyst prepared by the preparation method described in the present invention.

[0075] The noble metal modified catalyst provided by the present invention has the advantages of high reaction activity, high selectivity of the target product, good reaction stability, and low catalyst deactivation rate when used in the reaction of hydrogenating carbon dioxide to prepare methanol. Therefore, the fourth aspect of the present invention provides the application of the noble metal modified catalyst described in the present invention and the noble metal modified catalyst prepared by the preparation method described in the present invention in the reaction of hydrogenating carbon dioxide to prepare methanol.

[0076] According to the present invention, in order to improve the reaction efficiency of hydrogenating carbon dioxide to prepare methanol, preferably, the conditions for the reaction of hydrogenating carbon dioxide to prepare methanol include: a reaction pressure of 1.0 - 5.0 MPa, a reaction temperature of 200 - 400 °C, and a volume space velocity of the raw materials (including carbon dioxide and hydrogen) of 4500 - 18000 h -1 ,H 2 / CO 2 The molar ratio is 1 - 10. Further preferably, the conditions for hydrogenating carbon dioxide include: the reaction pressure is between 3 - 5 MPa, the reaction temperature is between 240 - 300 °C, the volume space velocity of the raw materials is between 7000 - 13000 h -1 ,and the H 2 / CO 2 The molar ratio is between 3 - 6.

[0077] The present invention will be described in detail below through examples.

[0078] In the following examples and comparative examples, unless otherwise specified, the substances used are all commercially available, and the room temperature is 25 ± 5 °C;

[0079] P123 is commercially available from Sigma - aldrich, and the brand is poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol).

[0080] The structure of the magnesium - aluminum modified indium oxide catalyst was measured by XRD, and the content of each component in the catalyst was tested by the XRF method.

[0081] Example 1

[0082] (1) 4.1 g of surfactant P123 and 80 mL of anhydrous ethanol were mixed and dissolved under ultrasound, and then 6.3 mL of concentrated nitric acid was added. After clarification, 4.9 g of aluminum isopropoxide and 3.0 g of magnesium nitrate were added. The mixture was stirred at 150 rpm for 5 h, dried at 60° C. for 48 h, and finally calcined at 800° C. for 3 h to obtain a doped carrier. The obtained doped carrier was characterized and analyzed by XRD. Figure 1 The results show that the doped components have an ordered mesoporous structure;

[0083] (2) 7.61 g In(NO 3 ) 3 ·4H 2 O is added to a mixture of 40 mL of anhydrous ethanol and 24 mL of deionized water to obtain a solution containing a metal indium salt, 8 g of urea is added to a mixture of 40 mL of anhydrous ethanol and 10 mL of deionized water to obtain a precipitant solution, the precipitant solution is added dropwise to the solution containing the metal indium salt at 30° C., and then 2 g of the doping carrier obtained in step (1) is added, and the mixture is stirred at a speed of 150 rpm for 6 h to obtain a precipitation mother solution;

[0084] (3) adding the precipitation mother solution obtained in step (2) into a 100 mL polytetrafluoroethylene-lined hydrothermal synthesis reactor, placing the reactor in a forced air drying oven for aging at 120° C. for 20 h to form a precipitate;

[0085] (4) The product obtained in step (3) was naturally cooled to room temperature and then centrifuged, and the centrifugal precipitate was washed with deionized water until the pH value was 7, and then dried at 60° C. for 20 h, and then calcined at 350° C. for 3 h to obtain the finished catalyst;

[0086] (5) 0.057 g of palladium nitrate was dissolved in 10 mL of deionized water to obtain a solution containing a metal palladium salt, and 2 g of the catalyst product obtained in step (4) was added to the solution containing a metal palladium salt, stirred at 25° C. and 150 rpm for 1 h, and then dried by rotary evaporation at 45° C., 20 rpm, and a vacuum degree of 0.1 MPa for 3 h, and finally calcined at 350° C. for 4 h to obtain a noble metal modified catalyst (the contents of each component of which are shown in Table 1), which was pressed into tablets and sieved into 40-60 mesh; the obtained catalyst was subjected to XRD characterization analysis. Figure 2 The results show that indium oxide has a cubic structure;

[0087] (6) In a stainless steel reactor with an inner diameter of 8 mm, the noble metal modified catalyst prepared in step (5) is used as a reaction catalyst. The reaction conditions are as follows: reaction pressure of 3.0 MPa, reaction temperature of 280° C., volume space velocity of raw materials (carbon dioxide and hydrogen) of 9000 h / min -1 , H2 / CO 2 The molar ratio was 4. After the reaction was completed, the liquid product was collected in an ice-water bath. The product composition was analyzed by gas chromatography. The evaluation results are shown in Table 2.

[0088] Example 2

[0089] (1) 3.9 g of surfactant P123 and 80 mL of anhydrous ethanol were mixed and dissolved under ultrasound, and then 6.1 mL of concentrated nitric acid was added. After clarification, 9.4 g of aluminum isopropoxide and 1.6 g of magnesium nitrate were added. After stirring and mixing at a speed of 300 rpm for 5 h, the mixture was dried at 60 ° C for 48 h, and finally calcined at 800 ° C for 3 h to obtain a doped carrier with an ordered mesoporous structure;

[0090] (2) 7.58 g In(NO 3 ) 3 ·4H 2 O is added to a mixture of 40 mL of anhydrous ethanol and 25 mL of deionized water to obtain a solution containing a metal indium salt, 8 g of urea is added to a mixture of 60 mL of anhydrous ethanol and 20 mL of deionized water to obtain a precipitant solution, the precipitant solution is added dropwise to the solution containing the metal indium salt at 30° C., and then 1 g of the doping carrier obtained in step (1) is added, and the mixture is stirred at a speed of 300 rpm for 6 h to obtain a precipitation mother solution;

[0091] (3) adding the precipitation mother solution obtained in step (2) into a 100 mL polytetrafluoroethylene-lined hydrothermal synthesis reactor, placing the reactor in a forced air drying oven for aging at a temperature of 140° C. for 15 h to form a precipitate;

[0092] (4) The product obtained in step (3) was naturally cooled to room temperature and then centrifuged, and the centrifugal precipitate was washed with deionized water until the pH value was 7.5, and then dried at 60° C. for 24 h, and then calcined at 300° C. for 3 h to obtain the finished catalyst;

[0093] (5) 0.039 g of palladium nitrate was dissolved in 5 mL of deionized water to obtain a solution containing a metal palladium salt, and 2 g of the catalyst obtained in step (4) was added to the solution containing a metal palladium salt, and stirred at 25° C. and 300 rpm for 1 h, and then dried by rotary evaporation at 45° C., 20 rpm, and a vacuum degree of 0.1 MPa for 3 h, and finally calcined at 350° C. for 4 h to obtain a noble metal modified catalyst (the contents of each component of which are shown in Table 1), which was pressed into a 40-60 mesh size, and the indium oxide in the obtained catalyst had a cubic structure;

[0094] (6) In a stainless steel reactor with an inner diameter of 8 mm, the noble metal modified catalyst prepared in step (5) is used as the reaction catalyst. The reaction conditions are as follows: reaction pressure of 5.0 MPa, reaction temperature of 220° C., volume space velocity of raw materials (carbon dioxide and hydrogen) of 7000 h / min -1 , H 2 / CO 2 The molar ratio was 6. After the reaction was completed, the liquid product was collected in an ice-water bath. The product composition was analyzed by gas chromatography. The evaluation results are shown in Table 2.

[0095] Example 3

[0096] (1) 5.1 g of surfactant P123 and 100 mL of anhydrous ethanol were mixed and dissolved under ultrasound, and then 7.3 mL of concentrated nitric acid was added. After clarification, 10.7 g of aluminum isopropoxide and 3.8 g of magnesium nitrate were added. After stirring and mixing at a speed of 200 rpm for 5 h, the mixture was dried at 60 ° C for 48 h, and finally calcined at 800 ° C for 3 h to obtain a doped carrier with an ordered mesoporous structure;

[0097] (2) 8.34 g In(NO 3 ) 3 ·4H 2 O is added to a mixture of 50 mL of anhydrous ethanol and 25 mL of deionized water to obtain a solution containing a metal indium salt, 8 g of urea is added to a mixture of 60 mL of anhydrous ethanol and 20 mL of deionized water to obtain a precipitant solution, the precipitant solution is added dropwise to the solution containing the metal indium salt at 30° C., and then 1.2 g of the doping carrier obtained in step (1) is added, and the mixture is stirred at a speed of 200 rpm for 4 h to obtain a precipitation mother solution;

[0098] (3) adding the precipitation mother solution obtained in step (2) into a 100 mL polytetrafluoroethylene-lined hydrothermal synthesis reactor, placing the reactor in a forced air drying oven for aging at 120° C. for 18 h to form a precipitate;

[0099] (4) The product obtained in step (3) was naturally cooled to room temperature and then centrifuged, the centrifugal precipitate was washed with deionized water until the pH value was 8, and then dried at 60° C. for 15 h, and then calcined at 380° C. for 3 h to obtain the finished catalyst;

[0100] (5) 0.038 g of palladium nitrate was dissolved in 6 mL of deionized water to obtain a solution containing a metal palladium salt, and 2 g of the catalyst obtained in step (4) was added to the solution containing a metal palladium salt, and stirred at 25° C. and a speed of 400 rpm for 1 h, and then dried by rotary evaporation at a temperature of 45° C., a speed of 20 rpm, and a vacuum degree of 0.1 MPa for 3 h, and finally calcined at 350° C. for 4 h to obtain a noble metal modified catalyst (the contents of each component of which are shown in Table 1), which was pressed into a tablet and sieved into 40-60 mesh. The indium oxide in the obtained catalyst had a cubic structure;

[0101] (6) In a stainless steel reactor with an inner diameter of 8 mm, the noble metal modified catalyst prepared in step (5) is used as the reaction catalyst. The reaction conditions are as follows: the reaction pressure is 5.0 MPa, the reaction temperature is 340° C., the volume space velocity of the raw materials (carbon dioxide and hydrogen) is 18000 h -1 , H 2 / CO 2 The molar ratio was 5. After the reaction was completed, the liquid product was collected in an ice-water bath. The product composition was analyzed by gas chromatography. The evaluation results are shown in Table 2.

[0102] Example 4

[0103] (1) 4.6 g of surfactant P123 and 90 mL of anhydrous ethanol were mixed and dissolved under ultrasound, and then 7.6 mL of concentrated nitric acid was added. After clarification, 8.4 g of aluminum isopropoxide and 4.8 g of magnesium nitrate were added. After stirring and mixing at a speed of 350 rpm for 5 h, the mixture was dried at 60 ° C for 48 h, and finally calcined at 800 ° C for 3 h to obtain a doped carrier with an ordered mesoporous structure;

[0104] (2) 9.57 g In(NO 3 ) 3 ·4H 2 O is added to a mixture of 80 mL of anhydrous ethanol and 40 mL of deionized water to obtain a solution containing a metal indium salt, 9.2 g of urea is added to a mixture of 80 mL of anhydrous ethanol and 30 mL of deionized water to obtain a precipitant solution, the precipitant solution is added dropwise to the solution containing the metal indium salt at 30° C., and then 1.2 g of the doping carrier obtained in step (1) is added, and the mixture is stirred at a speed of 350 rpm for 7 h to obtain a precipitation mother solution;

[0105] (3) adding the precipitation mother solution obtained in step (2) into a 100 mL polytetrafluoroethylene-lined hydrothermal synthesis reactor, placing the reactor in a forced air drying oven for aging at a temperature of 130° C. for 20 h to form a precipitate;

[0106] (4) The product obtained in step (3) is cooled to room temperature naturally and then centrifuged, the centrifugal precipitate is washed with deionized water until the pH value is 6, and then dried at 80° C. for 12 h, and then calcined at 450° C. for 3 h to obtain the finished catalyst;

[0107] (5) 0.061 g of palladium nitrate was dissolved in 10 mL of deionized water to obtain a solution containing a metal palladium salt, and 2 g of the catalyst product obtained in step (4) was added to the solution containing a metal palladium salt, stirred at 25° C. and 350 rpm for 1 h, and then dried by rotary evaporation at 45° C., 20 rpm, and a vacuum degree of 0.1 MPa for 3 h, and finally calcined at 350° C. for 4 h to obtain a noble metal modified catalyst (the contents of each component of which are shown in Table 1), which was pressed into a 40-60 mesh size, and the indium oxide in the obtained catalyst had a cubic structure;

[0108] (6) In a stainless steel reactor with an inner diameter of 8 mm, the noble metal modified catalyst prepared in step (5) is used as a reaction catalyst. The reaction conditions are as follows: reaction pressure of 1.0 MPa, reaction temperature of 400° C., volumetric space velocity of raw materials (carbon dioxide and hydrogen) of 9000 h / min -1 , H 2 / CO 2 The molar ratio was 4. After the reaction was completed, the liquid product was collected in an ice-water bath. The product composition was analyzed by gas chromatography. The evaluation results are shown in Table 2.

[0109] Example 5

[0110] (1) 6.3 g of surfactant P123 and 120 mL of anhydrous ethanol were mixed and dissolved under ultrasound, and then 8.5 mL of concentrated nitric acid was added. After clarification, 4.1 g of aluminum isopropoxide and 5.3 g of magnesium nitrate were added. After stirring and mixing at a speed of 150 rpm for 5 h, the mixture was dried at 60 ° C for 48 h, and finally calcined at 800 ° C for 3 h to obtain a doped carrier with an ordered mesoporous structure;

[0111] (2) 5.36 g In(NO 3 ) 3 ·4H 2 O is added to a mixture of 40 mL of anhydrous ethanol and 20 mL of deionized water to obtain a solution containing a metal indium salt, 6 g of urea is added to a mixture of 50 mL of anhydrous ethanol and 20 mL of deionized water to obtain a precipitant solution, the precipitant solution is added dropwise to the solution containing the metal indium salt at 30° C., and then 0.4 g of the doping carrier obtained in step (1) is added, and the mixture is stirred at a speed of 150 rpm for 6 h to obtain a precipitation mother solution;

[0112] (3) Add the precipitation mother liquor obtained in step (2) into a 100 mL hydrothermal synthesis reactor with a polytetrafluoroethylene liner, place it in a forced air drying oven for static aging. The aging temperature is 150 °C and the aging time is 16 h to form a precipitate.

[0113] (4) After the product obtained in step (3) naturally cools to room temperature, centrifuge it, wash the centrifuged precipitate with deionized water until the pH is 7.5, then dry it at 80 °C for 14 h, and then calcine it at 500 °C for 3 h to obtain the catalyst semifinished product.

[0114] (5) Dissolve 0.046 g of palladium nitrate in 10 mL of deionized water to obtain a solution containing metal palladium salt. Then put 2 g of the catalyst semifinished product obtained in step (4) into the solution containing metal palladium salt, stir at 25 °C with a rotation speed of 150 rpm for 1 h, then rotary evaporate and dry it at a temperature of 45 °C, a rotation speed of 20 rpm, and a vacuum degree of 0.1 MPa for 3 h. Finally, calcine it at 350 °C for 4 h to obtain the noble metal modified catalyst (the content of each component is shown in Table 1), press it into tablets and screen it to 40 - 60 mesh. The indium oxide in the obtained catalyst has a cubic structure.

[0115] (6) Conduct the reaction of hydrogenation of carbon dioxide to methanol in a stainless steel reactor with an inner diameter of 8 mm, using the noble metal modified catalyst prepared in step (5) as the reaction catalyst. The reaction conditions are as follows: the reaction pressure is 4.0 MPa, the reaction temperature is 240 °C, the volume space velocity of the raw materials (carbon dioxide and hydrogen) is 15000 h -1 、H 2 / CO 2 The molar ratio is 6. After the reaction, collect the liquid phase product with an ice - water bath, analyze the product composition by gas chromatography, and the evaluation results are shown in Table 2.

[0116] Example 6

[0117] According to the method of Example 1, the difference is that the preparation method of the doped carrier is as follows: Dissolve 9.1 g of aluminum nitrate and 3.2 g of magnesium nitrate in 500 mL of water to prepare a salt solution, dissolve 6.5 g of sodium carbonate in 500 mL of deionized water to prepare a precipitant solution. Conduct co - current precipitation of the two solutions, control the pH at about 7.5, stir the mixed solution for 1 h, statically age for 2 h, wash it 3 times by centrifugation with deionized water, dry it at 60 °C for 48 h, and finally calcine it at 800 °C for 3 h to obtain the doped carrier.

[0118] Example 7

[0119] According to the method of Example 1, the difference is that the dosage of magnesium nitrate in step (1) is replaced by 6.6 g.

[0120] Example 8

[0121] According to the method of Example 1, except that the dosage of the doped carrier in step (2) is replaced with 0.5 g.

[0122] Comparative Example 1

[0123] (1) 7.61 g of In(NO 3 ) 3 ·4H 2 O was added to a mixed solution of 40 mL of absolute ethanol and 24 mL of deionized water to obtain a solution containing metal indium salt. 8 g of urea was added to a mixed solution of 40 mL of absolute ethanol and 10 mL of deionized water to obtain a precipitant solution. The precipitant solution was added to the solution containing metal indium salt at 30 °C, and stirred thoroughly at a rotation speed of 150 rpm for 6 h to obtain a precipitate mother liquor;

[0124] (2) The precipitate mother liquor obtained in step (1) was added to a hydrothermal synthesis reactor with a 100 mL polytetrafluoroethylene lining, placed in a forced-air drying oven and allowed to stand for aging. The aging temperature was 120 °C and the aging time was 20 h to form a precipitate;

[0125] (3) After the product obtained in step (2) was naturally cooled to room temperature, it was centrifuged, and the centrifuged precipitate was washed with deionized water until the pH was 7, then dried at 60 °C for 20 h, and then calcined at 350 °C for 3 h to obtain an indium oxide catalyst, which was tableted and sieved into 40-60 mesh;

[0126] (4) The indium oxide catalyst obtained in step (3) was subjected to activity evaluation on a fixed-bed reactor. The reaction conditions were the same as those in Example 1, and the test results are shown in Table 2.

[0127] Comparative Example 2

[0128] (1) The preparation of indium oxide was the same as that in Comparative Example 1;

[0129] (2) 0.057 g of palladium nitrate was dissolved in 10 mL of deionized water to obtain a solution containing metal palladium salt. Then, 2 g of the indium oxide obtained in step (1) was put into the solution containing metal palladium salt, and stirred at a rotation speed of 150 rpm at 25 °C for 1 h. Then, it was rotary evaporated and dried at a temperature of 45 °C, a rotation speed of 20 rpm, and a vacuum degree of 0.1 MPa for 3 h. Finally, it was calcined at 350 °C for 4 h to obtain a Pd-modified indium oxide catalyst, which was tableted and sieved into 40-60 mesh;

[0130] (3) The Pd-modified indium oxide catalyst obtained in step (2) was subjected to activity evaluation on a fixed-bed reactor. The reaction conditions were the same as those in Example 1, and the test results are shown in Table 2.

[0131] Comparative Example 3

[0132] (1) Mix 4.1 g of surfactant P123 and 80 mL of absolute ethanol, dissolve them under ultrasonic treatment, then add 6.3 mL of concentrated nitric acid. After clarification, add 4.9 g of aluminum isopropoxide and 3.0 g of magnesium nitrate, stir and mix at a rotation speed of 150 rpm for 5 h, dry at 60 °C for 48 h, and finally calcine at 800 °C for 3 h to obtain a doped support;

[0133] (2) Add 7.61 g of In(NO 3 ) 3 ·4H 2 O to a mixed solution of 40 mL of absolute ethanol and 24 mL of deionized water to obtain a solution containing metal indium salt. Add 8 g of urea to a mixed solution of 40 mL of absolute ethanol and 10 mL of deionized water to obtain a precipitant solution. At 30 °C, slowly add the precipitant solution dropwise to the solution containing metal indium salt, then add 2 g of the doped support obtained in step (1), and stir thoroughly at a rotation speed of 150 rpm for 6 h to obtain a mother liquor of the precipitate;

[0134] (3) Add the mother liquor of the precipitate obtained in step (2) to a hydrothermal synthesis reactor lined with 100 mL of polytetrafluoroethylene, place it in a forced-air drying oven and let it stand for aging. The aging temperature is 120 °C and the aging time is 20 h to form a precipitate;

[0135] (4) After the product obtained in step (3) naturally cools to room temperature, centrifuge it, wash the centrifuged precipitate with deionized water until the pH is 7, then dry it at 60 °C for 20 h, and then calcine it at 350 °C for 3 h to obtain a magnesium-aluminum modified indium oxide catalyst. Press and sieve it to 40 - 60 mesh;

[0136] (5) Evaluate the activity of the magnesium-aluminum modified indium oxide catalyst obtained in step (4) on a fixed-bed reactor. The reaction conditions are the same as those in Example 1, and the test results are shown in Table 2.

[0137] Table 1

[0138]

[0139] Note: The content of each component in Table 1 is in mass percentage

[0140] Table 2

[0141]

[0142]

[0143] As can be seen from the results in Table 1, when the noble metal modified catalysts prepared by the method provided in Examples 1-8 are used for the reaction of hydrogenating carbon dioxide to prepare methanol, compared with the catalysts prepared in Comparative Examples 1-3, they have significantly better catalytic performance, high reaction activity, high selectivity for target products, and good reaction stability.

[0144] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A noble metal modified catalyst, which catalyst contains an active component, a doped support and a noble metal component. The active component is indium oxide with a cubic structure, the doped support is a mixture of magnesium oxide and alumina, and the noble metal component is Pd; Wherein, the content of the active component accounts for 40%-85% of the total mass of the active component and the doped support; the doped support accounts for 15%-60% of the total mass of the active component and the doped support; the noble metal component accounts for 0.01%-1.5% of the total mass of the catalyst; the mass ratio of the active component to the doped support is 1-6:1; magnesium oxide accounts for 2%-18% of the total mass of the active component and the doped support, and alumina accounts for 14%-54% of the total mass of the active component and the doped support; the doped support has an ordered mesoporous structure; the preparation method of the doped support includes: in the presence of a surfactant and in the presence of a solvent, mixing an acid, an aluminum precursor and a magnesium precursor, and then drying and calcining.

2. The noble metal modified catalyst according to claim 1, Wherein, the content of the active component accounts for 55%-75% of the total mass of the active component and the doped support; the doped support accounts for 25%-45% of the total mass of the active component and the doped support.

3. The noble metal modified catalyst according to claim 1, Wherein, the noble metal component accounts for 0.75%-1.5% of the total mass of the catalyst.

4. The noble metal modified catalyst according to claim 1, Wherein, the mass ratio of the active component to the doped support is 1-3:

1.

5. The noble metal modified catalyst according to any one of claims 1-4, Wherein, magnesium oxide accounts for 2.5%-12.5% of the total mass of the active component and the doped support; alumina accounts for 18.5%-40.5% of the total mass of the active component and the doped support.

6. The preparation method of the noble metal modified catalyst according to any one of claims 1-5, this method includes: (1) Mixing a solution containing a metal indium salt, a precipitant solution and a doped support to obtain a precipitation mother liquor; the doped support is a mixture of magnesium oxide and alumina; (2) Aging the precipitation mother liquor to form a precipitate; (3) Separating the solid and liquid of the product obtained in step (2), and then drying and calcining to obtain a catalyst semi-finished product; (4) Contacting a solution containing a metal palladium salt with the catalyst semi-finished product, and then drying and calcining.

7. The method according to claim 6, Wherein, the dosages of the metal indium salt, the doped support and the metal palladium salt are such that in the prepared catalyst, indium oxide accounts for 40%-85% of the total mass of indium oxide and the doped support; the doped support accounts for 15%-60% of the total mass of indium oxide and the doped support; palladium element accounts for 0.01%-1.5% of the total mass of the catalyst.

8. The method according to claim 7, Wherein, the dosages of the metal indium salt, the doped support and the metal palladium salt are such that in the prepared catalyst, indium oxide accounts for 55%-75% of the total mass of indium oxide and the doped support; the doped support accounts for 25%-45% of the total mass of indium oxide and the doped support; palladium element accounts for 0.75%-1.5% of the total mass of the catalyst.

9. The method according to claim 6, Among them, the mass ratio of the metal indium salt and the doped carrier in terms of oxide is 1-6:

1.

10. According to the method described in claim 9, Among them, the mass ratio of the metal indium salt and the doped carrier in terms of oxide is 1-3:

1.

11. According to the method described in claim 6, Among them, the doped carrier is prepared by a solvent evaporation-induced self-assembly method.

12. According to the method described in claim 11, Among them, the preparation method of the doped carrier includes: in the presence of a surfactant and in the presence of a solvent, mixing an acid, an aluminum precursor and a magnesium precursor, and then drying and calcining.

13. According to the method described in claim 12, Among them, the amounts of the aluminum precursor and the magnesium precursor are such that in the prepared catalyst, magnesium oxide accounts for 2-18% of the total mass of indium oxide and the doped carrier; aluminum oxide accounts for 14-54% of the total mass of indium oxide and the doped carrier.

14. According to the method described in claim 13, Among them, the amounts of the aluminum precursor and the magnesium precursor are such that in the prepared catalyst, magnesium oxide accounts for 2.5-12.5% of the total mass of indium oxide and the doped carrier; aluminum oxide accounts for 18.5-40.5% of the total mass of indium oxide and the doped carrier.

15. According to the method described in claim 12, Among them, the surfactant is selected from at least one of P123, CTAB, malic acid, sodium 2-ethylhexane sulfosuccinate and nonylphenol polyoxyethylene ether; the solvent 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 aluminum precursor is at least one of aluminum isopropoxide, aluminum nitrate, aluminum chloride and aluminum sulfate.

16. According to the method described in claim 12, Among them, the mixing time is 3-9 h.

17. According to the method described in claim 16, Among them, the mixing is carried out under stirring conditions.

18. According to the method described in claim 12, Among them, the calcination conditions include: the temperature is 600-1200 °C and the time is 3-6 h.

19. According to the method described in claim 6, Among them, the solvents in the solution containing the metal indium salt and the precipitant solution in step (1) are independently organic solvents and / or water.

20. According to the method described in claim 19, Among them, the solvents in the solution containing the metal indium salt and the precipitant solution in step (1) are organic solvents and water, and the organic solvents are selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, triethylene glycol and N,N-dimethylacetamide.

21. According to the method described in claim 6, Among them, the concentration of the solution containing the metal indium salt is 0.1-1 mol / L.

22. According to the method described in claim 6, Among them, the concentration of the precipitant solution is 1-3 mol / L.

23. According to the method described in claim 6, Among them, the precipitant is urea.

24. According to the method described in claim 6, Among them, the mixing in step (1) is carried out under stirring conditions.

25. According to the method described in claim 24, Among them, The mixing described in step (1) is carried out under stirring conditions for 1 - 10 h.

26. The method according to claim 6, wherein, the mixing described in step (1) includes first performing a first mixing on the solution containing metal indium salt and the precipitant solution, and then adding the doping carrier.

27. The method according to claim 6, wherein, the conditions for aging in step (2) include: the temperature is 80 - 180 °C and the time is 12 - 22 h.

28. The method according to any one of claims 6 - 27, wherein, the method further includes washing the product obtained in step (2).

29. The method according to claim 28, wherein, washing is carried out until the pH value of the product obtained in step (2) is between 6 - 8.

30. The method according to any one of claims 6 - 27, wherein, the conditions for calcination in step (3) include: the temperature is 300 - 500 °C and the time is 3 - 6 h.

31. The method according to any one of claims 6 - 27, wherein, the metal palladium salt is selected from at least one of palladium nitrate, palladium chloride, palladium acetate, ammonium tetrachloropalladate, ammonium hexachloropalladate, dichlorodiamminepalladium, and dichlorotetraamminepalladium.

32. The method according to any one of claims 6 - 27, wherein, the conditions for contacting in step (4) include: carried out under stirring conditions, the temperature is 20 - 35 °C, and the time is 0.5 - 2 h.

33. The method according to any one of claims 6 - 27, wherein, the concentration of the solution containing metal palladium salt is 0.005 - 0.03 wt%.

34. The method according to any one of claims 6 - 27, wherein, the drying is rotary evaporation drying.

35. The method according to claim 34, wherein, the conditions for rotary evaporation drying include: the temperature is 45 - 72 °C, the rotation speed is 10 - 30 rpm, the vacuum degree is 0.05 - 0.1 MPa, and the rotary evaporation time is 1 - 3 h.

36. The method according to any one of claims 6 - 27, wherein, the conditions for calcination in step (4) include: the temperature is 300 - 500 °C and the time is 1 - 5 h.

37. Application of the noble metal modified catalyst according to any one of claims 1 - 5 or the noble metal modified catalyst prepared by the preparation method according to any one of claims 6 - 36 in the reaction of hydrogenating carbon dioxide to prepare methanol.

38. The application according to claim 37, wherein, The conditions for the reaction of hydrogenating carbon dioxide to produce methanol include: the reaction pressure is 1.0 - 5.0 MPa, the reaction temperature is 200 - 400 °C, and the raw material volume space velocity is 4500 - 18000 h -1 , H 2 / CO 2 The molar ratio is 1 - 6.

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