A bifunctional catalyst for methanol synthesis and a preparation method and application thereof

Abstract

The application discloses a bifunctional catalyst for methanol synthesis, a preparation method and application thereof. The catalyst is composed of 1T phase molybdenum disulfide and metal elements, and the metal elements can be at least one selected from zinc, gallium, indium, copper, palladium, cadmium and chromium. The mass fraction of the metal elements is 0.5% to 5%, and the balance is 1T phase molybdenum disulfide. The catalyst is prepared by an in-situ hydrothermal method. The catalyst is used for CO2 / CO co-hydrogenation reaction, CO2, CO and H2 are used as reaction raw materials, the methanol selectivity is higher than 95%, CO2 and CO can be co-converted, and the stability is more than 300 hours. The catalyst has the advantages of low price, simple preparation method, high methanol selectivity, good stability and wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrogenation catalysis, in particular to a bifunctional catalyst for methanol synthesis with high selectivity and high stability, and a preparation method and application thereof. BACKGROUND

[0002] Fossil fuels, while providing energy for the development and prosperity of human society, have also caused a series of environmental problems such as carbon dioxide emissions and greenhouse effect. Under the background of carbon peak and carbon neutral, the use of renewable energy to electrolyze water to produce hydrogen and the hydrogenation of carbon dioxide to synthesize methanol has attracted much attention. Methanol, as an important basic chemical raw material, can be used to synthesize olefins, aromatic hydrocarbons, esters and other chemicals, and is also an important hydrogen storage carrier, with wide application prospects. At present, there are three major categories of catalyst systems for the hydrogenation of carbon dioxide to synthesize methanol, including Cu-based catalysts, Pd-based catalysts and oxide catalysts.

[0003] Cu-based catalysts, mainly Cu / ZnO / Al2O3 (An et al., J. Am. Chem. Soc., 2017, 139, 3834-3840), Cu / ZrO2 (Yu et al., Chem. Eng. J., 2021, 419, 129656-129669), etc., have high carbon dioxide conversion rate and good catalytic activity, but are easily sintered and oxidized in the reaction atmosphere, leading to catalyst deactivation and poor stability. Noble metal catalysts, such as Pd / In2O3 (Rui et al., Appl. Catal. B, 2017, 218, 488-497), PdZn (Yin et al., Appl. Catal. B, 2018, 234, 143-152), etc., in which the oxygen vacancies in In2O3 can effectively activate carbon dioxide, and the noble metal catalysts have good activity at low temperature and low pressure. However, this type of catalyst has low methanol space-time yield and is expensive, making it difficult to be applied in industrialization. Solid solution catalysts, such as ZnO-ZrO2 (Wang et al., Sci. Adv., 2017, 3, e1701290), GaZrO X (CN113058583A) etc., in which the strong synergistic effect between the metal components enhances the ability to activate H2, but the activity of this type of catalyst is poor, which affects its further industrial application. Therefore, there is an urgent need to develop a methanol synthesis catalyst with high selectivity and high stability. SUMMARY

[0004] The present application relates to the field of hydrogenation catalysis, in particular to a bifunctional catalyst for methanol synthesis with high selectivity and high stability, and a preparation method and application thereof.

[0005] To achieve the above object, the application adopts the following technical scheme:

[0006] A bifunctional catalyst for methanol synthesis, which is composed of 1T phase molybdenum disulfide and metal elements, the metal elements can be selected from at least one of zinc, gallium, indium, copper, palladium, cadmium and chromium, the mass fraction of the metal elements is 0.5% to 5%, and the rest is 1T phase molybdenum disulfide.

[0007] The preparation method of the bifunctional catalyst for methanol synthesis comprises the following steps:

[0008] 1) A measured amount of a molybdenum source, a sulfur source and a metal salt are dissolved in deionized water, stirred, and the obtained solution is subjected to hydrothermal reaction at 160-200°C for 2-24h to obtain a product;

[0009] 2) The product obtained in step 1) is centrifuged, washed, dried, and then calcined under a protective gas;

[0010] 3) The calcined product obtained in step 2) is reduced to obtain the bifunctional catalyst for methanol synthesis.

[0011] In step 1), the molybdenum source is one or more of molybdenum dioxide, molybdenum trioxide, sodium molybdate, ammonium molybdate, potassium molybdate, ammonium tetrathiomolybdate, molybdenum blue, hexacarbonylmolybdenum, molybdenum oxalate and molybdenum ethoxide; and the sulfur source is one or more of thiourea, sulfur powder, sodium sulfide, potassium sulfide, hydrogen sulfide, dimethyl sulfoxide, thioacetamide and potassium thiocyanate.

[0012] In step 1), the molar ratio of molybdenum atoms to sulfur atoms in the molybdenum source and the sulfur source is 1:1 to 1:5.

[0013] In step 1), the metal salt is at least one of zinc salt, gallium salt, indium salt, copper salt, palladium salt, cadmium salt and chromium salt.

[0014] In step 1), the mass ratio of deionized water to the molybdenum source is 3:1 to 20:1, the stirring temperature is 20-80°C, and the stirring time is 5-60min.

[0015] In step 2), the washing is centrifugal washing with deionized water and ethanol for 1-5 times, each time for 2-5min.

[0016] In step 2), the drying temperature is 80-180°C, and the drying time is 1-12h.

[0017] In step 2), the protective gas is helium, nitrogen or argon, the calcination temperature is 200-600°C, and the calcination time is 2-10h.

[0018] In step 3), the reduction conditions are 1-5 bar, 10%-30% H2 / N2 atmosphere, 1℃ / min to 200-400℃ for 0.5-4h.

[0019] The catalyst of the present application is used for CO2 / CO co-hydrogenation reaction, the reaction temperature of CO2 / CO co-hydrogenation is 180-300℃, the reaction pressure is 10-100 bar, the volume ratio of CO2 / CO / H2 is 1:1:2-1:1:9, and the reaction gas space velocity is 1000-50000 mLh -1 g -1 .

[0020] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0021] (1) The catalyst used shows excellent performance in CO2 / CO co-hydrogenation to prepare methanol, the methanol selectivity can reach more than 95%, and CO2 and CO can be co-converted;

[0022] (2) The catalyst used is 1T metal phase molybdenum disulfide, which shows similar properties to metal compared with 2H semiconductor phase, and can provide more catalytically active sites;

[0023] (3) The catalyst used is a bifunctional catalyst, the in-plane sulfur vacancy of molybdenum disulfide activates carbon dioxide molecules, and metal atoms activate hydrogen molecules, and the two work together to improve catalytic activity;

[0024] (4) The catalyst used has good stability, and can be stably operated for more than 300h, and has good application prospect;

[0025] (5) The catalyst used is relatively simple to prepare, low in price, and easy to scale up production. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 XRD comparison chart of 1T-MoS2 prepared according to the present application and commercial 2H-MoS2;

[0027] Figure 2 Stability evaluation results of 1Ga-MoS2 catalyst prepared in Example 7. DETAILED DESCRIPTION

[0028] In order to make the technical problems to be solved by the present application, the technical scheme and the beneficial effects more clear, specific, the following will be combined with the drawings and examples, and the present application will be further described in detail.

[0029] Example 1

[0030] Weigh 13.90g (NH4) 6Mo7O 24• 4H2O, 11.99 g CH4N2S, 0.58 g Zn(N03)2-6H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, and transferred to a polytetrafluoroethylene-lined autoclave, which was hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction was completed, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 min each time, and dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h at a temperature rising rate of 4 °C / min under flowing N2(30 mL / min), pressed into a tablet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor, reduced at 300 °C for 4 h at a temperature rising rate of 1 °C / min under a 10% H2 / N2atmosphere at normal pressure to prepare a 1% Zn-loaded molybdenum disulfide catalyst, which was denoted as 1Zn-MoS2.

[0031] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 °C, the volume ratio of CO2 / CO / H2was 1:1:5, and the reaction gas space velocity was 6000 mL h -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0032] Example 2

[0033] 13.90 g (NH4)6Mo7O 24 • 4H2O, 11.99 g CH4N2S, 0.58 g Zn(N03)2-6H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, and transferred to a polytetrafluoroethylene-lined autoclave, which was hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction was completed, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 min each time, and dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h at a temperature rising rate of 4 °C / min under flowing N2(30 mL / min), pressed into a tablet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor, reduced at 300 °C for 4 h at a temperature rising rate of 1 °C / min under a 10% H2 / N2atmosphere at normal pressure to prepare a 1% Zn-loaded molybdenum disulfide catalyst, which was denoted as 1Zn-MoS2.

[0034] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 ℃, the volume ratio of CO2 / CO / H2 was 1:1:5, and the reaction gas space velocity was 6000 mL h -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0035] Example 3

[0036] 13.90 g of (NH4)6Mo7O 24 4.5H2O, 11.99 g of CH4N2S, and 0.42 g of In(NO3)3·4.5H2O were dissolved in 100 mL of deionized water, stirred at room temperature for 60 min, transferred to a polytetrafluoroethylene-lined autoclave, and hydrothermally treated at 200 ℃ for 20 h. After the hydrothermal treatment was completed, centrifugal separation was performed at 9000 rpm to obtain a solid, which was washed with deionized water and ethanol for 5 min each time, 5 times in total. After the centrifugation was completed, the solid was dried in a vacuum drying box at 80 ℃ overnight. The obtained dried solid was calcined at 400 ℃ for 4 h at a temperature rising rate of 4 ℃ / min under flowing N2(30 mL / min), pressed into a tablet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor, reduced at 300 ℃ for 4 h under a normal pressure 10% H2 / N2 atmosphere at a temperature rising rate of 1 ℃ / min to prepare a 1% In-loaded molybdenum disulfide catalyst, which was recorded as 1In-MoS2.

[0037] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 ℃, the volume ratio of CO2 / CO / H2 was 1:1:5, and the reaction gas space velocity was 6000 mL h -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0038] Example 4

[0039] 13.90 g of (NH4)6Mo7O 24• 4H2O, 11.99 g CH4N2S, 0.48 g Cu(N03)2-3H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, and transferred to a Teflon-lined autoclave, which was hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 min each time, and dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h at a temperature rising rate of 4 °C / min under flowing N2(30 mL / min), and then pressed into a tablet, which was shaped by a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor and reduced at 300 °C for 4 h at a temperature rising rate of 1 °C / min under a 10% H2 / N2atmosphere to obtain a 1% Cu-loaded molybdenum disulfide catalyst, which was denoted as 1Cu-MoS2.

[0040] The catalyst was used for the evaluation of CO2 / CO co-hydrogenation reaction. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 °C, the volume ratio of CO2 / CO / H2was 1:1:5, and the reaction gas space velocity was 6000 mL h -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0041] Example 5

[0042] 13.90 g (NH4)6Mo7O 24 • 4H2O, 11.99 g CH4N2S, 0.48 g Cu(N03)2-3H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, and transferred to a Teflon-lined autoclave, which was hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 min each time, and dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h at a temperature rising rate of 4 °C / min under flowing N2(30 mL / min), and then pressed into a tablet, which was shaped by a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor and reduced at 300 °C for 4 h at a temperature rising rate of 1 °C / min under a 10% H2 / N2atmosphere to obtain a 1% Cu-loaded molybdenum disulfide catalyst, which was denoted as 1Cu-MoS2.

[0043] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 ℃, the volume ratio of CO2 / CO / H2 was 1:1:5, and the reaction gas space velocity was 6000 mL h-1. -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0044] Example 6

[0045] 13.90 g of (NH4)6Mo7O 24 4H2O, 11.99 g of CH4N2S, and 0.55 g of Y(NO3)3·6H2O were dissolved in 100 mL of deionized water, stirred at room temperature for 60 min, transferred to a polytetrafluoroethylene-lined autoclave, and hydrothermally treated at 200 ℃ for 20 h. After the hydrothermal treatment was completed, centrifugal separation was performed at 9000 rpm to obtain a solid, which was washed with deionized water and ethanol for 5 min each time, 5 times in total. After centrifugation, the solid was dried in a vacuum drying box at 80 ℃ overnight. The obtained dried solid was calcined at 400 ℃ for 4 h at a temperature rising rate of 4 ℃ / min under flowing N2(30 mL / min), pressed into a tablet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor, reduced at 300 ℃ for 4 h under a 10% H2 / N2 atmosphere at a temperature rising rate of 1 ℃ / min to prepare a 1% Y-loaded molybdenum disulfide catalyst, which was recorded as 1Y-MoS2.

[0046] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 ℃, the volume ratio of CO2 / CO / H2 was 1:1:5, and the reaction gas space velocity was 6000 mL h-1. -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0047] Example 7

[0048] 13.90 g of (NH4)6Mo7O 24• 4H2O, 11.99 g CH4N2S, 0.76 g Ga(N03)3-9H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, transferred to a polytetrafluoroethylene lined autoclave, and hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction was completed, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 times, 5 min each time. After centrifugation, the solid was dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h with a temperature increase of 4 °C / min under flowing N2(30 mL / min), pressed into a pellet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor and reduced at 300 °C for 4 h with a temperature increase of 1 °C / min under a 10% H2 / N2atmosphere at normal pressure to obtain a 1% Ga loaded molybdenum disulfide catalyst, denoted as 1Ga-MoS2.

[0049] The catalyst was used for CO2 / CO co-hydrogenation reaction evaluation. The specific operation was as follows: a fixed bed reactor was used, the catalyst loading was 0.5 g, the CO2 / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature was 220 °C, the volume ratio of CO2 / CO / H2was 1:1:5, and the reaction gas space velocity was 6000 mL h -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0050] The stability of the catalyst is shown in Figure 2 From Figure 2 it can be seen that the catalyst used has good stability, and can be stably operated for more than 300 h, and has good application prospect.

[0051] Example 8

[0052] 13.90 g (NH4)6Mo7O 24 • 4H2O, 11.99 g CH4N2S, 0.76 g Ga(N03)3-9H2O were dissolved in 100 mL deionized water, stirred at room temperature for 60 min, transferred to a polytetrafluoroethylene lined autoclave, and hydrothermally treated at 200 °C for 20 h. After the hydrothermal reaction was completed, the solid was obtained by centrifugation at 9000 rpm, washed with deionized water and ethanol for 5 times, 5 min each time. After centrifugation, the solid was dried in a vacuum drying oven at 80 °C overnight. The obtained dried solid was calcined at 400 °C for 4 h with a temperature increase of 4 °C / min under flowing N2(30 mL / min), pressed into a pellet, and shaped with a 30-60 mesh sieve to obtain a catalyst precursor. The catalyst precursor was loaded into a reactor and reduced at 300 °C for 4 h with a temperature increase of 1 °C / min under a 10% H2 / N2atmosphere at normal pressure to obtain a 1% Ga loaded molybdenum disulfide catalyst, denoted as 1Ga-MoS2.

[0053] The catalyst was used to evaluate the CO / CO co-hydrogenation reaction. The specific operation was as follows: a fixed-bed reactor was used, with a catalyst loading of 0.5 g. The CO / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature to 220℃, the CO / CO / H2 volume ratio to be 1:1:5, and the gas hourly space velocity (GHSV) to be 6000 mL / h. -1 g -1 The performance evaluation results of the catalyst are shown in Table 1.

[0054] Comparative Example 1

[0055] Weigh out 13.90g of (NH4)6Mo7O 24 11.99 g of CH4N2S and 4H2O were dissolved in 100 mL of deionized water and stirred at room temperature for 60 min. The mixture was then transferred to a polytetrafluoroethylene-lined autoclave and hydrothermally heated at 200 °C for 20 h. After hydrothermal treatment, the solid was obtained by centrifugation at 9000 rpm and washed five times each with deionized water and ethanol for 5 min each time. After centrifugation, the solid was dried overnight at 80 °C in a vacuum drying oven. The dried solid was calcined in flowing N2 (30 mL / min) at 4 °C / min to 400 °C for 4 h, pressed into tablets, and sieved through a 30–60 mesh sieve to obtain the catalyst precursor. The catalyst precursor was loaded into a reactor and reduced at atmospheric pressure under a 10% H2 / N2 atmosphere at 1 °C / min to 300 °C for 4 h to obtain the molybdenum disulfide catalyst, denoted as 1T-MoS2.

[0056] The catalyst was used to evaluate the CO / CO co-hydrogenation reaction. The specific operation was as follows: a fixed-bed reactor was used, with a catalyst loading of 0.5 g. The CO / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature to 220℃, the CO / CO / H2 volume ratio to be 1:1:5, and the gas hourly space velocity (GHSV) to be 6000 mL / h. -1 g -1 The performance evaluation results of the catalyst are shown in Table 1, and the XRD test results of the catalyst are shown in Table 2. Figure 1 .

[0057] Comparative Example 2

[0058] The performance of commercial molybdenum disulfide (2H-MoS2) from Shanghai Jizhi Biochemical Technology Co., Ltd. was compared with that of a self-made catalyst.

[0059] The catalyst was used to evaluate the CO / CO co-hydrogenation reaction. The specific operation was as follows: a fixed-bed reactor was used, with a catalyst loading of 0.5 g. The CO / CO co-hydrogenation reaction pressure was adjusted to 50 bar, the reaction temperature to 220℃, the CO / CO / H2 volume ratio to be 1:1:5, and the gas hourly space velocity (GHSV) to be 6000 mL / h. -1 g -1The performance evaluation results of the catalysts are shown in Table 1, and the XRD test results of the catalysts are shown in Figure 1 .

[0060] From Figure 1 From the results in Table 1, it can be seen that the catalyst molybdenum disulfide used in Comparative Example 1 is a 1T metal phase, which exhibits properties similar to a metal compared to a 2H semiconductor phase, and can provide more catalytically active sites.

[0061] From the following Table 1, it can be seen that the catalysts of the present application exhibit excellent performance for preparing methanol by CO2 / CO co-hydrogenation, and the methanol selectivity can reach more than 95%, and the co-conversion of CO2 and CO can be achieved.

[0062] Table 1

[0063]

[0064] In addition, the catalyst used in the present application is relatively simple to prepare, low in price, easy to scale up production, and has practical application value.

Claims

1. A process for the preparation of a bifunctional catalyst for methanol synthesis, characterized in that The method comprises the following steps: 1) a measured amount of a molybdenum source, a sulfur source and a metal salt are dissolved in deionized water, stirred, and the obtained solution is subjected to hydrothermal reaction at 160-200°C for 2-24 hours to obtain a product; 2) the product obtained in step 1) is centrifuged, washed, dried, and then calcined under a protective gas; the protective gas is helium, nitrogen or argon, the calcination temperature is 200-600°C, and the calcination time is 2-10 hours; 3) the calcined product obtained in step 2) is reduced to obtain a bifunctional catalyst for methanol synthesis; the reduction conditions are as follows: under an atmosphere of 1-5 bar, 10%-30% H2 / N2, the temperature is raised to 200-400°C at a rate of 1°C / min, and the reduction is performed for 0.5-4 hours; The bifunctional catalyst for methanol synthesis is composed of 1T-phase molybdenum disulfide and metal elements selected from at least one of zinc, gallium, indium, copper, palladium, cadmium and chromium; the mass fraction of the metal elements is 0.5%-5%, and the balance is 1T-phase molybdenum disulfide.

2. A process for the preparation of a bifunctional catalyst for methanol synthesis according to claim 1, characterized in that: In step 1), the molybdenum source is one or two or more of molybdenum dioxide, molybdenum trioxide, sodium molybdate, ammonium molybdate, potassium molybdate, ammonium tetrathiomolybdate, molybdenum blue, hexacarbonylmolybdenum, molybdenum oxalate and molybdenum ethoxide; and the sulfur source is one or two or more of thiourea, sulfur powder, sodium sulfide, potassium sulfide, hydrogen sulfide, dimethyl sulfoxide, thioacetamide and potassium thiocyanate.

3. A process for the preparation of a bifunctional catalyst for the synthesis of methanol according to claim 1, characterized in that: In step 1), the molar ratio of molybdenum atoms to sulfur atoms in the molybdenum source and the sulfur source is 1:1-1:

5.

4. A process for the preparation of a bifunctional catalyst for the synthesis of methanol according to claim 1, characterized in that: In step 1), the metal salt is at least one of a zinc salt, a gallium salt, an indium salt, a copper salt, a palladium salt, a cadmium salt and a chromium salt.

5. A process for the preparation of a bifunctional catalyst for the synthesis of methanol according to claim 1, characterized in that: In step 1), the mass ratio of deionized water to the molybdenum source is 3:1-20:1; the stirring temperature is 20-80°C, and the stirring time is 5-60 minutes.

6. Use of a catalyst produced by the production process according to any one of claims 1 to 5, characterized in that: The bifunctional catalyst for methanol synthesis is used for CO2 / CO co-hydrogenation reaction.

7. Use according to claim 6, characterized in that: The reaction temperature of the CO2 / CO co-hydrogenation is 180-300°C, the reaction pressure is 10-100 bar, the volume ratio of CO2 / CO / H2 is 1:1:2-1:1:9, and the reaction gas space velocity is 1000-50000 mL h -1 g -1 .

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