A supported Re / In2O3 catalyst and its preparation method and its application in the hydrogenation of carbon dioxide to methanol

Abstract

The present invention discloses a supported Re / In2O3 catalyst, a preparation method thereof, and an application thereof in the hydrogenation of carbon dioxide to methanol. The supported catalyst comprises an active component and a carrier In2O3; the active component comprises a Re element, and the Re species is dispersed at the atomic level on the In2O3 carrier. Compared with a single In2O3 catalyst, the Re / In2O3 catalyst of the present invention can simultaneously improve the carbon dioxide conversion rate and methanol selectivity. Under the conditions of 5MPa, 300°C, and 24000mL / (g·h), the carbon dioxide single-pass conversion rate can reach 11.5%, the methanol selectivity exceeds 80%, and the methanol space-time yield reaches 758mg / (g·h), and the stability of the catalyst is significantly improved.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and specifically relates to an application of a supported Re / In2O3 catalyst and a preparation method thereof in the hydrogenation of carbon dioxide to produce methanol. Background Art

[0002] Since the Industrial Revolution, with the continuous development of human society, uneven energy distribution and excessive CO2 emissions have led to greenhouse effects, ocean acidification and other climate and environmental changes that have become global issues. Against the backdrop of the global advocacy of CO2 emission reduction, carbon peak and carbon neutrality have also become important strategic goals for my country.

[0003] At present, the treatment of CO2 mainly adopts the CCUS (carbon capture, utilization and storage) route. Among them, the use of renewable energy (such as photovoltaic, solar thermal, nuclear energy, hydropower, wind power, etc.) to generate electricity, and then the "green hydrogen" produced by water electrolysis and CO2 catalytic reaction can produce CO, methane, hydrocarbons (low-carbon olefins, gasoline, diesel and aromatics), methanol, dimethyl ether and other products, while slowing down the increase in atmospheric carbon dioxide concentration, producing valuable chemicals and fuels, which is expected to alleviate ecological environment and energy problems at the same time, so it is regarded as a sustainable technical route.

[0004] Methanol can be used as a fuel additive, is an ideal clean fuel substitute, and is also an important chemical raw material. The use of CO2 hydrogenation to synthesize methanol is one of the most effective strategies to achieve the above route. At present, the most studied catalysts for CO2 hydrogenation to synthesize methanol are Cu-based catalysts derived from synthesis gas to methanol. The catalyst system studied is mainly Cu-ZnO, loaded on carriers such as Al2O3, ZrO2, SiO2, TiO2, and various metal elements are added to the catalyst as additives for modification. In recent years, there have been many studies to improve the performance of catalysts from aspects such as catalyst preparation, but in general, the side reactions (RWGS) on Cu-based catalysts are obvious, resulting in low methanol selectivity (generally not higher than 60%). In addition, the hydrogenation of carbon dioxide to methanol is an exothermic reaction, and the heat resistance of Cu-based catalysts is poor. At the same time, water is generated during the reaction, which will accelerate the sintering of Cu-based catalysts. In addition to Cu-based catalysts, researchers have predicted through theoretical calculations and experimental results that In2O3 is a carbon dioxide hydrogenation catalyst with high methanol selectivity (JYYe et al., ACS Catal. 2013, 3, 1296-1306; K. Sun et al., Journal of CO2 Utilization 2015, 12, 1–6; Oliver Martin et al., Angew. Chem. Int. Ed. 2016, 55, 6261–6265). However, indium oxide alone is not very active, and indium may be over-reduced to form In during the reaction, resulting in reduced selectivity and activity, so it is also insufficient in terms of stability. Summary of the invention

[0005] The present invention provides a Re / In2O3 catalyst for synthesizing methanol by hydrogenation of carbon dioxide, the catalyst comprising an active component Re and a carrier In2O3, the catalyst has good activity, and can well inhibit the reverse water gas reaction, thereby achieving a high methanol selectivity. In addition, compared with a single In2O3 as a catalyst, the supported Re / In2O3 catalyst exhibits better stability.

[0006] In one aspect, the present invention provides a supported catalyst, which includes an active component and a carrier In2O3; the active component includes the Re element.

[0007] Optionally, the active component, calculated as the mass fraction of the Re element, is 0.1% to 30% of the carrier In2O3, preferably 0.5% to 10%.

[0008] Preferably, the Re element is dispersed at the atomic level on the In2O3 carrier. Re is dispersed at the atomic level, that is, the Re species are dispersed and distributed mutually. Specifically, the valence state of the Re species may be a zero-valent metal state or a positive-valent oxidation state (coordinated and interacting with the carrier).

[0009] Another aspect of the present invention provides a method for preparing any of the above-mentioned supported catalysts, wherein the preparation method is selected from method A or method B;

[0010] The method A comprises the following steps:

[0011] Step a-1, obtaining a carrier In2O3;

[0012] Step a-2, immersing the carrier In2O3 in a solution containing the Re element, removing the solvent, and obtaining the supported catalyst.

[0013] Optionally, in step a-2, the solvent is removed and then calcined.

[0014] Optionally, the content of Re element in the solution containing Re element is 0.001 mol / L to 2 mol / L; and the solvent in the solution containing Re element is water.

[0015] Optionally, in step a-2, the ratio of the carrier In2O3 to the impregnation solution is 0.01 g / mL to 10 g / mL.

[0016] Optionally, the method for obtaining the carrier In2O3 is to adopt a precipitation method; specifically, a solution containing an In precursor is mixed with a solution containing and a precipitant to obtain a precipitate containing In(OH)3, and the precipitate is dried and calcined to obtain an In2O3 carrier.

[0017] Optionally, in the method for obtaining the carrier In2O3, the mixing temperature is 0℃~40℃, the lower limit of the mixing temperature is selected from 0℃ and 20℃, and the upper limit of the temperature is selected from 20℃ and 40℃; the drying temperature is 50℃~120℃, the lower limit of the drying temperature is selected from 50℃ and 70℃, and the upper limit of the drying temperature is selected from 70℃ and 120℃; the roasting temperature is 250℃~500℃, the lower limit of the roasting temperature is selected from 250℃ and 300℃, and the upper limit of the roasting temperature is selected from 300℃ and 500℃; the roasting time is 2~12h, the lower limit of the roasting time is selected from 2h and 3h; the upper limit of the roasting time is selected from 3h and 12h.

[0018] The immersion time is 0.5 to 12 hours, the lower limit of the immersion time is 0.5 to 1 hour, and the upper limit of the immersion time is 1 to 12 hours.

[0019] The method B comprises the following steps:

[0020] Step b-1, mixing a solution containing an In precursor with a solution containing a precipitant to obtain a precipitate containing In(OH)3;

[0021] Step b-2, immersing the precipitate containing In(OH) 3 in a solution containing Re element, removing the solvent, and calcining to obtain the supported catalyst.

[0022] Optionally, in step b-1, the content of In element in the solution containing the In precursor is: 0.1 mol / L to 10 mol / L;

[0023] Optionally, in the solution containing the precipitant, the content of the precipitant is 0.1 mol / L to 10 mol / L;

[0024] Optionally, the ratio of the solution containing the In precursor to the solution containing the precipitant is 10:1 to 1:10;

[0025] Optionally, the solvent in the solution containing the precipitant is selected from water or ethanol;

[0026] Optionally, the solvent of the solution containing the In precursor is selected from water or ethanol;

[0027] Optionally, in step b-2, the content of Re element in the solution containing Re element is 0.001 mol / L to 2 mol / L; the solvent in the solution containing Re element is water; and the ratio of In(OH)3 to the solution containing Re element is 0.01 g / mL to 10 g / mL.

[0028] Optionally, in step a-2 and step b-2, the immersion temperature is 90-130°C, the lower limit of the immersion temperature is selected from 90°C and 100°C, and the upper limit of the immersion temperature is selected from 100°C and 130°C; optionally, the solvent is removed by vacuum drying, the vacuum drying temperature is 70-130°C, the lower limit of the vacuum drying temperature is selected from 70°C and 100°C, and the upper limit of the vacuum drying temperature is selected from 100°C and 130°C; the immersion time is 0.5-12h, the lower limit of the immersion time is selected from 0.5 and 1h, and the upper limit of the immersion time is selected from 1 and 12h.

[0029] Optionally, the precursor containing In is selected from at least one of indium nitrate, indium halide, indium sulfate and indium acetate.

[0030] Optionally, the precipitant is selected from at least one of aqueous ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide and potassium hydroxide.

[0031] Optionally, the Re element comes from at least one of a high-valent acid salt, a halide, an oxide and a sulfide of the Re element.

[0032] Optionally, the Re element comes from chloride of the Re element.

[0033] Optionally, the Re element comes from at least one of ammonium perrhenate, potassium perrhenate, sodium perrhenate, rhenium halide, rhenium oxide and rhenium sulfide.

[0034] Optionally, in step b-2, the calcination is selected from static calcination or flowing atmosphere calcination, and the calcination atmosphere is selected from at least one of air, oxygen, nitrogen, and argon; the calcination temperature is 200-600°C, preferably 300-500°C, the lower limit of the calcination temperature is selected from 200°C, 300°C, and 500°C, and the upper limit of the calcination temperature is selected from 300°C, 500°C, and 600°C; the calcination time is 2-12h, preferably 3-6h, the lower limit of the calcination time is selected from 2h, 3h, and 6h, and the upper limit of the calcination time is selected from 3h, 6h, and 12h.

[0035] In another aspect, the present invention provides a method for preparing methanol by hydrogenating carbon dioxide, wherein the catalyst used in the method is selected from any of the above-mentioned supported catalysts or any of the above-mentioned supported catalysts obtained by the preparation methods.

[0036] Optionally, the reaction is carried out in a pressurized fixed bed continuous flow reactor.

[0037] Optionally, the reaction conditions are as follows: the molar ratio of n(H2):n(CO2) in the raw gas is 1 to 8, the lower limit of the molar ratio of n(H2):n(CO2) is selected from 1 and 3, and the upper limit of the molar ratio of n(H2):n(CO2) is selected from 3 and 8; the pressure is 1 to 10 MPa, the lower limit of the pressure is selected from 1 MPa, 2 MPa, and 5 MPa, and the upper limit of the pressure is selected from 2 MPa, 5 MPa, and 10 MPa; the reaction temperature is 200 to 400°C, the lower limit of the reaction temperature is selected from 200°C and 300°C, and the upper limit of the reaction temperature is selected from 300°C and 400°C; the space velocity is 3000 to 60000 mL / (g·h), the lower limit of the space velocity is selected from 3000 mL / (g·h), 12000 mL / (g·h), and 36000 mL / (g·h), and the upper limit of the space velocity is selected from 12000 mL / (g·h), 36000mL / (g·h), 60000mL / (g·h).

[0038] Preferably, the catalyst is activated in an activation atmosphere for 0.5 to 12 h before the reaction, and the lower limit of the activation treatment time is selected from 0.5 h and 1 h; the upper limit of the activation treatment time is selected from 1 h and 12 h; the temperature of the activation treatment is 180 to 400 ° C, and the lower limit of the activation treatment temperature is selected from 180 ° C and 280 ° C, and the upper limit of the activation treatment temperature is selected from 280 ° C and 400 ° C; the atmosphere is a non-oxidizing atmosphere, preferably a pure hydrogen atmosphere, a nitrogen atmosphere, an argon atmosphere, a nitrogen or argon diluted hydrogen atmosphere.

[0039] The present invention has the following advantages: Compared with a single In2O3 catalyst, the supported Re / In2O3 catalyst of the present invention can simultaneously improve the carbon dioxide conversion rate and methanol selectivity, and the catalyst stability is also significantly improved. Under the conditions of 5MPa, 300°C, and 24000mL / (g·h), the carbon dioxide single-pass conversion rate can reach 11.5%, the methanol selectivity exceeds 80%, and the methanol space-time yield reaches 758mg / (g·h). BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The XRD diagrams of the catalysts obtained in Examples 1, 2, 3, 4 of the present invention and Comparative Example 1 are shown.

[0041] Figure 2 This is a high-resolution STEM electron microscope result image of the catalyst obtained in Example 3 of the present invention.

[0042] Figure 3 Element distribution diagram of the catalyst obtained in Example 3 of the present invention, wherein Figure a is a high-resolution electron microscope image of the catalyst; Figure b is a distribution diagram of the In element; Figure c is a distribution diagram of the O element; and Figure d is a distribution diagram of the Re element.

[0043] Figure 4 This is a diagram showing the stability evaluation results of the catalysts obtained in Example 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below through examples of implementation. These examples are only used to illustrate the present invention, and are not intended to limit the scope of the present invention.

[0045] Method A:

[0046] Step a-1, preparing a certain concentration of In precursor solution and precipitant solution, pouring the precipitant solution into the In precursor solution to obtain In(OH)3 suspension; removing the solvent in the suspension, washing, drying and calcining the precipitate to obtain In2O3 carrier;

[0047] Step a-2, weigh a measured amount of Re precursor and dissolve it in deionized water, add the required amount of the above-mentioned In2O3 carrier, and the resulting suspension is stirred and evaporated to dryness at 90-130°C and vacuum dried at 70-130°C. After drying, it can be calcined or not to obtain a Re / In2O3 catalyst.

[0048] Method B:

[0049] Step b-1, preparing an In precursor solution and a precipitant solution of a certain concentration, and pouring the precipitant solution into the In precursor solution to obtain an In(OH)3 suspension;

[0050] Step b-2, remove the solvent in the suspension of step b-1 and wash to obtain In(OH)3 precipitate, weigh a measured amount of Re precursor, disperse it in water and mix it with the In(OH)3 precipitate, evaporate to dryness with stirring at 90-130°C and vacuum dry at 70-130°C, and further calcine to obtain Re / In2O3 catalyst.

[0051] In the following examples, the activity evaluation of the catalyst for the hydrogenation of carbon dioxide to methanol was carried out in a pressurized fixed bed continuous flow reactor-GC combined system. Before the reaction, no pretreatment activation can be performed or the catalyst can be activated with pure hydrogen, nitrogen, argon or hydrogen diluted with nitrogen and argon at 180-400°C for 0.5-12h. The conditions for the hydrogenation of carbon dioxide to methanol are: the molar ratio of n(H2):n(CO2) in the raw gas is 1-8, the pressure is 1-10MPa, the reaction temperature is 200-400°C, and the space velocity is 3000-60000mL / (g·h). The reaction tail gas is unloaded to normal pressure through a back pressure valve, and sampled through a gas chromatograph ten-way valve at 150°C, and analyzed online by a thermal conductivity detector (TCD) and a hydrogen flame detector (FID) of an Agilent GC-8890 gas chromatograph. The former chromatographic column is a 5A molecular sieve combined with Propark Q (Agilent), with a column length of 3m, using H2 as carrier gas, working at 85°C, and is used to separate and detect CO2, Ar, and CO; the latter chromatographic column is an HP-PLOT Q capillary column with a specification of 30m×0.32mm×20μm, using N2 as carrier gas, and is used to separate and detect low-carbon hydrocarbons and alcohols. The CO2 conversion rate and the C-based selectivity and time-space yield of carbon-containing products such as CO, alcohols, and hydrocarbons are calculated by the C-based normalization method.

[0052] The calculation formula for CO2 conversion rate is:

[0053]

[0054] The numerator is the total amount of each product in the gas after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3 and C4 products; the denominator is the total amount of each carbon-containing substance in the gas after the reaction, including unreacted CO2 and product CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3 and C4 substances.

[0055] The calculation formula for methanol selectivity is:

[0056]

[0057] The numerator is the amount of CH3OH product in the gas after the reaction; the denominator is the total amount of each product in the gas after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3 and C4 products.

[0058] The calculation formula for CO selectivity is:

[0059]

[0060] The numerator is the amount of CO product in the gas after the reaction; the denominator is the total amount of each product in the gas after the reaction, including CO, CH4, CH3OH, C2H4, C2H6, CH3OCH3, C3 and C4 products.

[0061] The calculation formula for methanol yield is:

[0062]

[0063] Where GHSV represents the mass space velocity of the reaction, the unit is mL / (g·h), V%(CO2) represents the volume fraction of the reactant CO2 in the reaction gas, and X CO2 Represents the conversion rate of CO2, S CH3OH Represents the selectivity of methanol.

[0064] Example 1

[0065] Weigh 30.083g of In(NO3)3 and prepare it into 500mL aqueous solution. Measure 90mL NH4OH (25%-28%) and mix it with 270mL ethanol. Add it to the above indium nitrate solution and stir evenly. Then transfer it to an 80℃ water bath and continue stirring and aging for 30min. Cool, centrifuge, wash 3 times with deionized water, dry the solid obtained by centrifugation in a vacuum drying oven at 70℃, and roast it in air at 300℃ for 3h to obtain In2O3 carrier.

[0066] Weigh 0.072g NH4ReO4 and dissolve it in 10mL deionized water, add 10.0g of the synthesized In2O3, stir and soak at 100℃ until evaporated, then transfer to a vacuum drying oven and dry at 100℃ to obtain a supported 0.5% Re / In2O3 catalyst, press into tablets, crush, and screen 40-80 mesh particles, mark it as 1#, and use it for activity evaluation.

[0067] 0.1g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 6mm, and reduced at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 2-5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0068] The 0.5% Re / In2O3 catalyst after the reaction was carefully ground and the obtained powder was used for powder XRD test. The XRD pattern of the sample was as follows: Figure 1 .from Figure 1 It can be seen that the 0.5% Re / In2O3 catalyst only shows the diffraction peak of In2O3, and no diffraction peak of Re species is observed, which indicates that the Re species is in a highly dispersed state.

[0069] Example 2

[0070] The preparation of In2O3 carrier is the same as that in Example 1.

[0071] Weigh 0.216g NH4ReO4 and dissolve it in 10mL deionized water, add 10.0g of the synthesized In2O3, stir and soak at 100℃ until evaporated, then transfer to a vacuum drying oven and dry at 100℃ to obtain a catalyst marked as supported 1.5% Re / In2O3, press into tablets, crush, and screen 40-80 mesh particles, marked as 2#, for activity evaluation.

[0072] 0.1g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 6mm, and reduced at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 2-5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0073] The 1.5% Re / In2O3 catalyst after the reaction was carefully ground and the obtained powder was used for powder XRD test. The XRD pattern of the sample was as follows: Figure 1 .from Figure 1 It can be seen that the 1.5% Re / In2O3 catalyst only has the diffraction peak of In2O3, and no diffraction peak of Re species is observed, which indicates that the Re species is in a highly dispersed state.

[0074] Example 3

[0075] The preparation of In2O3 carrier is the same as that in Example 1.

[0076] Weigh 0.432g NH4ReO4 and dissolve it in 10mL deionized water, add 10.0g of the synthesized In2O3, stir and soak at 100℃ until evaporated, then transfer to a vacuum drying oven and dry at 100℃ to obtain a supported 3% Re / In2O3 catalyst, press into tablets, crush, and screen 40-80 mesh particles, mark it as 3#, and use it for activity and stability evaluation.

[0077] Weigh 0.1g of the selected catalyst and load it into a reaction tube with an inner diameter of 6mm. Reduce it at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min. Then, introduce the raw gas n(H2):n(CO2)=3. The reaction is carried out under the conditions of 2~5MPa, 260~300℃, GHSV=12000~36000 mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0078] Activity test without reduction: Weigh 0.1g of the screened catalyst and load it into a reaction tube with an inner diameter of 6 mm, introduce the raw gas n(H2):n(CO2)=3, and react at 5MPa, 300℃, GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0079] The 3% Re / In2O3 catalyst after the reaction was carefully ground, and the obtained powder was used for powder XRD test and high-resolution electron microscopy structure characterization.

[0080] The XRD pattern of the sample is shown in Figure 1 .from Figure 1 It can be seen that the 3% Re / In2O3 catalyst only has the diffraction peak of In2O3, and no diffraction peak of Re species is observed, which indicates that the Re species is in a highly dispersed state.

[0081] The high-resolution STEM results of this sample are shown in Figure 2 .from Figure 2 Highly dispersed bright spots can be seen, indicating that the Re species are dispersed at the atomic level on the In2O3 support.

[0082] The element distribution diagram of the sample is shown in Figure 3 , it can be seen that the Re element is evenly dispersed on the entire carrier, which also proves the highly dispersed state of Re.

[0083] Weigh 0.1g of the screened catalyst and load it into a reaction tube with an inner diameter of 6mm. Reduce it at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min. Then introduce the raw gas n(H2):n(CO2)=3. The reaction is carried out continuously for 50h at 5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst stability evaluation results are shown in Figure 4 .

[0084] Figure 4 The results show that after 50 hours of reaction, the methanol space-time yield of 3% Re / In2O3 catalyst dropped from 728 mg / (g·h) to 681 mg / (g·h) and remained stable, with only a decrease of 6%.

[0085] Example 4

[0086] The preparation of In2O3 carrier is the same as that in Example 1.

[0087] Weigh 0.720g NH4ReO4 and dissolve it in 10mL deionized water, add 10.0g of the synthesized In2O3, stir and soak at 100℃ until evaporated, then transfer to a vacuum drying oven and dry at 100℃ to obtain a catalyst marked as supported 5%Re / In2O3, press into tablets, crush, and screen 40-80 mesh particles, marked as 4#, for activity evaluation.

[0088] 0.1g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 6mm, and reduced at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 2-5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0089] The 5% Re / In2O3 catalyst after the reaction was carefully ground and the obtained powder was used for powder XRD test. The XRD pattern of the sample was as follows: Figure 1 .from Figure 1 It can be seen that the 5% Re / In2O3 catalyst only has the diffraction peak of In2O3, and no diffraction peak of Re species is observed, which indicates that the Re species is in a highly dispersed state.

[0090] Example 5

[0091] The preparation of In2O3 carrier is the same as that in Example 1.

[0092] Weigh 1.440g NH4ReO4 and dissolve it in 10mL deionized water, add 10.0g of the synthesized In2O3 mentioned above, stir and soak at 100℃ until evaporated, then transfer to a vacuum drying oven and dry at 100℃ to obtain a catalyst marked as supported 10% Re / In2O3, marked as 5#, tableted, crushed, and screened to 40-80 mesh particles, marked as 5#, for activity evaluation.

[0093] 0.1g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 6mm, and reduced at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 2-5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0094] Example 6

[0095] Weigh 30.083g In(NO3)3 and prepare it into 500mL aqueous solution. Measure 90mL NH4OH (25%-28%) and mix it with 270mL ethanol. Add it to the above indium nitrate solution and stir evenly. Then transfer it to an 80℃ water bath and continue stirring and aging for 30min. Cool, centrifuge, and wash it 3 times with deionized water to obtain the precipitate In(OH)3. Weigh 0.432g NH4ReO4 and dissolve it in 10mL deionized water. Add it to the above In(OH)3 precipitate and stir and soak it at 100℃ until it evaporates to dryness. Then transfer it to a vacuum drying oven at 100℃ for drying. Then, roast it in air at 300℃ for 3h to obtain a catalyst marked as supported 3% Re / In2O3(OH). Press it into tablets, crush it, and screen the particles of 40-80 mesh. Mark it as 6# for activity evaluation.

[0096] 0.1 g of the selected catalyst was weighed and loaded into a reaction tube with an inner diameter of 6 mm, and reduced at 280°C for 1 h in pure H2 at normal pressure with a flow rate of 20 mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 5 MPa, 300°C, and GHSV=24000 mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0097] Comparative Example 1

[0098] Weigh 30.083g In(NO3)3 and prepare it into 500mL aqueous solution. Measure 90mL NH4OH (25%-28%) and mix it with 270mL ethanol. Add it to the above indium nitrate solution and stir evenly. Then transfer it to a 80℃ water bath and continue stirring and aging for 30min. Cool, centrifuge, wash with deionized water 3 times, dry the solid obtained by centrifugation in a vacuum drying oven at 70℃, and calcine it in air at 300℃ for 3h to obtain the catalyst In2O3. Press it into tablets, crush it, and screen the particles of 40-80 mesh, mark it as 7#, and use it for activity and stability evaluation.

[0099] 0.1g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 6mm, and reduced at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min, and then the raw gas n(H2):n(CO2)=3 was introduced, and the reaction was carried out under the conditions of 2-5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst activity evaluation results are shown in Table 1.

[0100] The In2O3 catalyst after the reaction was carefully ground and the obtained powder was used for powder XRD test. The XRD pattern of the sample was as follows: Figure 1 .from Figure 1 It can be seen that the diffraction peak of the In2O3 catalyst corresponds to the standard card PDF#71-2194, proving the crystal structure of the In2O3 catalyst.

[0101] Weigh 0.1g of the screened catalyst and load it into a reaction tube with an inner diameter of 6mm. Reduce it at 280℃ for 1h in pure H2 at normal pressure with a flow rate of 20mL / min. Then introduce the raw gas n(H2):n(CO2)=3. The reaction is carried out continuously for 50h at 5MPa, 300℃, and GHSV=24000mL / (g·h). The catalyst stability evaluation results are shown in Figure 4 .

[0102] Figure 4 The results in Figure 2 show that after 50 hours of reaction, the methanol space-time yield of the In2O3 catalyst decreased from 403 mg / (g·h) to 297 mg / (g·h), a decrease of 26%. In contrast, the methanol space-time yield of the 3% Re / In2O3 catalyst in Example 3 only decreased by 6% after 50 hours, indicating that compared with In2O3 alone, the Re / In2O3 catalyst has higher stability in the carbon dioxide hydrogenation to methanol reaction.

[0103] Table 1 Evaluation results of catalyst activity of examples and comparative examples

[0104]

[0105]

Claims

1. A supported catalyst, characterized in that: The supported catalyst consists of an active component and a carrier In2O3; The active component is Re element; The active component is 0.5% to 10% of the carrier In2O3 in terms of the mass of the Re element; The Re element is dispersed at the atomic level on the In2O3 carrier.

2. A method for preparing a supported catalyst according to claim 1, characterized in that: The preparation method is selected from method A or method B; The method A comprises the following steps: Step a-1, mixing a solution containing an In precursor with a solution containing a precipitant to obtain a precipitate containing In(OH)3, and drying and calcining the precipitate to obtain an In2O3 carrier; Step a-2, immersing the carrier In2O3 in a solution containing the Re element, removing the solvent, and calcining to obtain the supported catalyst; The method B comprises the following steps: Step b-1, mixing a solution containing an In precursor with a solution containing a precipitant to obtain a precipitate containing In(OH)3; Step b-2, immersing In(OH)3 in a solution containing Re element, removing the solvent, and calcining to obtain the supported catalyst; The In precursor is selected from at least one of indium nitrate, indium halide, indium sulfate and indium acetate; The precipitant is selected from at least one of ammonia water, sodium hydroxide and potassium hydroxide.

3. The preparation method according to claim 2, characterized in that: In step a-2, the content of Re element in the solution containing Re element is 0.001 mol / L~2 mol / L; and the solvent in the solution containing Re element is water.

4. The preparation method according to claim 2, characterized in that: In step a-2, the ratio of the carrier In2O3 to the impregnation solution is 0.01 g / mL to 10 g / mL.

5. The preparation method according to claim 2, characterized in that: The content of In element in the solution containing the In precursor is 0.1 mol / L~10 mol / L.

6. The preparation method according to claim 2, characterized in that: In the solution containing the precipitant, the content of the precipitant is 0.1 mol / L~10 mol / L.

7. The preparation method according to claim 2, characterized in that: The solvent in the solution containing the precipitant is selected from water or ethanol.

8. The preparation method according to claim 2, characterized in that: The solvent of the solution containing the In precursor is selected from water or ethanol.

9. The preparation method according to claim 2, characterized in that: In step b-2, the content of Re element in the solution containing Re element is 0.001 mol / L~2 mol / L; the solvent in the solution containing Re element is water; and the ratio of In(OH)3 to the solution containing Re element is 0.01 g / mL~10 g / mL.

10. The preparation method according to claim 2, characterized in that: In the steps a-2 and b-2, the immersion temperature is 90-130°C.

11. The preparation method according to claim 2, characterized in that: In the steps a-2 and b-2, the solvent is removed by vacuum drying, and the vacuum drying temperature is 70-130°C.

12. The preparation method according to claim 2, characterized in that: The Re element comes from at least one of a high-valent acid salt, a halide, an oxide, and a sulfide of the Re element.

13. The preparation method according to claim 2, characterized in that: The Re element is derived from chloride of the Re element.

14. The preparation method according to claim 2, characterized in that: The Re element is derived from at least one of ammonium perrhenate, potassium perrhenate, sodium perrhenate, rhenium halide, rhenium oxide and rhenium sulfide.

15. The preparation method according to claim 2, characterized in that: The calcination in step b-2 is selected from static calcination or flowing atmosphere calcination, and the calcination atmosphere is selected from at least one of air, oxygen, nitrogen, and argon; the calcination temperature is 200-600° C.; and the calcination time is 2-12 hours.

16. The preparation method according to claim 2, characterized in that: The calcination temperature is 300-500°C.

17. The preparation method according to claim 2, characterized in that: The calcination time is 3 to 6 hours.

18. A method for preparing methanol by hydrogenating carbon dioxide, characterized in that: The raw gas containing CO2 and H2 is contacted with a catalyst to react and produce methanol; the catalyst used in the method is selected from the supported catalyst described in claim 1 or any one of the supported catalysts obtained by the preparation method described in any one of claims 2 to 17.

19. The method for preparing methanol by hydrogenation of carbon dioxide according to claim 18, characterized in that: The reaction is carried out in a pressurized fixed-bed continuous flow reactor; The reaction conditions are as follows: the molar ratio of n(H2):n(CO2) in the raw gas is 1-8, the pressure is 1-10 MPa, the reaction temperature is 200-400°C, and the space velocity is 3000-60000 mL / (g·h).

20. The method for preparing methanol by hydrogenation of carbon dioxide according to claim 18, characterized in that: The catalyst is activated in an activation atmosphere for 0.5 to 12 hours before the reaction, and the treatment temperature is 180 to 400° C.; the activation atmosphere is a non-oxidizing atmosphere.

21. The method for preparing methanol by hydrogenation of carbon dioxide according to claim 20, characterized in that: The activation atmosphere is a pure hydrogen atmosphere, a nitrogen atmosphere, an argon atmosphere, or a hydrogen atmosphere diluted with nitrogen or argon.

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