A novel high-performance molybdenum-based hydrogenation catalyst and a preparation method and application thereof

Abstract

The application belongs to the technical field of carbon dioxide capture, utilization and storage, and relates to a novel high-performance molybdenum-based hydrogenation catalyst as well as a preparation method and application thereof. The catalyst comprises active metal molybdenum, auxiliary metal and a carrier; the mass fraction of the active metal molybdenum is 10-30%; and the mass fraction of the auxiliary metal is 0-1%wt. The application can synergistically promote the catalytic performance of the active metal by adding the auxiliary metal, effectively improve the sulfur vacancies on the surface of the catalyst, and make the catalyst maintain high activity in the reaction. By sulfidation modification, specific sulfur vacancies can be constructed on the active surface of the catalyst, the electronic structure of the active metal can be precisely controlled, the distribution of acid-base sites on the surface of the catalyst and the adsorption characteristics of the reaction interface can be effectively controlled, the overall adsorption hydrogen capacity of the catalyst and the performance of adsorption, activation, conversion of carbamate and formamide and the selectivity of hydrogenation denitrification to synthesize methanol can be optimized, and the catalytic reaction can be efficiently carried out under mild conditions.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide capture, utilization, and storage technology, and relates to a novel high-performance molybdenum-based hydrogenation catalyst, its preparation method, and its application. It can be applied in carbon dioxide fixation with ethanolamine and in-situ hydrogenation to methanol, and specifically in the capture of CO2 from industrial exhaust gas and air, in-situ methanol production, and hydrogen energy storage. Background Technology

[0002] With the rapid advancement of global industrialization, the large-scale consumption of fossil fuels has led to a continuous rise in atmospheric carbon dioxide concentration, triggering a series of environmental problems such as the greenhouse effect, global warming, and ecological imbalance. Against the backdrop of a global consensus on carbon emission reduction and the continued depletion and uneven geographical distribution of fossil resources, methanol synthesis technology has become a core large-scale technology for building a sustainable carbon cycle and achieving efficient energy storage and recycling. Compared to the mature pure carbon dioxide-to-methanol route, directly synthesizing methanol from stationary carbon dioxide captured in the decarbonization process eliminates the need for carbon dioxide desorption, compression, and transportation, making it a highly promising low-cost technology.

[0003] Among existing carbon dioxide capture and reduction technologies, the monoethanolamine (MEA) absorption system possesses excellent absorption kinetics and high absorption capacity, thus holding a dominant position in the carbon dioxide emission reduction industry. Prior to the energy-intensive carbon dioxide desorption process, carbon dioxide is fixed in the form of carbamates. However, this route faces the challenge of lagging development of key catalysts: fixed carbon dioxide requires an amide intermediate to undergo hydrogenation, existing catalysts have low activity, and there are also problems such as N-methylation side reactions.

[0004] To address these needs, researchers have developed homogeneous and heterogeneous catalysts over the past decade for the hydrogenation of the key intermediate formamide. However, homogeneous catalysts suffer from low turnover number (TON) and turnover frequency (TOF) (TON < 10000, TOF < 100 h⁻¹). -1Existing heterogeneous catalysts suffer from drawbacks such as insufficient stability; moreover, they are more prone to undesirable N-methylation side reactions (carbon-oxygen bond breaking), making it difficult to achieve the target pathway of carbon-nitrogen bond breaking to generate methanol. To date, high-performance, low-cost catalysts remain scarce for the direct hydrogenation of monoethanolamine (MEA) stationary CO2 system. Chinese patent CN119425684A discloses a novel high-performance atomically dispersed hydrogenation catalytic material synthesis method and application. Based on the single-atom catalysis concept, it developed a heterogeneous catalytic material (0.025wt% Pt / TiO2-800℃) with atomically dispersed active metal components, coupled with carbon capture and hydrogenation to synthesize green methanol using formamide intermediates. However, regarding the catalytic material itself, the preparation method proposed in this patent requires the precious metal Pt as the active metal, resulting in excessively high costs that fail to meet the demands of industrial catalytic materials, thus limiting the research and production of high-performance catalytic materials.

[0005] Molybdenum sulfide (MoS2) is widely used in metallurgy, electronics, chemical industry, and construction, and it also shows potential in hydrogen production via water electrolysis and methanol production via gas-phase carbon dioxide hydrogenation. Sulfur vacancies are considered one of the active sites in molybdenum sulfide catalysts. Currently, the main methods to increase sulfur vacancy concentration include plasma bombardment, hydrogen thermal reduction, and electrochemical etching; however, these methods suffer from drawbacks such as demanding processing conditions, high energy consumption, and low vacancy concentrations in the prepared catalysts. Chinese patent CN122209424A discloses a molybdenum sulfide-metal oxide catalyst and its preparation method and application. A simple and easy physical mixing method was used to prepare a molybdenum sulfide-metal oxide catalyst with a synergistic effect, which was applied to the gas-phase CO2 hydrogenation to methanol reaction. The synergistic effect between molybdenum sulfide and the metal oxide promoted the formation of methanol on the molybdenum sulfide. However, no molybdenum-based catalysts applicable to ethanolamine carbon dioxide capture or in-situ hydrogenation of fixed carbon dioxide to methanol have been reported.

[0006] Although various heterogeneous catalysts have been reported, they are still limited to high-cost or gas-phase reaction systems and cannot meet the requirements of actual production. Therefore, it is still necessary to study and develop new high-performance molybdenum-based hydrogenation catalysts and their preparation methods and applications. Summary of the Invention

[0007] In view of the high cost and low cost-effectiveness of existing catalysts for capturing carbon dioxide and in-situ hydrogenating fixed carbon dioxide to methanol using ethanolamine, this invention provides a novel high-performance molybdenum-based hydrogenation catalyst, its preparation method, and its application. This catalyst is low in cost, has a high methanol yield, excellent low-temperature activity and selectivity, a simple preparation method, and can meet the requirements for large-scale industrial production.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] On the one hand, the present invention provides a novel high-performance molybdenum-based hydrogenation catalyst, comprising: active metal molybdenum, auxiliary metal, and support.

[0010] Furthermore, the active metal molybdenum has a mass fraction of 10-30%.

[0011] Furthermore, the metal mass fraction of the additive is 0~1%wt.

[0012] Furthermore, the additive metal is one or a mixture of two of the following: platinum, cobalt, iron, tungsten, nickel, and copper.

[0013] Furthermore, the carrier material is one or a mixture of two of the following: alumina, titanium oxide, cerium oxide, activated carbon, zinc oxide, lanthanum oxide, silicon oxide, and zirconium oxide.

[0014] This invention also provides a novel method for preparing a high-performance molybdenum-based hydrogenation catalyst, comprising the following steps: Step 1: Prepare a deionized molybdate aqueous solution. Add the carrier material to the deionized molybdate aqueous solution, stir, sonicate, and let stand at room temperature to obtain a mixture. Step 2: The mixture is dried in an oven, then removed and calcined to obtain catalyst precursor 1; Step 3: Prepare a sulfurizing agent organic solution, add catalyst precursor 1, fill the reaction vessel with hydrogen gas, carry out the sulfurization reaction at a certain temperature, take out the sample after the reaction is completed, filter, wash and dry to obtain a new high-performance molybdenum-based hydrogenation catalyst with 0%wt of auxiliary metal. Step 4: Test the water absorption performance of the catalyst in Step 3, prepare a deionized aqueous solution of the auxiliary metal compound, add the catalyst from Step 3 to the auxiliary metal compound solution, stir and sonicate, and let stand at room temperature to obtain catalyst precursor 2. Step 5: The catalyst precursor 2 is dried in an oven, then taken out and calcined under nitrogen protection to obtain a novel high-performance molybdenum-based hydrogenation catalyst.

[0015] Further, in step 1, the molybdate is one of ammonium heptamolybdate, sodium molybdate, potassium molybdate, ammonium orthomolybdate, sodium dimolybdate, or potassium dimolybdate.

[0016] Furthermore, in step 1, the concentration of the molybdate deionized aqueous solution is calculated based on the water absorption performance of the support, and the final mass fraction of active molybdenum in the novel high-performance molybdenum-based hydrogenation catalyst is 10-30%.

[0017] Furthermore, in step 1, the volume of the molybdate deionized aqueous solution is equal to the theoretical water absorption volume of the added carrier material.

[0018] Furthermore, in step 1, the stirring time is 2 to 8 hours.

[0019] Furthermore, in step 1, the stirring speed is 200~800 r / min.

[0020] Furthermore, in step 1, the ultrasound time is 12~24 hours.

[0021] Furthermore, in step 1, the ultrasonic frequency is 50~200kHz.

[0022] Furthermore, in step 1, the settling time is 8~24h.

[0023] Furthermore, in step 2, the oven temperature is 60~100℃; the drying time is 8~24h.

[0024] Furthermore, in step 2, the calcination heating rate is 2~10℃ / min; the calcination temperature is 400~700℃; and the calcination time is 2~8h.

[0025] Furthermore, in step 3, the vulcanizing agent is one of carbon disulfide, thiophene, or dibenzothiophene.

[0026] Furthermore, in step 3, the organic solvent is one of the following: n-hexane, n-heptane, n-octane, n-nonane, n-decane, isohexane, cyclopentane, and cyclohexane.

[0027] Furthermore, in step 3, the concentration of the vulcanizing agent organic solution is 5~20%wt.

[0028] Furthermore, in step 3, the volume ratio (mL) of the sulfiding agent solution to the mass ratio (g) of catalyst precursor 1 is 50~200:1.

[0029] Furthermore, in step 3, the pressure inside the reactor is 2~6 MPa.

[0030] Furthermore, in step 3, the temperature of the vulcanization reaction is 200~400℃; the time of the vulcanization reaction is 8~24h.

[0031] Furthermore, in step 3, the washing solvent is one of methanol, ethanol, ethyl acetate, petroleum ether, dichloromethane, and n-pentane.

[0032] Furthermore, in step 3, the drying temperature is 40~100℃; the drying time is 4~10h.

[0033] Furthermore, in step 4, the additive metal is one or a mixture of two of the following: platinum, cobalt, iron, tungsten, nickel, and copper.

[0034] Furthermore, in step 4, the auxiliary metal compound is one of the chlorate, acetylacetonate, sulfate, or nitrate of the auxiliary metal.

[0035] Furthermore, in step 4, the concentration of the deionized aqueous solution of the auxiliary metal compound is calculated based on the water absorption performance of the catalyst in step 3. Finally, the mass fraction of the auxiliary metal in the novel high-performance molybdenum-based hydrogenation catalyst is 0~0.1%; when the auxiliary metal is 0%wt, steps 4 and 5 are not required.

[0036] Furthermore, in step 4, the volume of the auxiliary metal compound solution is equal to the theoretical water absorption volume of the catalyst added in step 3.

[0037] Furthermore, in step 4, the stirring time is 2 to 8 hours.

[0038] Furthermore, in step 4, the stirring speed is 200~800 r / min.

[0039] Furthermore, in step 4, the ultrasound time is 12~24 hours.

[0040] Furthermore, in step 4, the ultrasonic frequency is 50~200kHz.

[0041] Furthermore, in step 4, the settling time is 8~24h.

[0042] Furthermore, in step 5, the oven temperature is 60~100℃.

[0043] Furthermore, in step 5, the drying time is 8~24 hours.

[0044] Furthermore, in step 5, the calcination heating rate is 2~10℃ / min; the calcination temperature is 400~700℃; and the calcination time is 2~8h.

[0045] On the other hand, the present invention provides the application of the novel high-performance molybdenum-based hydrogenation catalyst in the carbon dioxide capture and in-situ hydrogenation of ethanolamine to methanol reaction, the specific operation of which is as follows: Step 1: Preparation of CO2 carbon-rich solution by weighing method: Add the capturing solvent to the reaction vessel equipped with bubbling, stirring and weighing device, introduce CO2 gas flow at room temperature, bubble and stir, weigh the solution to prepare CO2 carbon-rich solution. Step 2: Catalyst activation: A novel high-performance molybdenum-based hydrogenation catalyst is added to the reactor, replaced with hydrogen, and activated at a certain temperature by purging with hydrogen. Step 3: Add the activated catalyst and carbon-rich liquid to the reactor, replace with hydrogen, purge with hydrogen and maintain pressure, and heat the reactor to the reaction temperature to carry out the reaction.

[0046] Furthermore, in step 1, the capturing solvent is one of ethanolamine, diethanolamine, or methyldiethanolamine.

[0047] Furthermore, in step 2, the activation pressure is 3~6 MPa; the activation temperature is 100~200℃; and the activation time is 6~30 h.

[0048] Furthermore, in step 3, the ratio of the activated catalyst mass (g) to the carbon-rich liquid volume (mL) is 1:10~50.

[0049] Furthermore, in step 3, the reaction pressure is 4~8 MPa; the reaction temperature is 100~200℃; and the reaction time is 6~30 h.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0051] 1. The novel high-performance molybdenum-based hydrogenation catalyst preparation method provided by this invention has the advantages of simple process, universality, easy scale-up, excellent performance, low price, significantly reduced precious metal usage, and significantly reduced industrial production costs.

[0052] 2. This invention, through the addition of auxiliary metals, synergistically promotes the catalytic performance of active metals, while effectively improving the sulfur vacancies on the catalyst surface, so that the catalyst maintains high activity during the reaction.

[0053] 3. Through sulfidation modification, this invention can construct specific sulfur vacancies on the active surface of the catalyst, precisely control the electronic structure of the active metal, and effectively control the distribution of acid and base sites on the catalyst surface and the adsorption characteristics of the reaction interface. It can also optimize the overall hydrogen adsorption capacity of the catalyst and the performance of adsorption, activation, and conversion of carbamates and formamide, as well as the selectivity of hydrogenation denitrification to methanol synthesis, so that the catalytic reaction can be carried out efficiently under mild conditions. Attached Figure Description

[0054] Figure 1 EPR characterization diagrams of the L1, L2, I3 and I4 catalysts.

[0055] Figure 2 CO2-TPD spectra of catalysts L1, L2, L3 and L4.

[0056] Figure 3 TEM images of the catalyst (a, L1, b, L2, c, L3, d, L4). Detailed Implementation

[0057] The claims of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention shall still be within the scope of protection of the claims of the present invention.

[0058] A novel high-performance molybdenum-based hydrogenation catalyst comprises: active metal molybdenum, auxiliary metal, and support.

[0059] Furthermore, the active metal molybdenum has a mass fraction of 10-30%, preferably 15-25%.

[0060] Furthermore, the metal mass fraction of the additive is 0~1%wt, preferably 0~0.05%.

[0061] Furthermore, the additive metal is one or a mixture of two of the following: platinum, cobalt, iron, tungsten, nickel, and copper, preferably nickel and / or platinum.

[0062] Furthermore, the carrier material is one or a mixture of two of the following: alumina, titanium oxide, cerium oxide, activated carbon, zinc oxide, lanthanum oxide, silicon oxide, and zirconium oxide, preferably alumina and / or activated carbon.

[0063] A novel method for preparing a high-performance molybdenum-based hydrogenation catalyst includes the following steps: Step 1: Prepare a deionized molybdate aqueous solution. Add the carrier material to the deionized molybdate aqueous solution, stir, sonicate, and let stand at room temperature to obtain a mixture. Step 2: The mixture is dried in an oven, then removed and calcined to obtain catalyst precursor 1; Step 3: Prepare a sulfurizing agent organic solution, add catalyst precursor 1, fill the reaction vessel with hydrogen gas, carry out the sulfurization reaction at a certain temperature, take out the sample after the reaction is completed, filter, wash and dry to obtain a new high-performance molybdenum-based hydrogenation catalyst with 0%wt of auxiliary metal. Step 4: Test the water absorption performance of the catalyst in Step 3, prepare a deionized aqueous solution of the auxiliary metal compound, add the catalyst from Step 3 to the auxiliary metal compound solution, stir and sonicate, and let stand at room temperature to obtain catalyst precursor 2. Step 5: The catalyst precursor 2 is dried in an oven, then taken out and calcined under nitrogen protection to obtain a novel high-performance molybdenum-based hydrogenation catalyst.

[0064] Further, in step 1, the molybdate is one of ammonium heptamolybdate, sodium molybdate, potassium molybdate, ammonium orthomolybdate, sodium dimolybdate, or potassium dimolybdate, preferably ammonium heptamolybdate or sodium molybdate.

[0065] Furthermore, in step 1, the concentration of the molybdate deionized aqueous solution is calculated based on the water absorption performance of the support, and the final mass fraction of active molybdenum in the novel high-performance molybdenum-based hydrogenation catalyst is 10-30%, preferably 15-25%.

[0066] Furthermore, in step 1, the volume of the molybdate deionized aqueous solution is equal to the theoretical water absorption volume of the added carrier material.

[0067] Furthermore, in step 1, the stirring time is 2~8 hours, preferably 4~6 hours.

[0068] Furthermore, in step 1, the stirring speed is 200~800 r / min, preferably 400~600 r / min.

[0069] Furthermore, in step 1, the ultrasound time is 12~24h, preferably 16~20h.

[0070] Furthermore, in step 1, the ultrasonic frequency is 50~200kHz, preferably 70~180kHz.

[0071] Furthermore, in step 1, the settling time is 8~24h, preferably 8~16h.

[0072] Furthermore, in step 2, the oven temperature is 60~100℃, preferably 60~80℃; the drying time is 8~24h, preferably 8~12h.

[0073] Furthermore, in step 2, the calcination heating rate is 2~10℃ / min, preferably 5~10℃ / min; the calcination temperature is 400~700℃, preferably 500~600℃; and the calcination time is 2~8h, preferably 4~6h.

[0074] Furthermore, in step 3, the vulcanizing agent is one of carbon disulfide, thiophene, and dibenzothiophene, preferably carbon disulfide.

[0075] Further, in step 3, the organic solvent is one of n-hexane, n-heptane, n-octane, n-nonane, n-decane, isohexane, cyclopentane, and cyclohexane, preferably n-nonane or n-decane.

[0076] Furthermore, in step 3, the concentration of the vulcanizing agent organic solution is 5~20%wt, preferably 10~15%wt.

[0077] Furthermore, in step 3, the volume ratio (mL) of the sulfiding agent solution to the mass ratio (g) of the catalyst precursor 1 is 50~200:1, preferably 50~100:1.

[0078] Furthermore, in step 3, the pressure inside the reactor is 2~6 MPa, preferably 3~5 MPa.

[0079] Furthermore, in step 3, the temperature of the vulcanization reaction is 200~400℃, preferably 250~350℃; the time of the vulcanization reaction is 8~24h, preferably 8~16h.

[0080] Furthermore, in step 3, the washing solvent is one of methanol, ethanol, ethyl acetate, petroleum ether, dichloromethane, and n-pentane, preferably ethanol or dichloromethane.

[0081] Furthermore, in step 3, the drying temperature is 40~100℃, preferably 40~60℃; the drying time is 4~10h, preferably 4~6h.

[0082] Furthermore, in step 4, the additive metal is one or a mixture of two of the following: platinum, cobalt, iron, tungsten, nickel, and copper, preferably nickel and / or platinum.

[0083] Further, in step 4, the auxiliary metal compound is one of the chlorate, acetylacetonate, sulfate or nitrate of the auxiliary metal, preferably chlorate or acetylacetonate.

[0084] Furthermore, in step 4, the concentration of the deionized aqueous solution of the auxiliary metal compound is calculated based on the water absorption performance of the catalyst in step 3. Finally, the mass fraction of the auxiliary metal in the novel high-performance molybdenum-based hydrogenation catalyst is 0~0.1%, preferably 0~0.05%; when the auxiliary metal is 0%wt, steps 4 and 5 are omitted.

[0085] Furthermore, in step 4, the volume of the auxiliary metal compound solution is equal to the theoretical water absorption volume of the catalyst added in step 3.

[0086] Furthermore, in step 4, the stirring time is 2 to 8 hours, preferably 4 to 6 hours.

[0087] Furthermore, in step 4, the stirring speed is 200~800 r / min, preferably 400~600 r / min.

[0088] Furthermore, in step 4, the ultrasound time is 12~24h, preferably 16~20h.

[0089] Furthermore, in step 4, the ultrasonic frequency is 50~200kHz, preferably 70~180kHz.

[0090] Furthermore, in step 4, the settling time is 8~24h, preferably 8~16h.

[0091] Furthermore, in step 5, the oven temperature is 60~100℃, preferably 60~80℃.

[0092] Furthermore, in step 5, the drying time is 8~24h, preferably 8~12h.

[0093] Furthermore, in step 5, the calcination heating rate is 2~10℃ / min, preferably 5~10℃ / min; the calcination temperature is 400~700℃, preferably 500~600℃; and the calcination time is 2~8h, preferably 4~6h.

[0094] This invention also provides the application of the novel high-performance molybdenum-based hydrogenation catalyst in the capture of carbon dioxide and in-situ hydrogenation of ethanolamine to methanol, the specific operation of which is as follows: Step 1: Preparation of CO2 carbon-rich solution by weighing method: Add the capturing solvent to the reaction vessel equipped with bubbling, stirring and weighing device, introduce CO2 gas flow at room temperature, bubble and stir, weigh the solution to prepare CO2 carbon-rich solution. Step 2: Catalyst activation: A novel high-performance molybdenum-based hydrogenation catalyst is added to the reactor, replaced with hydrogen, and activated at a certain temperature by purging with hydrogen. Step 3: Add the activated catalyst and carbon-rich liquid to the reactor, replace with hydrogen, purge with hydrogen and maintain pressure, and heat the reactor to the reaction temperature to carry out the reaction.

[0095] Further, in step 1, the capturing solvent is one of ethanolamine, diethanolamine, or methyldiethanolamine, preferably ethanolamine.

[0096] Furthermore, in step 2, the activation pressure is 3~6 MPa, preferably 3~5 MPa; the activation temperature is 100~200℃, preferably 100~150℃; and the activation time is 6~30h, preferably 8~16h.

[0097] Furthermore, in step 3, the ratio of the activated catalyst mass (g) to the carbon-rich liquid volume (mL) is 1:10~50, preferably 1:20~40.

[0098] Furthermore, in step 3, the reaction pressure is 4~8 MPa, preferably 4~6 MPa; the reaction temperature is 100~200℃, preferably 150~200℃; and the reaction time is 6~30h, preferably 8~20h.

[0099] Example 1.

[0100] A novel high-performance molybdenum-based hydrogenation catalyst L1 is prepared as follows: 2.0388 g of ammonium heptamolybdate was dissolved in 2.5 mL of deionized water, followed by the addition of 2.5 g of alumina. The mixture was stirred vigorously for 4 h, sonicated for 16 h, and then allowed to stand for 12 h. The mixture was then dried in an oven at 70 °C for 12 h. The resulting solid was then heated in a muffle furnace at 5 °C for 1 min. -1 The catalyst precursor 1 was obtained by calcining at 500 °C for 4 h at a heating rate of 300 mL. 300 mL of 10 wt% carbon disulfide (CS2) n-decane solution and 4 g of catalyst precursor 1 were loaded into a reactor and sulfided at 4.0 MPa and 300 °C for 12 h. The catalyst was then removed, filtered, washed with ethanol, and dried in an oven at 50 °C for 6 h to obtain the catalyst. Subsequently, 0.0003 g of nickel nitrate was dissolved in 2 mL of deionized water, followed by the addition of 2.5 g of catalyst. The mixture was stirred vigorously for 4 h, sonicated for 16 h, and then allowed to stand for 12 h. It was then dried in an oven at 70 °C for 12 h. The resulting solid was then subjected to nitrogen protection in a tube furnace at 5 °C for 1 min. -1The heating rate was increased to 500 °C for 4 h to obtain a novel high-performance molybdenum-based hydrogenation catalyst L1.

[0101] Example 2.

[0102] A novel high-performance molybdenum-based hydrogenation catalyst L2 is prepared as follows: 2.0388 g of ammonium heptamolybdate was dissolved in 2.5 mL of deionized water, followed by the addition of 2.5 g of alumina. The mixture was stirred vigorously for 4 h, sonicated for 16 h, and then allowed to stand for 12 h. The mixture was then dried in an oven at 70 °C for 12 h. The resulting solid was then heated in a muffle furnace at 5 °C for 1 min. -1 The catalyst precursor 1 was obtained by calcining at 500 °C for 4 h. 300 mL of 10 wt% carbon disulfide (CS2) n-decane solution and 4 g of catalyst precursor 1 were loaded into a reactor and sulfided at 4.0 MPa and 300 °C for 12 h. The catalyst was then removed, filtered, washed with ethanol, and dried in an oven at 50 °C for 6 h to obtain a novel high-performance molybdenum-based hydrogenation catalyst L2.

[0103] Example 3.

[0104] A novel high-performance molybdenum-based hydrogenation catalyst L3 is prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that the alumina support is replaced with activated carbon.

[0105] Example 4.

[0106] A novel high-performance molybdenum-based hydrogenation catalyst L4 is prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that nickel nitrate is replaced with platinum nitrate.

[0107] Example 5.

[0108] A novel high-performance molybdenum-based hydrogenation catalyst L5 is prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that ammonium heptamolybdate is replaced with sodium molybdate.

[0109] Comparative Example 1.

[0110] Catalyst I1 was prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that the mass of ammonium heptamolybdate was adjusted to 1.0 g.

[0111] Comparative Example 2.

[0112] Catalyst I2 was prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that the mass of nickel nitrate was adjusted to 0.005 g.

[0113] Comparative Example 3.

[0114] Catalyst I3 is prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L1, except that it is prepared without sulfidation treatment.

[0115] Comparative Example 4.

[0116] Catalyst I4 is prepared using the same method as the novel high-performance molybdenum-based hydrogenation catalyst L2, except that it is prepared without sulfidation treatment.

[0117] Catalyst testing 1. EPR test Figure 1 EPR spectra of I3 catalysts with different catalyst promoters, different catalyst supports, and without sulfurization are presented. In the optimal catalysts L1 and L2, a significant peak was observed at g=2.0037, confirming the presence of numerous sulfur vacancies on the catalyst surface; while in I3 and I4, almost no sulfur vacancy characteristic peaks were observed. This indicates that after sulfurization, the Mo species are fully sulfurized and transformed into sulfur-vacancy-rich MoS2 species on the support surface.

[0118] 2. CO2-TPD test Figure 2 The CO2-TPD spectra of catalysts L1, L2, L3, and L4 are shown. As shown in the figure, all catalyst surfaces exhibit two distinct CO2 desorption peaks (290℃ and 425℃), corresponding to weakly basic and strongly basic sites on the catalyst surface, respectively. The optimal L1 catalyst exhibits a moderate content of both weakly and strongly basic sites. In contrast, the L4 catalyst with platinum additive has a low content of weakly basic sites and almost no strongly basic sites, while the L3 catalyst using activated carbon support has extremely high contents of both weakly and strongly basic sites. This indicates that the Al2O3 support is more conducive to the formation of a moderate content of basic sites. These results suggest that, in addition to the sulfur vacancies mentioned earlier, a suitable amount of basic sites on the catalyst surface also contributes to the performance of the catalyst in CO2-coupled hydrogenation to methanol.

[0119] 3. Electron microscopy test Figure 3 The TEM morphology of four catalysts, L1, L2, L3, and L4, is shown. Figure 3 In (a), abundant molybdenum sulfide clusters (corresponding to the black stripes in the figure) can be observed in the L1 catalyst. The number of layers is small, which is conducive to exposing more sulfur vacancies. Figure 3 The L2 catalyst in (b) is similar to L1, but the molybdenum sulfide clusters are larger and have more layers, which is not conducive to the formation of abundant sulfur vacancies. Furthermore, Figure 3 (c)h and Figure 3 In (d), the molybdenum sulfide clusters in the L3 and L4 catalysts are too small and sparsely distributed, which is also not conducive to the formation of abundant sulfur vacancies. The abundant few-layer molybdenum sulfide clusters in the L1 catalyst not only provide sufficient sites for the high dispersion of Ni promoter, but also facilitate the exposure of more sulfur vacancies, laying the structural foundation for achieving efficient catalysis.

[0120] 4. Catalytic activity test 0.2 g of catalyst was added to the reactor, purged with hydrogen, and the pressure was increased to 5 MPa. The reactor was activated at 120 °C for 8 h. After activation, the temperature was lowered to room temperature. 5 mL of ethanolamine carbon-rich solution was added to the reactor, purged with hydrogen, and the pressure was increased to 6 MPa. The reactor was stirred and reacted at 170 °C for 12 h. After the reaction was completed, the temperature was lowered to room temperature. A portion of the sample was taken out, and the methanol yield was determined by gas chromatography equipped with a flame ionization detector (FID).

[0121] Table 1. Methanol yield using the catalysts of each example and comparative example.

[0122] As shown in Table 1 above, the novel high-performance molybdenum-based hydrogenation catalyst of this invention maintains a methanol yield of over 20%, which is much higher than the reported methanol yield of 8.8% for Pt / TiO2 catalyst (Adv. Energy Mater. 2022, 12(46), 2202369). The novel high-performance molybdenum-based hydrogenation catalyst exhibits excellent catalytic performance and mild reaction conditions.

[0123] Compared with the novel high-performance molybdenum-based hydrogenation catalysts L1 and I1, too low a content of active metal molybdenum will lead to a significant reduction in catalytic performance. Compared with the novel high-performance molybdenum-based hydrogenation catalysts L1, L2 and I2, the addition of an appropriate amount of auxiliary metal can effectively improve the catalytic activity of the catalyst, but excessive auxiliary metal has little effect on the catalytic activity and may even reduce the catalytic activity of the catalyst.

[0124] Compared with the novel high-performance molybdenum-based hydrogenation catalysts L1, L2, I3 and I4, sulfidation modification significantly improves the catalytic performance of the catalysts.

[0125] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A novel high-performance molybdenum-based hydrogenation catalyst, characterized in that, include: Composed of active metal molybdenum, auxiliary metals, and a carrier; the mass fraction of active metal molybdenum is 10-30%; the mass fraction of auxiliary metals is 0-1%wt.

2. The novel high-performance molybdenum-based hydrogenation catalyst according to claim 1, characterized in that, The additive metal is one or a mixture of two of the following: platinum, cobalt, iron, tungsten, nickel, and copper; the carrier material is one or a mixture of two of the following: alumina, titanium oxide, cerium oxide, activated carbon, zinc oxide, lanthanum oxide, silicon oxide, and zirconium oxide.

3. A novel method for preparing a high-performance molybdenum-based hydrogenation catalyst, characterized in that, Includes the following steps: Step 1: Prepare a deionized molybdate aqueous solution. Add the carrier material to the deionized molybdate aqueous solution, stir, sonicate, and let stand at room temperature to obtain a mixture. Step 2: The mixture is dried in an oven, then removed and calcined to obtain catalyst precursor 1; Step 3: Prepare a sulfurizing agent organic solution, add catalyst precursor 1, fill the reaction vessel with hydrogen gas, carry out the sulfurization reaction at a certain temperature, take out the sample after the reaction is completed, filter, wash and dry to obtain a new high-performance molybdenum-based hydrogenation catalyst with 0%wt of auxiliary metal. Step 4: Test the water absorption performance of the catalyst in Step 3, prepare a deionized aqueous solution of the auxiliary metal compound, add the catalyst from Step 3 to the auxiliary metal compound solution, stir and sonicate, and let stand at room temperature to obtain catalyst precursor 2. Step 5: The catalyst precursor 2 is dried in an oven, then taken out and calcined under nitrogen protection to obtain a novel high-performance molybdenum-based hydrogenation catalyst.

4. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 1, the concentration of the molybdate deionized aqueous solution is calculated based on the water absorption performance of the support, and the final mass fraction of active molybdenum in the novel high-performance molybdenum-based hydrogenation catalyst is 10-30%.

5. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 2, the calcination heating rate is 2~10℃ / min; the calcination temperature is 400~700℃; and the calcination time is 2~8h.

6. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 3, the volume ratio of the sulfiding agent solution to the mass ratio of the catalyst precursor is 50~200:

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7. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 3, the pressure inside the reactor is 2-6 MPa; the temperature of the sulfidation reaction is 200-400℃; and the time of the sulfidation reaction is 8-24 h.

8. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 4, the concentration of the deionized aqueous solution of the auxiliary metal compound is calculated based on the water absorption performance of the catalyst in step 3. Finally, the mass fraction of the auxiliary metal in the novel high-performance molybdenum-based hydrogenation catalyst is 0~0.1%; when the auxiliary metal is 0%wt, steps 4 and 5 are not required.

9. The method for preparing the novel high-performance molybdenum-based hydrogenation catalyst according to claim 3, characterized in that, In step 5, the calcination heating rate is 2~10℃ / min; the calcination temperature is 400~700℃; and the calcination time is 2~8h.

10. The application of a novel high-performance molybdenum-based hydrogenation catalyst in the hydrogenation of carbon dioxide to methanol, characterized in that, The specific steps are as follows: Step 1: Preparation of CO2 carbon-rich solution by weighing method: Add the capturing solvent to the reaction vessel equipped with bubbling, stirring and weighing device, introduce CO2 gas flow at room temperature, bubble and stir, weigh the solution to prepare CO2 carbon-rich solution. Step 2: Catalyst activation: A novel high-performance molybdenum-based hydrogenation catalyst is added to the reactor, replaced with hydrogen, and activated at a certain temperature by purging with hydrogen. Step 3: Add the activated catalyst and carbon-rich liquid to the reactor, replace with hydrogen, purge with hydrogen and maintain pressure, and heat the reactor to the reaction temperature to carry out the reaction.

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