A supported CuPt bimetallic active site catalyst, and methods of making and using the same

Abstract

The application discloses a supported CuPt bimetallic active site catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts. In the application, Pt and Cu bimetallic active sites are introduced on a rod-shaped tungsten oxide carrier, wherein the loading amount of Pt is very low, the Pt exists in the form of a single atom, and the Cu exists in the form of a particle; the Pt serves as an adsorption and activation site of hydrogen, the Cu serves as an activation site of a C=O double bond, and the WO3 carrier rich in oxygen defects on the surface serves as a reducible carrier to make hydrogen overflow possible; according to a catalyst model, H2 molecules are activated at the Pt site to generate activated hydrogen atoms, CO2 and DMC molecules are adsorbed on the surface of the Cu particle through a C=O double bond, the hydrogen atoms are overflowed to the surface of the Cu particle through the WO3 surface, and then the CO2 and the DMC are hydrogenated to generate methanol.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a supported CuPt bimetallic active site catalyst and a preparation method and application thereof. BACKGROUND

[0002] Methanol, as a clean energy, plays an important role in chemical industry and production and life. Large-scale commercial production of methanol mainly comes from synthesis gas, wherein the main component of the synthesis gas is a mixture of CO and H2, which comes from non-renewable resources such as coal and natural gas. Catalytic hydrogenation of CO2 is an important means for preparing methanol, which can not only reduce CO2 emission, but also improve the economy of methanol preparation, and can promote carbon cycle and recycling, and upgrade and optimize hydrogen energy industry. However, there are some disadvantages in preparing methanol by directly hydrogenating CO2. First, in thermodynamics, according to the chemical reaction equation: CO2+3H2=CH3OH+H2O H298k=-49.5kJmol -1 The reaction is an exothermic reaction, and the lower the temperature is, the more beneficial to the generation of methanol; secondly, CO2 is a straight-chain small molecule, and the energy of two C=O bonds is 1598 kJ / mol, which has thermodynamic stability, and high temperature and high pressure environment is needed to activate CO2 molecules; finally, when the reaction temperature is increased, side reactions will inevitably occur, and the most important one is the reverse water gas shift reaction (RWGS, CO2+H2=CO+H2O H298k=41.2kJmol -1 ), thereby reducing the selectivity of methanol. Therefore, in order to improve the CO2 conversion efficiency and the selectivity of methanol, it is the key of the reaction to reasonably design the catalyst.

[0003] In Cu-based catalysts, Cu is the reaction site for the catalytic hydrogenation of CO2. As early as 1923, ALWIN et al. found that CH3OH can be prepared using Cu / ZnO as a catalyst under high temperature (400℃) and high pressure (20 MPa) conditions. This is because ZnO can enhance the dispersion and stability of Cu, and the oxygen vacancies and electrons in the ZnO lattice have catalytic activity for the formation of CH3OH. These characteristics make Cu / ZnO catalysts perform well in the reaction of catalytically synthesizing CH3OH. The CH3OH formation pathway under the catalysis of Cu / ZnO is as follows: H2 is adsorbed and dissociated at the Cu site, while CO2 is adsorbed on the ZnO site to form bicarbonate and then undergoes a hydrogenation reaction; Au and Pd are commonly used noble metal catalysts for the catalytic hydrogenation of CO2 to CH3OH. HARTADI et al. prepared a supported Au / ZnO catalyst. Compared with the industrial Cu / ZnO / Al2O3 catalyst, the Au / ZnO catalyst has long-term stability, and the selectivity of CH3OH increases from 55% to 70%; BAHRUJI et al. studied the structure-activity relationship of CO2 catalytic hydrogenation on Pd / ZnO catalysts prepared by different methods. The results show that the PdZn alloy formed during the reaction or high-temperature pre-reduction process is the active center for the formation of CH3OH, which greatly reduces the competitiveness of the RWGS reaction, and the smaller the diameter of the PdZn alloy, the higher the selectivity of CH3OH. When the diameter of the PdZn alloy is 3 nm, the selectivity of CH3OH and the conversion rate of CO2 are 60% and 11%, respectively. However, the above catalysts either have complex preparation methods or use noble metals, which increases the cost, and the selectivity of CH3OH needs to be improved. Therefore, it is necessary to prepare a supported bimetallic catalyst that is low in price, simple in preparation method, and high in selectivity. SUMMARY

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the purpose of the present application is to provide a supported CuPt bimetallic active site catalyst and its preparation method and application, in order to solve the problems of high cost, complex preparation method and low selectivity of the existing catalysts for hydrogenation to prepare methanol.

[0005] The technical scheme for solving the above technical problems is as follows: a supported CuPt bimetallic active site catalyst is provided, which comprises a tungsten oxide nanorod (NR-WO3) carrier, the NR-WO3 carrier is loaded with Pt in a single atom form and Cu in a particle form, the loading amount of Pt is 0.009-0.011wt%, and the loading amount of Cu is 0.2-10wt%.

[0006] The present application has the following beneficial effects: the present application introduces Pt and Cu bimetallic active sites on the rod-shaped tungsten trioxide (NR-WO3) carrier, wherein the loading amount of Pt is very low, and Pt exists in the form of a single atom, and Cu exists in the form of a particle; Pt and Cu respectively serve as adsorption and activation sites of hydrogen and activation sites of C=O double bond, and the WO3 carrier rich in surface oxygen defects serves as a reducible carrier to provide the possibility for hydrogen overflow; according to the catalyst model, H2 molecules are activated at the Pt sites to produce activated hydrogen atoms, CO2 and DMC molecules are adsorbed on the surface of the Cu particle through C=O double bond, and the hydrogen atoms overflow to the surface of the Cu particle on the WO3 surface, thereby realizing the hydrogenation of CO2 and DMC to generate methanol.

[0007] Another object of the present application is to provide a preparation method of a supported CuPt bimetallic active site catalyst, comprising the following steps:

[0008] (1) Preparation of the NR-WO3 carrier:

[0009] The tungstate is prepared into a suspension, then acid is added to the suspension, and the suspension is condensed and refluxed at 80-90 DEG C for 0.5-2 h; then the precipitate after the reaction is taken out, and the precipitate is subjected to hydrothermal reaction at 150-180 DEG C for 10-15 h; then the precipitate is centrifuged, filtered, washed, and dried to obtain the NR-WO3 carrier;

[0010] (2) Preparation of the Pt1 / NR-WO3 catalyst precursor:

[0011] The NR-WO3 carrier is uniformly dispersed in a first organic solvent at room temperature to obtain a suspension, and a platinum salt aqueous solution is added dropwise to the suspension, and stirred for 1 h; then the first organic solvent is removed to obtain a solid powder, and the solid powder is calcined in a H2 / Ar mixed gas with a hydrogen volume fraction of 5% at 350 DEG C for 2 h to obtain the Pt1 / NR-WO3 catalyst precursor;

[0012] (3) Preparation of the Pt1-mCu / NR-WO3 catalyst:

[0013] The Pt1 / NR-WO3 precursor is uniformly dispersed in a second organic solvent at room temperature to obtain a suspension, and a copper salt aqueous solution is added dropwise to the suspension, and stirred for 1 h; then the second organic solvent is removed to obtain a solid powder, and the solid powder is calcined in a H2 / Ar mixed gas with a hydrogen volume fraction of 5% at 350 DEG C for 2 h to obtain the Pt1-mCu / NR-WO3 catalyst, wherein m is the loading amount of copper.

[0014] On the basis of the above technical solution, the present application can be further improved as follows:

[0015] Further, the tungstate is (NH4) 10 W12 O 41 • 5H2O, the concentration of the suspension made therefrom is 62.5 mmol / L; the acid is nitric acid with a concentration of 2.5 mol / L; the molar ratio of nitric acid to (NH4) 10 W 12 O 41 • 5H2O is 10:1.

[0016] Further, the aqueous platinum salt solution is an aqueous platinum nitrate solution with a platinum ion concentration of 5 mg / mL, and the mass ratio of the platinum nitrate to the NR-WO3 carrier in the system after mixing is 0.01:100; the aqueous copper salt solution is an aqueous copper nitrate solution with a copper ion concentration of 5 mg / mL; and the first organic solvent and the second organic solvent are both ethanol.

[0017] Further, the temperature rising in steps (2) and (3) is performed at a rate of 5 ℃ / min.

[0018] Another object of the present application is to provide an application of the supported CuPt bimetallic active site catalyst in a methanol preparation reaction by hydrogenation.

[0019] On the basis of the above technical solution, the present application can be further improved as follows:

[0020] Further, the reaction is a reaction of preparing methanol by hydrogenation of CO2, and includes the following steps:

[0021] Pt1-mCu / NR-WO3 is used as the catalyst, tetrahydrofuran is used as the solvent, and a mixed gas with a volume ratio of CO2:H2=1:3 is used as the synthesis gas, and the reaction is performed at 2 MPa and 100 ℃ for 5 h.

[0022] Further, the loading amount of Cu on the Pt1-mCu / NR-WO3 catalyst in the above reaction is 1 wt%.

[0023] Further, the reaction is a reaction of preparing methanol by hydrogenation of DMC, and includes the following steps:

[0024] (1) Pt1-mCu / NR-WO3 is dispersed in a reaction bottle containing 2 mL of DMC, and is transferred into a 500 mL autoclave, and is washed with 1 MPa H2 for 3 times;

[0025] (2) The reaction is stirred for 2 h in a 1 MPa H2 atmosphere, and the reaction temperature is 80 ℃.

[0026] Further, the loading amount of Cu on the Pt1-mCu / NR-WO3 catalyst in the above reaction is 7 wt%.

[0027] The present application has the following beneficial effects:

[0028] 1. The catalyst of the present application is prepared by a traditional impregnation method, which is simple and efficient, ensuring that the noble metal ions are completely loaded on the tungsten oxide carrier; at the same time, the preparation method of the rod-shaped tungsten oxide material with surface oxygen defects is simple, the raw materials are low in price and environmentally friendly, and is suitable for large-scale production;

[0029] 2. In terms of catalytic hydrogenation to prepare methanol, hydrogen is selected as the source of hydrogen ions, which is in line with the development concept of green pollution-free and environment-friendly, and is widely used in industry; the catalytic reaction conditions are mild, the yield and selectivity of methanol are high, the utilization rate of the catalyst is high, and the stability is good, which has important industrial application value and is suitable for industrial promotion. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Transmission electron microscopy (a) (TEM) and energy spectrum (b) (HAADF-STEM) of the NR-WO3 carrier loaded with metal Pt and Cu (Pt1-1Cu / NR-WO3) catalyst of Example 3;

[0031] Figure 2 Performance chart of different Cu metal loadings of Examples 1-5 for CO2 hydrogenation to prepare methanol;

[0032] Figure 3 Performance chart of the catalysts of Example 3 and Comparative Examples 1-4 for CO2 hydrogenation to prepare methanol;

[0033] Figure 4 Transmission electron microscopy (a) (TEM), energy spectrum (b) (HAADF-STEM) and energy spectrum (c) (HAADF-STEM) of the NR-WO3 carrier loaded with metal Pt and Cu (Pt1-7Cu / NR-WO3) catalyst of Example 9;

[0034] Figure 5 Performance chart of different Cu metal loadings of Examples 6-10 for DMC hydrogenation to prepare methanol;

[0035] Figure 6 Performance chart of the catalysts of Comparative Examples 5-9 for DMC hydrogenation to prepare methanol. DETAILED DESCRIPTION

[0036] The principles and characteristics of the present application are described below in conjunction with the examples, which are used only to explain the present application and are not intended to limit the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0037] Because platinum is a precious metal, the concentration labeling of purchased products is based on the platinum content. The platinum nitrate solution (5 mg / mL) mentioned in the following examples and comparative examples indicates that the platinum content is 5 mg / mL; for consistency, the copper nitrate solution (5 mg / mL) also indicates that the copper content is 5 mg / mL.

[0038] Examples 1-5:

[0039] A supported CuPt bimetallic active site catalyst includes a tungsten oxide nanorod (NR-WO3) support on which Pt in single-atom form and Cu in particulate form are loaded.

[0040] The catalyst in this embodiment was prepared through the following steps:

[0041] (1) Preparation of NR-WO3 vector:

[0042] 1 mmol (3.06 g) of (NH4) 10 W 12 O 41 ·5H2O was placed in a round-bottom flask, 40mL of deionized water was added and stirred to obtain a suspension; 10mL of 2.5mol / L dilute HNO3 was slowly added dropwise to the above suspension, and the mixture was refluxed at 85℃ for 1h. The precipitate after the reaction was poured into a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner, heated at 160℃ for 12h, cooled to room temperature, centrifuged, filtered and the precipitate was washed 3 times with deionized water and dried at 60℃ overnight to obtain light yellow tungsten oxide powder, i.e., NR-WO3 carrier;

[0043] (2) Preparation of Pt1 / NR-WO3 catalyst precursor:

[0044] At room temperature, 300 mg of NR-WO3 powder was uniformly dispersed in 30 mL of ethanol by ultrasound and stirring to obtain a suspension. 6 μL of a 5 mg / mL platinum nitrate aqueous solution was added dropwise to the suspension, and the mixture was stirred for 1 h. The ethanol was then heated to complete evaporation to obtain a solid powder, which was calcined in a 5% hydrogen H2 / Ar mixture at a rate of 5 °C / min to 350 °C for 2 h to obtain the Pt1 / NR-WO3 catalyst precursor; the Pt metal loading at this point was 0.01 wt%.

[0045] (3) Preparation of Pt1-mCu / NR-WO3 catalyst:

[0046] At room temperature, 300 mg of Pt1 / NR-WO3 precursor powder was uniformly dispersed in 30 mL of ethanol by ultrasonic and stirring, and different amounts (120 μL, 300 μL, 600 μL, 900 μL, and 1200 μL of copper nitrate aqueous solution for Examples 1-5) of 5 mg / mL copper nitrate aqueous solution were added dropwise to the suspension, stirred for 1 h, and then heated to completely evaporate the ethanol to obtain a solid powder, which was calcined at 350℃ at a rate of 5℃ / min in a H2 / Ar mixed gas with a hydrogen volume fraction of 5% for 2 h to obtain Pt1-mCu / NR-WO3 catalysts with different copper contents, where m=0.2, 0.5, 1, 1.5, and 2.

[0047] The Pt1-mCu / NR-WO3 catalyst prepared above was used in the experiment of preparing methanol by hydrogenation of CO2, and the specific experimental steps were as follows:

[0048] (1) 20 mg of catalyst (Pt1-0.2Cu / NR-WO3, Pt1-0.5Cu / NR-WO3, Pt1-1Cu / NR-WO3, Pt1-1.5Cu / NR-WO3, and Pt1-2Cu / NR-WO3 for Examples 1-5) was weighed into a 50 mL high-pressure reactor, and 4 mL of tetrahydrofuran (THF) was used as the solvent.

[0049] (2) The mixed gas with a volume ratio of CO2:H2=1:3 was used as the reaction gas, and the reaction was carried out at a pressure of 2 MPa and a temperature of 100℃ for 5 h.

[0050] Performance test: After the reaction of preparing methanol by hydrogenation of CO2 was completed, the content of methanol in the liquid phase was quantitatively analyzed by a gas chromatograph, and the yield of methanol for each catalyst was recorded.

[0051] Examples 6-10:

[0052] A supported CuPt bimetallic active site catalyst includes a tungsten oxide nanorod (NR-WO3) carrier, and single-atom Pt and particle Cu are loaded on the NR-WO3 carrier.

[0053] The catalyst in this example was prepared by the following steps:

[0054] The preparation method was the same as that of Examples 1-5, except that the loading amount of Cu in step (3) was changed, and the amount of copper nitrate aqueous solution for Examples 6-10 was 600 μL, 1800 μL, 3000 μL, 4200 μL, and 6000 μL, and m=1, 3, 5, 7, and 10.

[0055] The Pt1-mCu / NR-WO3 catalyst prepared above was used in the experiment of preparing methanol by hydrogenation of DMC, and the specific experimental steps were as follows:

[0056] (1) 10 mg of catalyst (Examples 6-10: Pt1-1Cu / NR-WO3, Pt1-3Cu / NR-WO3, Pt1-5Cu / NR-WO3, Pt1-7Cu / NR-WO3 and Pt1-10Cu / NR-WO3) was weighed into a glass reaction bottle containing 2 mL of DMC, and was transferred to a 500 mL autoclave, and was washed with 1 MPa H2for 3 times;

[0057] (2) The reaction was carried out in 1 MPa H2atmosphere, magnetic stirring, reaction for 2 h, temperature control at 80℃.

[0058] Performance test: After the DMC hydrogenation reaction to prepare methanol was completed, the content of methanol in the liquid phase was quantitatively analyzed by gas chromatograph, and the yield of methanol for each catalyst was recorded.

[0059] Comparative Example 1:

[0060] A supported metal Pt catalyst, comprising a tungsten oxide nanorod (NR-WO3) carrier, and the NR-WO3 carrier is loaded with Pt in the form of single atoms.

[0061] Prepared by the following steps:

[0062] The same as the preparation method of Examples 1-5, except that step (3) is omitted.

[0063] The Pt1 / NR-WO3 catalyst prepared above was used for CO2 hydrogenation to prepare methanol experiment, and the specific experimental steps were the same as Examples 1-5.

[0064] The performance test was the same as Examples 1-5.

[0065] Comparative Example 2:

[0066] A PtCu / NR-WO3 alloy catalyst.

[0067] The catalyst in this example was prepared by the following steps:

[0068] At room temperature, 300 mg of NR-WO3 powder was uniformly dispersed in 30 mL of ethanol by ultrasonic and stirring to obtain a suspension; 6 μL of 5 mg / mL aqueous solution of platinum nitrate and 600 μL of 5 mg / mL aqueous solution of copper nitrate were added dropwise to the suspension, stirred for 1 h, then heated to completely evaporate the ethanol, to obtain a solid powder, and heated to 350℃ at a rate of 5℃ / min in a H2 / Ar mixed gas with a hydrogen volume fraction of 5%, and calcined for 2 h to obtain a PtCu / NR-WO3 catalyst; at this time, the Pt metal loading was 0.01 wt%, and the Cu loading was 1 wt%;

[0069] The catalyst prepared above was used in the experiment of preparing methanol by hydrogenation of CO2, and the specific experimental steps were the same as those in Example 1-5.

[0070] The performance test was the same as that in Example 1-5.

[0071] Comparative Example 3:

[0072] A physical mixing catalyst of Pt1 / NR-WO3 and Cu / NR-WO3.

[0073] The catalyst in the present example was prepared by the following steps:

[0074] (1) Preparation of Pt1 / NR-WO3 catalyst: the same as the preparation method in Comparative Example 1;

[0075] (2) Preparation of Cu / NR-WO3 catalyst: the same as the preparation method in Example 1-5, except that step (2) was omitted, and the Pt1 / NR-WO3 precursor powder in step (3) was replaced with NR-WO3 carrier, and the amount of copper nitrate aqueous solution was 600 μL, and at this time m = 1.

[0076] (3) 20 mg of each of the two catalysts of Pt1 / NR-WO3 and Cu / NR-WO3 were physically mixed uniformly.

[0077] The catalyst prepared above was used in the experiment of preparing methanol by hydrogenation of CO2, and the specific experimental steps were the same as those in Example 1-5.

[0078] The performance test was the same as that in Example 1-5.

[0079] Comparative Example 4:

[0080] A Pt1-1Cu / NR-SiO2 alloy catalyst.

[0081] The catalyst in the present example was prepared by the following steps:

[0082] At room temperature, 300 mg of SiO2 powder was uniformly dispersed in 30 mL of ethanol by ultrasonic and stirring to obtain a suspension; 6 μL of 5 mg / mL platinum nitrate aqueous solution and 600 μL of 5 mg / mL copper nitrate aqueous solution were added dropwise to the suspension, stirred for 1 h, and then heated to completely evaporate the ethanol to obtain a solid powder, and then heated to 350 ℃ at a rate of 5 ℃ / min in a H2 / Ar mixed gas with a hydrogen volume fraction of 5%, and calcined for 2 h to obtain a Pt1-Cu / SiO2 catalyst precursor; at this time, the Pt metal loading was 0.01 wt%, and the Cu loading was 1 wt%.

[0083] The catalyst prepared above was used in the experiment of preparing methanol by hydrogenation of CO2, and the specific experimental steps were the same as those in Example 1-5.

[0084] Performance test same as example 1-5.

[0085] Comparative example 5:

[0086] A supported metal Pt catalyst comprising tungsten oxide nanorod (NR-WO3) support, on which is supported Pt in monatomic form.

[0087] Prepared by the following steps:

[0088] Same as the preparation method of example 1-5, except that step (3) is omitted.

[0089] The above-prepared Pt1 / NR-WO3 catalyst was used in the experiment of preparing methanol by hydrogenation of DMC, and the specific experimental steps were the same as example 6-10.

[0090] Performance test same as example 6-10.

[0091] Comparative example 6:

[0092] A supported metal Cu catalyst comprising tungsten oxide nanorod (NR-WO3) support, on which is supported copper in particulate form.

[0093] Prepared by the following steps:

[0094] Same as the preparation method of example 1-5, except that step (2) is omitted, and the Pt1 / NR-WO3 precursor powder in step (3) is replaced by NR-WO3 support, and the amount of copper nitrate aqueous solution is 4200 μL, at this time m = 7.

[0095] The above-prepared 7Cu / NR-WO3 catalyst was used in the experiment of preparing methanol by hydrogenation of DMC, and the specific experimental steps were the same as example 6-10.

[0096] Performance test same as example 6-10.

[0097] Comparative example 7:

[0098] A WO3 catalyst.

[0099] Prepared by the following steps:

[0100] Same as the preparation method of example 1-5, except that step (2) and step (3) are omitted.

[0101] The above-prepared catalyst was used in the experiment of preparing methanol by hydrogenation of DMC, and the specific experimental steps were the same as example 6-10.

[0102] Performance test same as example 6-10.

[0103] Comparative example 8:

[0104] A physical mixed catalyst of Pt1 / NR-WO3 and Cu / NR-WO3.

[0105] The catalyst in the embodiment was prepared by the following steps:

[0106] The preparation method was the same as that of Comparative Example 3.

[0107] The prepared catalyst was used in the experiment of preparing methanol by DMC hydrogenation, and the specific experimental steps were the same as those of Examples 6-10.

[0108] The performance test was the same as that of Examples 6-10.

[0109] Comparative Example 9:

[0110] A PtCu / NR-WO3 alloy catalyst.

[0111] The catalyst in the embodiment was prepared by the following steps:

[0112] The preparation method was the same as that of Comparative Example 2.

[0113] The prepared PtCu / NR-WO3 alloy catalyst was used in the experiment of preparing methanol by DMC hydrogenation, and the specific experimental steps were the same as those of Examples 6-10.

[0114] The performance test was the same as that of Examples 6-10.

[0115] The Pt1-1Cu / NR-WO3 catalyst of Example 3 was characterized by high-resolution transmission electron microscopy (HRTEM), and the results are shown in Figure 1 As can be seen from a, the tungsten oxide carrier presents a rod-like morphology, and the lattice fringe spacing is 0.369 nm, which is consistent with the (200) crystal plane; then through energy spectrum area scanning, as can be seen from b, Pt and Cu have been perfectly introduced into the WO3 carrier. Figure 1 As can be seen from a, the tungsten oxide carrier presents a rod-like morphology, and the lattice fringe spacing is 0.369 nm, which is consistent with the (200) crystal plane; then through energy spectrum area scanning, as can be seen from b, Pt and Cu have been perfectly introduced into the WO3 carrier.

[0116] As can be seen from a, the tungsten oxide carrier presents a rod-like morphology, and the lattice fringe spacing is 0.369 nm, which is consistent with the (200) crystal plane; then through energy spectrum area scanning, as can be seen from b, Pt and Cu have been perfectly introduced into the WO3 carrier. Figure 2 As can be seen from a, the tungsten oxide carrier presents a rod-like morphology, and the lattice fringe spacing is 0.369 nm, which is consistent with the (200) crystal plane; then through energy spectrum area scanning, as can be seen from b, Pt and Cu have been perfectly introduced into the WO3 carrier. MeOH mmol Pt -1 h -1 When the Cu loading was 2wt%, the methanol production was 2124.8 mmol MeOH mmol Pt -1 h -1 . Figure 3As can be seen, compared with Examples 1-5, the four comparative catalysts exhibited very low methanol yields.

[0117] The hydrogenation of CO2 to methanol often produces byproducts, such as CO and CH4. Figure 2 and Figure 3 As can be seen, any catalyst exhibits high selectivity for methanol, exceeding 99%. This demonstrates that the bimetallic supported tungsten oxide catalysts in Examples 1-5 (Pt-mCu / NR-WO3) not only demonstrate high selectivity in the CO2 hydrogenation to methanol production but also significantly improve the methanol yield.

[0118] The Pt1-7Cu / NR-WO3 catalyst of Example 9 was characterized by high-resolution transmission electron microscopy (HRTEM). Figure 4 As can be seen from a, tungsten oxide has a rod-like morphology with obvious lattice stripes on the surface. The lattice spacing is 0.369 nm, and the (200) crystal plane is exposed. Figure 4 The presence of Cu particles can be directly observed in a, with a lattice spacing of 0.225 nm, consistent with the (111) crystal plane. Figure 4 b and Figure 4 In step c, a surface scan of the Pt1-7Cu / NR-WO3 catalyst surface revealed that Pt and Cu were isolated active sites, demonstrating that Pt and Cu were perfectly introduced onto the WO3 support.

[0119] from Figure 5 As can be seen, the methanol yield increases with increasing Cu loading, and the methanol yield reaches its highest value of 21.2 mmol g when the Cu content is 7 wt%. -1 h -1 As the Cu loading was further increased, the methanol yield decreased. When the Cu loading was 10 wt%, the methanol yield was 10.4 mmol g. -1 h -1 . Figure 6 As can be seen, the catalysts of Comparative Examples 5-9 exhibited very low methanol yields compared to Examples 6-10.

[0120] The hydrogenation of DMC to methanol often produces byproducts such as CO and CO2. It can be seen that any catalyst exhibits high selectivity for methanol, exceeding 99%. This demonstrates that the bimetallic supported tungsten oxide catalyst in Examples 6-10 (Pt1-mCu / NR-WO3) not only demonstrates high selectivity in the hydrogenation of DMC to methanol but also significantly improves the methanol yield.

[0121] In summary, the Pt1-mCu / NR-WO3 supported bimetallic active site catalyst provided by the application can effectively catalyze the hydrogenation reaction for preparing methanol, has high selectivity and conversion rate, and Pt is distributed in the form of single atoms on the carrier, the loading amount is very low, the cost is reduced, and the application is suitable for production and promotion.

[0122] The above merely provides the preferred embodiments of the application, but should not be used to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. The application of a supported CuPt bimetallic active site catalyst, characterized in that: The supported CuPt bimetallic active site catalyst is used in the reaction of hydrogenation to prepare methanol; the supported CuPt bimetallic active site catalyst includes a tungsten oxide nanorod support, on which Pt in single-atom form and Cu in particulate form are loaded; the loading amount of Pt is 0.009~0.011wt%, and the loading amount of Cu is 0.2~10wt%.

2. The application of the supported CuPt bimetallic active site catalyst according to claim 1, characterized in that, The preparation method of the supported CuPt bimetallic active site catalyst includes the following steps: (1) Preparation of NR-WO3 vector: Tungstate was prepared into a suspension, and then acid was added to the suspension. The mixture was refluxed at 80-90°C for 0.5-2 hours. The precipitate after the reaction was then taken and subjected to a hydrothermal reaction at 150-180°C for 10-15 hours. The mixture was then centrifuged, filtered, washed, and dried to obtain the NR-WO3 carrier. (2) Preparation of Pt1 / NR-WO3 catalyst precursor: At room temperature, the NR-WO3 support was uniformly dispersed in the first organic solvent to obtain a suspension. A platinum salt aqueous solution was added dropwise to the suspension and stirred for 1 hour. Then, the first organic solvent was removed to obtain a solid powder. The powder was then heated to 350°C in a H2 / Ar mixture with a hydrogen gas fraction of 5% and calcined for 2 hours to obtain the Pt1 / NR-WO3 catalyst precursor. (3) Preparation of Pt1-mCu / NR-WO3 catalyst: At room temperature, the Pt1 / NR-WO3 precursor was uniformly dispersed in a second organic solvent to obtain a suspension. A copper salt aqueous solution was added dropwise to the suspension and stirred for 1 h. The second organic solvent was then removed to obtain a solid powder, which was then heated to 350 °C and calcined for 2 h in an H2 / Ar mixture with a hydrogen integral of 5% to obtain the Pt1-mCu / NR-WO3 catalyst, where m is the loading of metallic copper.

3. The application of the supported CuPt bimetallic active site catalyst according to claim 2, characterized in that: The tungstate is (NH4). 10 W 12 O 41 The concentration of the suspension prepared from ·5H₂O is 62.5 mmol / L; the acid is nitric acid with a concentration of 2.5 mol / L; the nitric acid reacts with (NH₄)₂. 10 W 12 O 41 The molar ratio of ·5H2O is 10:

1.

4. The application of the supported CuPt bimetallic active site catalyst according to claim 2, characterized in that, The platinum salt aqueous solution is a platinum nitrate aqueous solution with a platinum ion concentration of 5 mg / mL, and the mass ratio of platinum nitrate to NR-WO3 carrier in the mixed system is 0.01:100; the copper salt aqueous solution is a copper nitrate aqueous solution with a copper ion concentration of 5 mg / mL; the first organic solvent and the second organic solvent are both ethanol.

5. The application of the supported CuPt bimetallic active site catalyst according to claim 2, characterized in that: The heating described in steps (2) and (3) is carried out at a rate of 5°C / min.

6. The application of the supported CuPt bimetallic active site catalyst according to claim 1, characterized in that, The hydrogenation reaction to prepare methanol is a reaction of CO2 hydrogenation to prepare methanol, including the following steps: Using Pt1-mCu / NR-WO3 as a catalyst, tetrahydrofuran as a solvent, and a mixture of CO2:H2 with a volume ratio of 1:3 as the synthesis gas, the reaction was carried out at 2 MPa and 100 °C for 5 h to obtain the product.

7. The application of the supported CuPt bimetallic active site catalyst according to claim 6, characterized in that: The Cu loading on the Pt1-mCu / NR-WO3 catalyst is 1 wt%.

8. The application of the supported CuPt bimetallic active site catalyst according to claim 1, characterized in that, The hydrogenation reaction to prepare methanol is the hydrogenation reaction of DMC to prepare methanol, including the following steps: (1) Disperse the Pt1-mCu / NR-WO3 catalyst in a reaction flask containing 2 mL of DMC, and transfer it to a 500 mL autoclave, and wash it three times with 1 MPa H2; (2) Stir the reaction in a 1MPa H2 atmosphere for 2 hours at a reaction temperature of 80℃ to obtain the product.

9. The application of the supported CuPt bimetallic active site catalyst according to claim 8, characterized in that: The Cu loading on the Pt1-mCu / NR-WO3 catalyst is 7 wt%.

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