A surface-hydroxylated copper-zirconium-based solid solution catalyst, and a preparation method and application thereof

Abstract

This invention relates to a surface-hydroxylated copper-zirconium-based solid solution catalyst, its preparation method, and its application. The copper-zirconium-based solid solution catalyst comprises a Cu1ZrOx solid solution catalyst or a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The Cu1ZrOx solid solution catalyst comprises a ZrO2 support and Cu single atoms supported on the ZrO2 support. The metal oxide MOx-modified Cu1ZrOx solid solution catalyst comprises a ZrO2 support, Cu single atoms supported on the ZrO2 support, and metal oxide MOx supported on the surface of the Cu1ZrOx. The metal element M in the metal oxide MOx includes Mn or Zn. The surface hydroxyl concentration of the surface-hydroxylated copper-zirconium-based solid solution catalyst is 10-15 μmol / g. The catalyst of this invention can promote the adsorption and activation of CO2, improve methanol selectivity and space-time yield, and thus enhance the performance of CO2 hydrogenation to methanol reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a surface-hydroxylated copper-zirconium-based solid solution catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, due to its high energy density, clean renewability, and zero carbon emissions, is considered an important carrier for building a low-carbon energy system. Producing hydrogen through water electrolysis using renewable electricity enables the efficient conversion of electrical energy into chemical energy, thus achieving deep integration of renewable energy and chemical fuel systems. However, hydrogen faces challenges in storage and transportation, including high safety risks, low volumetric energy density, and high infrastructure construction costs, severely hindering its large-scale application in energy systems.

[0003] To overcome the aforementioned challenges, storing hydrogen energy as a liquid chemical through chemical conversion has become a highly sought-after solution in recent years. Methanol (CH3OH), with its high volumetric energy density, room-temperature liquid state, ease of storage and transportation, recyclability, and wide range of downstream applications (such as fuel cells, olefin production, and fine chemical synthesis), is considered an ideal "liquid solar fuel" and "hydrogen energy carrier." By hydrogenating renewable hydrogen with captured carbon dioxide (CO2) to methanol under the action of a catalyst, not only can carbon cycling and hydrogen energy storage be organically combined, but greenhouse gas emissions can also be effectively reduced. Therefore, developing efficient, stable, and controllable catalysts for CO2 hydrogenation to methanol has become a key issue in achieving green energy conversion and the high-value utilization of carbon resources.

[0004] Currently, the widely used Cu / ZnO / Al2O3 catalyst in industry exhibits certain activity in the CO2 hydrogenation to methanol reaction, but it still suffers from problems such as low CO2 conversion rate, insufficient methanol selectivity, and easy deactivation at high temperatures. Studies have shown that the performance of Cu-based catalysts is closely related to the concentration of surface hydroxyl groups (-OH) and oxygen vacancies. Hydroxyl groups serve as key sites for CO2 adsorption and intermediate stabilization during the reaction, significantly influencing the reaction pathway and product selectivity. Specifically, the presence of hydroxyl groups promotes the formation of intermediate species such as carbonates, bicarbonates, and formates on the surface, accelerating their conversion to methanol via hydrogen transfer. However, the surface hydroxyl content in traditional Cu-based catalyst systems is difficult to control precisely, and it is prone to irreversible changes under high-temperature reduction or reaction conditions, leading to fluctuations in catalytic performance.

[0005] Therefore, developing a catalyst that can improve the performance of CO2 hydrogenation to methanol reaction has become an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a surface-hydroxylated copper-zirconium-based solid solution catalyst, its preparation method and application. This catalyst can promote the adsorption and activation of CO2, improve methanol selectivity and space-time yield, and thus enhance the performance of CO2 hydrogenation to methanol reaction.

[0007] To achieve the above objectives, the first aspect of the present invention provides a surface-hydroxylated copper-zirconium-based solid solution catalyst, wherein the copper-zirconium-based solid solution catalyst comprises a Cu1ZrOx solid solution catalyst or a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The Cu1ZrOx solid solution catalyst comprises a ZrO2 support and Cu single atoms supported in the ZrO2 support; The metal oxide MOx modified Cu1ZrOx solid solution catalyst comprises a ZrO2 support, Cu single atoms supported in the ZrO2 support, and a metal oxide MOx supported on the surface of the Cu1ZrOx. The metal element M in the metal oxide MOx includes Mn or Zn; The surface hydroxyl concentration of the surface-hydroxylated copper-zirconium-based solid solution catalyst is 10-15 μmol / g.

[0008] Optionally, in the metal oxide MOx modified Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.1%≤Cu / (Cu+Zr+M)≤2%; in the Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.5%≤Cu / (Cu+Zr)≤15%.

[0009] A second aspect of the present invention provides a method for preparing a surface-hydroxylated copper-zirconium-based solid solution catalyst provided in the first aspect of the present invention, the preparation method comprising: The copper-zirconium-based solid solution catalyst was subjected to surface hydroxylation treatment under water vapor induced conditions; The copper-zirconium based solid solution catalyst includes Cu1ZrOx solid solution catalyst or Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The conditions for the surface hydroxylation treatment include: a treatment temperature of 50-120℃, a treatment time of 10-24 h, and a heating rate of 2-10℃ / min.

[0010] Optionally, the water vapor induction method includes one or more of water vapor spraying, bubbling, and immersion.

[0011] Optionally, the preparation method further includes: Cu salt and Zr salt are dissolved in deionized water to form solution A, and a precipitant is dissolved in deionized water to form solution B; the molar ratio of Cu salt, Zr salt and precipitant is 1:(15-20):(30-35); Solution A and solution B are simultaneously added dropwise to deionized water at a first temperature to obtain a suspension; the dropping rate of solution A and solution B is 0.1-3 mL / min. The suspension was aged at a second temperature, and a precipitate was obtained after cooling. The precipitate was separated, dried, and subjected to a first calcination to obtain the Cu1ZrOx solid solution catalyst.

[0012] Optionally, the Cu salt and Zr salt include one or more of nitrates, acetates, halides, and sulfates.

[0013] Optionally, the precipitant includes one or more of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0014] Optionally, the conditions for the first calcination include: the calcination atmosphere being one or more of air, oxygen, and nitrogen; the calcination temperature being 400-600 ℃; the calcination time being 3-5 h; and the heating rate being 2-10 ℃ / min.

[0015] Optionally, the first temperature and the second temperature are each independently 50-90°C, and the aging time is 1-5 h.

[0016] Optionally, the preparation method further includes: The Cu1ZrOx solid solution catalyst was mixed and ground with a metal M salt, and then subjected to a second calcination to obtain a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The mass ratio of the Cu1ZrOx solid solution catalyst to the metal M salt is 1:(0.01-0.2).

[0017] Optionally, the metal M salt includes Mn salt or Zn salt; the Mn salt and Zn salt include one or more of nitrate, acetate, halide, and sulfate. Optionally, the mixing and grinding time is 0.1-2 h.

[0018] Optionally, the conditions for the second calcination include: the calcination atmosphere being one or more of air, oxygen, and nitrogen; the calcination temperature being 300-500 ℃; the calcination time being 0.5-10 h; and the heating rate being 2-10 ℃ / min.

[0019] The third aspect of this invention provides the application of the surface-hydroxylated copper-zirconium-based solid solution catalyst provided in the first aspect of this invention or the surface-hydroxylated copper-zirconium-based solid solution catalyst obtained by the preparation method provided in the second aspect of this invention in the reaction of carbon dioxide hydrogenation to methanol, wherein the reaction pressure is 2-5 MPa, the reaction temperature is 200-340 °C, and the reaction space velocity is 6000-24000 mL / (gh). -1 The ratio of raw material gas n(H2):n(CO2) is 3:1.

[0020] Optionally, before carrying out the carbon dioxide hydrogenation to methanol reaction, the surface-hydroxylated copper zirconium-based solid solution catalyst is subjected to reduction and activation treatment. The conditions for the reduction and activation treatment include: the reducing atmosphere is hydrogen or a mixture of hydrogen and an inert gas, the inert gas being selected from nitrogen or argon; the flow rate of the reducing gas is 2-30 mL / min; the reduction temperature is 300-400℃; the heating rate is 1-10℃ / min; the pressure is atmospheric pressure; and the reduction time is 1-5 h.

[0021] Through the above technical solution, in the copper-zirconium based solid solution catalyst of the present invention, Cu exists in the form of single atoms and is stably dispersed in the ZrO2 support to form a solid solution, which avoids the problem of easy sintering and deactivation of traditional Cu-based catalysts during the reaction process; by performing surface hydroxylation treatment on the copper-zirconium based solid solution catalyst, the appropriate hydroxyl content can significantly promote the adsorption and activation of CO2, and improve the methanol selectivity and space-time yield.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 XRD patterns of Cu1ZrOx single-atom solid solution catalyst and its dehydroxylated and hydroxylated treatments; Figure 2 Comparison of surface hydroxyl concentration after dehydroxylation and hydroxylation treatment of Cu1ZrOx single-atom solid solution catalyst; Figure 3 In-situ infrared images of Cu1ZrOx single-atom solid solution catalysts after dehydroxylation and hydroxylation treatment; Figure 4 A comparison of the performance of Cu1ZrOx single-atom solid solution catalysts after dehydroxylation and hydroxylation treatments; Figure 5The space-time yield (STY) diagrams are for Cu1ZrOx single-atom solid solution catalysts and after dehydroxylation and hydroxylation treatments. Figure 6 The image shows a comparison of the performance of Mn-Cu1ZrOx and Zn-Cu1ZrOx catalysts after dehydroxylation and hydroxylation treatments. Figure 7 The space-time yield (STY) diagrams are for Mn-Cu1ZrOx, Zn-Cu1ZrOx catalysts, and both after dehydroxylation and hydroxylation treatments. Figure 8 X-ray absorption spectra (XANES and EXAFS) of Cu1ZrOx single-atom solid solution catalyst and Cu k-edge after dehydroxylation and hydroxylation treatment. Figure 9 Aberration-corrected transmission electron microscope image of Cu1ZrOx single-atom solid solution catalyst after dehydroxylation and hydroxylation treatment. Detailed Implementation

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] The first aspect of this invention provides a surface-hydroxylated copper-zirconium-based solid solution catalyst, wherein the copper-zirconium-based solid solution catalyst includes a Cu1ZrOx solid solution catalyst or a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The Cu1ZrOx solid solution catalyst comprises a ZrO2 support and Cu single atoms supported in the ZrO2 support; The metal oxide MOx modified Cu1ZrOx solid solution catalyst comprises a ZrO2 support, Cu single atoms supported in the ZrO2 support, and a metal oxide MOx supported on the surface of the Cu1ZrOx. The metal element M in the metal oxide MOx includes Mn or Zn; The surface hydroxyl concentration of the surface-hydroxylated copper-zirconium-based solid solution catalyst is 10-15 μmol / g.

[0026] The surface hydroxyl concentration of Cu1ZrO is the determining factor in this invention. x The key factor in the performance of single-atom solid solution catalysts for CO2 hydrogenation to methanol is that surface hydroxyl groups can act as basic sites to promote the adsorption of acidic CO2 molecules. Increasing the concentration of surface hydroxyl groups can effectively enhance the catalyst's adsorption and activation capacity for CO2, thereby improving CO2 conversion and methanol yield.

[0027] According to the present invention, optionally, in the metal oxide MOx modified Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.1%≤Cu / (Cu+Zr+M)≤2%; in the Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.5%≤Cu / (Cu+Zr)≤15%.

[0028] The above-mentioned proportions of the present invention can, on the one hand, ensure that Cu does not aggregate to form nanoparticles, but is stably dispersed in the ZrO2 support in the form of single atoms to form a solid solution, ensuring sufficient active site density and achieving effective catalytic performance; on the other hand, the catalyst can maintain the t-ZrO2 crystal structure and Cu single-atom coordination environment unchanged during the dehydroxylation and hydroxylation treatment, forming a stable solid solution structure.

[0029] A second aspect of the present invention provides a method for preparing a surface-hydroxylated copper-zirconium-based solid solution catalyst provided in the first aspect of the present invention, the preparation method comprising: The copper-zirconium-based solid solution catalyst was subjected to surface hydroxylation treatment under water vapor induced conditions; The copper-zirconium based solid solution catalyst includes Cu1ZrOx solid solution catalyst or Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The conditions for the surface hydroxylation treatment include: a treatment temperature of 50-120℃, a treatment time of 10-24 h, and a heating rate of 2-10℃ / min.

[0030] According to the present invention, optionally, the water vapor induction method includes one or more of water vapor spraying, bubbling, and immersion; the water vapor induction can be carried out in a tubular furnace or a double-row tube.

[0031] According to the present invention, optionally, the water vapor spraying method is to spray water into the reactor in the form of a mist; the bubbling method is to allow the carrier gas to pass through liquid water and carry water vapor into the reactor; the wetting method is to directly contact the catalyst with liquid water or saturated water vapor.

[0032] According to the present invention, optionally, the preparation method further includes: Cu salt and Zr salt are dissolved in deionized water to form solution A, and a precipitant is dissolved in deionized water to form solution B; the molar ratio of Cu salt, Zr salt and precipitant is 1:(15-20):(30-35); Solution A and solution B are simultaneously added dropwise to deionized water at a first temperature to obtain a suspension; the dropping rate of solution A and solution B is 0.1-3 mL / min. The suspension was aged at a second temperature, and a precipitate was obtained after cooling. The precipitate was separated, dried, and subjected to a first calcination to obtain the Cu1ZrOx solid solution catalyst.

[0033] According to the present invention, optionally, the Cu salt or Zr salt includes one or more of nitrates, acetates, halides, and sulfates.

[0034] According to the present invention, optionally, the precipitant includes one or more of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0035] According to the present invention, optionally, the roasting includes static roasting or roasting in a flowing atmosphere, and the roasting equipment includes a muffle furnace or a tube furnace. The conditions for the first roasting include: the roasting atmosphere is one or more of air, oxygen, and nitrogen, the roasting temperature is 400-600 ℃, the roasting time is 3-5 h, and the heating rate is 2-10 ℃ / min.

[0036] According to the present invention, optionally, the first temperature and the second temperature are each independently 50-90°C, and the aging time is 1-5 hours. The first temperature and the second temperature are maintained by water bath heating.

[0037] According to the present invention, optionally, the drying temperature is 80-150°C and the drying time is 4-24h.

[0038] According to the present invention, optionally, the preparation method further includes: The Cu1ZrOx solid solution catalyst was mixed and ground with a metal M salt, and then subjected to a second calcination to obtain a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The mass ratio of the Cu1ZrOx solid solution catalyst to the metal M salt is 1:(0.01-0.2).

[0039] According to the present invention, optionally, the metal M salt includes a Mn salt or a Zn salt; the Mn salt and Zn salt include one or more of nitrates, acetates, halides, and sulfates; According to the present invention, optionally, the mixing and grinding time is 0.1-2 h.

[0040] According to the present invention, optionally, the conditions for the second calcination include: the calcination atmosphere being one or more of air, oxygen, and nitrogen; the calcination temperature being 300-500 °C; the calcination time being 0.5-10 h; and the heating rate being 2-10 °C / min.

[0041] According to the present invention, optionally, for comparison, the present invention further performs a dehydroxylation treatment on the copper-zirconium-based solid solution catalyst. The dehydroxylation treatment is carried out by calcination in an inert atmosphere. The calcination equipment includes a muffle furnace or a tube furnace. The calcination atmosphere is one or more of nitrogen, argon, and helium. The calcination temperature is 400-800℃, the calcination time is 10-24 h, and the heating rate is 2-10℃ / min.

[0042] The third aspect of this invention provides the application of the surface-hydroxylated copper-zirconium-based solid solution catalyst provided in the first aspect of this invention or the surface-hydroxylated copper-zirconium-based solid solution catalyst obtained by the preparation method provided in the second aspect of this invention in the reaction of carbon dioxide hydrogenation to methanol, wherein the reaction pressure is 2-5 MPa, the reaction temperature is 200-340 °C, and the reaction space velocity is 6000-24000 mL / (gh). -1 The ratio of raw material gas n(H2):n(CO2) is 3:1.

[0043] According to the present invention, optionally, the surface-hydroxylated copper zirconium-based solid solution catalyst is subjected to reduction and activation treatment before the reaction of carbon dioxide hydrogenation to methanol is carried out. The conditions for the reduction and activation treatment include: the reducing atmosphere is hydrogen or a mixture of hydrogen and an inert gas, the inert gas being selected from nitrogen or argon; the flow rate of the reducing gas is 2-30 mL / min; the reduction temperature is 300-400℃; the heating rate is 1-10℃ / min; the pressure is atmospheric pressure; and the reduction time is 1-5 h.

[0044] The present invention has the following beneficial effects through the technical solution shown: (1) This invention successfully prepared Cu1ZrO x The single-atom solid solution catalyst uses Cu to form a stable solid solution in a ZrO2 support in the form of single atoms, which avoids the problem of sintering and deactivation that is common in traditional Cu-based catalysts during the reaction process.

[0045] (2) This invention improves the carbon dioxide conversion rate and methanol yield in the carbon dioxide hydrogenation reaction by increasing the hydroxyl content on the surface of the copper-zirconium-based solid solution catalyst. Furthermore, the process of increasing the hydroxyl content on the surface of the copper-zirconium-based solid solution catalyst does not alter the main crystal structure of the catalyst or the dispersion state of Cu single atoms, thus ensuring the stability of the catalyst. The catalyst treated with surface hydroxylation exhibits excellent catalytic performance in the carbon dioxide hydrogenation to methanol reaction.

[0046] (3) The surface hydroxyl group regulation method proposed in this invention is also applicable to Cu1ZrO modified with MOx metal oxides (Mn, Zn). x The catalyst system has good versatility and application value.

[0047] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0048] Example 1 This example illustrates the preparation of a Cu1ZrOx single-atom solid solution catalyst: Weigh 0.0997 g Cu(NO3)2·3H2O and 2.2349 g Zr(NO3)2·5H2O into a 500 mL beaker, add 200 mL of deionized water, and stir until dissolved (solution A). Separately weigh 1.2683 g (NH3)2CO3 into a 500 mL beaker, add 500 mL of deionized water, and stir until dissolved (solution B). Slowly add solutions A and B simultaneously to a round-bottom flask containing 100 mL of deionized water. Under 80 ℃ water bath heating, use magnetic stirring at 600 rpm and a dropping rate of 0.3 mL / min. After the addition is complete, maintain the 80 ℃ water bath condition and allow to stand for 2 h. Then cool to room temperature and centrifuge at 10000 rpm for 5 min to obtain a blue gel solid. Wash three times with deionized water and dry in an oven at 110 ℃ for 12 h. The obtained blue solid was ground into powder in an agate mortar. The blue powder precursor was weighed and calcined in a muffle furnace. The calcination temperature was 500℃, the calcination time was 3 h, and the heating rate was 2℃ / min. The blue catalyst obtained after calcination was denoted as Cu1ZrOx.

[0049] In this embodiment, the atomic percentage of Cu atoms in the catalyst is Cu / (Cu+Zr)=7%.

[0050] Example 2 This embodiment describes the surface hydroxylation treatment of the Cu1ZrOx solid solution catalyst obtained in Example 1. Specifically, the catalyst was prepared using the Cu1ZrOx catalyst from Example 1 as a precursor. 0.2 g of Cu1ZrOx catalyst was spread evenly in a ceramic boat. Water vapor was introduced into a tube furnace under normal pressure by bubbling. The temperature was increased from room temperature to 60°C at a rate of 2°C / min for 12 h. The resulting catalyst was designated Cu1ZrOx-OH, and the surface hydroxyl concentration of the catalyst was 13.6 μmol / g.

[0051] Example 3 This example illustrates the preparation of a MnOx-modified Cu1ZrOx solid solution catalyst: The 0.2 g Cu1ZrOx and 0.0026 g Mn(NO3)2·xH2O obtained in Example 1 were thoroughly mixed and ground in a mortar for 30 min. The mixture was then calcined in a muffle furnace at a heating rate of 2 °C / min from room temperature to 500 °C for 2 h. The resulting catalyst was designated Mn-Cu1ZrOx. The Cu atoms in Mn-Cu1ZrOx accounted for 2% of the total metal atoms.

[0052] Example 4 In this embodiment, the Mn-Cu1ZrOx solid solution catalyst obtained in Example 3 was subjected to surface hydroxylation treatment. The hydroxylation treatment process was the same as in Example 2, and the resulting catalyst was Mn-Cu1ZrOx-OH.

[0053] Example 5 This example illustrates the preparation of a ZnOx-modified Cu1ZrOx solid solution catalyst: The 0.2 g Cu1ZrOx and 0.0033 g Zn(NO3)2·6H2O obtained in Example 1 were thoroughly mixed and ground in a mortar for 30 min. The mixture was then calcined in a muffle furnace at a heating rate of 2 °C / min from room temperature to 500 °C for 2 h. The resulting catalyst was designated Zn-Cu1ZrOx. The Cu atoms in Zn-Cu1ZrOx accounted for 2% of the total metal atoms.

[0054] Example 6 In this embodiment, the Zn-Cu1ZrOx solid solution catalyst obtained in Example 5 was subjected to surface hydroxylation treatment. The hydroxylation treatment process was the same as in Example 2, and the resulting catalyst was Zn-Cu1ZrOx-OH.

[0055] Comparative Examples 1-3 Comparative Examples 1-3 involved the dehydroxylation treatment of the Cu1ZrOx solid solution catalyst, Mn-Cu1ZrOx solid solution catalyst, and Zn-Cu1ZrOx solid solution catalyst obtained in Examples 1, 3, and 5, respectively. Specifically, 0.2 g of Cu1ZrOx, Mn-Cu1ZrOx, and Zn-Cu1ZrOx catalysts were spread evenly in a ceramic boat and treated in a tube furnace under normal pressure and N2 conditions, with the temperature increased from room temperature to 500 °C at a heating rate of 5 °C / min for 10 h. The resulting catalysts were designated as Cu1ZrOx-De, Mn-Cu1ZrOx-De, and Zn-Cu1ZrOx-De, respectively, and the surface hydroxyl concentration of the catalysts was 1.5 μmol / g.

[0056] Test case The catalysts of the examples and comparative examples were subjected to XRD, X-ray absorption spectroscopy, aberration transmission electron microscopy, surface hydroxyl concentration, in-situ infrared spectroscopy, and catalytic performance tests. The results are as follows: Figure 1-9 As shown, where, Catalytic performance testing: The catalyst was compressed (8 MPa, 5 min), crushed, and screened to a 40-60 mesh size for catalytic performance evaluation. 0.1 g of the screened catalyst was weighed and loaded into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 350℃ for 3 h in pure H2 at atmospheric pressure and a flow rate of 30 mL / min. Then, a feed gas with n(H2):n(CO2) = 3 was introduced, and the reaction was carried out at 5 MPa, 280-340℃, and GWSV = 24000 mL / (gh). -1 Catalytic performance was evaluated under the following conditions.

[0057] Surface hydroxyl concentration: determined by Grignard reagent titration of magnesium methyl bromide. The concentration of hydroxyl on the catalyst surface can be calculated by analyzing the yield of methane products collected from the reaction by gas chromatography.

[0058] The XRD patterns of the catalysts obtained in Comparative Example 1, Example 2, and Comparative Example 1 are shown below. Figure 1 As shown, the characteristic peaks of t-ZrO2 can be observed in the XRD pattern, proving that the bulk phase structure of the Cu1ZrOx catalyst solid solution support is t-ZrO2. Meanwhile, no obvious Cu diffraction peaks are observed in the XRD pattern, indicating that the Cu metal species are well dispersed and that the dehydroxylation and surface hydroxylation processes do not cause changes in the catalyst phase structure.

[0059] Figure 8 X-ray absorption spectra (XANES and EXAFS) of Cu1ZrOx single-atom solid solution catalyst and Cu k-edge after dehydroxylation and hydroxylation treatment. Figure 9 These are aberration-corrected transmission electron microscope (TEM) images of Cu1ZrOx single-atom solid solution catalyst after dehydroxylation and hydroxylation treatment. Figure 9 A is the Cu1ZrOx-De catalyst after dehydroxylation treatment. Figure 9 B is a Cu1ZrOx-OH catalyst after hydroxylation treatment. (The rest of the text appears to be incomplete and requires further context.) Figure 8 and Figure 9 As can be seen, this embodiment successfully prepared Cu1ZrOx single-atom solid solution catalyst. The isolated dispersion state of Cu atoms can be directly observed, and Cu exists in single-atom form on the ZrO2 support without Cu-Cu bonds.

[0060] Comparing the surface hydroxyl concentrations of the catalysts obtained in Example 2 and Comparative Example 1, such as Figure 2 As shown, only trace amounts of hydroxyl species exist on the Cu1ZrOx-De surface, while a large number of hydroxyl species exist on the Cu1ZrOx-OH surface.

[0061] In-situ infrared spectroscopy was used to monitor the changes in hydroxyl species content during the dehydroxylation and hydroxylation processes of Cu1ZrOx in real time, such as... Figure 3 As shown, the dehydroxylation and hydroxylation process provided by the present invention can effectively control the surface hydroxyl concentration of Cu1ZrOx.

[0062] The catalysts obtained in the examples and comparative examples were used in the carbon dioxide hydrogenation to methanol reaction, and their catalytic activities were compared. The test results are shown below. Figure 4 , Figure 5 , Figure 6 and Figure 7 .

[0063] The catalytic performance of Cu1ZrOx single-atom solid solution catalyst and catalysts after dehydroxylation and hydroxylation treatments were compared. The test results are shown in [Table missing]. Figure 4 and Figure 5 Compared to Cu1ZrOx, the Cu1ZrOx-OH catalyst with surface hydroxylation treatment showed a significantly improved carbon dioxide conversion capacity, while the Cu1ZrOx-De catalyst, which has almost no hydroxyl groups on its surface, showed a significantly decreased carbon dioxide conversion capacity. Comparing their methanol yields, the space-time yield of Cu1ZrOx-OH was approximately three times that of Cu1ZrOx-De, demonstrating that the presence of surface hydroxyl species can effectively promote carbon dioxide conversion and methanol product formation.

[0064] To investigate the applicability of this surface hydroxyl modulation method to other catalyst systems, this invention compared the catalytic performance of Mn-Cu1ZrOx-De, Mn-Cu1ZrOx-OH, Zn-Cu1ZrOx-De, and Zn-Cu1ZrOx-OH catalysts. The test results are shown in […]. Figure 6 and Figure 7 Compared to the dehydroxylated catalysts Mn-Cu1ZrOx-De and Zn-Cu1ZrOx-De, the hydroxylated catalysts Mn-Cu1ZrOx-OH and Zn-Cu1ZrOx-OH show significantly improved carbon dioxide conversion and methanol space-time yield, demonstrating that the surface hydroxyl concentration control method provided by this invention has the potential for application in other catalyst systems and reaction systems.

[0065] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0067] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A surface-hydroxylated copper-zirconium-based solid solution catalyst, characterized by, The copper-zirconium based solid solution catalyst includes Cu1ZrOx solid solution catalyst or Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The Cu1ZrOx solid solution catalyst comprises a ZrO2 support and Cu single atoms supported in the ZrO2 support; The metal oxide MOx modified Cu1ZrOx solid solution catalyst includes a ZrO2 support, Cu single atoms supported in the ZrO2 support, and a metal oxide MOx supported on the surface of the Cu1ZrOx. The metal element M in the metal oxide MOx includes Mn or Zn; The surface hydroxyl concentration of the surface-hydroxylated copper-zirconium-based solid solution catalyst is 10-15 μmol / g.

2. The copper-zirconium based solid solution catalyst according to claim 1, wherein, In the metal oxide MOx modified Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.1%≤Cu / (Cu+Zr+M)≤2%; In the Cu1ZrOx solid solution catalyst, the atomic percentage of Cu atoms in the total metal atoms is 0.5%≤Cu / (Cu+Zr)≤15%.

3. A method for preparing a surface-hydroxylated copper-zirconium-based solid solution catalyst as described in claim 1 or 2, characterized in that, The preparation method includes: The copper-zirconium-based solid solution catalyst was subjected to surface hydroxylation treatment under water vapor-induced conditions; The copper-zirconium based solid solution catalyst includes Cu1ZrOx solid solution catalyst or Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The conditions for the surface hydroxylation treatment include: a treatment temperature of 60-120℃, a treatment time of 10-24 h, and a heating rate of 2-10℃ / min.

4. The preparation method according to claim 3, wherein, The water vapor induction method includes one or more of water vapor spraying, bubbling, and immersion.

5. The preparation method according to claim 3, wherein, The preparation method further includes: Cu salt and Zr salt are dissolved in deionized water to form solution A, and a precipitant is dissolved in deionized water to form solution B; the molar ratio of Cu salt, Zr salt and precipitant is 1:(15-20):(30-35); Solution A and solution B are simultaneously added dropwise to deionized water at a first temperature to obtain a suspension; the dropping rate of solution A and solution B is 0.1-3 mL / min. The suspension was aged at a second temperature, and a precipitate was obtained after cooling. The precipitate was separated, dried, and subjected to a first calcination to obtain the Cu1ZrOx solid solution catalyst.

6. The preparation method according to claim 5, wherein, The Cu salts and Zr salts include one or more of nitrates, acetates, halides, and sulfates; The precipitant includes one or more of ammonia, ammonium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide. The conditions for the first calcination include: the calcination atmosphere is one or more of air, oxygen, and nitrogen; the calcination temperature is 400-600 ℃; the calcination time is 3-5 h; and the heating rate is 2-10 ℃ / min. The first temperature and the second temperature are each independently 50-90°C, and the aging time is 1-5 h.

7. The preparation method according to claim 5, wherein, The preparation method further includes: The Cu1ZrOx solid solution catalyst was mixed and ground with a metal M salt, and then subjected to a second calcination to obtain a Cu1ZrOx solid solution catalyst modified with metal oxide MOx. The mass ratio of the Cu1ZrOx solid solution catalyst to the metal M salt is 1:(0.01-0.2).

8. The preparation method according to claim 7, wherein, The metal M salt includes Mn salt or Zn salt; the Mn salt and Zn salt include one or more of nitrate, acetate, halide, and sulfate. The mixing and grinding time is 0.1-2 h; The conditions for the second calcination include: the calcination atmosphere is one or more of air, oxygen, and nitrogen; the calcination temperature is 300-500 ℃; the calcination time is 0.5-10 h; and the heating rate is 2-10 ℃ / min.

9. The application of a surface-hydroxylated copper-zirconium-based solid solution catalyst according to claim 1 or 2, or a surface-hydroxylated copper-zirconium-based solid solution catalyst obtained by any one of claims 3-8, in the reaction of carbon dioxide hydrogenation to methanol, characterized in that, The reaction pressure is 2-5 MPa, the reaction temperature is 200-340 ℃, and the reaction space velocity is 6000-24000 mL / (gh). -1 The ratio of raw material gas n(H2):n(CO2) is 3:

1.

10. The application according to claim 9, characterized in that, Before carrying out the carbon dioxide hydrogenation to methanol reaction, the surface-hydroxylated copper zirconium-based solid solution catalyst is subjected to reduction and activation treatment. The conditions for the reduction and activation treatment include: the reducing atmosphere is hydrogen or a mixture of hydrogen and an inert gas, the inert gas being selected from nitrogen or argon; the flow rate of the reducing gas is 2-30 mL / min; the reduction temperature is 300-400℃; the heating rate is 1-10℃ / min; the pressure is atmospheric pressure; and the reduction time is 1-5 h.

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