A copper-zirconium-magnesium ternary composite oxide reverse phase catalyst, a preparation method and application thereof

Abstract

The application discloses a reverse phase catalyst of copper-zirconium-magnesium ternary composite oxide and a preparation method and application thereof, and the preparation method comprises the following steps: co-precipitating a copper source, a zirconium source and a magnesium source with a precipitant, and performing washing, drying and air calcination to construct a reverse loading structure with copper oxide nanoparticles as a core and an amorphous ZrO2-MgO blending layer as a coating layer. The structure regulates oxygen vacancies through Mg and enhances the synergistic effect of active sites and ZrO2-MgO interfaces. + / Cu 0 The catalyst is used for preparing methanol through carbon dioxide hydrogenation, has high methanol selectivity, methanol space-time yield and long-period running stability under a relatively high gas volume space velocity, and has a simple preparation process and is suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide resource recycling technology, specifically to a reverse-phase catalyst of a copper-zirconium-magnesium ternary composite oxide, its preparation method, and its application in the hydrogenation of carbon dioxide to methanol. Background Technology

[0002] With the continued consumption of fossil fuels and the acceleration of industrialization, the greenhouse effect and ocean acidification caused by carbon dioxide emissions have become significant global environmental and energy issues. Carbon dioxide hydrogenation to methanol technology can convert carbon dioxide into liquid oxygenated fuels and basic chemical feedstocks, combining functions such as carbon capture and utilization, renewable hydrogen storage, and green methanol production, and has important industrial application prospects.

[0003] Copper-based catalysts are widely used in the hydrogenation of carbon dioxide to methanol due to their relatively low cost and good methanol selectivity. However, traditional supported or co-precipitated copper-based catalysts still have significant shortcomings: First, their carbon dioxide activation ability is weak at low temperatures, and insufficient copper dispersion and interfacial active sites result in low methanol space-time yields below 250°C; second, the reverse water-gas shift reaction intensifies upon heating, leading to increased CO byproducts and decreased methanol selectivity; third, copper nanoparticles are prone to sintering, migration, or being covered by byproducts during long-term operation, causing activity degradation.

[0004] CN120227875A discloses a catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method. The catalyst consists of an active component and an auxiliary agent and / or a modifier. The active component is CuO or In₂O₃; the auxiliary agent is one or more of ZnO, ZrO₂, and Al₂O₃; and the modifier is one or more of La₂O₃, Y₂O₃, and CeO₂. The catalyst is prepared using a single-step co-precipitation method, which significantly simplifies the preparation process and reduces costs, has the potential for large-scale production, and can improve CO₂ catalytic efficiency by 1-5% and methanol yield by 1-10%.

[0005] CN114029063A discloses a catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method. The catalyst comprises metallic copper, metallic zinc, metallic zirconium, a metal additive, and carbon materials. The mass fraction of metallic copper is 30%–70%, metallic zinc is 10%–30%, metallic zirconium is 10%–30%, the mass fraction of the metal additive is 1%–10%, and the balance is carbon materials. The metal additive can be selected from at least one of cerium, yttrium, aluminum, gallium, palladium, platinum, magnesium, manganese, and chromium. The carbon materials can be selected from at least one of silicon carbide, carbon nanofibers, activated carbon, carbon nanotubes, graphite fibers, carbon nitride, and carbon-based foam, all with a large specific surface area. This catalyst is suitable for the hydrogenation reaction of carbon dioxide, using carbon dioxide and hydrogen as reactants, achieving a carbon dioxide conversion rate exceeding 25% and a methanol selectivity exceeding 80%. The catalyst preparation method is simple, inexpensive, and exhibits excellent performance, showing broad prospects for industrial application.

[0006] Existing research indicates that the interfacial synergy between copper species and reducible oxide supports plays a crucial role in carbon dioxide adsorption, activation, formate / methoxy intermediate conversion, and methanol desorption. Zirconium oxides can provide oxygen vacancies and stabilize the interface, while magnesium oxides can enhance surface basicity and modulate carbon dioxide adsorption capacity. However, simple mechanical mixing or conventional loading methods cannot simultaneously achieve stable confinement of copper cores, exposure of amorphous oxide interfaces, and synergistic regulation of basic sites / oxygen vacancies.

[0007] Therefore, there is an urgent need to develop a copper-zirconium-magnesium composite oxide catalyst with a simple preparation process, stable structure, and easy scale-up, so that it can have high methanol selectivity, high space-time yield, and long-term anti-sintering stability at a lower temperature. Summary of the Invention

[0008] This invention addresses the problems of insufficient low-temperature activity, decreased methanol selectivity, and poor long-term stability of existing copper-based catalysts by providing a reverse-phase catalyst based on a copper-zirconium-magnesium ternary composite oxide. The introduction of magnesium enhances the interface of this catalyst, which exhibits excellent catalytic performance in the production of methanol from carbon dioxide even at low temperatures, maintaining high methanol selectivity and space-time yield.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a reverse-phase catalyst of a copper-zirconium-magnesium ternary composite oxide includes the following steps: Step 1: Dissolve and mix the copper source, zirconium source and magnesium source to obtain solution A, and dissolve the precipitant to obtain solution B; Step 2: Add solution A to solution B while stirring continuously to obtain a suspension containing precipitate. After washing and solid-liquid separation, obtain a solid precipitate. Step 3: The solid precipitate is dried and then calcined to obtain the reversed catalyst.

[0010] This invention utilizes a one-step co-precipitation combined with calcination to form a highly mixed precursor of copper, zirconium, and magnesium during precipitation. After air calcination, a reverse loading structure is constructed with copper oxide nanoparticles as the core and amorphous ZrO2-MgO as the blended coating layer. This structure differs from the traditional forward loading structure where metallic copper is dispersed on an oxide support surface. Instead, it utilizes the amorphous oxide layer to confine and anchor the copper oxide / copper core, while simultaneously exposing the Cu-Zr-Mg interface sites. Upon introduction of Mg, the ZrO2-MgO blended coating layer simultaneously provides oxygen vacancies and basic sites, promoting CO2 adsorption and activation; the reduced Cu... 0 / Cu + The site and oxygen vacancy interface work synergistically to improve the methanol synthesis rate.

[0011] The copper source, zirconium source, and magnesium source are each independently selected from one or more combinations of nitrates, chlorides, and acetates of the corresponding metals; The solvent for solution A includes one or more of anhydrous ethanol, deionized water, methanol, isopropanol, ethylene glycol, and ethylene glycol monomethyl ether.

[0012] The precipitant includes one or more of oxalic acid, citric acid, ammonium carbonate, sodium carbonate, and urea; the concentration of the precipitant in solution B is 0.05-0.50 mol / L.

[0013] Preferably, the copper source is copper nitrate trihydrate, the zirconium source is zirconium nitrate pentahydrate, the magnesium source is magnesium nitrate hexahydrate; the precipitant is oxalic acid dihydrate; and the solvent is anhydrous ethanol.

[0014] In solution A, the molar ratio of zirconium to copper is 0.05-0.50, and the molar ratio of magnesium to copper is 0.02-0.30. Preferably, the molar ratio of zirconium to copper in solution A is 0.05-0.20, and the molar ratio of magnesium to copper is 0.05-0.20. The addition of the zirconium source facilitates the formation of a zirconium-containing oxide interface on the surface of copper species and provides oxygen vacancies, thereby promoting the adsorption and activation of carbon dioxide. When the molar ratio of zirconium to copper is within this range, the number of copper-zirconium interface sites formed is just right, avoiding the problem of excessive zirconium oxide potentially covering some copper active sites. This has a significant effect on the dispersion and stabilization of copper species and is beneficial for methanol formation.

[0015] When the molar ratio of magnesium to copper is too low, its effect on regulating surface alkalinity and interfacial structure is not obvious. As the magnesium content increases, the methanol selectivity and space-time yield of the catalyst are improved. However, when the molar ratio of magnesium to copper exceeds the appropriate range, excess magnesium species may cover or dilute the copper active sites and change the carbon dioxide adsorption intensity, making it difficult for reaction intermediates to be further converted or desorbed, thereby leading to a decrease in catalytic performance.

[0016] More preferably, the molar ratio of zirconium to copper in solution A is 0.10, and the molar ratio of magnesium to copper is 0.05-0.15. Even more preferably, the molar ratio of magnesium to copper is 0.10. The addition of a magnesium source can regulate the alkalinity and oxygen vacancy environment on the catalyst surface, enhance carbon dioxide adsorption, and promote the synergistic effect between Cu species and the ZrO2-MgO interface. At this ratio, the catalyst exhibits superior catalytic performance.

[0017] The molar ratio of total metal elements in solution A to precipitant in solution B is 1:2-1:5, preferably 1:3-1:4. Insufficient precipitant dosage leads to incomplete metal ion precipitation, potentially causing loss of metal components or deviation from the designed composition. Appropriately increasing the precipitant dosage promotes the simultaneous precipitation of copper, zirconium, and magnesium precursors, forming a uniformly mixed solid precursor. However, excessive precipitant dosage increases the burden of subsequent washing, and residual organic matter or anions may affect precursor decomposition and the pore structure of the catalyst after calcination. Therefore, controlling the molar ratio of total metal elements to precipitant within the range of 1:2-1:5 balances precipitation completeness, component uniformity, and post-processing convenience.

[0018] In step 2, after adding solution A to solution B, continue stirring for 30-60 minutes, or continue stirring for 30-60 minutes and then age at room temperature to 70°C for 0.1-4 hours. In step 2, the washing is performed 2-5 times with anhydrous ethanol and / or deionized water. The solid-liquid separation is performed by centrifugation at a speed of 3000-8000 rpm for 3-10 min.

[0019] In step 3, drying is carried out at 60-100 ℃ for 8-24 h; calcination is carried out at 350-550 ℃ in air atmosphere for 2-6 h.

[0020] Preferably, the calcined product is ground into powder, pressed into tablets, crushed, and sieved to obtain catalyst particles suitable for loading into a fixed-bed reactor; more preferably, catalyst particles of 40-60 mesh are sieved for use in the reaction of carbon dioxide hydrogenation to methanol.

[0021] This invention also provides a reverse-phase catalyst for a copper-zirconium-magnesium ternary composite oxide prepared by the aforementioned method. This catalyst uses 10-50 nm copper oxide nanoparticles as the core, with an amorphous ZrO2-MgO blend coating layer formed on its surface; after reduction, it forms Cu. 0 / Cu +The active sites, in synergy with the oxygen vacancies and basic sites provided by ZrO2-MgO, promote carbon dioxide adsorption activation and methanol generation. HRTEM characterization revealed that lattice fringes matching the corresponding crystal planes of CuO were observed in the catalyst, including one or more of the (111), (-111), (200), (110), (-202), (-311), and (220) crystal planes.

[0022] The present invention also provides the application of the reversed-phase catalyst of the copper-zirconium-magnesium ternary composite oxide in the catalytic hydrogenation of carbon dioxide to methanol reaction.

[0023] The reaction pressure for the carbon dioxide hydrogenation to methanol reaction is 1.0-5.0 MPa, the reaction temperature is 180-300℃, the gas hourly space velocity (VHSV) based on catalyst mass is 20,000-60,000 mL / (g·h), and the molar ratio of H2 to CO2 in the feed gas is 2:1-4:1.

[0024] The preferred reaction temperature is 180-240℃, the volume hourly space velocity is 36,000-57,600 mL / (g·h), and the molar ratio of H2 to CO2 in the feed gas is 3:1.

[0025] In the aforementioned applications, when the catalyst is used for the hydrogenation of carbon dioxide to methanol at a reaction temperature of 180-240 °C, the methanol selectivity is above 90%, and the methanol space-time yield is 0.3 g. MeOH ·g cat -1 ·h -1 The activity decline rate was less than 5% in the long-term stability test.

[0026] The reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide is subjected to in-situ reduction treatment before use. The in-situ reduction treatment is carried out in a hydrogen-containing gas stream at 200-400℃ for 0.5-4 hours. The hydrogen-containing gas stream is pure hydrogen or a 10% H2 / N2 mixture.

[0027] The space-time yield of methanol generally increases with increasing reaction temperature; when the catalyst is used for the hydrogenation of carbon dioxide to methanol at 270-300℃, the space-time yield can reach 3.0 g. MeOH ·g cat -1 ·h -1 above.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) By introducing Mg, this invention constructs an amorphous ZrO2-MgO amorphous layer reverse loading structure. The amorphous coating layer has a spatial confinement and anchoring effect on the copper nucleus, which is beneficial to suppressing the migration and sintering of copper particles during reduction and reaction. The ZrO2-MgO blend coating layer simultaneously provides oxygen vacancies and basic sites, promoting CO2 adsorption and activation; the reduced Cu 0 / Cu + The site and oxygen vacancy interface work synergistically to improve the methanol synthesis rate.

[0029] (2) In the lower temperature range of 180-240 °C, the catalyst of the present invention can maintain high methanol selectivity and space-time yield, and reduce the tendency of side reactions. Moreover, since the amorphous coating layer in the catalyst can suppress the aggregation of copper nuclei, the catalyst is suitable for long-term continuous fixed-bed operation.

[0030] (3) The catalyst preparation process of the present invention uses a common metal salt, oxalic acid and ethanol system. The process includes dissolution, dropwise addition of co-precipitation, washing, drying and calcination. The conditions are mild and easy to scale up industrially. Attached Figure Description

[0031] Figure 1 CuO@a-ZrO2-Mg prepared in Example 1 0.1 XRD pattern of the catalyst.

[0032] Figure 2 CuO@a-ZrO2-Mg prepared in Example 1 0.1 TEM and HRTEM images of the catalyst.

[0033] Figure 3 The Cu 2p and Cu LMM XPS spectra of the catalysts prepared in Examples 1-3 and Comparative Example 1 are shown.

[0034] Figure 4 The O 1s XPS spectra of the catalysts prepared in Examples 1-4 and Comparative Example 1 are shown.

[0035] Figure 5 CuO@a-ZrO2-Mg prepared in Example 1 0.1 Nitrogen adsorption-desorption isotherms and pore size distribution of the catalyst.

[0036] Figure 6 The graph shows a comparison of the activity of the catalysts in Examples 1-3 and Comparative Example 1 for the hydrogenation of carbon dioxide to methanol.

[0037] Figure 7 The graph shows the change in activity of the catalyst prepared in Example 1 for the hydrogenation of carbon dioxide to methanol as a function of temperature.

[0038] Figure 8CuO@a-ZrO2-Mg prepared in Example 1 0.1 Long-term stability test curve of the catalyst in the carbon dioxide hydrogenation to methanol reaction. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0040] All reagents used in the following specific embodiments are commercially available, and all operations without special instructions are performed under normal experimental conditions.

[0041] Example 1: CuO@a-ZrO2-Mg 0.1 Catalyst preparation Step 1: Weigh 20 mmol of copper nitrate trihydrate, 2 mmol of zirconium nitrate pentahydrate, and 2 mmol of magnesium nitrate hexahydrate, add them to anhydrous ethanol, and continuously stir and sonicate for 20 min to completely dissolve them, obtaining a mixed metal salt solution A. Weigh oxalic acid dihydrate and dissolve it in 50 mL of anhydrous ethanol to obtain a precipitant solution B. The molar ratio of total metal cations in solution A to oxalic acid dihydrate in solution B is 1:4.

[0042] Step 2: Under vigorous stirring, solution A is slowly added dropwise to solution B. After the addition is complete, stirring continues for 45 minutes. The resulting suspension is centrifuged at 5000 rpm for 5 minutes, washed three times with anhydrous ethanol, and dried at 60 °C for 12 hours. The dried solid is ground, heated to 400 °C at a rate of 5 °C / min, and calcined for 2 hours. After cooling, it is pressed into tablets and sieved through a 40-60 mesh to obtain CuO@a-ZrO2-Mg. 0.1 Catalyst, its XRD is as follows Figure 1 As shown, by Figure 1 As can be seen, the catalyst of this invention mainly exhibits CuO crystal phase characteristic diffraction peaks, and the position of its diffraction peaks is basically consistent with that of the CuO standard card (PDF#80-1916); no obvious MgO and ZrO2 crystal phase diffraction peaks were observed, indicating that MgO and ZrO2 mainly exist in highly dispersed or amorphous forms.

[0043] TEM and HRTEM, such as Figure 2As shown, the catalyst particles exhibit a near-spherical aggregated structure with a low-contrast coating layer on the periphery. The HRTEM image reveals a lattice spacing of approximately 0.235 nm, corresponding to the CuO(111) crystal plane. These results indicate that after co-precipitation and calcination, a composite oxide structure with CuO as the main component and highly dispersed ZrO2-MgO was formed.

[0044] Example 2 CuO@a-ZrO2-Mg 0.05 Catalyst preparation Following the method in Example 1, magnesium nitrate hexahydrate was adjusted to 1 mmol, so that n Mg / n Cu =0.05, with other conditions remaining unchanged, CuO@a-ZrO2-Mg was obtained. 0.05 catalyst.

[0045] Example 3 CuO@a-ZrO2-Mg 0.15 Catalyst preparation Following the method in Example 1, magnesium nitrate hexahydrate was adjusted to 3 mmol, so that n Mg / n Cu =0.15, with other conditions remaining unchanged, CuO@a-ZrO2-Mg was obtained. 0.15 catalyst.

[0046] Example 4 CuO@a-ZrO2-Mg 0.2 Catalyst preparation Following the method in Example 1, magnesium nitrate hexahydrate was adjusted to 4 mmol, so that n Mg / n Cu =0.20, with other conditions remaining unchanged, CuO@a-ZrO2-Mg was obtained. 0.2 catalyst.

[0047] Example 5 CuO@a-ZrO2-Mg 0.3 Catalyst preparation Following the method in Example 1, magnesium nitrate hexahydrate was adjusted to 6 mmol, so that n Mg / n Cu =0.30, with other conditions remaining unchanged, CuO@a-ZrO2-Mg was obtained. 0.3 catalyst.

[0048] Comparative Example 1: Preparation of Cu-Zr binary catalyst Following the method of Example 1, but without adding magnesium nitrate hexahydrate, and keeping all other conditions the same, a Cu-Zr binary catalyst was obtained. This comparative example is used to illustrate the effect of the introduction of Mg on the valence state distribution of copper species on the catalyst surface, the interfacial structure, and the performance of carbon dioxide hydrogenation to methanol.

[0049] The Cu 2p and Cu LMM XPS spectra of the catalysts prepared in Examples 1-4 and Comparative Example 1 after reduction treatment are shown below. Figure 3 As shown, Cu 2p is present in all samples. 3 / 2 and Cu 2p 1 / 2 Characteristic peaks. Due to Cu 0 and Cu + The binding energies in the Cu 2p spectra are quite similar, and further analysis of the valence state composition of copper species using Cu LMM Auger spectroscopy was conducted. Peak fitting of the Cu LMM spectra revealed the presence of Cu on the surface of each catalyst. 0 and Cu + Species, Cu in catalysts with different magnesium contents + / Cu 0 The relative proportions differ. In Comparative Example 1 and Examples 1-4, Cu... + / Cu 0 The relative peak area ratios were 2.45, 1.94, 2.14, 1.75, and 1.43, respectively. These results indicate that the introduction of Mg and its content variations can regulate the valence state distribution of copper species on the catalyst surface, providing a characterization basis for differences in catalytic performance.

[0050] To further analyze the effect of Mg introduction and its content variation on oxygen species on the catalyst surface, the catalysts prepared in Examples 1-4 and Comparative Example 1 were characterized by O 1s XPS. The results are as follows: Figure 4 As shown. Peak fitting revealed that the O 1s spectrum could be divided into lattice oxygen, oxygen vacancy-related oxygen species, and surface-adsorbed oxygen species. The relative contents of oxygen vacancy-related oxygen species in Comparative Example 1 and Examples 1-4 were 22.81%, 35.14%, 28.98%, 27.70%, and 17.48%, respectively. Compared to Comparative Example 1, the relative content of oxygen vacancy-related oxygen species in Example 1 was significantly increased; as the Mg content further increased, the relative content of oxygen vacancy-related oxygen species gradually decreased. These results indicate that the introduction of an appropriate amount of Mg can regulate the oxygen species and defect structure on the catalyst surface. Example 1 formed a relatively suitable surface defect oxygen environment, providing a characterization basis for the adsorption and activation of carbon dioxide and the performance differences between different catalysts.

[0051] The catalyst prepared in Example 1 was subjected to nitrogen adsorption-desorption tests. Before the test, the catalyst sample was degassed under vacuum to remove adsorbed moisture and other physical adsorbates from the sample surface. Subsequently, the nitrogen adsorption-desorption isotherm of the sample was measured at liquid nitrogen temperature. The specific surface area of ​​the sample was calculated using the BET method, and the pore size distribution was calculated using the BJH method. The test results are as follows: Figure 5As shown in the figure, the nitrogen adsorption-desorption isotherm of the catalyst in Example 1 shows a significant increase in adsorption in the higher relative pressure region, and forms an adsorption-desorption hysteresis loop, indicating that the catalyst has a certain mesoporous structure. The pore size distribution curve shows that the pore size of the catalyst is mainly distributed in the mesoporous range, and its pore size distribution peak is mainly located around 16.8 nm. This pore structure is conducive to the diffusion of reactant gases in the catalyst particles and the exposure of the active interface.

[0052] Application Example 1: Performance Evaluation of Methanol Production via Carbon Dioxide Hydrogenation Catalyst performance was evaluated in a microreactor equipped with a high-pressure fixed-bed reactor. Before each test, 50 mg of catalyst sample was weighed and thoroughly mixed with 200 mg of silicon carbide, and then packed into a quartz reaction tube with an inner diameter of 11 mm. The two ends of the bed were fixed with quartz wool.

[0053] Before the reaction, pure H2 was introduced under normal pressure, and the reduction was carried out in situ at 210 °C for 1 h. After the reduction was completed, the bed temperature was lowered to 180 °C, and the system pressure was adjusted to 4 MPa through the back pressure valve.

[0054] Subsequently, a feed gas was introduced, consisting of 25% CO2 and 75% H2, with a total flow rate of 240 mL / min, corresponding to an H2 / CO2 molar ratio of 3:1 and a mass hourly space velocity (MHSV) of 57,600 mL·g. cat -1 ·h -1 Catalytic activity and selectivity were tested in the range of 180–300 °C with a temperature gradient of 30 °C. Three parallel measurements were performed at each temperature point. After the reaction reached steady state and the baseline stabilized, the products were analyzed by online gas chromatography.

[0055] The online gas chromatograph is equipped with FID and TCD detectors, with a quantitative tube injection volume of 1 mL. Before testing, multi-point calibration is performed using standard gas, and the carrier gas is high-purity helium.

[0056] CO2 conversion, methanol selectivity, and methanol space-time yield were calculated based on the inlet and outlet CO2 molar flow rates, the methanol / carbon monoxide / methane molar fractions in the product gas, and the methanol formation rate, respectively. Examples 1-3 and Comparative Example 1 were tested at 240 °C, 4 MPa, H2 / CO2 = 3:1, and WHSV = 57,600 mL·g. cat -1 ·h -1 The performance evaluation results under the conditions are shown in Table 1 and Figure 6 "-" indicates that a 1000-hour long-term stability test was not conducted. It can be seen that the methanol selectivity of the Cu-Zr binary catalyst prepared in Comparative Example 1 is 80.23%, and the methanol space-time yield is 0.92 g. MeOH ·g cat-1 ·h -1 After the introduction of Mg, the methanol selectivity and methanol space-time yield of the catalysts in Examples 1-3 were improved, indicating that the introduction of Mg is beneficial to improving the performance of the catalysts in the hydrogenation of carbon dioxide to methanol.

[0057] The catalyst prepared in Example 1 exhibited the best catalytic performance, with a methanol selectivity of 90.84% ​​and a methanol space-time yield of 1.91 g. MeOH ·g cat -1 ·h -1 The methanol space-time yields in Examples 2 and 3 were 1.36 and 1.26 g, respectively, which were higher than those in Comparative Example 1. MeOH ·g cat -1 ·h -1 The values ​​were all higher than those of Comparative Example 1, but lower than those of Example 1. These results indicate that the introduction of an appropriate amount of Mg can regulate the valence state of copper species and the defect oxygen environment on the catalyst surface, enhancing the synergistic effect between Cu species and the ZrO2-MgO interface. When the Mg content deviates from the suitable range, the catalytic performance decreases; therefore, a magnesium to copper molar ratio of 0.10 exhibits superior overall catalytic performance.

[0058] Table 1. Activity test results of catalysts in Examples 1-3 and Comparative Example 1 for the hydrogenation of carbon dioxide to methanol. The activity of the catalyst prepared in Example 1 for the hydrogenation of carbon dioxide to methanol changes with temperature as follows: Figure 7 As shown in Table 2, it can be seen that the space-time yield of methanol gradually increases as the reaction temperature increases from 180℃ to 300℃, with the methanol space-time yield decreasing from 0.37 g / L. MeOH ·g cat -1 ·h -1 Increased to 4.39 g MeOH ·g cat -1 ·h -1 Meanwhile, the methanol selectivity decreased from 98.78% to 50.31%. These results indicate that increasing the temperature is beneficial for increasing the methanol formation rate, but at higher temperatures, side reactions such as reverse water-gas shift reaction intensify, leading to a decrease in methanol selectivity. The catalyst in Example 1 exhibits both high methanol selectivity and good methanol formation activity in the temperature range of 180-240℃.

[0059] Table 2. Activity test results of the catalyst prepared in Example 1 for the hydrogenation of carbon dioxide to methanol at different temperatures. Application Example 2: Long-Period Stability Evaluation To verify the deactivation resistance of the catalyst of the present invention under continuous fixed-bed reaction conditions, the Cu-Zr-Mg-0.1 catalyst prepared in Example 1 was selected for a long-term stability test of 1000 h.

[0060] During the test, 50 mg of the catalyst from Example 1 was weighed and thoroughly mixed with 200 mg of silicon carbide, then packed into a fixed-bed quartz reactor. Before the reaction, it was reduced in situ at 210 °C for 1 h under a pure H2 atmosphere. Subsequently, the reaction gas was switched to H2 / CO2 = 3:1, and the reaction temperature was controlled at 240 °C, the reaction pressure at 4 MPa, and the WHSV at 57,600 mL·g. cat -1 ·h -1 It runs continuously for 1000 hours.

[0061] During the test, exhaust gas was collected periodically and analyzed by online gas chromatography for CO2 conversion, methanol selectivity, and methanol space-time yield. The results are shown in Table 1 and... Figure 8 As shown, the catalyst in Example 1 maintained stable methanol production performance during 1000 h of operation, with an activity decrease rate of less than 5%, methanol selectivity maintained above 90% during the test, and methanol space-time yield remained at 1.2 g. MeOH ·g cat -1 ·h -1 The above demonstrates that its amorphous ZrO2-MgO layer reverse loading structure can effectively suppress copper particle sintering and interface deactivation, making it suitable for long-term industrial continuous operation.

[0062] Industrial applicability The catalyst of this invention can be prepared using inexpensive and readily available metal nitrates, oxalic acid, and anhydrous ethanol via a co-precipitation-calcination process. This process requires minimal equipment, is controllable, and is suitable for large-scale production. The resulting catalyst can be used in continuous fixed-bed carbon dioxide hydrogenation to methanol processes, and is applicable to green methanol production, carbon dioxide capture and utilization, renewable energy storage, and low-carbon chemical processes.

Claims

1. A method for preparing a reverse-phase catalyst of a copper-zirconium-magnesium ternary composite oxide, characterized in that, Includes the following steps: Step 1: Dissolve and mix the copper source, zirconium source and magnesium source to obtain solution A, and dissolve the precipitant to obtain solution B; Step 2: Add solution A to solution B while stirring continuously to obtain a suspension containing precipitate. After washing and solid-liquid separation, obtain a solid precipitate. Step 3: The solid precipitate is dried and then calcined to obtain the reversed catalyst.

2. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, The copper source, zirconium source, and magnesium source are each independently selected from one or more combinations of nitrates, chlorides, and acetates of the corresponding metals; The solvent for solution A includes one or more of anhydrous ethanol, deionized water, methanol, isopropanol, ethylene glycol, and ethylene glycol monomethyl ether.

3. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, In solution A, the molar ratio of zirconium to copper is 0.05-0.50, and the molar ratio of magnesium to copper is 0.02-0.

30.

4. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, The precipitant includes one or more of oxalic acid, citric acid, ammonium carbonate, sodium carbonate, and urea; the concentration of the precipitant in solution B is 0.05-0.50 mol / L.

5. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, The molar ratio of total metal elements in solution A to precipitant in solution B is 1:2-1:

5.

6. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, In step 2, after adding solution A to solution B, continue stirring for 30-60 minutes, or continue stirring for 30-60 minutes and then age at room temperature to 70°C for 0.1-4 hours. In step 2, the washing is performed 2-5 times with anhydrous ethanol and / or deionized water. The solid-liquid separation is performed by centrifugation at a speed of 3000-8000 rpm for 3-10 min.

7. The method for preparing the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide according to claim 1, characterized in that, In step 3, drying is carried out at 60-100 ℃ for 8-24 h; calcination is carried out at 350-550 ℃ in air atmosphere for 2-6 h.

8. The reverse-phase catalyst of copper-zirconium-magnesium ternary composite oxide prepared by the preparation method according to any one of claims 1-7.

9. The application of the copper-zirconium-magnesium ternary composite oxide reversed-phase catalyst according to claim 8 in the catalytic hydrogenation of carbon dioxide to methanol reaction.

10. The application according to claim 9, characterized in that, The reaction pressure for the carbon dioxide hydrogenation to methanol reaction is 1.0-5.0 MPa, the reaction temperature is 180-300℃, the mass hourly space velocity is 20,000-60,000 mL / (g·h), and the molar ratio of H2 to CO2 in the feed gas is 2:1-4:

1. And / or, the reverse-phase catalyst of the copper-zirconium-magnesium ternary composite oxide is subjected to in-situ reduction treatment before use, which is a reduction at 200-400℃ for 0.5-4 h in a hydrogen-containing gas stream.

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