Cu-based reverse catalyst for preparing methanol through low-temperature CO2 hydrogenation as well as preparation method and application of Cu-based reverse catalyst

Abstract

The invention belongs to the technical field of carbon dioxide recycling, and discloses a Cu-based reverse-phase catalyst for preparing methanol through low-temperature CO2 hydrogenation as well as a preparation method and application of the Cu-based reverse-phase catalyst. The Cu-based reverse-phase catalyst is a reverse-phase catalyst with an oxide / metal Cu reverse-phase interface structure formed by uniformly dispersing MOx oxide serving as an active component on metal Cu. Wherein M is a mixture of metal Zn and metal Ce. In the catalyst provided by the invention, an MOx / Cu reverse phase interface site formed by an oxide phase and metal Cu is the most active site for CO2 hydrogenation, and a hydrogen overflow effect and CO2 activation are promoted through a synergistic effect of ZnO and CeO2, so that excellent CO2 conversion rate, CH3OH selectivity and CH3OH space time yield at a relatively low reaction temperature are realized.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide resource utilization technology, and relates to a Cu-based reverse-phase catalyst for low-temperature CO2 hydrogenation to methanol, its preparation method and application. Background Technology

[0002] The increase in global carbon dioxide emissions has triggered serious environmental problems, including exacerbated ocean acidification and frequent extreme weather events. Against this backdrop, carbon dioxide catalytic conversion technology has become a strategic focus of the global energy transition because it offers dual benefits: converting industrial carbon dioxide waste into value-added chemicals while simultaneously promoting the development of a circular economy. Carbon dioxide can be hydrogenated using hydrogen produced from renewable energy sources to generate various products such as methanol (CH3OH), ethanol, light olefins, and gasoline. Compared to producing CO or CH4, the hydrogenation of CO2 to methanol offers several advantages. Transportation and storage are more efficient, and handling and storage are more convenient. In particular, methanol can be used to store renewable hydrogen energy (H2, generated by solar, hydropower, and wind power), and it can also serve as a transit point for further conversion into other high-value-added chemicals. However, due to the chemical inertness of carbon dioxide molecules, significant challenges remain. Extensive catalytic research and experimentation are urgently needed to effectively facilitate this process.

[0003] Currently, catalysts for CO2 hydrogenation to methanol can be classified into three categories: copper-based catalysts, noble metal catalysts, and metal oxide catalysts. Copper-based catalysts have attracted much attention in the field of green hydrogen catalysis for CO2 to methanol (CO2 + 3H2 → CH3OH + H2O) due to their cost advantages and excellent catalytic performance. Currently, the widely used commercial Cu / ZnO / Al2O3 catalyst in industry typically operates at temperatures between 250-300 °C. o C. Syngas is converted to methanol under high pressure of 5-10 MPa. However, under high temperature conditions, the competitive reverse water gas (RWGS, CO2 + H2 → CO + H2O) reaction significantly reduces the selectivity of methanol (at 250°C). o At temperatures typically below 50%, and the high water production rate during the reaction accelerates the sintering of copper nanoparticles and the reconstruction of the oxidation interface, leading to catalyst deactivation and hindering the large-scale industrial application of commercial catalysts. More importantly, while low temperatures favor methanol production, achieving low-temperature CO2 activation remains challenging due to the highly oxidized and thermodynamically stable nature of CO2 molecules. Therefore, exploring efficient catalysts for CO2 activation at low temperatures has been a key process in this reaction. Summary of the Invention

[0004] To address the aforementioned issues, this discovery presents a Cu-based reversed-phase catalyst prepared using a coprecipitation method that is convenient to operate, inexpensive to prepare, and highly practical. The construction of the reversed-phase interface structure facilitates CO2 adsorption and enhances the activation of CO2 by key active H species by promoting the hydrogen spillover effect. This achieves excellent CO2 conversion, CH3OH selectivity, and CH3OH space-time yield under relatively low temperature conditions, thereby reducing energy consumption and achieving a more environmentally friendly and economically efficient outcome, which is of great significance for reducing greenhouse gas (CO2).

[0005] The technical solution of the present invention:

[0006] This invention provides a Cu-based reversed-phase catalyst for low-temperature CO2 hydrogenation to methanol, wherein the Cu-based reversed-phase catalyst is MO. x / Cu, where M is a mixture of metallic Zn and metallic Ce, and it is in the form of MO x The composite oxide is uniformly dispersed as the active component on metallic Cu, forming a reverse-phase catalyst with an oxide / metal reverse-phase interface structure. x The total molar content is 1 mmol. x mass fraction of MO x / Cu reversed-phase catalyst 5-20 wt%.

[0007] Furthermore, the mass fraction of the active ingredient is 5-20 wt% of the total catalyst, preferably 10 wt% of the total catalyst.

[0008] Furthermore, the ZnCeO mentioned above x In the Cu reverse catalyst, the molar ratio of Zn to Ce is 0.5-1.5:1, preferably 3:2.

[0009] A method for preparing a Cu-based reverse-phase catalyst for low-temperature CO2 hydrogenation to methanol comprises the following steps:

[0010] (1) Preparation of MO by coprecipitation method x / Cu reverse catalyst

[0011] A precursor solution was prepared by dissolving Cu, Zn, and Ce salts in an alcohol solution. A certain amount of precipitant solution was slowly added dropwise to the above mixture while continuously stirring until the solution was fully mixed. The resulting solution was then heated and stirred, and aged at room temperature. Next, the mixture was washed with deionized water and alcohol solution alternately by centrifugation. The resulting precipitate was then dried to obtain MO. x / Cu precursor.

[0012] (2) High-temperature roasting

[0013] The MO dried in step (1) x / Cu precursors were calcined at high temperature in air atmosphere to obtain Cu-based reverse catalyst precursors.

[0014] (3) Activation and reduction

[0015] In a reducing atmosphere, the Cu-based reverse catalyst precursor obtained in step (2) is reduced to obtain the Cu-based reverse catalyst.

[0016] Further, the precursor salt in step (1) is selected from at least one of its corresponding nitrate, chloride, and sulfate, preferably a nitrate.

[0017] Further, the alcohol mentioned in step (1) is selected from commonly used alcohol solvents such as ethanol, isopropanol, n-butanol, ethylene glycol, and n-hexanol, with ethanol being preferred. The ratio of precursor salt to ethanol is (0.01-8) g:(150-250) mL. Preferably, the ratio of precursor salt to ethanol is (0.01-8) g:200 mL.

[0018] Further, the precipitant solution in step (1) is selected from one of the aqueous solutions of oxalic acid, ammonia, sodium carbonate, and urea, preferably an aqueous solution of oxalic acid, and the concentration of the oxalic acid precipitant solution is 0.1-0.5 mol / L, preferably 0.2 mol / L, wherein the volume ratio of the oxalic acid precipitant solution to the precursor solution is 1:1-1:5, preferably 1:2.5.

[0019] Furthermore, the dropping rate of the precipitant solution in step (1) is 1-10 mL / min, preferably 5 mL / min.

[0020] Furthermore, in step (1), stirring is performed using a water bath or oil bath heating method at 50-100°C. o The reaction is carried out at temperature C, preferably 70°C. o C. The stirring time is 1-5 h, preferably 1 h. The aging time at room temperature is 1-5 h, preferably 2 h.

[0021] Furthermore, the solid precipitate in step (1) needs to be washed with alcohol at least once and with deionized water at least once. Preferably, it is washed with deionized water and ethanol alternately 2-3 times.

[0022] Furthermore, the drying temperature in step (1) is 50-100 °C, preferably 80 °C, and the drying time is 12-48 h, preferably 24 h.

[0023] Furthermore, the calcination temperature in step (2) is 300-600 °C, preferably 450 °C. o C, calcination time is 1-5h, preferably 4h.

[0024] Further, 0.1-0.5 g of the catalyst to be tested is placed in a fixed-bed stainless steel reactor, preferably 0.3-0.375 g, and most preferably 0.3 g.

[0025] Further, in step (3), the reducing gas atmosphere is at least one of pure H2, an H2-Ar mixture (gas volume ratio H2 / Ar = 1 / 9), or a CO2-H2-Ar mixture (gas volume ratio CO2 / H2 / Ar = 24 / 72 / 4), preferably pure H2, wherein the H2 flow rate is 10-50 mL / min, preferably 50 mL / min, and the reduction temperature is 200-400 ℃, preferably 300 ℃. o C, the reduction time is 1-5 h, preferably 3 h.

[0026] A Cu-based reverse-phase catalyst for low-temperature CO2 hydrogenation to methanol is prepared according to the following steps:

[0027] Furthermore, the molar ratio of the reacting gases is CO2 / H2 = 1 / 3-1 / 5, preferably CO2 / H2 = 1 / 3.

[0028] Furthermore, the reaction pressure is 1-3 MPa, preferably 3 MPa.

[0029] Furthermore, the volumetric space velocity is 9000-45000 h. -1 Preferably 12000-15000 h -1 The optimal value is 15000h. -1 .

[0030] Furthermore, the reaction temperature is 180-260 ℃, preferably 200 ℃.

[0031] The beneficial effects of this invention are:

[0032] (1) The Cu-based reverse catalyst is prepared by co-precipitation method. It is easy to operate, has low preparation cost and good practicality. It significantly reduces the operating cost of the production unit and provides a solution for the large-scale energy-saving industrialization of CO2 hydrogenation to methanol. It has industrial scale-up prospects.

[0033] (2) The preparation process uses less water, which can save water resources and there is no sewage discharge, which is beneficial to environmental protection.

[0034] (3) MO xThe oxide is uniformly dispersed on metallic Cu, forming a reverse-phase catalyst with an oxide / metallic Cu reverse-phase interface structure. In the CO2 hydrogenation to methanol reaction, it exhibits excellent CO2 conversion, CH3OH selectivity, and CH3OH space-time yield at low temperatures. This directly reduces reaction energy consumption and equipment requirements, providing a highly efficient and energy-saving catalytic solution for the resource utilization of CO2 under low-temperature conditions. Attached Figure Description

[0035] Figure 1 It's MO x / Cu and Cu / MO x Catalyst at 200 o C, 3 MPa, 12000 h -1 Results of CO2 conversion, CH3OH selectivity and CH3OH space-time yield for catalytic CO2 hydrogenation to methanol under the specified conditions, where M is a mixture of Zn and Ce metals.

[0036] Figure 2 It is Zn3Ce2O x / Cu and Cu / Zn3Ce2O x Catalyst at 200 o C, 3 MPa, 9000-18000 h -1 Results of CO2 conversion and CH3OH space-time yield in catalytic CO2 hydrogenation to methanol under certain conditions.

[0037] Figure 3 It is Zn3Ce2O x / Cu catalyst at 180-260 o C, 3 MPa, 15000 h -1 Results of CO2 conversion, CH3OH selectivity and CH3OH space-time yield for catalytic CO2 hydrogenation to methanol under certain conditions.

[0038] Figure 4 It is Zn3Ce2O x / Cu and Cu / Zn3Ce2O x XRD pattern of the catalyst. Detailed Implementation

[0039] The specific embodiments of the present invention will be further described below with reference to the technical solutions and accompanying drawings.

[0040] The Cu-based reversed-phase catalyst of this invention is synthesized by precipitation method, using oxalic acid as the precipitant.

[0041] (1) According to MO x Total moles 1 mmol, MO xCu(NO3)2•3H2O, Ce(NO3)2•6H2O, and Zn(NO3)2•6H2O were calculated and weighed based on a mass fraction of 10 wt% of the catalyst and dissolved in 200 ml of ethanol. The precursor ethanol solution was stirred at room temperature. 80 ml of 0.2 mol / L oxalic acid aqueous solution was added to the precursor solution as a precipitant at a dropping rate of 5 mL / min and stirred continuously in a 70 °C oil bath for 1 h, followed by aging at room temperature for 2 h. The mixture was then washed 2-3 times by alternating centrifugation with ethanol and deionized water, and the resulting precipitate was dried at 80 °C for 24 h.

[0042] (2) After thoroughly grinding the dried precipitate from step (1), place it in a muffle furnace and calcine at 450 °C for 4 h to obtain a Cu-based reverse-phase catalyst precursor.

[0043] (3) In a pure H2 atmosphere, the Cu-based reverse-phase catalyst precursor obtained in step (2) was subjected to a temperature of 300°C. o C reduction for 3 h yields Cu-based reversed-phase catalyst.

[0044] Example 1: A Cu-based reversed-phase catalyst with the structure Zn3Ce2O x / Cu-based catalyst

[0045] Weigh 0.18 g of Zn(NO3)2•6H2O, 0.17 g of Ce(NO3)2•6H2O, and 3.99 g of Cu(NO3)2•3H2O and dissolve them in 200 ml of ethanol solution. Stir the precursor solution at room temperature. Add 80 ml of 0.2 mol / L oxalic acid solution as a precipitant to the above precursor solution at a dropping rate of 5 mL / min and mix and stir continuously in an oil bath at 70 °C for 1 h, then let it stand at room temperature for 2 h for aging. Subsequently, the mixture is centrifuged and washed 2-3 times alternately with ethanol and deionized water. The precipitate is dried at 80 °C for 24 h, thoroughly ground, and calcined in a muffle furnace at 450 °C for 4 h to obtain a Cu-based reverse-phase catalyst precursor. Pack 0.375 g of the catalyst precursor into a fixed-bed reactor and reduce it by introducing pure H2 at a flow rate of 50 mL / min at 300 °C. o Reduction at C for 3 h yields a Cu-based reversed-phase catalyst, abbreviated as Zn3Ce2 / Cu catalyst.

[0046] Zn3Ce2O prepared in Example 1 xThe Cu catalyst is used in the catalytic hydrogenation of CO2 to methanol. The catalytic reaction steps are as follows: A reactant gas is introduced to initiate the catalytic reaction. N2 is introduced for protection during the heating and cooling processes. The reactant gas is a CO2:H2 mixture with a volume ratio of 1:3, the reaction pressure is 3 MPa, and the reaction temperature is 200°C. o C, the reaction volume hourly space velocity is 12000 h⁻¹ -1 The results of the catalytic reaction are listed in Table 1.

[0047] Example 2: A Cu-based reversed-phase catalyst with the structure Zn₂Ce₃O x / Cu-based catalyst

[0048] Example 2 The preparation process of the catalyst was the same as that of Example 1, except that 0.12 g of Zn(NO3)2•6H2O, 0.26 g of Ce(NO3)2•6H2O and 4.60 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution, which was referred to as Zn2Ce3 / Cu catalyst. The catalytic reaction results are listed in Table 1.

[0049] Example 3: A Cu-based reversed-phase catalyst with the structure Zn1Ce1O x / Cu-based catalyst

[0050] Example 3 The preparation process of the catalyst is the same as that of Example 1, except that 0.15 g of Zn(NO3)2•6H2O, 0.22 g of Ce(NO3)2•6H2O and 4.30 g of Cu(NO3)2•3H2O are weighed and dissolved in 200 ml of ethanol solution, which is referred to as Zn1Ce1 / Cu catalyst.

[0051] Example 4: A Cu-based reversed-phase catalyst with the structure Zn1Ce2O x / Cu-based catalyst

[0052] Example 4 The preparation process of the catalyst is the same as that of Example 1, except that 0.20 g of Zn(NO3)2•6H2O, 0.15 g of Ce(NO3)2•6H2O and 3.77 g of Cu(NO3)2•3H2O are weighed and dissolved in 200 ml of ethanol solution, which is referred to as Zn1Ce2 / Cu catalyst.

[0053] This invention aims to investigate the excellent CO2 conversion, CH3OH selectivity, and CH3OH space-time yield of the constructed Cu-based reversed-phase catalyst. Therefore, a traditional normal-phase Cu-based catalyst is constructed as a comparison to demonstrate the performance of both the normal and reversed-phase catalysts. The normal-phase catalyst uses metallic Cu as the active component, while MO... xAs a carrier for constructing Cu / MO x The total molar amount of catalyst M is 1 mmol, and the mass fraction of active ingredient is still 10 wt% of the catalyst mass.

[0054] Comparative Example 1: A Cu-based normal-phase catalyst with the structure Cu / Zn3Ce2O x Basic catalyst

[0055] The preparation process of the catalyst in Comparative Example 1 was the same as that in Example 1, except that 0.18 g of Zn(NO3)2•6H2O, 0.17 g of Ce(NO3)2•6H2O and 0.05 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution, which was referred to as Cu / Zn3Ce2 catalyst. The catalytic reaction results are listed in Table 1.

[0056] Comparative Example 2: A Cu-based normal-phase catalyst with the structure Cu / Zn2Ce3O x Basic catalyst

[0057] The preparation process of the catalyst in Comparative Example 2 was the same as that in Example 1, except that 0.12 g of Zn(NO3)2•6H2O, 0.26 g of Ce(NO3)2•6H2O and 0.06 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution, which was referred to as Cu / Zn2Ce3 catalyst. The catalytic reaction results are listed in Table 1.

[0058] Comparative Example 3: A Cu-based reversed-phase catalyst, the structure of which is a CeO2 / Cu-based catalyst.

[0059] The preparation process of the catalyst in Comparative Example 3 was the same as that in Example 1, except that 0.43 g of Ce(NO3)2•6H2O and 5.84 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst is referred to as Ce / Cu catalyst. The catalytic reaction results are listed in Table 1.

[0060] Comparative Example 4: A Cu-based normal-phase catalyst, the structure of which is a Cu / CeO2-based catalyst.

[0061] The preparation process of the catalyst in Comparative Example 4 was the same as that in Example 1, except that 0.43 g of Ce(NO3)2•6H2O and 0.07 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst is referred to as Cu / Ce catalyst. The catalytic reaction results are listed in Table 1.

[0062] Comparative Example 5: A Cu-based reversed-phase catalyst, the structure of which is a ZnO / Cu-based catalyst.

[0063] The preparation process of the catalyst in Comparative Example 5 was the same as that in Example 1, except that 0.30 g of Zn(NO3)2•6H2O and 2.75 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst is referred to as Zn / Cu catalyst. The catalytic reaction results are listed in Table 1.

[0064] Comparative Example 6: A Cu-based normal-phase catalyst, the structure of which is a Cu / ZnO-based catalyst.

[0065] The preparation process of the catalyst in Comparative Example 6 was the same as that in Example 1, except that 0.30 g of Zn(NO3)2•6H2O and 0.03 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst is referred to as Cu / Zn catalyst. The catalytic reaction results are listed in Table 1.

[0066] Comparative Example 7: A Cu-based reversed-phase catalyst with the structure Zn1Ce4O x / Cu-based catalyst

[0067] The preparation process of the catalyst in Comparative Example 7 was the same as that in Example 1, except that 0.06 g of Zn(NO3)2•6H2O, 0.35 g of Ce(NO3)2•6H2O and 5.23 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst was referred to as Zn1Ce4 / Cu catalyst. The catalytic reaction results are listed in Table 1.

[0068] Comparative Example 8: A Cu-based normal-phase catalyst with the structure Cu / Zn1Ce4O x Basic catalyst

[0069] The preparation process of the catalyst in Comparative Example 8 was the same as that in Example 1, except that 0.06 g of Zn(NO3)2•6H2O, 0.35 g of Ce(NO3)2•6H2O and 0.06 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution, and it was referred to as Cu / Zn1Ce4 catalyst. The catalytic reaction results are listed in Table 1.

[0070] Comparative Example 9: A Cu-based reversed-phase catalyst with the structure Zn4Ce1O x / Cu-based catalyst

[0071] The preparation process of the catalyst in Comparative Example 9 was the same as that in Example 1, except that 0.24 g of Zn(NO3)2•6H2O, 0.09 g of Ce(NO3)2•6H2O and 3.34 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution. This catalyst was referred to as Zn4Ce1 / Cu catalyst. The catalytic reaction results are listed in Table 1.

[0072] Comparative Example 10: A Cu-based normal-phase catalyst with the structure Cu / Zn4Ce1O x Basic catalyst

[0073] The preparation process of the catalyst in Comparative Example 10 was the same as that in Example 1, except that 0.24 g of Zn(NO3)2•6H2O, 0.09 g of Ce(NO3)2•6H2O and 0.04 g of Cu(NO3)2•3H2O were weighed and dissolved in 200 ml of ethanol solution, and it was referred to as Cu / Zn4Ce1 catalyst. The catalytic reaction results are listed in Table 1.

[0074] Application Example 1: The catalyst prepared in Example 1 was used for CO2 hydrogenation to methanol. The reaction was carried out in a fixed bed, and the activity change was tested at different volume hourly space velocities (VHSVs). The reactant gas was a CO2:H2 mixture with a volume ratio of 1:3. The reaction pressure was 3 MPa, the reaction temperature was 200 °C, and the VHSVs were 9000, 12000, 15000, and 18000 h⁻¹. -1 The results are shown in Table 2.

[0075] Application Example 2: The catalyst prepared in Example 1 was used for the hydrogenation of CO2 to methanol. The reaction was carried out in a fixed bed, and the activity changes at different temperatures were tested. The feed gas was a CO2:H2 mixture with a volume ratio of 1:3, the reaction pressure was 3 MPa, the reaction temperature was 180-260 °C, and the reaction volume hourly space velocity was 15000 h⁻¹. -1 The results are shown in Table 3.

[0076] Application Example 3: The catalyst prepared in Comparative Example 1 was used for CO2 hydrogenation to methanol. The reaction was carried out in a fixed bed, and the activity change was tested at different volume hourly space velocities (VHSVs). The reactant gas was a CO2:H2 mixture with a volume ratio of 1:3. The reaction pressure was 3 MPa, the reaction temperature was 200 °C, and the VHSVs were 9000, 12000, 15000, and 18000 h⁻¹. -1 The results are shown in Table 2.

[0077] Table 1 Performance evaluation of forward and reverse phase Cu-based catalysts

[0078]

[0079] Performance tests of CO2 hydrogenation to methanol using both forward and reverse phase catalysts revealed that, under the same conditions, the ZnO / Cu reverse phase catalyst exhibited a higher space-time yield of CH3OH (248.0 g kg / kg). -1 h -1 The efficiency is higher than that of Cu / ZnO catalysts (225.0 g kg). -1 h -1 CeO2 / Cu reverse catalyst (189.7 g kg) -1 h -1 It is also significantly superior to Cu / CeO2 (117.2 g kg). -1 h -1 However, even with superior single-oxide reversed-phase catalysts (ZnO / Cu, CeO2 / Cu), the CO2 conversion (7.6% and 6.5%, respectively) and CH3OH space-time yield still have significant room for improvement at low temperatures of 200°C. Therefore, constructing ZnCeO by supporting composite oxides on metallic Cu is a promising approach. x / Cu reverse-phase catalyst, through precise control of the Zn to Ce ratio in the composite oxide, achieved a significant leap in catalytic performance, particularly Zn3Ce2O x / Cu reverse catalyst at 200 o C, 3 MPa, 12000 h -1 Under the specified conditions, the catalytic hydrogenation of CO2 to methanol exhibits the best catalytic performance, with a CO2 conversion rate of 10.6%, a CH3OH selectivity of 98.2%, and a CH3OH space-time yield of 357.6 g·kg⁻¹. -1 ·h -1 Superior to Cu / Zn3Ce2O x Normal-phase catalyst (CO2 conversion 9.2%, CH3OH space-time yield 311.6 g·kg⁻¹) -1 ·h -1 In addition, Zn3Ce2O x The catalytic performance of the ZnO / Cu reversed-phase catalyst not only far exceeds that of single ZnO / Cu or CeO2 / Cu reversed-phase catalysts, but also surpasses that of composite catalysts with other ratios (such as Zn1Ce4 and Zn4Ce1). This indicates that the constructed Zn3Ce2O x The / Cu interface exhibits excellent CO2 conversion, CH3OH selectivity, and CH3OH space-time yield at low temperatures through the synergistic effect of ZnO (which is beneficial for H2 activation and methanol generation) and CeO2 (which is beneficial for CO2 adsorption).

[0080] Table 2 Performance evaluation of forward and reverse phase Cu-based catalysts

[0081]

[0082] Zn3Ce2O was tested x / Cu and Cu / Zn3Ce2O x Catalyst at 200 o C, 3 MPa, 9000-18000 h -1 The catalytic performance under the given conditions was as follows: the space-time yield of CH3OH for both catalysts first increased and then decreased with increasing volume hourly space velocity (GHSV), with the yield decreasing at GHSV = 15000 h⁻¹. -1 Under these conditions, Zn3Ce2O x The Cu catalyst exhibits the best space-time yield of 403.5 g·kg⁻¹. -1 ·h -1 Cu / Zn3Ce2O x The space-time yield of the catalyst was only 273.2 g·kg⁻¹. -1 ·h -1 Compared to Cu / Zn3Ce2O x Catalyst, Zn3Ce2O x The methanol space-time yield of the Cu catalyst was increased by approximately 48%. This indicates that the reversed-phase interface formed by loading the composite oxide onto the Cu metal surface is more conducive to the catalytic reaction at low temperatures than the traditional normal-phase interface.

[0083] Table 3 Performance evaluation of Z3C2 / Cu reverse catalyst

[0084]

[0085] According to the catalyst performance evaluation results, MO prepared by oxalic acid co-precipitation... x The performance of Cu-based reversed-phase catalysts is significantly better than that of Cu / MO. x Traditional normal-phase catalysts demonstrate that MO is constructed by uniformly dispersing oxides on a Cu support. x The Cu / Zn interface is more conducive to CO2 adsorption and enhances the activation of CO2 by key active H species by promoting the hydrogen spillover effect. Therefore, it exhibits excellent CO2 conversion, CH3OH selectivity, and CH3OH space-time yield at low temperatures. x / Cu-based reversed-phase catalyst at 200 o C, 3 MPa, 15000 h -1 Under the specified conditions, the catalytic hydrogenation of CO2 to methanol exhibits the best catalytic performance, with a CO2 conversion rate of 9.5%, a CH3OH selectivity of 98.2%, and a CH3OH space-time yield of 403.5 g·kg⁻¹. -1 ·h -1 .

[0086] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described herein. Many equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included within the scope of the present invention.

Claims

1. A Cu-based reverse-phase catalyst for low-temperature CO2 hydrogenation to methanol, characterized in that, The Cu-based reversed-phase catalyst is based on MO x The oxide is uniformly dispersed on the metal Cu as the active component, where M is a mixture of metal Zn and metal Ce.

2. The Cu-based reversed-phase catalyst according to claim 1, characterized in that, The MO x The oxides account for 5-20 wt% of the total mass of the Cu-based reversed-phase catalyst.

3. The Cu-based reversed-phase catalyst according to claim 1, characterized in that, The molar ratio of metallic Zn to metallic Ce is 0.5-1.5:

1.

4. A method for preparing a Cu-based reverse-phase catalyst for low-temperature CO2 hydrogenation to methanol, characterized in that, Includes the following steps: (1) Dissolve the precursor salt in an alcohol solution to prepare a precursor solution. Slowly and uniformly add the precipitant solution to the precursor solution, stir thoroughly to obtain a mixed solution, heat and stir, age at room temperature, then wash the mixed solution alternately by centrifugation with deionized water and alcohol solution, and dry to obtain MO. x / Cu precursor; (2) Take the MO obtained in step (1) x / Cu precursor was calcined at high temperature in air atmosphere to obtain Cu-based reverse catalyst precursor; (3) The Cu-based reverse catalyst precursor obtained in step (2) is reduced in a reducing atmosphere to obtain the Cu-based reverse catalyst.

5. The preparation method according to claim 4, characterized in that, The precursor salt in step (1) includes a mixture of Cu salt, Zn salt, and Ce salt, selected from at least one or more of their corresponding nitrate, chloride, and sulfate salts; the alcohol solution is a mixture of at least one or more of ethanol, isopropanol, n-butanol, ethylene glycol, and n-hexanol; the ratio of precursor salt to alcohol solution is (0.01-8) g:(150-250) mL; the precipitant solution is selected from an aqueous solution of oxalic acid, ammonia, sodium carbonate, and urea, wherein the concentration of the precipitant solution is 0.1-0.5 mol / L, the volume ratio of the precipitant solution to the precursor solution is 1:1-1:5, and the dropping rate of the precipitant solution is 1-10 mL / min.

6. The preparation method according to claim 4, characterized in that, In step (1), stirring is carried out by water bath heating or oil bath heating, and the reaction is carried out at a temperature of 50-100 °C; the stirring time is 1-5 h; the aging time at room temperature is 1-5 h; the solid precipitate is washed with alcohol at least once and with deionized water at least once; the drying temperature is 50-100 °C and the drying time is 12-48 h.

7. The preparation method according to claim 4, characterized in that, In step (2), the calcination temperature is 300-600 °C and the calcination time is 1-5 h.

8. The preparation method according to claim 4, characterized in that, In step (3), the reducing gas atmosphere is at least one of pure H2, H2-Ar mixture (gas volume ratio H2 / Ar = 1 / 9), or CO2-H2-Ar mixture (gas volume ratio CO2 / H2 / Ar = 24 / 72 / 4), wherein the gas flow rate is 10-50 mL / min, the reduction temperature is 200-400 ℃, and the reduction time is 1-5 h.

9. The application of the Cu-based reverse-phase catalyst according to any one of claims 1-3 in the hydrogenation of CO2 to methanol, characterized in that, In the CO2 hydrogenation to methanol reaction, the molar ratio of the reactant gases is CO2 / H2 = 1 / 3-1 / 5, the reaction pressure is 1-3 MPa, and the volume hourly space velocity is 9000-45000 h⁻¹. -1 The reaction temperature is 180-260 ℃.

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