A porous Cu-ZnO / Na-attapulgite clay composite catalyst and a preparation method and application thereof

Abstract

The application belongs to the technical field of catalyst preparation, and particularly discloses a porous Cu-ZnO / Na-palygorskite clay composite catalyst, a preparation method and application thereof; the carrier of the catalyst is porous sodium-containing palygorskite clay obtained by solvothermal treatment of a mixed aqueous solution of HNO3 solution and Na2SiO3 solution, and the active component is Cu and ZnO; the total loading amount of the active components Cu and ZnO is 10% to 40% of the total mass of the catalyst, and the mass ratio of Cu to ZnO is 1 to 3; the porous sodium-containing palygorskite clay is used as the carrier to load Cu-ZnO, the Cu-ZnO / Na-palygorskite clay composite catalyst is prepared by the impregnation method, Cu-ZnO is uniformly distributed in the porous sodium-containing palygorskite clay structure, the reaction activity and selectivity of the catalyst for the preparation of methanol by catalytic hydrogenation of CO2 are improved, and the hydrothermal stability of the catalyst is improved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to a porous Cu-ZnO / Na-attapulgite clay composite catalyst, its preparation method, and its application in the catalytic hydrogenation of CO2 to methanol. Background Technology

[0002] With the continued advancement of global industrialization and the large-scale consumption of fossil fuels, the concentration of carbon dioxide (CO2) in the atmosphere continues to rise, triggering a series of environmental problems such as the greenhouse effect, climate anomalies, and ecological imbalance. At the same time, fossil fuel reserves are increasingly depleted, and the contradiction between energy supply and demand is becoming increasingly prominent. The CO2 catalytic hydrogenation technology for methanol production can convert industrial emissions and atmospheric captured CO2 into methanol. Methanol, as an important basic chemical raw material, a clean liquid fuel, and a hydrogen energy carrier, possesses dual value in environmental governance and energy regeneration, exhibiting extremely high potential for industrial application and significant economic and social benefits.

[0003] Currently, the main catalysts developed in the research field for CO2 hydrogenation to methanol production include copper-based catalysts, noble metal catalysts, and oxide catalysts. Among them, Cu-ZnO-based composite catalysts have become the most widely used catalytic system due to their low cost and excellent activity (Applied Catalysis A: General, 2025, Vol. 692, pp. 120098). However, existing traditional Cu-ZnO catalysts still have many inherent defects in practical applications. For example, the Cu-ZnO system has a limited specific surface area, serious agglomeration of active components, and insufficient exposure of active sites, resulting in weak CO2 adsorption and activation capacity, poor low-temperature reaction activity, and low overall CO2 conversion rate (Nature Synthesis, 2025, Vol. 4, pp. 288-302). Secondly, under high temperature and high pressure conditions during the reaction, Cu grains are prone to sintering, growth, and shedding. At the same time, a large amount of water is generated during the reaction, causing the catalyst to be exposed to a hydrothermal environment, which shortens the catalyst's service life and deteriorates its stability (Molecular Catalysis, 2023, Vol. 549, pp. 113494). Furthermore, the disordered pore structure of traditional catalysts leads to significant mass transfer resistance, insufficient contact between reactants and active sites, and delayed product desorption, further reducing catalytic reaction efficiency (Applied Catalysis A: General, 2019, Vol. 571, pp. 51-60). These factors severely limit their industrial application.

[0004] To address the aforementioned issues, the supporting role of a carrier can effectively improve the dispersion of Cu-ZnO active components, increase the specific surface area of ​​the catalyst, and optimize the pore structure. However, currently developed carriers have various limitations, making it difficult to simultaneously achieve high CO2 conversion and high methanol selectivity, and their function in improving the hydrothermal stability of the catalyst is limited. Attapulgite clay is a natural nano-layered silicate mineral material with a unique one-dimensional rod-shaped crystal structure, excellent adsorption performance, good thermal and mechanical stability, and abundant, inexpensive, and environmentally friendly raw material reserves, making it an ideal catalyst carrier material (CN111054350 B). Unmodified natural attapulgite clay has many surface impurities, uneven pore size distribution, insufficient surface active sites, and weak ion exchange capacity, failing to fully utilize the advantages of a carrier. Therefore, existing Cu-ZnO-based catalysts supported on attapulgite clay still suffer from insufficient active sites, poor selectivity, low hydrothermal stability, and the high cost and limited modification effect of traditional carriers. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a porous Cu-ZnO / Na-attapulgite clay composite catalyst, which uses Na-modified porous attapulgite clay as a support to carry Cu-ZnO, promoting the dispersion of active components. Relying on the porous structure, strong adsorption performance, and interface regulation effect of Na-attapulgite clay, combined with the catalytic activity advantages of Cu-ZnO, it enhances the adsorption of CO2 molecules and improves the hydrothermal stability of the catalyst.

[0006] The second objective of this invention is to provide a method for preparing the catalyst, wherein a porous Cu-ZnO / Na-attapulgite clay composite catalyst is prepared by impregnation, so that Cu-ZnO is uniformly and highly dispersed in the porous Na-modified attapulgite clay structure.

[0007] The third objective of this invention is to provide the application of this catalyst in the catalytic hydrogenation of carbon dioxide to methanol. The porous Cu-ZnO / Na-attapulgite clay composite catalyst provided by this invention effectively solves many defects of the prior art, significantly improves the catalytic efficiency, product selectivity and hydrothermal stability of CO2 hydrogenation to methanol, and has important scientific research value and industrial application prospects.

[0008] This invention is achieved through the following technical solution: A porous Cu-ZnO / Na-attapulgite clay composite catalyst, wherein the catalyst support is porous Na-containing attapulgite clay, the active components are Cu and ZnO, the loading of active components Cu and ZnO is 10%~40%, and the molar ratio of Cu to ZnO is 1~3.

[0009] A further improvement to the present invention is as follows: A method for preparing a porous Cu-ZnO / Na-attapulgite clay composite catalyst includes the following steps: S1. Disperse the attapulgite clay powder thoroughly in distilled water. After standing, take the upper layer of attapulgite clay colloidal solution, filter and dry it. Add distilled water to the lower solid layer and stir thoroughly. After standing again, take the upper layer of attapulgite clay colloidal solution, filter and dry it. Repeat this process several times until sufficient attapulgite clay solid powder is obtained. S2. Disperse the attapulgite clay solid powder obtained in S1 in a mixed aqueous solution of HNO3 and H2SiO3, and perform hydrothermal treatment. After the hydrothermal treatment is completed, filter, wash and dry to obtain porous attapulgite clay. S3. Add the solid obtained in S2 to NaOH solution and stir continuously. After washing and drying again, porous Na-containing attapulgite clay is obtained. S4. Weigh out Cu(NO3)2·3H2O and Zn(NO3)3·6H2O respectively and dissolve them in anhydrous ethanol to prepare a mixed solution. Add the mixed solution dropwise to the porous Na-containing attapulgite clay solid powder obtained in S3. Heat and stir continuously until the solution is completely volatilized. Then, after reduction, a porous Cu-ZnO / Na-attapulgite clay composite catalyst is obtained.

[0010] Furthermore, the settling time mentioned in S1 is 2 h to 5 h.

[0011] Furthermore, the concentration of the HNO3 aqueous solution in S2 is 0.2~2.0 mol / L; the concentration of the H2SiO3 aqueous solution is 0.1~0.6 mol / L.

[0012] Furthermore, in S2, the hydrothermal treatment temperature is 80℃~120℃, and the hydrothermal treatment time is 1 h-24 h; the drying temperature is 100℃~200℃, and the time is 8 h-24 h.

[0013] Furthermore, in S3, the concentration of the NaOH aqueous solution is 0.1~2 mol / L, the stirring temperature is room temperature, and the stirring time is 2 h-10 h; the washing is done with deionized water until neutral; and the drying temperature is 100℃~140℃, and the time is 2 h-8 h.

[0014] Furthermore, the mass of Zn(NO3)3·6H2O and Cu(NO3)2·3H2O in S4 is calculated based on the amount of ZnO and Cu it contains, and the molar ratio of Cu to ZnO is 1~3; the loading of Cu and ZnO is 10%~40% of the total mass of the catalyst.

[0015] Furthermore, the heating and stirring temperature described in S4 is 60℃~100℃.

[0016] Furthermore, during the reduction described in S4, the temperature is 250℃~300℃, the reducing gas is 5%~10% H2 / N2, and the time is 2 h~4 h.

[0017] A further improvement of the present invention is as follows: The application of the above-mentioned porous Cu-ZnO / Na-attapulgite clay composite catalyst in the catalytic hydrogenation of carbon dioxide to methanol.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses sodium-modified porous attapulgite clay as a carrier. Attapulgite clay is a hydrated magnesium-aluminum silicate composed of two layers of silicon-oxygen tetrahedra sandwiching a layer of magnesium and aluminum-oxygen octahedra. Its structure exhibits both layered and chain-like characteristics, containing regular nanopores and forming a rod-like / fibrous multi-level structure. It possesses excellent adsorption properties and, compared to commonly used catalyst carriers such as Al2O3, exhibits higher hydrothermal stability. However, compared to commonly used industrial catalyst carriers, natural attapulgite clay has a relatively low specific surface area, and its pores are mostly interparticle pores, limiting its effectiveness as a catalyst carrier.

[0019] 2. In the preparation method of this invention, magnesium and aluminum oxide octahedra in the structure of natural attapulgite clay are dissolved by nitric acid using a hydrothermal method, while silica sol is used to fill the octapulgite clay, creating more pores in the clay structure and increasing its specific surface area, which is more conducive to the diffusion of reactant molecules and the dispersion of active metals. Furthermore, sodium ions are used to modify the surface of the attapulgite clay, promoting CO2 adsorption. Using sodium-modified porous attapulgite clay as a carrier, a porous Cu-ZnO / Na-attapulgite clay composite catalyst is prepared by impregnation. This ensures that Cu-ZnO is uniformly and highly dispersed in the modified porous attapulgite clay structure, improving the catalyst's physical structure and surface chemical properties, enhancing its reactivity and selectivity, and significantly improving its hydrothermal stability.

[0020] 3. The porous Cu-ZnO / Na-attapulgite clay composite catalyst of the present invention is used for the reaction of CO2 hydrogenation to methanol. Data show that at a pressure of 5 MPa, a temperature of 240 °C, and a space velocity of 9600 mL h⁻¹, the reaction is successful. −1 g -1 Even after hydrothermal treatment at 180℃, the porous Cu-ZnO / Na-attapulgite clay composite catalyst still exhibits very high activity, with a CO2 conversion rate of 13% and a selectivity of 77%. It shows promising prospects for industrialization. Detailed Implementation

[0021] This invention provides a porous Cu-ZnO / Na-attapulgite clay composite catalyst, its preparation method, and its application. In the specific embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available. The invention will be described in detail below with reference to specific embodiments.

[0022] Example 1: Preparation of Cu-ZnO / Al2O3 catalyst Weigh 8.6 g of Na2CO3 and dissolve it in water to prepare a 100 mL solution; separately weigh 18.4 g of Al(NO3)3·9H2O and dissolve it in water to prepare a 100 mL solution. Then, slowly add the above solutions dropwise to 100 mL of distilled water under stirring. After aging for 0.5 h, wash the resulting precipitate with distilled water until neutral, then dry it at 120 °C and calcine it at 450 °C for 4 h to obtain the Al2O3 support.

[0023] Weigh 1.0 g of Al2O3 support, and separately weigh 0.30 g of Zn(NO3)3·6H2O and 0.48 g of Cu(NO3)2·3H2O, dissolving them in 5 mL of anhydrous ethanol. Add the prepared ethanol solution to the Al2O3 solid powder, then stir at 80℃ until the solution is completely evaporated and dried, and reduce it at 280℃ with 10% H2 / N2 for 2 h to obtain an Al2O3-supported catalyst with a total Cu and ZnO loading of 20%, wherein the molar ratio of metallic Cu to ZnO is 2, and the sample is denoted as Cu-ZnO / Al2O3.

[0024] Example 2: Preparation of Cu-ZnO / ATP catalyst The purchased commercial attapulgite clay powder was fully dispersed in distilled water, and after standing for 4 hours, the upper layer of colloidal solution containing attapulgite clay was taken, filtered, and dried in an oven at 120°C to obtain attapulgite clay, denoted as ATP.

[0025] Weigh 1.0 g of ATP, and separately weigh 0.30 g of Zn(NO3)3·6H2O and 0.48 g of Cu(NO3)2·3H2O, dissolving them in 5 mL of anhydrous ethanol. Add the prepared ethanol solution to the ATP solid powder, then stir at 80 °C until the solution is completely evaporated and dried. Reduce the solution at 280 °C with 10% H2 / N2 for 2 h to obtain an ATP-supported catalyst with a total Cu and ZnO loading of 20%, wherein the molar ratio of metallic Cu to ZnO is 2, and the sample is denoted as Cu-ZnO / ATP.

[0026] Example 3: Preparation of Cu-ZnO / ATP-P catalyst The preparation of ATP was the same as in Example 2. 2.0 g of ATP solid powder was weighed and placed in 100 mL of aqueous solution containing 1 mol / L HNO3 and 0.2 mol / L H2SiO3. The mixture was hydrothermally treated at 100 °C for 10 h. After hydrothermal treatment, the mixture was filtered and washed with distilled water until neutral. Then it was dried at 120 °C for 10 h to obtain porous attapulgite clay, denoted as ATP-P.

[0027] Weigh 1.0 g of ATP-P, and separately weigh 0.30 g of Zn(NO3)3·6H2O and 0.48 g of Cu(NO3)2·3H2O, dissolving them in 5 mL of anhydrous ethanol. Add the prepared ethanol solution to the ATP-P solid powder, then stir at 80 °C until the solution is completely evaporated and dried, and reduce it at 280 °C with 10% H2 / N2 for 2 h to obtain an ATP-P supported catalyst with a total Cu and ZnO loading of 20%, wherein the molar ratio of metallic Cu to ZnO is 2, and the sample is numbered Cu-ZnO / ATP-P.

[0028] Example 4: Preparation of Cu-ZnO / Na-ATP-P catalyst The preparation of ATP-P is the same as in Example 3. 1.0 g of ATP-P solid powder was weighed and added to a 1 mol / L NaOH aqueous solution. After stirring at room temperature for 4 h, it was washed with distilled water until neutral and then dried at 120 ℃ for 10 h to obtain sodium-modified porous attapulgite clay, denoted as Na-ATP-P.

[0029] Weigh 1.0 g of Na-ATP-P, and separately weigh 0.30 g of Zn(NO3)3·6H2O and 0.48 g of Cu(NO3)2·3H2O, dissolve them in 5 mL of anhydrous ethanol. Add the prepared ethanol solution to the Na-ATP-P solid powder, stir at 80 °C until the solution is completely evaporated and dried, and then reduce it at 280 °C with 10% H2 / N2 for 2 h to obtain a Na-ATP-P supported catalyst with a total Cu and ZnO loading of 20%, wherein the molar ratio of metallic Cu to ZnO is 2, and the sample is denoted as Cu-ZnO / Na-ATP-P.

[0030] Example 5: Hydrothermal treatment of Cu-ZnO / Al2O3 catalyst The Cu-ZnO / Al2O3 catalyst prepared in Example 1 was weighed and transferred to a hydrothermal reactor containing 20 mL of water in a N2 atmosphere. The temperature was raised to 180°C and maintained for 5 h. After cooling to room temperature, the catalyst was filtered and dried. The resulting sample was denoted as Cu-ZnO / Al2O3-H.

[0031] Example 6: Hydrothermal treatment of Cu-ZnO / ATP catalyst Weigh the Cu-ZnO / ATP catalyst prepared in Example 2 and transfer it to a hydrothermal reactor containing 20 mL of water in a N2 atmosphere. Heat the reactor to 180°C and maintain the temperature for 5 h. After cooling to room temperature, filter and dry the product. The resulting sample is denoted as Cu-ZnO / ATP-H.

[0032] Example 7: Hydrothermal treatment of Cu-ZnO / ATP-P catalyst Weigh the Cu-ZnO / ATP-P catalyst prepared in Example 3 and transfer it to a hydrothermal reactor containing 20 mL of water in a N2 atmosphere. Heat the reactor to 180°C and maintain the temperature for 5 h. After cooling to room temperature, filter and dry the product. The resulting sample is named Cu-ZnO / ATP-PH.

[0033] Example 8: Hydrothermal treatment of Cu-ZnO / Na-ATP-P catalyst The Cu-ZnO / Na-ATP-P catalyst prepared in Example 4 was weighed and transferred to a hydrothermal reactor containing 20 mL of water in a N2 atmosphere. The temperature was raised to 180°C and maintained for 5 h. After cooling to room temperature, the catalyst was filtered and dried. The resulting sample was named Cu-ZnO / Na-ATP-PH.

[0034] Example 9: Structural Characterization and Adsorption Performance Testing The physical structure and CO2 adsorption test results of the catalysts prepared in Examples 2-4 are shown in Table 1.

[0035] Table 1. Catalyst physical structure and CO2 adsorption detection results <![CDATA[Specific surface area (m 2 / g)]]> 104 123 119 <![CDATA[Pore volume (cm 3 / g)]]> 0.29 0.48 0.44 <![CDATA[Initial heat of CO2 adsorption (kJ / mol)]]> 84 72 87 <![CDATA[CO2 saturated adsorption capacity (mmol / g)]]> 105 112 134 The specific surface area and pore volume were obtained through tests using a specific surface area and pore size analyzer. The initial heat of adsorption and saturated adsorption capacity of CO2 were used to characterize the basicity of the catalyst surface and the number of active CO2 adsorption sites; these data were obtained using a micro-adsorption calorimeter. The results show that the specific surface area and pore volume of the catalyst significantly increased after hydrothermal treatment. Furthermore, Na modification significantly improved the initial heat of adsorption and saturated adsorption capacity of CO2 on the catalyst surface, promoting CO2 adsorption and activation, thereby enhancing CO2 conversion on the catalyst surface.

[0036] Example 10: Application of Cu-ZnO / Al2O3 catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / Al2O3 sample prepared in Example 1 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0037] Example 11: Application of Cu-ZnO / ATP catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / ATP sample prepared in Example 2 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0038] Example 12: Application of Cu-ZnO / ATP-P catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / ATP-P sample prepared in Example 3 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0039] Example 13: Application of Cu-ZnO / Na-ATP-P catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / Na-ATP-P sample prepared in Example 4 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0040] Example 14: Application of Cu-ZnO / Al2O3-H catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / Al2O3-H sample prepared in Example 5 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0041] Example 15: Application of Cu-ZnO / ATP-H catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / ATP-H sample prepared in Example 6 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0042] Example 16: Application of Cu-ZnO / ATP-PH catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / ATP-PH sample prepared in Example 7 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g −1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0043] Example 17: Application of Cu-ZnO / Na-ATP-PH catalyst in the catalytic hydrogenation of carbon dioxide to methanol 0.4 g of the Cu-ZnO / Na-ATP-PH sample prepared in Example 8 was weighed and placed into a micro fixed-bed reactor with an outer diameter of 8 mm. The temperature was increased to 280 °C at a rate of 1 °C / min, followed by reduction with 10% H2 / N2 for 2 h. The reaction temperature was set at 240 °C, V(H2) / V(CO2) = 3 / 1, and GHSV = 9600 mL / h. −1 g−1 The pressure was 5 MPa. The conversion rate and selectivity of the reaction are shown in Table 2.

[0044] Table 2. Conversion and selectivity of catalyst for CO2 catalytic hydrogenation to methanol before and after hydrothermal treatment. Example 10 <![CDATA[Cu-ZnO / Al2O3]]> 7% 58% Example 11 Cu-ZnO / ATP 10% 69% Example 12 Cu-ZnO / ATP-P 11% 65% Example 13 Cu-ZnO / Na-ATP-P 14% 81% Example 14 <![CDATA[Cu-ZnO / Al2O3-H]]> 4% 41% Example 15 Cu-ZnO / ATP-H 8% 66% Example 16 Cu-ZnO / ATP-PH 10% 61% Example 17 Cu-ZnO / Na-ATP-PH 13% 77% Analysis of the data in Table 2 shows that using sodium-modified porous attapulgite clay as a support can improve the reactivity and selectivity of Cu-ZnO-based catalysts and significantly improve their hydrothermal stability.

[0045] The above description of the embodiments is only for illustrating the technical concept and features of the present invention. Its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. Those skilled in the art can obviously easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the above embodiments should not be used to limit the scope of protection of the present invention. All improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A porous Cu-ZnO / Na-attapulgite clay composite catalyst, characterized in that, The catalyst is supported by porous Na-containing attapulgite clay, and the active components are Cu and ZnO. The loading of Cu and ZnO is 10% to 40%, and the molar ratio of Cu to ZnO is 1 to 3.

2. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst as described in claim 1, characterized in that, Includes the following steps: S1. Disperse the attapulgite clay powder thoroughly in distilled water. After standing, take the upper layer of attapulgite clay colloidal solution, filter and dry it. Add distilled water to the lower solid layer and stir thoroughly. After standing again, take the upper layer of attapulgite clay colloidal solution, filter and dry it. Repeat this process several times until sufficient attapulgite clay solid powder is obtained. S2. Disperse the attapulgite clay solid powder obtained in S1 in a mixed aqueous solution of HNO3 and H2SiO3, and perform hydrothermal treatment. After the hydrothermal treatment is completed, filter, wash and dry to obtain porous attapulgite clay. S3. Add the solid obtained in S2 to NaOH solution and stir continuously. After washing and drying again, porous Na-containing attapulgite clay is obtained. S4. Weigh out Cu(NO3)2·3H2O and Zn(NO3)3·6H2O respectively and dissolve them in anhydrous ethanol to prepare a mixed solution. Add the mixed solution dropwise to the porous Na-containing attapulgite clay solid powder obtained in S3. Heat and stir continuously until the solution is completely volatilized. Then, after reduction, a porous Cu-ZnO / Na-attapulgite clay composite catalyst is obtained.

3. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The settling time mentioned in S1 is 2 h to 5 h.

4. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The concentration of the HNO3 aqueous solution in S2 is 0.2~2.0 mol / L; the concentration of the H2SiO3 aqueous solution is 0.1~0.6 mol / L.

5. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The hydrothermal treatment temperature in S2 is 80℃~120℃, and the hydrothermal treatment time is 1 h-24 h; the drying temperature is 100℃~200℃, and the time is 8 h-24 h.

6. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The concentration of the NaOH aqueous solution in S3 is 0.1~2 mol / L, the stirring temperature is room temperature, and the stirring time is 2 h-10 h; the washing is done with deionized water until neutral; the drying temperature is 100℃~140℃, and the time is 2 h-8 h.

7. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The mass of Zn(NO3)3·6H2O and Cu(NO3)2·3H2O in S4 is calculated based on the amount of ZnO and Cu they contain, with the molar ratio of Cu to ZnO being 1 to 3; the loading of Cu and ZnO is 10% to 40% of the total mass of the catalyst.

8. The method for preparing a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: The heating and stirring temperature described in S4 is 60℃~100℃.

9. The preparation method of a porous Cu-ZnO / Na-attapulgite clay composite catalyst according to claim 2, characterized in that: During the reduction described in S4, the temperature is 250℃~300℃, the reducing gas is 5%~10% H2 / N2, and the time is 2 h~4 h.

10. The application of the porous Cu-ZnO / Na-attapulgite clay composite catalyst as described in claim 1 in the catalytic hydrogenation of carbon dioxide to methanol.