CuO-ZnO-coated Cu-MOR high-selectivity catalyst as well as preparation method and application thereof

Abstract

The invention provides a CuO-ZnO-coated Cu-MOR high-selectivity catalyst as well as a preparation method and application of the CuO-ZnO-coated Cu-MOR high-selectivity catalyst. Specifically, the invention provides a CuO-ZnO-coated Cu-MOR catalyst capable of being used for preparing methanol through CO2 hydrogenation, the CuO-ZnO-coated Cu-MOR catalyst can be obtained by roasting a solid-phase mixture of copper salt, zinc salt and a Cu-MOR molecular sieve, the preparation method is simple and rapid, environment-friendly and energy-saving, the catalytic performance is excellent, and the methanol selectivity is high.

Description

Technical Field

[0001] The present invention belongs to the field of catalysis technology, and in particular relates to a CuO-ZnO@Cu-MOR highly selective catalyst for CO2 hydrogenation to methanol, and a preparation method and application thereof. Background Art

[0002] The catalytic conversion of carbon dioxide (CO2) into valuable products such as methane, methanol, dimethyl ether, formic acid and olefins has become a promising approach to address climate change, ocean acidification and the utilization of carbon resources. In recent years, there has been increasing interest in the production of methanol by CO2 hydrogenation. Methanol is not only a clean, renewable liquid fuel, but also an important raw material for the production of olefins, aromatics and gasoline. In his book Methanol Economics, Nobel Prize winner George Olah believes that this method of directly synthesizing methanol by CO2 hydrogenation is an important and promising method for CO2 utilization. Research on copper-based catalysts in the thermal catalytic reaction of CO2 hydrogenation has been widely carried out. In order to solve the problems of low methanol selectivity caused by side reactions such as reverse water gas reaction (RWGS) and CO2 methanation, and limited catalyst durability caused by the presence of H2O in the by-product, researchers have developed multimetallic catalysts (Pd-Cu / SBA-15, CuZnGa-LDH) and hybrid oxides (In2O3 / ZrO2, Cu-ZnO / Al2O3

[24] ). These methods effectively stabilize the active catalytic sites within the catalyst while also tailoring the interface structure and surface properties. However, these catalysts still rapidly deactivate under hydrothermal conditions due to sintering of the active phase. Therefore, improving the selectivity and stability of the catalysts (e.g., water resistance) is crucial.

[0003] Zeolites are widely used as catalysts and supports due to their exceptional surface area, diverse structural composition, and remarkable stability at high temperatures. The pore structure of zeolites plays a crucial role in the catalytic conversion of hydrocarbons and other molecules by effectively regulating the entry of feedstock molecules, the transport of intermediates, and the release of final products. Zeolites are also widely used as water adsorbents to promote catalytic hydrogenation. For example, Heracleous et al. proposed adding 13X zeolite as a highly efficient water absorbent to a reactor along with a Cu / ZnO / Al2O3 catalyst, significantly improving CO2 conversion (approximately 39.3%) and CH3OH selectivity (approximately 71.1%) until saturation was achieved. Furthermore, LTA and FAU zeolites have been proposed as water adsorbents to improve CO2 conversion and methanol yield. Furthermore, zeolites such as SAPO-34, ZSM-5, and Silicalite-1, as metal oxide supports and effective acidic catalytic active sites, have also been widely used in CO2 hydrogenation research. Most of these catalysts are prepared using physical mixing or double-layer bed methods, resulting in spatial isolation between the catalytically active sites and the water scavenger. Consequently, these catalysts face challenges such as uneven metal oxide aggregation, limited adsorption capacity, and spatial isolation between the catalytically active sites and water.

[0004] Furthermore, it is worth noting that the complex preparation processes for the above-mentioned catalysts have limited the further development and industrial application value of this research field. Therefore, the development of new methods that can rapidly prepare highly selective catalysts is a key issue that needs to be addressed in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide an ultra-fast solid-phase method capable of preparing a highly selective catalyst, aiming to reduce solvent usage, be environmentally friendly, and obtain a catalyst with better performance.

[0006] In a first aspect, the present invention provides a method for preparing a catalyst for producing methanol by hydrogenation of CO2, comprising the steps of:

[0007] (i) providing a solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve; and

[0008] (ii) calcining the solid phase mixture and cooling it to obtain a CuO-ZnO@Cu-MOR catalyst for CO2 hydrogenation to methanol.

[0009] In another preferred embodiment, the copper salt is selected from the following group or its hydrate: copper nitrate, copper chloride, copper sulfate, basic copper carbonate, or a combination thereof.

[0010] In another preferred embodiment, the zinc salt is selected from the following group or its hydrate: zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, or a combination thereof.

[0011] In another preferred embodiment, in the solid phase mixture, the Cu / Zn molar ratio of the copper salt and the zinc salt is (0.5-10):1, preferably (0.8-5):1, more preferably (0.8-2):1, such as 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1.

[0012] In another preferred embodiment, in the solid phase mixture, the molar ratio of copper salt and Cu in Cu-MOR is (0.5-20):1, preferably (1-15):1, more preferably (5-10):1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, and 15:1.

[0013] In another preferred embodiment, the Cu content in Cu-MOR is 0.1-2 wt%, such as 0.5 wt% or 1 wt%.

[0014] In another preferred embodiment, the method for preparing the solid phase mixture comprises: thoroughly mixing the copper salt, the zinc salt and Cu-MOR by grinding to obtain the solid phase mixture; and optionally drying the solid phase mixture before using it in step (ii).

[0015] In another preferred embodiment, the grinding is room temperature grinding, such as 0-40°C, preferably 10-25°C.

[0016] In another preferred embodiment, the grinding time is 5-60 min, preferably 10-30 min, and more preferably 15-20 min.

[0017] In another preferred embodiment, in step (ii), the calcination temperature is 400-700°C, preferably 450-600°C, and more preferably 480-550°C.

[0018] In another preferred embodiment, in step (ii), the calcination time is 3-8 h, preferably 4-6 h.

[0019] In another preferred embodiment, the cooling is natural cooling.

[0020] In another preferred embodiment, the calcination is to calcine the solid phase mixture in a muffle furnace, wherein the muffle furnace heating program is 2-4°C / min, maintained at 450-550°C for 3-6 hours, and then naturally cooled; the preferred muffle furnace heating program is 3°C / min, maintained at 500°C for 4 hours, and then naturally cooled.

[0021] In a second aspect, the present invention provides a CuO-ZnO@Cu-MOR catalyst, which is obtained by calcining a solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve.

[0022] In another preferred embodiment, the CuO-ZnO@Cu-MOR catalyst is prepared by the method described in the first aspect of the present invention.

[0023] In another preferred embodiment, in the catalyst, the mass ratio of CuO-ZnO and Cu-MOR is (0.1-10):1, preferably, (0.2-8):1, and more preferably, (0.5-5):1, such as 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1.

[0024] In another preferred embodiment, the molar ratio of Cu:Zn in CuO-ZnO is (0.5-10):1, preferably (0.6-5):1, more preferably (0.8-2):1, such as 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1.

[0025] In another preferred embodiment, the Cu content in Cu-MOR is 0.1-2 wt%, such as 0.5 wt% or 1 wt%.

[0026] The third aspect of the present invention provides use of the CuO-ZnO@Cu-MOR catalyst described in the second aspect of the present invention as a catalyst for CO2 hydrogenation to methanol.

[0027] In a fourth aspect, the present invention provides a method for producing methanol by hydrogenating CO2, comprising the step of catalytic hydrogenation using the CuO-ZnO@Cu-MOR catalyst as described in the second aspect of the present invention.

[0028] In another preferred embodiment, the CuO-ZnO@Cu-MOR catalyst is used to realize CO2 hydrogenation to methanol through a fixed bed test device at a temperature of 200-300°C, a pressure of 3.0-4.0 MPa, a H / C ratio of 3 / 1 and a reaction temperature of 5000 h. -1 At an air velocity of 1.5-2.5 ℃, the selectivity for methanol is 95-98%, and the CO2 conversion rate is 15-25%.

[0029] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features described in detail below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be listed here one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 .XRD spectra of MOR, Cu-MOR and CuO-ZnO@Cu-MOR catalysts.

[0031] Figure 2 .(a) SEM images of MOR and (b) CuO-ZnO@Cu-MOR; (c) TEM image, (d) HRTEM image, (e,f) inverse Fourier transform images and (gj) EDS images of CuO-ZnO@Cu-MOR catalysts.

[0032] Figure 3 .Long-term performance test diagram of CuO-ZnO@Cu-MOR catalyst. DETAILED DESCRIPTION

[0033] After extensive and in-depth research, screening, and testing, the present inventors have developed a highly selective CuO-ZnO@Cu-MOR catalyst, its preparation method, and its application. This invention provides a CO2 hydrogenation to methanol catalyst with a simple, rapid, and environmentally friendly preparation method. This catalyst significantly improves CO2 conversion efficiency, achieving methanol selectivity exceeding 95%. Furthermore, the catalyst exhibits a long service life, excellent stability, and resistance to deactivation, providing a novel solution for the development of low-cost, high-efficiency CO2 hydrogenation to methanol catalysts. This is the basis for the present invention.

[0034] the term

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0036] As used herein, when used in reference to a specific recited value, the term "about" means that the value may vary by no more than 1% from the recited value. For example, as used herein, the expression "about 100" includes all values ​​between 99 and 101 (e.g., 99.1, 99.2, 99.3, 99.4, etc.).

[0037] As used herein, the terms "comprising" or "including" may be open, semi-closed, or closed. In other words, the terms also include "consisting essentially of" or "consisting of."

[0038] As used herein, the term "room temperature" or "normal temperature" refers to a temperature of 0-40°C, preferably, 25±5°C.

[0039] MOR molecular sieve

[0040] In the present invention, the terms "MOR" and "MOR molecular sieve" are used interchangeably to refer to a class of molecular sieves with a MOR framework structure. The most typical example is mordenite. The MOR molecular sieves useful in the present invention can be any MOR molecular sieve having various Si / Al ratios known in the art, with the optimal Si / Al ratio being 10 to 15.

[0041] The Si / Al ratio of the MOR of the present invention is about 12, and the Si / Al ratio of the MOR that can be used in the present invention is 8 to 25.

[0042] Furthermore, MOR is stirred in a copper salt solution (preferably at a concentration of 0.1-2 mol / L, more preferably 0.5-1 mol / L) (part of the Al is replaced by Cu), washed, dried, and then calcined to obtain Cu-MOR. Preferably, the calcination is performed at a temperature of 450-550° C. for 3-6 hours.

[0043] Preferably, the Cu content in Cu-MOR is 0.1-2 wt%, such as 0.5 wt% or 1 wt%.

[0044] The inventors discovered that Cu-MOR can not only absorb water, but also promote the conversion of by-product CH4 and water into methanol, thereby realizing the coupling of CO2 hydrogenation and methane oxidation reactions. The design idea of ​​realizing the close circulation and rational utilization of by-products in the reaction coupling is the key problem solved by this application.

[0045] CuO-ZnO@Cu-MOR catalyst and its application

[0046] The invention provides a CuO-ZnO@Cu-MOR catalyst, which is obtained by calcining a (dried) solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve.

[0047] from Figure 2 As can be seen from (a) and (b), the length of the CuO-ZnO@Cu-MOR prepared by the present invention is about 40 μm and the diameter is about 20 μm (columnar). From Figure (cf), it can be observed that the sample shell has lattice gaps characteristic of CuO (110) and ZnO (102). The element energy spectrum scan (Figure gj) shows that Cu and Zn elements are evenly distributed between Si and Al elements (belonging to MOR), resulting in a capsule-like structure with Cu-MOR inside and CuO-ZnO outside.

[0048] Typically, the copper salt can be selected from the group consisting of copper nitrate, copper chloride, copper sulfate, basic copper carbonate, or a combination thereof or a hydrate thereof.

[0049] Typically, the zinc salt can be selected from the group consisting of zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, or a combination thereof or a hydrate thereof.

[0050] Preferably, in the catalyst, the mass ratio of CuO-ZnO and Cu-MOR is (0.1-10):1, preferably, (0.2-8):1, more preferably, (0.5-5):1, such as 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1.

[0051] Preferably, the molar ratio of Cu:Zn in CuO-ZnO is (0.5-10):1, preferably (0.6-5):1, more preferably (0.8-2):1, such as 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1.

[0052] Preferably, the Cu content in Cu-MOR is 0.1-2 wt%, such as 0.5 wt% or 1 wt%.

[0053] Preferably, the average length of the CuO-ZnO@Cu-MOR catalyst is 10-100 μm, preferably 20-60 μm, and more preferably 35-45 μm.

[0054] Preferably, the average diameter of the CuO-ZnO@Cu-MOR catalyst is 10-50 μm, preferably 15-40 μm, and more preferably 20-30 μm.

[0055] The present invention provides the use of CuO-ZnO@Cu-MOR as a catalyst for CO2 hydrogenation to methanol, which can significantly improve the CO2 conversion efficiency and achieve methanol selectivity of more than 95%.

[0056] The present invention also provides a method for producing methanol by hydrogenating CO2, comprising the step of catalytic hydrogenation using the CuO-ZnO@Cu-MOR catalyst.

[0057] Preparation method

[0058] The present invention provides a method for preparing a catalyst for producing methanol by hydrogenation of CO2, comprising the steps of:

[0059] (i) providing a solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve; and

[0060] (ii) calcining the solid phase mixture and cooling it to obtain a CuO-ZnO@Cu-MOR catalyst for CO2 hydrogenation to methanol.

[0061] In another preferred embodiment, the method for preparing the solid phase mixture comprises: thoroughly mixing the copper salt, the zinc salt and Cu-MOR by grinding to obtain the solid phase mixture; and optionally drying the solid phase mixture before using it in step (ii).

[0062] Preferably, the grinding is performed at room temperature. The grinding can be performed by a grinding method commonly used in the art, such as manual grinding or machine grinding, as long as sufficient mixing is achieved. For example, manual grinding for about 20 minutes is sufficient.

[0063] Since free water or water of crystallization may be present in the raw materials, it is preferred to dry the solid phase mixture before calcination.

[0064] In the present invention, a typical preparation method comprises the steps of:

[0065] Step 1: Weigh a certain amount of sodium hydroxide and aluminum nitrate and dissolve them in distilled water. While rapidly stirring, slowly add a certain amount of silica sol to form a uniform reaction precursor (2Na2O:100SiO2:2Al2O3:500H2O). After aging at room temperature for 20 hours, place the mixture in an autoclave and react in a forced-air oven at 180°C for 5 days. After the reaction, repeatedly wash with distilled water to obtain the crystallized MOR molecular sieve.

[0066] Step 2: Weigh a certain amount of MOR molecular sieve and disperse it in a 0.05M copper solution. Stir at 50°C for 12 hours, then wash off the excess salt solution. Repeat this process three times. After modification, calcine in a muffle furnace at 500°C for 4 hours to obtain the modified Cu-MOR molecular sieve.

[0067] Step 3: Weigh a certain amount of copper salt, zinc salt, and Cu-MOR, place them in an agate mortar, and grind them clockwise for 20 minutes at room temperature to obtain the CuO-ZnO@Cu-MOR precursor. The copper salts are copper nitrate, copper chloride, copper sulfate, and basic copper carbonate; the zinc salts are zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate.

[0068] Step 4: The CuO-ZnO@Cu-MOR precursor obtained in Step 1 was dried overnight at 120°C in a forced air oven, placed in an alumina boat, and calcined in a muffle furnace. Once cooled to room temperature, the CuO-ZnO@Cu-MOR catalyst was obtained. The muffle furnace temperature was ramped at 3°C / min, maintained at 500°C for 4 hours, and then naturally cooled.

[0069] Preferably, the mass ratio of CuO-ZnO / Cu-MOR is CuO-ZnO / Cu-MOR=(0.5-5):1.

[0070] The main advantages of the present invention include:

[0071] The preparation method of the present invention is fast, simple, environmentally friendly and energy-saving (no solvent is required). The CuO-ZnO@Cu-MOR catalyst precursor can be obtained by grinding for 20 minutes. After calcination, it can be used for CO2 hydrogenation to produce methanol, which can significantly improve the CO2 conversion efficiency and the methanol selectivity can reach more than 95%.

[0072] The CuO-ZnO@Cu-MOR catalyst of the present invention has good stability after long-term testing, indicating that the catalyst prepared by the present invention has a long life, good stability, and is not easy to deactivate, thereby providing a new idea for the preparation of catalysts for CO2 hydrogenation to methanol.

[0073] The present invention will be further described below in conjunction with specific implementation. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0074] Preparation of Cu-MOR

[0075] Weigh a certain amount of sodium hydroxide and aluminum nitrate and dissolve them in distilled water. While stirring rapidly, slowly add a certain amount of silica sol to form a uniform reaction precursor (2Na2O:100SiO2:2Al2O3:500H2O). After aging at room temperature for 20 hours, put it into a high-pressure reactor and react in a blast oven at 180°C for 5 days. After the reaction is completed, the crystallized MOR molecular sieve is repeatedly washed with distilled water. The chemical composition of the obtained MOR is Na2Al2Si 24 O 48 7H2O.

[0076] 5 g of the MOR molecular sieve synthesized by the above process and 0.05 mol of copper nitrate trihydrate were added to 50 mL of deionized water and stirred overnight. After completion, the mixture was washed three times with deionized water and dried at 120°C for 12 hours. The dried sample was placed in a muffle furnace and calcined at 500°C for 4 hours, increasing the temperature at 3°C / min, and then naturally cooled to obtain a Cu-MOR molecular sieve with a mass ratio of Cu to MOR of approximately 0.1-2 wt%.

[0077] Example 1

[0078] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0079] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 10.60 g of Cu-MOR into an agate mortar. Grind them clockwise for 20 minutes at room temperature to obtain a 1CuO-ZnO / 2Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 0.5.

[0080] Step 2: The 1CuO-ZnO / 2Cu-MOR precursor obtained in step 1 was first dried in a forced air oven at 120°C overnight, then placed in an alumina porcelain boat, and sent to a muffle furnace for calcination. The muffle furnace temperature program was 3°C / min, maintained at 500°C for 4 hours, and then naturally cooled to room temperature to obtain the 1CuO-ZnO / 2Cu-MOR catalyst.

[0081] Step 3: Catalyst Activity Evaluation Results: 0.5 g of the 1CuO-ZnO / 2Cu-MOR catalyst from Step 2 was placed in a CO2 hydrogenation to methanol micro-fixed bed reactor. The reactor was first reduced at 250°C for 3 h under a H2 / CO2 = 3 / 1 atmosphere, with a heating rate of 3°C / min and a space velocity (GHSV) of 5000 h-1. -1 The evaluation temperature was 240°C, the pressure was 3.5 MPa, and the time was 30 hours. Finally, the tail gas and liquid products were analyzed using an Agilent Technologies 7890B gas chromatograph (GC), and the CO conversion rate (Equation 1) and the selectivity for CHOH production (Equation 2) were calculated. The results are shown in Table 1.

[0082]

[0083]

[0084] Example 2

[0085] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0086] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 5.30 g of Cu-MOR into an agate mortar. Grind them clockwise for 20 minutes at room temperature to obtain a 1CuO-ZnO / 1Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 1.

[0087] Step 2: The 1CuO-ZnO / 1Cu-MOR catalyst was obtained in the same manner as in Step 2 of Example 1.

[0088] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0089] Example 3

[0090] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0091] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 2.65 g of Cu-MOR, place them in an agate mortar, and grind them clockwise for 20 minutes at room temperature to obtain a 2CuO-ZnO / 1Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 2.

[0092] Step 2: The 2CuO-ZnO / 1Cu-MOR catalyst was obtained in the same manner as in Step 2 of Example 1.

[0093] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0094] Example 4

[0095] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0096] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 1.77 g of Cu-MOR into an agate mortar. Grind them clockwise at room temperature for 20 minutes to obtain a 3CuO-ZnO / 1Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 3.

[0097] Step 2: The 3CuO-ZnO / 1Cu-MOR catalyst was obtained in the same manner as in Step 2 of Example 1.

[0098] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0099] Example 5

[0100] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0101] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 1.33 g of Cu-MOR into an agate mortar. Grind them clockwise for 20 minutes at room temperature to obtain a 4CuO-ZnO / 1Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 4.

[0102] Step 2: The 4CuO-ZnO / 1Cu-MOR catalyst was obtained in the same manner as in Step 2 of Example 1.

[0103] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0104] Example 6

[0105] The CuO-ZnO@Cu-MOR catalyst was synthesized as follows:

[0106] Step 1: Weigh 2.899 g of copper nitrate trihydrate, 2.38 g of zinc nitrate hexahydrate, and 1.06 g of Cu-MOR into an agate mortar. Grind them clockwise for 20 minutes at room temperature to obtain a 5CuO-ZnO / 1Cu-MOR precursor with a CuO-ZnO / Cu-MOR mass ratio of 5.

[0107] Step 2: The 5CuO-ZnO / 1Cu-MOR catalyst was obtained in the same manner as in Step 2 of Example 1.

[0108] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0109] Comparative Example 1

[0110] The CuO-ZnO catalyst was synthesized as follows:

[0111] Step 1: Add 9.66g of copper nitrate trihydrate and 11.9g of zinc nitrate hexahydrate to 200mL of deionized water, stirring until completely dissolved. This solution is Solution A. Prepare a saturated Na2CO3 solution as Solution B. Heat in a water bath at 80°C. Add Solutions A and B simultaneously to a separate beaker containing 100mL of deionized water, maintaining a pH of 9. After adding Solution A, continue heating and aging for 30 minutes. Remove the beaker and allow it to cool naturally at room temperature. Wash three times with deionized water, then dry at 80°C for 12 hours.

[0112] Step 2: Place the dried sample in a muffle furnace and calcine at 350°C for 3 hours, heating at 3°C / min, and then cool naturally to obtain a CuO-ZnO catalyst.

[0113] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0114] Comparative Example 2

[0115] The CuO-ZnO-Al2O3 catalyst was synthesized as follows:

[0116] Step 1: Add 9.66g of copper nitrate trihydrate, 11.9g of zinc nitrate hexahydrate, and 15g of aluminum nitrate nonahydrate to 200mL of deionized water, stirring until completely dissolved. This solution is Solution A. Prepare a saturated Na2CO3 solution as Solution B. While heating in a water bath at 80°C, add Solutions A and B simultaneously to a beaker containing 100mL of deionized water, maintaining a pH of 9. After adding Solution A, continue heating and aging for 30 minutes. Remove the beaker and allow it to cool naturally at room temperature. Wash it three times with deionized water, and then dry it at 80°C for 12 hours.

[0117] Step 2: The CuO-ZnO-Al2O3 catalyst is obtained in the same manner as in step 2 of Comparative Example 1.

[0118] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0119] Comparative Example 3

[0120] The CuO-ZnO-Al2O3-ZrO2 catalyst was synthesized as follows:

[0121] Step 1: Add 9.66g of copper nitrate trihydrate, 11.9g of zinc nitrate hexahydrate, 15g of aluminum nitrate nonahydrate, and 2.7g of zirconium chlorate octahydrate to 200mL of deionized water, stirring until completely dissolved. This solution is Solution A. Prepare a saturated Na2CO3 solution as Solution B. While heating in a water bath at 80°C, add Solutions A and B simultaneously to a beaker containing 100mL of deionized water, maintaining a pH of 9. After adding Solution A, continue heating and aging for 30 minutes. Remove the beaker and allow it to cool naturally at room temperature. Wash it three times with deionized water, and then dry it at 80°C for 12 hours.

[0122] Step 2: The CuO-ZnO-Al2O3-ZrO2 catalyst is obtained in the same manner as in step 2 of comparative example 1.

[0123] Step 3: Catalyst activity evaluation was the same as in Step 3 of Example 1. The results are shown in Table 1.

[0124] Table 1 Catalytic performance of the CuO-ZnO@Cu-MOR catalysts synthesized in the above examples

[0125] Example Catalyst composition <![CDATA[CO2 conversion rate (%)]]> <![CDATA[CH3OH selectivity (%)]]> 1 1CuO-ZnO / 2Cu-MOR 14.1 97.9 2 1CuO-ZnO / 1Cu-MOR 22.8 95.6 3 2CuO-ZnO / 1Cu-MOR 23.1 85.3 4 3CuO-ZnO / 1Cu-MOR 24.5 83.2 5 4CuO-ZnO / 1Cu-MOR 25.1 82.5 6 5CuO-ZnO / 1Cu-MOR 25.3 81.7 Comparative Example 1 CuO-ZnO 19.6 75.4 2 <![CDATA[CuO-ZnO-Al2O3]]> 22.8 72.9 3 <![CDATA[CuO-ZnO-Al2O3-ZrO2]]> 24.2 84.6

[0126] The preparation method of the present invention is simple and solvent-free. The CuO-ZnO@Cu-MOR catalyst can be quickly prepared by a solid-phase method. The catalyst is used for CO2 hydrogenation to produce methanol, which can significantly improve the CO2 conversion efficiency and achieve methanol selectivity of more than 95%.

[0127] In addition, catalysts prepared using traditional co-precipitation methods require strict control of pH, temperature, concentration conditions, as well as post-processing steps such as washing and filtration.

[0128] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that such equivalents also fall within the scope of the claims appended hereto.

Claims

1. A method for preparing a catalyst for CO2 hydrogenation to methanol, characterized in that: Including steps: (i) providing a solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve; and (ii) calcining the solid phase mixture and cooling it to obtain a CuO-ZnO@Cu-MOR catalyst for CO2 hydrogenation to methanol.

2. The method according to claim 1, wherein The copper salt is selected from the group consisting of copper nitrate, copper chloride, copper sulfate, basic copper carbonate, or a combination thereof or a hydrate thereof.

3. The method according to claim 1, wherein The zinc salt is selected from the group consisting of zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, or a combination thereof or a hydrate thereof.

4. The method according to claim 1, wherein The preparation method of the solid phase mixture comprises: thoroughly mixing copper salt, zinc salt and Cu-MOR by grinding to obtain the solid phase mixture; and optionally drying the solid phase mixture before using it in step (ii).

5. A CuO-ZnO@Cu-MOR catalyst, which is obtained by calcining a solid phase mixture of a copper salt, a zinc salt and a Cu-MOR molecular sieve.

6. The catalyst according to claim 5, characterized in that In the catalyst, the mass ratio of CuO-ZnO to Cu-MOR is (0.1-10):1, preferably, (0.2-8):1, and more preferably, (0.5-5):1, such as 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:

1.

7. The catalyst according to claim 5, characterized in that The molar ratio of Cu:Zn in CuO-ZnO is (0.5-10):1, preferably (0.6-5):1, more preferably (0.8-2):1, such as 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:

1.

8. The catalyst according to claim 5, characterized in that The content of Cu in Cu-MOR is 0.1-2 wt%, such as 0.5 wt% or 1 wt%.

9. Use of the CuO-ZnO@Cu-MOR catalyst according to any one of claims 5 to 8 as a catalyst for CO2 hydrogenation to methanol.

10. A method for preparing methanol by hydrogenating CO2, characterized in that: The method comprises the step of catalytic hydrogenation using the CuO-ZnO@Cu-MOR catalyst according to any one of claims 5 to 8.

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