Catalyst for preparing methanol through catalytic hydrogenation of carbon dioxide as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for preparing methanol through catalytic hydrogenation of carbon dioxide, which is prepared by the following steps: (s1) uniformly mixing an aqueous solution of copper salt and zinc salt with an ethanol solution of 1, 3, 5-benzenetricarboxylic acid (BTC); (s2) filling the reaction liquid in the step (s1) into a reaction kettle, and reacting under a microwave heating condition; (s3) fully washing with ethanol, and performing vacuum drying to prepare Cu / Zn-BTC crystals with different copper-zinc ratios, wherein the Cu / Zn-BTC crystals are used as precursors for catalyst preparation; and (s4) carrying out high-temperature calcination in air to prepare the Cu / Zn-BTC derived CuO-ZnO catalyst. The preparation method disclosed by the invention is simple and efficient, simple and convenient to operate, easy to control reaction conditions, free of strict reaction conditions such as contents of gases such as hydrogen and argon, and easy for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing methanol by catalytic hydrogenation of carbon dioxide, and in particular to a catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide, and a preparation method and application thereof. Background Art

[0002] Methanol has a high octane number, good anti-knock performance, and good combustion performance. It is a liquid fuel with excellent combustion performance and is easy to store and transport. Moreover, methanol is an important C1 chemical product and an important raw material and intermediate for the preparation of gasoline, aromatics, olefins and other high-value chemicals (such as formaldehyde, acetic acid, methyl tert-butyl ether and dimethyl ether, etc.). Among the basic organic chemical raw materials in the world, methanol consumption ranks fourth, second only to ethylene, propylene and benzene. Therefore, the preparation and application of methanol have attracted widespread attention from the scientific and industrial communities. At present, large-scale industrial production of methanol is mainly prepared by synthesis gas (a mixture of CO and H2) (Equation f1). A small amount of CO2 (about 2–8%) is usually added to CO / H2 to balance the H / C ratio to the required stoichiometry and accelerate the reaction rate. In recent years, due to the pressure of CO2 emission reduction, the research on CO2 catalytic hydrogenation to produce methanol (equation f2) has aroused great interest among researchers and is considered to be the most attractive way for CO2 conversion and utilization. It is not only conducive to reducing CO2 emissions and achieving my country's "dual carbon" goals, but also conducive to reducing dependence on overseas oil and maintaining my country's energy security.

[0003] (f1)

[0004] (f2)

[0005] (f3)

[0006] Due to the high thermodynamic stability of CO2 molecules and the inert reaction kinetics, the activation of CO2 is usually difficult and needs to be carried out under high temperature conditions. Therefore, external energy input and efficient catalysts are the prerequisites for converting CO2 into methanol. In the past two decades, researchers at home and abroad have been exploring highly active catalysts for the hydrogenation of CO2 to produce methanol. Catalysts for the catalytic hydrogenation of CO2 to produce methanol mainly include metal oxides, precious metals and metal alloys. Similar to the preparation of methanol from synthesis gas, copper-based catalysts are widely used in the catalytic hydrogenation of CO2 to produce methanol because of their relatively high catalytic activity and low preparation cost. In particular, CuO-ZnO catalysts dominate the synthesis of methanol.

[0007] CuO-ZnO catalysts are usually prepared by coprecipitation-high temperature pyrolysis, but the coprecipitation method can easily lead to the agglomeration of metal nanoparticles, thereby reducing the activity of the catalyst. In addition, due to the presence of many side reactions in the CO2 catalytic hydrogenation reaction to produce methanol, such as the reverse water gas shift reaction (Equation f3), the selectivity of methanol is usually less than 70%, and the CO2 single-pass conversion rate is usually less than 30%. Therefore, the research and development of new preparation methods is of great significance for the preparation of highly active and highly selective catalysts.

[0008] Therefore, it is necessary to develop a method for preparing a catalyst for catalytic hydrogenation of CO2 to produce methanol, which has high CO2 conversion rate, high methanol selectivity, simple formula, easy operation, easy control of reaction conditions, and easy industrial production. Summary of the invention

[0009] The purpose of the present invention is to provide a catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide, and a preparation method and application thereof. The preparation method of the present invention is simple and efficient, easy to operate, and the reaction conditions are easy to control and easy to industrialize. The Cu / Zn-BTC-derived CuO-ZnO catalyst prepared by the present invention has the catalytic characteristics of high activity and high selectivity.

[0010] In a first aspect of the present invention, there is provided a method for preparing a catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide, the method comprising the following steps:

[0011] (s1) providing a solution A and a solution B, and mixing the solution A and the solution B uniformly to obtain a reaction solution;

[0012] Wherein, the liquid A is an aqueous solution of copper salt and zinc salt, the liquid B is an ethanol solution of 1,3,5-benzenetricarboxylic acid (BTC), and the molar ratio of the components of the reaction solution is: copper salt: zinc salt: 1,3,5-benzenetricarboxylic acid: ethanol: water = (1.7-x): x: 1.6: 82.7: 264.7, wherein x = 0.10 to 1.00;

[0013] (s2) placing the reaction solution obtained in step (s1) into a reaction vessel, and performing a microwave heating reaction to obtain a precursor Cu / Zn-BTC crystal;

[0014] (s3) The Cu / Zn-BTC crystal obtained in step (s2) is used as a template and calcined in air at 350-650° C. to prepare a CuO-ZnO catalyst derived from Cu / Zn-BTC.

[0015] In another preferred embodiment, in step (s1), the copper salt is selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper acetate, or a combination thereof.

[0016] In another preferred embodiment, the copper salt is copper nitrate.

[0017] In another preferred embodiment, in step (s1), the zinc salt is selected from the group consisting of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, or a combination thereof.

[0018] In another preferred embodiment, the zinc salt is zinc nitrate.

[0019] In another preferred embodiment, x=0.15-0.85, preferably x=0.2-0.7, for example, x=0.4 and x=0.68.

[0020] In another preferred embodiment, in step (s1), the concentration of the copper salt in solution A is 0.03-0.5 g / g, preferably 0.06-0.12 g / g.

[0021] In another preferred embodiment, in step (s1), the concentration of the zinc salt in liquid A is 0.005-0.1 g / g, preferably 0.01-0.08 g / g.

[0022] In another preferred embodiment, in step (s1), the concentration of 1,3,5-benzenetricarboxylic acid in liquid B is 0.005-0.5 g / g, preferably 0.05-0.1 g / g, for example 0.088 g / g.

[0023] In another preferred embodiment, in step (s2), the reaction is carried out at 80-150°C, preferably 100-120°C, for example 100°C and 120°C.

[0024] In another preferred embodiment, in step (s2), the reaction time is 1 to 12 h, preferably 4 to 8 h, more preferably 4 to 6 h, such as 4 h and 5 h.

[0025] In another preferred embodiment, in step (s2), the reaction further comprises a post-treatment step.

[0026] In another preferred embodiment, in step (s2), the post-treatment step includes fully washing the prepared Cu / Zn-BTC crystals with ethanol and vacuum drying.

[0027] In another preferred embodiment, in step (s3), the calcination in air is carried out at 350-650°C, preferably 450-600°C.

[0028] In another preferred embodiment, in step (s3), the calcination in air is carried out at 350-600°C, for example, 350°C, 400°C, 450°C, 500°C, 550°C and 600°C.

[0029] In another preferred embodiment, the calcination time is 1 to 8 hours, preferably 2 to 6 hours, such as 4-5 hours.

[0030] In another preferred embodiment, in step (s1), the molar ratio of the copper salt to the zinc salt is 1:5 to 10:1, preferably 1:1 to 9:1, and more preferably 1:1 to 4:1.

[0031] In another preferred embodiment, in step (s1), the molar ratio of the copper salt to the zinc salt is 1:1 to 9:1, for example, 9:1, 8:2, 7:3, 6:4 and 5:5.

[0032] In another preferred embodiment, in step (s1), the molar ratio of copper to zinc in the reaction solution is 1:5 to 10:1, preferably 1:1 to 9:1, and more preferably 1:1 to 4:1.

[0033] In another preferred embodiment, in step (s1), the molar ratio of copper to zinc in the reaction solution is 1:1 to 9:1, for example, 9:1, 8:2, 7:3, 6:4 and 5:5.

[0034] The second aspect of the present invention provides a catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide. The catalyst is a CuO-ZnO catalyst prepared by the method described in the first aspect of the present invention.

[0035] In another preferred embodiment, the particle size of the catalyst is 100-400 nm, preferably 200-300 nm.

[0036] In another preferred embodiment, the catalyst has substantially Figure 2 X-ray diffraction pattern shown.

[0037] In another preferred embodiment, the catalyst has one or more characteristics selected from the following group:

[0038] (c1) having a high carbon dioxide conversion rate at 200° C. and 3 MPa, wherein the carbon dioxide conversion rate is greater than 15%, preferably 25%, and more preferably 30%;

[0039] (c2) having high methanol selectivity at 200°C and 3 MPa, wherein the methanol selectivity is greater than 90%, preferably 92%, and more preferably 93%.

[0040] In the third aspect of the present invention, there is provided a use of the catalyst as described in the second aspect of the present invention, for catalyzing the reaction of preparing methanol by catalytic hydrogenation of carbon dioxide.

[0041] In a fourth aspect of the present invention, a method for preparing methanol by catalytic hydrogenation of carbon dioxide is provided, the method comprising the following steps:

[0042] (1) Providing the catalyst according to the second aspect of the present invention;

[0043] (2) The catalyst in step (1) is fixed in a catalytic reactor where H2 and CO2 are fully mixed to carry out the reaction.

[0044] In another preferred embodiment, the volume ratio of H2 and CO2 is 1:1 to 5:1, preferably 2:1 to 4:1.

[0045] In another preferred embodiment, the reaction pressure of the reactor is 2 to 5 MPa, preferably 2.5 to 3.5 MPa.

[0046] In another preferred embodiment, the reaction temperature of the reactor is 150-350°C, preferably 200-300°C, more preferably 200-250°C.

[0047] In another preferred embodiment, the gas hourly space velocity (GHSV) of the reactor is 2000-8000h -1 , preferably 3500~6000h -1 .

[0048] In another preferred embodiment, the step (2) comprises: encapsulating the catalyst of step (1) in a fixed bed catalytic reactor, and then fully mixing H2 and CO2 in a volume ratio of 3:1 in a gas mixing device, and then feeding them into the reactor. The flow rate of each gas is controlled by a gas mass flow controller. The reaction is controlled at a pressure of 3.0 MPa, a temperature of 200-300°C, and a gas hourly space velocity (GHSV) of 4000 h -1 The reaction products were analyzed by gas chromatography (Agilent 7890B) to calculate the CO2 conversion rate and methanol selectivity.

[0049] 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 specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Shows the scanning electron micrograph of the CuO-ZnO catalyst derived from 6Cu / 4Zn-BTC crystals prepared under microwave heating conditions.

[0051] Figure 2 Shown is the X-ray diffraction pattern of the CuO-ZnO catalyst derived from 6Cu / 4Zn-BTC crystals prepared under microwave heating conditions. DETAILED DESCRIPTION

[0052] After extensive and in-depth research, the inventors have discovered for the first time a catalyst preparation and application of catalytic hydrogenation of carbon dioxide to prepare methanol. The preparation method of the present invention has a simple formula, is easy to operate, and the reaction conditions are easy to control. It is not necessary to control strict reaction conditions such as the content of gases such as hydrogen and argon, and it is easy to industrialize production. The CuO-ZnO catalyst derived from Cu / Zn-BTC prepared by microwave heating in the present invention has the catalytic characteristics of high activity and high selectivity. The present invention was completed on this basis.

[0053] the term

[0054] 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.

[0055] As used herein, the terms "comprise", "include", and "contain" are used interchangeably and include not only closed definitions, but also semi-closed and open definitions. In other words, the terms include "consisting of", "consisting essentially of".

[0056] As used herein, when used in reference to a specific recited numerical 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.).

[0057] Preparation method of catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide

[0058] Metal-organic frameworks (MOFs) are crystalline materials formed by inorganic metal ions or clusters and organic ligands connected by coordination bonds. They have ultra-high specific surface area, diverse composition and structure, ordered pore structure and framework, and are widely used in gas adsorption and storage, membrane separation, chemical sensing and catalytic reactions. In particular, most metal-organic frameworks are composed of transition metal ions and organic ligands, and have numerous catalytic active sites. Using metal-organic frameworks as precursors, porous carbon, metal compounds and their composites can be derived by high-temperature calcination and used as catalysts for chemical reactions. Compared with catalysts prepared by traditional methods, catalysts derived from metal-organic frameworks have the advantages of large specific surface area, high porosity, adjustable morphology, and uniform heteroatom doping, and have very broad application prospects in heterogeneous catalysis. Cu-BTC is a representative porous metal-organic framework material with unique three-dimensional pore structure, high specific surface area, cheap raw materials, simple preparation, and nanoscale pores of different levels. By doping with Zn atoms, it is expected to prepare the copper-zinc binary metal organic framework material Cu / Zn-BTC, and then by high-temperature sintering, the Cu / Zn-BTC-derived CuO-ZnO catalyst is prepared. After high-temperature pyrolysis, the ordered porous structure and high specific surface area inherited from the original metal organic framework Cu / Zn-BTC can provide high-throughput mass transfer and high active center exposure, which helps to improve the activity of the CuO-ZnO catalyst and is expected to become a new and efficient CO2 catalytic hydrogenation to methanol catalyst. Microwave heating has the advantages of rapid and uniformity, and it is expected to prepare a catalyst with a small particle size.

[0059] Based on this, the present invention discloses a preparation and application of a catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide. The preparation method of the catalyst of the present invention comprises the following steps: firstly, Zn atoms are doped into a metal organic framework Cu-BTC, and microwave heating is performed to synthesize and prepare a copper-zinc binary metal organic framework Cu / Zn-BTC; then, the prepared Cu / Zn-BTC crystals are calcined in air to prepare a CuO-ZnO catalyst derived from Cu / Zn-BTC, and used for catalytic hydrogenation of carbon dioxide to prepare methanol.

[0060] In order to achieve this purpose, the technical solution and route adopted by the present invention are as follows:

[0061] 1. Preparation of Cu / Zn-BTC with different Cu / Zn ratios by microwave heating synthesis

[0062] 1) Dissolve copper nitrate trihydrate and zinc nitrate hexahydrate in different proportions in distilled water, stir them evenly with a magnetic force, and obtain a nitrate aqueous solution. Dissolve 1,3,5-benzenetricarboxylic acid (BTC) in ethanol, stir them evenly with a magnetic force, and obtain a 1,3,5-benzenetricarboxylic acid ethanol solution. Mix the above two solutions and stir them evenly with a magnetic force. The molar ratio of the components in the solution is: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = (1.7-x): x: 1.6: 82.7: 264.7, where x = 0.10 to 1.00.

[0063] 2) The reaction solution is charged into a reaction kettle, and the reaction is carried out at a temperature of 80 to 150° C. by microwave heating for 1 to 12 hours; after the reaction is completed, the reaction is cooled to room temperature, and then the Cu / Zn-BTC crystals with different copper-zinc ratios are prepared by washing with ethanol and vacuum drying.

[0064] 2. Preparation of Cu / Zn-BTC-derived CuO-ZnO catalyst by high temperature pyrolysis

[0065] The prepared Cu / Zn-BTC crystals are calcined in air at 350-650° C. for 1-5 hours to prepare a CuO-ZnO catalyst derived from Cu / Zn-BTC.

[0066] 3. CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to produce methanol

[0067] The catalytic performance of the prepared catalyst for catalytic hydrogenation of carbon dioxide to methanol was evaluated in a conventional fixed bed reactor. The prepared CuO-ZnO catalyst was loaded in the reactor, and then H2 and CO2 with a volume ratio of 3:1 were fully mixed in a gas mixing device and then fed into the reactor. The flow rate of each gas was controlled by a gas mass flow controller. The reaction was carried out at a pressure of 1.5-4.0 MPa, a temperature of 200-300 °C, and a gas hourly space velocity (GHSV) of 4000 h -1 The reaction products and waste gas were analyzed by gas chromatography (Agilent 7890B) equipped with TCD and FID detectors to calculate the CO2 conversion rate and methanol selectivity.

[0068] Among them, the CuO-ZnO catalyst derived from Cu / Zn-BTC has a high carbon dioxide conversion rate, and its carbon dioxide conversion rate is greater than 15%, preferably 25%, and more preferably 30%.

[0069] Among them, the CuO-ZnO catalyst derived from Cu / Zn-BTC has high methanol selectivity, and its methanol selectivity is greater than 90%, preferably 92%, and more preferably 93%.

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

[0071] (1) The microwave heating preparation method of the CuO-ZnO catalyst of the present invention greatly shortens the preparation time and greatly reduces the particle size of the prepared catalyst particles. The catalyst precursor does not need to be reduced under a certain ratio of hydrogen and argon mixed gas, and the CuO-ZnO catalyst can be obtained by high-temperature calcination in air. There is no need to control strict reaction conditions such as the content of hydrogen, argon and other gases, and it is easy to industrialize production.

[0072] (2) The CuO-ZnO catalyst prepared in the present invention has a high carbon dioxide conversion rate, which is greater than 15%, preferably 25%, and more preferably 30%.

[0073] (3) The CuO-ZnO catalyst prepared in the present invention has high methanol selectivity, which is greater than 90%, preferably 92%, and more preferably 93%.

[0074] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0075] Example 1

[0076] Step 1 Preparation of metal organic framework Cu-BTC

[0077] Dissolve 4.1108 g of copper nitrate trihydrate in 32.4 g of distilled water and stir magnetically until completely dissolved. This solution is solution A. Dissolve 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) in 25.92 g of ethanol and stir magnetically until completely dissolved. This solution is solution B. Mix the above two solutions A and B and stir magnetically to make them uniform. The molar ratio of each component in the solution is: copper nitrate trihydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.7: 82.7: 264.7. The prepared reaction solution is placed in a reactor and heated by microwave at a temperature of 120°C for 4 hours. After the reaction is completed, cool to room temperature, then wash thoroughly with ethanol and vacuum dry to obtain the prepared Cu-BTC crystals.

[0078] Step 2 Preparation of Cu-BTC-derived CuO catalyst

[0079] The prepared Cu-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a Cu-BTC-derived CuO catalyst.

[0080] Step 3: Cu-BTC-derived CuO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0081] The prepared CuO catalyst was encapsulated in a fixed-bed catalytic reactor, and then H2 and CO2 with a volume ratio of 3:1 were fully mixed in a gas mixing device and then fed into the reactor. The flow rate of each gas was controlled by a gas mass flow controller. The catalyst was then activated in situ for 20 hours under a reaction atmosphere of 3.0 MPa and a temperature of 200-300 °C to obtain stable catalytic performance. Finally, the reaction was controlled at a pressure of 3.0 MPa, a temperature of 200-300 °C, and a gas hourly space velocity (GHSV) of 4000 h -1 The catalyst performance was evaluated under the following conditions. The reaction products were analyzed by gas chromatography (Agilent 7890B) to calculate the CO2 conversion rate and methanol selectivity.

[0082] Example 2

[0083] Step 1 Preparation of copper-zinc binary metal-organic framework 9Cu / 1Zn-BTC

[0084] 3.6997 g of copper nitrate trihydrate and 0.5062 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution was solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution was solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.53: 0.17: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 9: 1. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 120°C for 4 hours; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 9Cu / 1Zn-BTC crystal.

[0085] Step 2 Preparation of 9Cu / 1Zn-BTC derived CuO-ZnO catalyst

[0086] The prepared 9Cu / 1Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a 9Cu / 1Zn-BTC derived CuO-ZnO catalyst.

[0087] Step 3: 9Cu / 1Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0088] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0089] Example 3

[0090] Step 1 Preparation of copper-zinc binary metal-organic framework 8Cu / 2Zn-BTC

[0091] 3.2887 g of copper nitrate trihydrate and 1.0123 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution was solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution was solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.36: 0.34: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 8: 2. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 120°C for 4 hours; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 8Cu / 2Zn-BTC crystal.

[0092] Step 2 Preparation of 8Cu / 2Zn-BTC derived CuO-ZnO catalyst

[0093] The prepared 8Cu / 2Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a CuO-ZnO catalyst derived from 8Cu / 2Zn-BTC.

[0094] Step 3 8Cu / 2Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0095] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0096] Example 4

[0097] Step 1 Preparation of copper-zinc binary metal-organic framework 7Cu / 3Zn-BTC

[0098] 2.8776 g of copper nitrate trihydrate and 1.5185 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution was solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution was solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.19: 0.51: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 7: 3. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 120°C for 4 hours; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 7Cu / 3Zn-BTC crystal.

[0099] Step 2 Preparation of 7Cu / 3Zn-BTC derived CuO-ZnO catalyst

[0100] The prepared 7Cu / 3Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a 7Cu / 3Zn-BTC derived CuO-ZnO catalyst.

[0101] Step 3 7Cu / 3Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0102] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0103] Example 5

[0104] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0105] 2.4665 g of copper nitrate trihydrate and 2.0247 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution is solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution is solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.02: 0.68: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 6: 4. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 120°C for 4 hours; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 6Cu / 4Zn-BTC crystal.

[0106] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0107] The prepared 6Cu / 4Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0108] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0109] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0110] Example 6

[0111] Step 1 Preparation of copper-zinc binary metal-organic framework 5Cu / 5Zn-BTC

[0112] 2.0554 g of copper nitrate trihydrate and 2.5309 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution is solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution is solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 0.85: 0.85: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 5: 5. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 120°C for 4 hours; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 5Cu / 5Zn-BTC crystal.

[0113] Step 2 Preparation of 5Cu / 5Zn-BTC derived CuO-ZnO catalyst

[0114] The prepared 5Cu / 5Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a 5Cu / 5Zn-BTC derived CuO-ZnO catalyst.

[0115] Step 3: 5Cu / 5Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0116] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0117] Example 7

[0118] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0119] 2.4665 g of copper nitrate trihydrate and 2.0247 g of zinc nitrate hexahydrate were dissolved in 32.4 g of distilled water and stirred magnetically until completely dissolved. This solution is solution A. 2.2810 g of 1,3,5-benzenetricarboxylic acid (BTC) was dissolved in 25.92 g of ethanol and stirred magnetically until completely dissolved. This solution is solution B. The above two solutions A and B were mixed and stirred magnetically. The molar ratio of each component in the solution was: copper nitrate trihydrate: zinc nitrate hexahydrate: 1,3,5-benzenetricarboxylic acid: ethanol: water = 1.02: 0.68: 1.6: 82.7: 264.7, and the copper-zinc ratio in the solution was 6: 4. The prepared reaction solution was loaded into a reactor and heated by microwave at a temperature of 100 ° C for 5 h; after the reaction was completed, it was cooled to room temperature, and then fully washed with ethanol and vacuum dried to obtain the prepared 6Cu / 4Zn-BTC crystal.

[0120] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0121] The prepared 6Cu / 4Zn-BTC was calcined at 500°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0122] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0123] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0124] Example 8

[0125] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0126] 6Cu / 4Zn-BTC crystals were prepared according to the method of step 1 of Example 5.

[0127] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0128] The prepared 6Cu / 4Zn-BTC was calcined at 350°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0129] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0130] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0131] Example 9

[0132] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0133] 6Cu / 4Zn-BTC crystals were prepared according to the method of step 1 of Example 5.

[0134] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0135] The prepared 6Cu / 4Zn-BTC was calcined at 400°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0136] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0137] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0138] Example 10

[0139] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0140] 6Cu / 4Zn-BTC crystals were prepared according to the method of step 1 of Example 5.

[0141] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0142] The prepared 6Cu / 4Zn-BTC was calcined at 450°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0143] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0144] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0145] Embodiment 11

[0146] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0147] 6Cu / 4Zn-BTC crystals were prepared according to the method of step 1 of Example 5.

[0148] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0149] The prepared 6Cu / 4Zn-BTC was calcined at 550°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0150] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0151] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0152] Example 12

[0153] Step 1 Preparation of copper-zinc binary metal-organic framework 6Cu / 4Zn-BTC

[0154] 6Cu / 4Zn-BTC crystals were prepared according to the method of step 1 of Example 5.

[0155] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0156] The prepared 6Cu / 4Zn-BTC was calcined at 600°C in an air atmosphere for 5 hours to prepare a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst.

[0157] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0158] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0159] Example 13 (Comparative Example)

[0160] Step 1 Preparation of CuO-ZnO catalyst by coprecipitation method

[0161] Dissolve 9.66 g of copper nitrate trihydrate and 11.9 g of zinc nitrate hexahydrate in 200 ml of deionized water and stir magnetically until completely dissolved. This solution is solution A. Dissolve 40 g of sodium carbonate in 150 ml of distilled water to prepare a saturated sodium carbonate solution as solution B. Add solutions A and B simultaneously to a beaker containing 150 ml of deionized water while heating in a water bath at 80°C, keeping the pH value of the solution at 9. After all solution A is added dropwise, continue heating and aging for 30 minutes, take it out and cool it naturally at room temperature, wash the resulting precipitate with deionized water, filter it, and then dry it at 80°C for 12 hours. Finally, place the dried powder in a muffle furnace and calcine it at 350°C in an air atmosphere for 3 hours, then cool it naturally to obtain a CuO-ZnO catalyst.

[0162] Step 2: CuO-ZnO catalyst prepared by coprecipitation method is used for catalytic hydrogenation of carbon dioxide to produce methanol

[0163] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0164] Example 14 (Comparative Example)

[0165] Step 1 Preparation of CuO-ZnO catalyst by conventional heating method

[0166] A solution of 6Cu / 4Zn-BTC crystals was prepared according to the method of step 1 of Example 5, and then the prepared reaction solution was charged into a reactor, and heated in a conventional oven at a temperature of 120° C. for 4 hours; after the reaction was completed, it was cooled to room temperature, and then the prepared 6Cu / 4Zn-BTC crystals were fully washed with ethanol and vacuum dried.

[0167] Step 2 Preparation of 6Cu / 4Zn-BTC derived CuO-ZnO catalyst

[0168] According to step 1 of Example 5, a 6Cu / 4Zn-BTC derived CuO-ZnO catalyst was prepared.

[0169] Step 3: 6Cu / 4Zn-BTC derived CuO-ZnO catalyst for catalytic hydrogenation of carbon dioxide to methanol

[0170] The prepared CuO-ZnO catalyst was encapsulated in a fixed bed catalytic reactor, and the catalytic performance of the catalyst was evaluated according to the method of step 3 of Example 1.

[0171] Test Example 1. Catalytic performance of different materials

[0172] Table 1 below shows the catalytic performance of the catalysts prepared in various embodiments of the present invention at 200°C and 3MPa.

[0173] Table 1 Catalytic performance of the catalysts prepared in various embodiments of the present invention at 200°C and 3MPa

[0174]

[0175]

[0176] It can be seen that the catalytic performance of pure CuO catalyst without ZnO doping is poor, and the catalytic performance of CuO-ZnO catalyst obtained by co-precipitation method is also poor. The catalytic performance of CuO-ZnO catalyst prepared by traditional heating method is general, while the metal organic framework-derived CuO-ZnO catalyst synthesized by microwave heating has relatively excellent catalytic performance. The Cu:Zn doping ratio (molar ratio) is between 8:2 and 5:5, and the calcination temperature is between 350-550℃, which has high CO2 conversion rate and methanol selectivity, especially when the doping ratio is 6:4, it shows excellent CO2 conversion rate and methanol selectivity.

[0177] The CuO-ZnO catalyst derived from the Cu / Zn-BTC crystal synthesized in the present invention is an irregular nanoparticle with a size of 200-300 nanometers ( Figure 1 ).

[0178] The CuO-ZnO catalyst derived from the Cu / Zn-BTC crystal synthesized in the present invention is a pure phase CuO-ZnO ( Figure 2 ).

[0179] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A catalyst for preparing methanol by catalytic hydrogenation of carbon dioxide, characterized in that: Prepared by the following method: (s1) providing a solution A and a solution B, and mixing the solution A and the solution B uniformly to obtain a reaction solution; Wherein, the liquid A is an aqueous solution of copper salt and zinc salt, the liquid B is an ethanol solution of 1,3,5-benzenetricarboxylic acid (BTC), and the molar ratio of the components of the reaction solution is: copper salt: zinc salt: 1,3,5-benzenetricarboxylic acid: ethanol: water = (1.7-x): x: 1.6: 82.7: 264.7, wherein x = 0.10 to 1.00; (s2) placing the reaction solution obtained in step (s1) into a reaction vessel, heating the reaction with microwaves, and obtaining a precursor Cu / Zn-BTC crystal; (s3) calcining the Cu / Zn-BTC crystals obtained in step (s2) in air at 350-650° C. to obtain a CuO-ZnO catalyst derived from Cu / Zn-BTC.

2. The catalyst according to claim 1, characterized in that The copper salt is selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper acetate, or a combination thereof.

3. The catalyst according to claim 1, characterized in that The zinc salt is selected from the group consisting of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, or a combination thereof.

4. The catalyst according to claim 1, characterized in that In step (s1), the molar ratio of the copper salt to the zinc salt is 1:5 to 10:1, preferably 1:1 to 9:1, and more preferably 1:1 to 4:

1.

5. The catalyst according to claim 1, characterized in that The reaction is carried out at a temperature of 80-150°C, preferably 100-120°C.

6. The catalyst according to claim 1, characterized in that The reaction time is 1 to 12 hours, preferably 4 to 8 hours.

7. The catalyst according to claim 1, characterized in that The calcination temperature in air is 350-600°C, preferably 450-600°C.

8. A method for preparing the catalyst according to claim 1, characterized in that: The method comprises the following steps: (s1) providing a solution A and a solution B, and mixing the solution A and the solution B uniformly to obtain a reaction solution; Wherein, the liquid A is an aqueous solution of copper salt and zinc salt, the liquid B is an ethanol solution of 1,3,5-benzenetricarboxylic acid (BTC), and the molar ratio of the components of the reaction solution is: copper salt: zinc salt: 1,3,5-benzenetricarboxylic acid: ethanol: water = (1.7-x): x: 1.6: 82.7: 264.7, wherein x = 0.10 to 1.00; (s2) placing the reaction solution obtained in step (s1) into a reaction vessel, heating the reaction with microwaves, and obtaining a precursor Cu / Zn-BTC crystal; (s3) calcining the Cu / Zn-BTC crystals obtained in step (s2) in air at 350-650° C. to prepare a CuO-ZnO catalyst derived from Cu / Zn-BTC.

9. Use of the catalyst as claimed in claim 1, characterized in that: The catalyst is used for catalyzing the reaction of preparing methanol by catalytic hydrogenation of carbon dioxide.

10. A method for preparing methanol by catalytic hydrogenation of carbon dioxide, characterized in that: The method comprises the following steps: (1) providing the catalyst as claimed in claim 1; (2) The catalyst in step (1) is fixed in a catalytic reactor where H2 and CO2 are fully mixed to carry out the reaction.

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