A catalyst for methanol production and its preparation method and application

Abstract

The present application relates to the field of catalyst, in particular to a kind of catalyst for methanol and its preparation method and application;Catalyst is composed of copper, zinc, M1 and M2 metal oxide, by metal oxide, its mass percentage is CuO 40~60%, ZnO 20~30%, M1O x 5~20%, M2O y 0~15%;Wherein M1 and M2 are one of Al, Mg and Zr, and M1 and M2 are selected from different metal elements;The catalyst of the present application is simple in preparation method, easy to control conditions, and low in preparation cost. And for coke oven gas carbon supplement methanol reaction, it can effectively improve the conversion rate of CO and CO2, and has good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular to a catalyst for methanol production and a preparation method and application thereof. BACKGROUND

[0002] Coke oven gas (COG) is produced in the coking process, and the main components of COG are H2, CH4, CO, CO2, O2, N2, etc. Due to the high content of combustible components, COG belongs to high-calorific-value gas, and thus has high utilization value. The utilization of COG is mainly concentrated in the fields of producing chemical fertilizers, producing methanol, producing carbon black, producing hydrogen, and producing LNG. Among them, the production of methanol from COG is an effective scheme widely accepted, methanol is an important chemical raw material, which can be further converted into olefins, aromatic hydrocarbons and other downstream chemicals, and is also a potential liquid fuel. In addition, the cost of producing methanol from COG is lower than that of producing methanol from other raw materials, so the scheme of producing methanol from COG is a good choice.

[0003] It has been found through practice that there are many factors affecting the yield and purity of methanol in the production of methanol from COG, and the catalyst is one of the reasons. After separation and purification and carbon supplementation, COG can form a special proportion of mixed gas (H2-CO2) / (CO+CO2) = 2.05-2.15) which is beneficial to the synthesis of methanol. There is no mature technology for this gas at present. Studies have shown that Cu-based catalysts can catalytically convert synthesis gas (CO / CO2 / H2) into methanol under the conditions of 200-300℃ and 3-10 MPa, and Cu / ZnO catalyst is the most widely used catalyst for the hydrogenation of methanol. x However, in the existing evaluation results, the conversion rate of CO x in the mixed gas is low and the stability is poor, and the catalyst is easy to deactivate. In order to further improve the catalytic activity of the catalyst, other elements are selected as additives on the basis of the catalyst to improve the adsorption and activation of CO x and H2. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and provides a catalyst for producing methanol.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a catalyst for producing methanol, the catalyst is composed of copper, zinc, M1 and M2 metal oxides, and the mass percentage of the metal oxides is CuO 40-60%, ZnO 20-30%, M1O x 5-20%, and M2O y 0-15%; wherein M1 and M2 are one of Al, Mg and Zr, and M1 and M2 are selected from different metal elements.

[0006] Preferably, metal M1 and metal M2 are Al and Zr, respectively.

[0007] The present invention also provides a method for preparing the above-mentioned catalyst for methanol production, comprising the following steps:

[0008] (1) Weigh copper nitrate and zinc nitrate and dissolve them together in deionized water to obtain solution A; weigh sodium carbonate and dissolve it in deionized water to obtain solution B; under stirring at 70°C, add solution A and solution B dropwise into a beaker containing deionized water at the same time, and control the pH of the reaction solution to 7±0.5 by adjusting the dropping rate of the solution. After precipitation is completed, continue aging for 1 hour, then filter and wash to obtain the precursor.

[0009] (2) The precursor from step (1) was added to distilled water and slurried. Then, the nitrate solutions of M1 and M2 and the sodium carbonate solution were added to the precursor solution in a co-current manner, while controlling the pH of the solution to 7±0.5. After precipitation, the solution was aged for 1-2 hours, then filtered, washed, and dried. The sample was then ground and calcined in a muffle furnace to obtain CuO / ZnO / M1O. x / M2O y catalyst.

[0010] Furthermore, in step (1), the total concentration of the metal salt solution in solution A is 0.5–1 M, and the concentration of solution B is 0.5–1 M.

[0011] Preferably, in step (1), the total concentration of the metal salt solution is 0.5M, the concentration of the alkaline solution is 1M, the precipitation pH of the solution is 7, the precipitation temperature is 70℃, and the aging time is 1h.

[0012] Furthermore, in step (2), the drying conditions are drying at 60-80℃ for 12 hours and calcination conditions are calcination at 350-500℃ for 4 hours.

[0013] Preferably, in step (2), the precursor drying temperature is 60°C and the calcination condition is 400°C for 4 hours.

[0014] In addition, the present invention also provides an application of the catalyst for methanol production in a fixed-bed reactor for methanol production by carbon supplementation of coke oven gas.

[0015] Furthermore, the specific ratio of the mixed gas formed in the fixed bed after carbon supplementation with coke oven gas is ((H2-CO2) / (CO+CO2)=2.05~2.15), under conditions of 3MPa pressure, 180-280℃ temperature, and 3600~15000h space velocity. -1 Methanol synthesis reaction is carried out under the following conditions.

[0016] Furthermore, the catalyst of this invention is suitable for methanol production from coke oven gas in a fixed-bed reactor with a carbon supplementation ratio of (H2-CO2) / (CO+CO2)=2.05~2.15. The catalyst is reduced for 1~4h under the following conditions: H2 / N2 volume ratio of 1 / 10 mixed gas, space velocity (H2 / N2) of 3000 mL / (g·h), atmospheric pressure, and temperature of 250~300℃. Then, the methanol synthesis reaction is carried out under the following conditions: reaction temperature of 180~280℃, reaction pressure of 3MPa, and mass hourly space velocity of 3000 mL / (g·h).

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The special proportioned mixed gas described in this invention is a synthesis gas formulated after carbon supplementation of coke oven gas, which is conducive to methanol synthesis and effectively solves the problem of low efficiency in methanol synthesis from coke oven gas.

[0019] The catalyst described in this invention exhibits excellent performance in the methanol production reaction from syngas (CO / CO2 / H2), with a CO conversion rate of 35-45% and a CO2 conversion rate of around 10%. It also demonstrates good stability, with a deactivation rate of less than 10% after 100 hours.

[0020] The catalyst of this invention is obtained by introducing other metals into a CuO / ZnO catalyst. It can be prepared by co-precipitation using inexpensive nitrates as raw materials and sodium carbonate as a precipitant. By precipitating Cu and Zn first, the precursor structure of the copper zinc ore or zinc malachite formed between Cu and Zn can be well preserved. Then, other metals (Al, Zr) are added to form a good catalytic system, which can significantly improve the conversion rate and yield of methanol produced by carbon supplementation of coke oven gas. The catalyst preparation process is simple and low cost.

[0021] In the catalyst of this invention, the addition of Al and Zr can significantly increase the specific surface area and dispersibility of Cu, while also improving the performance of CO. x The adsorption and activation of the species were also enhanced, promoting the dissociation of H2 on the catalyst surface. Furthermore, CO, after being activated by Zr adsorption, can undergo a catalytic reaction with dissociated hydrogen atoms at Cu-Zn active sites to produce methanol. The presence of Al and Zr significantly reduced the activation energy barrier of the CO hydrogenation to CHO intermediate reaction, the rate-controlling step in the coke oven gas carbon supplementation to methanol production, thereby accelerating the catalytic reaction rate. The single-pass conversion rates of CO and CO2 were significantly improved, and the methanol yield was also significantly increased. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] Example 1

[0024] Weigh 5.177g of copper nitrate trihydrate, 3.148g of zinc nitrate hexahydrate, and 1.576g of aluminum nitrate nonahydrate and add them to 36mL of deionized water to prepare a 1M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300g of anhydrous sodium carbonate and dissolve it in 50mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100mL of water using a peristaltic pump. Maintain the pH of the solution at 7±0.5 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70℃ for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0025] The above precursor was dried overnight at 60°C for 12 hours. The dried sample was then ground and placed in an evaporating dish and calcined at 350°C for 4 hours in a muffle furnace to obtain the catalyst CuO / ZnO / Al2O3-1.

[0026] The reduction conditions, activity evaluation conditions, and evaluation results of this catalyst in the production of methanol via CO / CO2 hydrogenation are shown in Appendix Table 1. The specific steps are as follows:

[0027] First, the catalyst was pressed into tablets, and 0.5g of catalyst with a mesh size of 20-40 was selected. This tablet was then loaded into a stainless steel tube reactor with a length of 450mm and an inner diameter of 8mm. Quartz sand of the same particle size was placed at both ends of the catalyst bed. The reactor was placed in a fixed-bed reactor, and reduction was carried out at 250℃ and atmospheric pressure using 10 vol% H2 / Ar. After reduction, the feed gas was switched to a mixture with a volume composition of H2:CO:CO2 = 75:9:16. Then, a methanol synthesis reaction was carried out under specific temperature, pressure, and space velocity conditions. The reaction was terminated after a certain period of time.

[0028] Example 2

[0029] Weigh 5.436 g of copper nitrate trihydrate, 2.865 g of zinc nitrate hexahydrate, and 1.466 g of zirconium nitrate pentahydrate and add them to 36 mL of deionized water to prepare a 1 M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300 g of anhydrous sodium carbonate and dissolve it in 50 mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100 mL of water using a peristaltic pump. Maintain the pH of the solution at 7 ± 0.5 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70 °C for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0030] The above precursor was dried overnight at 60°C for 12 hours. The dried sample was then ground and placed in an evaporating dish and calcined at 350°C for 4 hours in a muffle furnace to obtain the catalyst CuO / ZnO / ZrO2.

[0031] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0032] Example 3

[0033] Weigh 5.654 g of copper nitrate trihydrate, 1.392 g of zinc nitrate hexahydrate, and 4.799 g of magnesium nitrate hexahydrate and add them to 47 mL of deionized water to prepare a 1 M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300 g of anhydrous sodium carbonate and dissolve it in 50 mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100 mL of water using a peristaltic pump. Maintain the pH of the solution at 7 ± 0.5 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70 °C for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0034] The above precursor was dried overnight at 60°C for 12 hours. The dried sample was then ground and placed in an evaporating dish and calcined at 350°C for 4 hours in a muffle furnace to obtain the catalyst CuO / ZnO / MgO.

[0035] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0036] Example 4

[0037] Weigh 3.593 g of copper nitrate trihydrate and 3.318 g of zinc nitrate hexahydrate and add them to 26 mL of deionized water to prepare a 1 M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300 g of anhydrous sodium carbonate and dissolve it in 50 mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100 mL of water using a peristaltic pump. Maintain the pH of the solution at 7 ± 0.5 by controlling the dropping rate. Immediately stop adding solution B after the addition of mixed solution A is complete. Then, age the solution at 70 °C for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0038] The above precursor was added to distilled water for slurry preparation. Then, 2.789 g of aluminum nitrate nonahydrate and 0.953 g of magnesium nitrate hexahydrate were weighed and prepared into a solution. Sodium carbonate solution was added to the precursor solution in a co-current manner. The pH of the solution was controlled at 7±0.5. After precipitation, the solution was aged for 1 h, then filtered, washed, dried at 60 °C for 12 h, and calcined at 350 °C for 4 h to obtain the corresponding catalyst CuO / ZnO / Al2O3 / MgO.

[0039] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0040] Example 5

[0041] Weigh 4.175g of copper nitrate trihydrate and 2.570g of zinc nitrate hexahydrate and add them to 26mL of deionized water to prepare a 1M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300g of anhydrous sodium carbonate and dissolve it in 50mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100mL of water using a peristaltic pump. Maintain the pH of the solution at 7±0.5 by controlling the dropping rate. Immediately stop adding solution B after the addition of mixed solution A is complete. Then, age the solution at 70℃ for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0042] The above precursor was added to distilled water and slurried. Then, 2.593 g of aluminum nitrate nonahydrate and 0.742 g of zirconium nitrate pentahydrate were weighed and added to the precursor solution along with sodium carbonate solution in a co-current manner. The pH of the solution was controlled at 7±0.5. After precipitation, the solution was aged for 1 h, then filtered, washed, and dried overnight at 60 °C for 12 h. The dried sample was ground and then placed in an evaporating dish and calcined in a muffle furnace at 350 °C for 4 h to obtain the catalyst CuO / ZnO / Al2O3 / ZrO2-1.

[0043] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0044] Example 6

[0045] Weigh 4.656 g of copper nitrate trihydrate and 2.457 g of zinc nitrate hexahydrate and add them to 54 mL of deionized water to prepare a 0.5 M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300 g of anhydrous sodium carbonate and dissolve it in 100 mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100 mL of water using a peristaltic pump. Maintain the pH of the solution at 7 ± 0.2 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70 °C for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0046] The above precursor was added to distilled water and slurried. Then, 1.032 g of aluminum nitrate nonahydrate and 1.773 g of zirconium nitrate pentahydrate were weighed and prepared into a solution. Sodium carbonate solution was added to the precursor solution in a co-current manner. The pH of the solution was controlled at 7±0.5. After precipitation, the solution was aged for 1 h, then filtered, washed, and dried overnight at 60 °C for 12 h. The dried sample was ground and then placed in an evaporating dish and calcined in a muffle furnace at 350 °C for 4 h to obtain the catalyst CuO / ZnO / Al2O3 / ZrO2-2.

[0047] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0048] Comparative Example 1

[0049] Weigh 5.863 g of copper nitrate trihydrate and 3.888 g of zinc nitrate hexahydrate and add them to 37 mL of deionized water to prepare a 1 M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300 g of anhydrous sodium carbonate and dissolve it in 50 mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100 mL of water using a peristaltic pump. Maintain the pH of the solution at 7 ± 0.5 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70 °C for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0050] The above precursor was dried overnight at 60°C for 12 hours. The dried sample was then ground and placed in an evaporating dish and calcined at 350°C for 4 hours in a muffle furnace to obtain the catalyst CuO / ZnO.

[0051] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0052] Comparative Example 2

[0053] Weigh 5.235g of copper nitrate trihydrate, 3.226g of zinc nitrate hexahydrate, and 0.678g of aluminum nitrate nonahydrate and add them to 36mL of deionized water to prepare a 1M mixed salt solution, denoted as solution A. Simultaneously, weigh 5.300g of anhydrous sodium carbonate and dissolve it in 50mL of deionized water, denoted as solution B. Simultaneously add both solutions to a beaker containing 100mL of water using a peristaltic pump. Maintain the pH of the solution at 7±0.5 by controlling the dropping rate. Immediately stop adding solution B after solution A has been added. Then, age the solution at 70℃ for 1 hour. Filter the aged solution while hot and wash to obtain the precursor filter cake.

[0054] The above precursor was dried overnight at 60°C for 12 hours. The dried sample was then ground and placed in an evaporating dish and calcined at 350°C for 4 hours in a muffle furnace to obtain the catalyst CuO / ZnO / Al2O3-2.

[0055] The reduction conditions, activity evaluation conditions, and evaluation results of the catalyst in the preparation of methanol by CO / CO2 hydrogenation are shown in Appendix Table 1, and the specific steps are as shown in Example 1.

[0056] Table 1 Measurement Results

[0057]

[0058] (Note: Deactivation rate refers to the percentage decrease in catalyst activity over a 100-hour reaction period.)

[0059] The test results show that the catalyst prepared in this invention has improved performance compared with the catalyst in the comparative example. The addition of elements such as Al, Mg, and Zr to Cu / ZnO has good catalytic performance for methanol production from coke oven gas. In particular, under the premise of preserving the special precursor structure of CuZn, the addition of Al and Zr and the adjustment of the ratio of each element have further improved the catalyst performance. Under the conditions of 230℃ and 3MPa, the CO conversion rate can reach up to 44% and the CO2 conversion rate can reach up to 11%, and it can maintain very good stability, indicating that the catalyst is fully suitable for the methanol production reaction system from coke oven gas.

Claims

1. The application of a catalyst for methanol production in a fixed-bed reactor for methanol production using coke oven gas supplementation, characterized in that, The special ratio of the mixed gas formed in the fixed bed after carbon supplementation with coke oven gas is ((H2-CO2) / (CO+CO2)=2.05~2.15), which is achieved at a pressure of 3MPa, a temperature of 180-280℃, and a space velocity of 3600~15000 h⁻¹. -1 Methanol synthesis reaction is carried out under the following conditions; The catalyst used for methanol production is prepared using the following steps: (1) Weigh 4.656g of copper nitrate trihydrate and 2.457g of zinc nitrate hexahydrate and add them to 54mL of deionized water to prepare a mixed salt solution with a concentration of 0.5M, which is denoted as solution A. At the same time, weigh 5.300g of anhydrous sodium carbonate and dissolve it in 100mL of deionized water, which is denoted as solution B. The two solutions are simultaneously fed into a beaker containing 100mL of water by a peristaltic pump. The pH of the solution is maintained at 7±0.2 by controlling the dripping rate. When the mixed solution A is finished, the dripping of solution B is stopped immediately. Then the solution is aged at 70℃ for 1 hour. The aged solution is filtered while hot and washed to obtain the precursor filter cake. (2) The above precursor was added to distilled water to form a slurry. Then, 1.032 g of aluminum nitrate nonahydrate and 1.773 g of zirconium nitrate pentahydrate were weighed and added to the precursor solution in a co-current manner with sodium carbonate solution. The pH of the solution was controlled to be 7±0.

5. After precipitation, the sample was aged for 1 h, filtered and washed, and dried overnight at 60 °C for 12 h. The dried sample was ground and then placed in an evaporating dish and calcined in a muffle furnace at 350 °C for 4 h to obtain the catalyst.

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