A methanol synthesis catalyst and a method for its preparation
By preparing spinel-type aluminates and aging them with microwave heating, the problem of easy sintering of copper-based methanol synthesis catalysts at high temperatures was solved, thereby improving the thermal stability and selectivity of the catalysts and enhancing their catalytic activity and mechanical strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIANGTAN ELECTROCHEMICAL SCI CO LTD
- Filing Date
- 2026-05-19
- Publication Date
- 2026-06-16
AI Technical Summary
Existing copper-based methanol synthesis catalysts are prone to sintering at high temperatures, leading to a decrease in activity. They cannot simultaneously meet the requirements for low-temperature activation, thermal stability, and high-temperature selectivity, thus failing to meet the needs of methanol synthesis.
By preparing spinel-type aluminate as the structural framework, uniformly dispersing the active components Cu/Zn and auxiliary elements, and aging with microwave heating and adding graphite, a catalyst with highly dispersed active centers and excellent structural stability is formed.
It improves the thermal stability and selectivity of the catalyst, enhances catalytic activity, inhibits the sintering of active components, optimizes the distribution of active sites, and improves formability and mechanical strength.
Smart Images
Figure CN122209397A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of catalyst technology, and in particular relates to a methanol synthesis catalyst and its preparation method. Background Technology
[0002] Currently, in order to maintain high single-pass conversion rates and handle large volumes of gas, methanol synthesis catalyst beds typically need to operate at high temperatures, with average temperatures consistently above 280°C and local hot spots even exceeding 300°C.
[0003] Existing copper-based methanol synthesis catalysts are prone to sintering at high temperatures, leading to decreased activity and reduced stability and lifespan in industrial applications. In contrast, copper-zinc-aluminum (Cu-Zn-Al) based catalysts derive their activity from the synergistic effect between highly dispersed CuO and ZnO, with Al2O3 primarily acting as a structural support and dispersing agent. Co-precipitation methods yield catalysts with high specific surface area and high Cu dispersion, achieving activity at low temperatures (e.g., 210-240℃). However, these catalysts exhibit inherent drawbacks under long-term high-temperature operation: firstly, the Cu crystallites sinter and grow due to prolonged exposure to high temperatures, rapidly reducing the number of active sites and lowering thermal stability; secondly, under high-temperature reaction conditions, the catalyst surface properties change, reducing its ability to suppress side reactions, i.e., decreasing high-temperature selectivity.
[0004] Existing technologies cannot simultaneously address the issues of low-temperature activation, thermal stability, and high-temperature selectivity, thus failing to meet the requirements for methanol synthesis. Summary of the Invention
[0005] This application provides a methanol synthesis catalyst and its preparation method, aiming to solve to some extent the problem that the low-temperature activation, thermal stability and high-temperature selectivity cannot meet the requirements of methanol synthesis.
[0006] In a first aspect, this application provides a method for preparing a methanol synthesis catalyst, comprising: S1, aluminum salt and metal salt M are co-dissolved in deionized water at a preset molar ratio to form a first solution, and a precipitant is dissolved in deionized water to form a second solution. The first solution and the second solution are added to the reaction vessel in parallel under stirring, and the reaction temperature and pH are maintained within a first preset range to form a first precipitate. The metal salt M is any one or more combinations of Zn, Mg, Mn, Ni or Fe. S2, the first precipitate is filtered, washed, dried and calcined to obtain spinel-type aluminate, with the formula MAl2O4; S3, the spinel aluminate particles are redispersed to form the first base liquid, and the copper salt, zinc salt and auxiliary salt are dissolved together in water to form the third solution. Under stirring, the third solution is added to the reaction system with the first base liquid in parallel flow with the precipitant. The reaction temperature and pH are maintained within the second preset range. After the third solution is added dropwise, the addition of the precipitant is stopped. The mixed solution is aged by microwave to obtain the second precipitate. S4, the second precipitate is filtered, washed and dried to obtain the catalyst precursor; S5, after calcining the catalyst precursor in air, graphite is added to the calcined decomposition products, mixed evenly, and the mixture is shaped to obtain the methanol synthesis catalyst.
[0007] In one embodiment, the aluminum salt includes any one or a combination of aluminum chloride, aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum isopropoxide, boehmite, or boehmite. Metal salts include any one or a combination of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, magnesium nitrate, magnesium chloride, magnesium sulfate, manganese nitrate, manganese sulfate, nickel nitrate, nickel chloride, ferric nitrate, ferric sulfate, and ferric chloride.
[0008] In one embodiment, the precipitant includes any one or more combinations of sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonia, potassium carbonate, potassium bicarbonate, and potassium hydroxide.
[0009] In one embodiment, in step S1, the preset molar ratio of aluminum salt to metal salt is (9~2):1, the reaction temperature in the first preset range is 50~80℃, and the pH value is 6.0~8.0.
[0010] In one embodiment, in step S2, the calcination temperature is 400℃~800℃, the calcination time is 2~6h, the calcination atmosphere is air or nitrogen, and the heating rate is 2℃ / min~5℃ / min.
[0011] In one embodiment, in step S3, the molar ratio of copper salt, zinc salt and auxiliary salt is 1:(0.5~1):(0.1~0.5). Among them, copper salts include any one or a combination of copper nitrate, copper chloride, and copper acetate; Zinc salts include any one or a combination of zinc nitrate, zinc sulfate, or zinc acetate; The auxiliary salts include any one or more combinations of magnesium salts, zirconium salts, cerium salts, manganese salts, strontium salts, lanthanum salts, niobium salts, barium salts, and yttrium salts.
[0012] In one embodiment, the reaction temperature within the second preset range is 60°C to 85°C, the pH value is 6.0 to 8.5, and the aging time is 0.5 to 3 hours.
[0013] In one embodiment, in step S4, the conductivity of the second precipitate after washing is less than or equal to 50 μS / cm, the drying temperature of the drying process is 80℃~120℃, and the drying time is 6h~12h.
[0014] In one embodiment, in step S5, the roasting temperature is 300℃~600℃ and the holding time is 2h~6h.
[0015] In one embodiment, copper in the methanol synthesis catalyst exists in the form of CuO, with CuO accounting for 50% to 70% by mass; zinc exists in the form of ZnO, with ZnO accounting for 20% to 35% by mass; aluminum exists in the form of Al2O3, with Al2O3 accounting for 5% to 15% by mass; and the auxiliary salt contains auxiliary oxides, with auxiliary oxides accounting for 0.5% to 3% by mass.
[0016] In a second aspect, this application provides a methanol synthesis catalyst, characterized in that it is prepared by the method for preparing a methanol synthesis catalyst as described in any one of the first aspects.
[0017] The advantages of this application compared to the prior art are: The method for preparing the methanol synthesis catalyst provided in this application includes the following steps: S1, aluminum salt and metal salt M are co-dissolved in deionized water at a preset molar ratio to form a first solution, and a precipitant is dissolved in deionized water to form a second solution. The first and second solutions are added to the reaction vessel in parallel under stirring, maintaining the reaction temperature and pH within a first preset range to form a first precipitate. The metal salt M is any one or more combinations of Zn, Mg, Mn, Ni, or Fe. S2, the first precipitate is filtered, washed, dried, and calcined to obtain spinel-type aluminate, expressed as MAl2O4. S3, the spinel-type aluminate particles are redispersed to form a first base liquid. Copper salt, zinc salt, and auxiliary salt are co-dissolved in water to form a third solution. Under stirring, this third solution is added in parallel with the precipitant to the reaction system containing the first base liquid, maintaining the reaction temperature and pH within a second preset range. After the third solution is completely added, the addition of the precipitant is stopped, and the mixed solution is microwaved. After aging, a second precipitate is obtained; S4, the second precipitate is filtered, washed, and dried to obtain a catalyst precursor; S5, the catalyst precursor is calcined in air, and graphite is added to the calcined decomposition products, mixed evenly, and the mixture is shaped to obtain a methanol synthesis catalyst; compared with the prior art, by first synthesizing a composite oxide aluminate with a stable spinel structure, and redispersing the composite oxide aluminate in the first base liquid as a structural framework introduced into the coprecipitation system, and by uniformly dispersing the active component Cu / Zn and auxiliary elements between the aluminates at the molecular and nanoscale, the spinel aluminate can uniformly load the active component and auxiliary elements. There are heat-insulating spinels between Cu / Zn and on the surface. At the same time, the spinel itself also has catalytic activity. Therefore, without reducing the catalytic activity of Cu / Zn itself, the addition of spinel increases the catalytic activity, improves the heat resistance of the catalyst, and improves the overall stability of the catalyst. In addition, aging by microwave heating alters the aging process, achieves uniform growth, suppresses the Ostwald effect, and effectively forms small particle active sites, further improving catalyst activity. The addition of graphite improves formability and mechanical strength, thus preparing a highly efficient heat-resistant methanol synthesis catalyst with highly dispersed active centers, strong interactions, and excellent structural stability. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1This is a schematic flowchart of a method for preparing a methanol synthesis catalyst provided in an embodiment of this application; Figure 2 This is a schematic diagram of the methanol synthesis catalyst in Example 1 using an electron microscope; Figure 3 This is a schematic diagram of the performance / data testing process for the methanol synthesis catalysts prepared in each embodiment. Detailed Implementation
[0020] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0021] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0022] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple.
[0023] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.
[0024] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0025] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0026] The weights of the relevant components mentioned in this application specification can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to this application specification is within the scope of disclosure in this application specification. Specifically, the mass mentioned in this application specification can be a well-known unit of mass in the chemical industry, such as μg, mg, g, or kg.
[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.
[0029] Driven by both energy transition and chemical industry upgrading, methanol, as a key C1 platform compound and clean fuel, has seen continuous growth in production capacity, with plants exhibiting a significant trend towards larger scale. While this trend improves economic efficiency, it also poses unprecedented challenges to catalysts. Currently, to maintain high single-pass conversion rates and handle massive gas volumes, methanol synthesis catalyst beds typically need to operate at high temperatures, with average temperatures consistently above 280°C, and local hotspots even exceeding 300°C.
[0030] Existing copper-based methanol synthesis catalysts are prone to sintering at high temperatures, leading to decreased activity and reduced stability and lifespan in industrial applications. In contrast, copper-zinc-aluminum (Cu-Zn-Al) based catalysts derive their activity from the synergistic effect between highly dispersed CuO and ZnO, with Al2O3 primarily acting as a structural support and dispersing agent. Co-precipitation methods yield catalysts with high specific surface area and high Cu dispersion, achieving activity at low temperatures (e.g., 210-240℃). However, these catalysts exhibit inherent drawbacks under long-term high-temperature operation: firstly, the Cu crystallites sinter and grow due to prolonged exposure to high temperatures, rapidly reducing the number of active sites and lowering thermal stability; secondly, under high-temperature reaction conditions, the catalyst surface properties change, reducing its ability to suppress side reactions, i.e., decreasing high-temperature selectivity.
[0031] Therefore, existing technologies cannot simultaneously address the issues of low-temperature activation, thermal stability, and high-temperature selectivity, thus failing to meet the requirements for methanol synthesis.
[0032] To address the aforementioned problems to some extent, firstly, such as Figure 1 As shown, this application provides a method for preparing a methanol synthesis catalyst, comprising: S1, aluminum salt and metal salt M are co-dissolved in deionized water at a preset molar ratio to form a first solution, and a precipitant is dissolved in deionized water to form a second solution. The first solution and the second solution are added to the reaction vessel in parallel under stirring, and the reaction temperature and pH are maintained within a first preset range to form a first precipitate. The metal salt M is any one or more combinations of Zn, Mg, Mn, Ni or Fe. S2, the first precipitate is filtered, washed, dried and calcined to obtain spinel-type aluminate, with the formula MAl2O4; S3, the spinel aluminate particles are redispersed to form the first base liquid, and the copper salt, zinc salt and auxiliary salt are dissolved together in water to form the third solution. Under stirring, the third solution is added to the reaction system with the first base liquid in parallel flow with the precipitant. The reaction temperature and pH are maintained within the second preset range. After the third solution is added dropwise, the addition of the precipitant is stopped. The mixed solution is aged by microwave to obtain the second precipitate. S4, the second precipitate is filtered, washed and dried to obtain the catalyst precursor; S5, after calcining the catalyst precursor in air, graphite is added to the calcined decomposition products, mixed evenly, and the mixture is shaped to obtain the methanol synthesis catalyst.
[0033] The method for preparing the methanol synthesis catalyst provided in this application, compared with the prior art, involves first synthesizing a composite oxide aluminate with a stable spinel structure using aluminum salts and metal salts. This composite oxide aluminate is then redispersed in a first base solution and introduced into the co-precipitation system as a structural framework. Active components Cu / Zn and auxiliary elements are uniformly dispersed at the molecular and nanoscale between the aluminates to construct a Cu-ZnO synergistic system (i.e., the active center for methanol synthesis). The auxiliary elements (Mg, Zr, Ce, etc.) are used to adjust the electronic structure or suppress side reactions. Furthermore, by adjusting the surface acidity / alkalinity or oxygen vacancy concentration, methanol selectivity is improved. This allows the spinel-type aluminate to uniformly load the active components and auxiliary elements, resulting in the presence of thermally insulating spinel between Cu / Zn and on the surface. Simultaneously, the spinel structure itself exhibits high thermal stability and a low specific surface area. With a moderate area, it can serve as a good support framework, enhancing metal-support interactions and inhibiting the sintering of active components. Spinel aluminates also exhibit catalytic activity. Therefore, without reducing their own Cu / Zn catalytic activity, the addition of spinel increases catalytic activity, improves the catalyst's heat resistance, and enhances the overall stability of the catalyst. Stepwise loading also optimizes the distribution of active sites. In addition, aging by microwave heating alters the aging process, achieving uniform growth, suppressing the Ostwald effect, and effectively forming small-particle active sites, further improving catalyst activity. Graphite acts as a pore-forming agent and lubricant. The addition of graphite improves formability, pore structure, and mechanical strength, thereby preparing a highly efficient, heat-resistant methanol synthesis catalyst with highly dispersed active centers, strong interactions, high selectivity, and excellent structural stability.
[0034] In one embodiment, the aluminum salt includes any one or a combination of aluminum chloride, aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum isopropoxide, boehmite, or boehmite; the metal salt includes any one or a combination of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, magnesium nitrate, magnesium chloride, magnesium sulfate, manganese nitrate, manganese sulfate, nickel nitrate, nickel chloride, ferric nitrate, ferric sulfate, and ferric chloride.
[0035] In one embodiment, the precipitant includes any one or more combinations of sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonia, potassium carbonate, potassium bicarbonate, and potassium hydroxide.
[0036] In one embodiment, in step S1, the preset molar ratio of aluminum salt to metal salt is (9~2):1, the reaction temperature in the first preset range is 50~80℃, and the pH value is 6.0~8.0.
[0037] In one embodiment, in step S2, the calcination temperature is 400℃~800℃, the calcination time is 2~6h, the calcination atmosphere is air or nitrogen, and the heating rate is 2℃ / min~5℃ / min.
[0038] In one embodiment, in step S3, the molar ratio of copper salt, zinc salt, and auxiliary salt is 1:(0.5~1):(0.1~0.5). Among them, copper salts include any one or a combination of copper nitrate, copper chloride, and copper acetate; Zinc salts include any one or a combination of zinc nitrate, zinc sulfate, or zinc acetate; The auxiliary salts include any one or more combinations of magnesium salts, zirconium salts, cerium salts, manganese salts, strontium salts, lanthanum salts, niobium salts, barium salts, and yttrium salts.
[0039] In one embodiment, the reaction temperature within the second preset range is 60°C to 85°C, the pH value is 6.0 to 8.5, and the aging time is 0.5 to 3 hours.
[0040] In one embodiment, in step S4, the conductivity of the second precipitate after washing is less than or equal to 50 μS / cm, the drying temperature of the drying process is 80℃~120℃, and the drying time is 6h~12h.
[0041] In one embodiment, in step S5, the roasting temperature is 300℃~600℃, and the holding time is 2h~6h.
[0042] In one embodiment, copper in the methanol synthesis catalyst exists in the form of CuO, with CuO accounting for 50% to 70% of the methanol synthesis catalyst by mass; zinc exists in the form of ZnO, with ZnO accounting for 20% to 35% of the methanol synthesis catalyst by mass; aluminum exists in the form of Al2O3, with Al2O3 accounting for 5% to 15% of the methanol synthesis catalyst by mass; and the promoter salt exists in the form of promoter oxide, with promoter oxide accounting for 0.5% to 3% of the methanol synthesis catalyst by mass. Further, CuO accounts for 58% to 65% of the methanol synthesis catalyst by mass, zinc exists in the form of ZnO, with ZnO accounting for 22% to 28% of the methanol synthesis catalyst by mass, aluminum exists in the form of Al2O3, with Al2O3 accounting for 8% to 14% of the methanol synthesis catalyst by mass, and promoter oxide accounts for 1% to 2% of the methanol synthesis catalyst by mass.
[0043] The technical solution of this application will be illustrated below through specific embodiments and comparative examples.
[0044] Example 1 A method for preparing a methanol synthesis catalyst, comprising: S1, 92.2g of aluminum nitrate nonahydrate and 11.2g of zinc nitrate hexahydrate were dissolved in 250mL of deionized water to form a first mixed metal salt solution. 1mol / L sodium carbonate was dissolved in deionized water to form a second solution (alkali solution). The first and second solutions were added concurrently to a reaction vessel preheated to 65℃ with stirring. The dropping rate was controlled to maintain the pH at 7.5. After the first solution was completely added, the feeding of the second solution was stopped, and the first precipitate was collected.
[0045] S2, after filtration, the first precipitate was washed with deionized water and dried in a 110℃ forced-air drying oven for 12 hours to obtain dried zinc aluminate. The zinc aluminate catalyst precursor was then calcined at 500℃ for 4 hours to obtain spinel-type zinc aluminate.
[0046] S3. Spindle-type zinc aluminate was redispersed in the first base solution. 280.8 g of copper nitrate trihydrate, 89.1 g of zinc nitrate hexahydrate, and 10.8 g of magnesium nitrate were dissolved in 1800 mL of deionized water to form a third solution. Under stirring, the third solution was added to the reaction system containing the first base solution in parallel with the sodium carbonate precipitant solution. The reaction temperature was maintained at 70 °C, and the pH was maintained at 7 by controlling the dropping rate. After the third solution was added, the reaction temperature was kept constant, and the mixed solution was transferred to a microwave reactor for aging treatment for 30 min to obtain the second precipitate.
[0047] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 5 μS / cm, and then dried in a 110℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0048] S5. After calcining the dried catalyst precursor at 350℃ for 3 hours, 2wt% of graphite was added to the calcined decomposition product and mixed evenly. Finally, the product was shaped into a tablet by a tablet press to obtain the methanol synthesis catalyst.
[0049] Figure 2 This is a schematic diagram of the methanol synthesis catalyst in Example 1 using an electron microscope.
[0050] Example 2 A method for preparing a methanol synthesis catalyst, comprising: S1, 88.2g of aluminum nitrate nonahydrate and 15.2g of magnesium nitrate hexahydrate were dissolved in 290mL of deionized water to form a first solution of mixed metal salts. 1mol / L sodium carbonate was dissolved in deionized water to form a second solution (alkali solution). The first and second solutions were added in parallel to a reaction vessel preheated to 70℃ under stirring. The dropping rate was controlled to maintain the pH at 8. After the first solution was completely added, the feeding of the second solution was stopped, and the first precipitate was collected.
[0051] S2, after filtration, the first precipitate was washed with deionized water and dried in a 120℃ forced-air drying oven for 12 hours to obtain dried magnesium aluminate. The magnesium aluminate catalyst precursor was calcined at 600℃ for 4 hours to obtain spinel-type magnesium aluminate.
[0052] S3. Spindle-type magnesium aluminate was redispersed in the first base solution. 270.8 g of copper nitrate trihydrate, 95.1 g of zinc nitrate hexahydrate, and 11.9 g of cerium nitrate were dissolved in 1600 mL of deionized water to form a third solution. Under stirring, this third solution was added to the reaction system containing the first base solution in parallel with the sodium carbonate precipitant solution. The reaction temperature was maintained at 75 °C, and the pH was maintained at 6.5 by controlling the dropping rate. After the third solution was completely added, the reaction temperature was kept constant, and the mixed solution was transferred to a microwave reactor for aging treatment for 20 min to obtain the second precipitate.
[0053] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 5 μS / cm, and then dried in a 110℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0054] S5. After calcining the dried catalyst precursor at 330℃ for 4 hours, 1 wt% of graphite was added to the calcined decomposition product and mixed evenly. Finally, the product was shaped into a tablet by a tablet press to obtain the methanol synthesis catalyst.
[0055] Example 3 A method for preparing a methanol synthesis catalyst, comprising: S1, 88.2g of aluminum nitrate nonahydrate and 15.2g of magnesium nitrate hexahydrate were dissolved in 290mL of deionized water to form a first mixed metal salt solution. 1mol / L sodium carbonate was dissolved in deionized water to form a second alkaline solution. The first and second solutions were added concurrently to a reaction vessel preheated to 70℃ with stirring. The dropping rate was controlled to maintain the pH at 8.0. After the first solution was completely added, the feeding of the second solution was stopped, and the first precipitate was collected.
[0056] S2, after filtration, the first precipitate was washed with deionized water and dried in a 120℃ forced-air drying oven for 12 hours to obtain dried magnesium aluminate. The magnesium aluminate catalyst precursor was calcined at 600℃ for 4 hours to obtain spinel-type magnesium aluminate.
[0057] S3. Spindle-type magnesium aluminate was redispersed in the first base solution. 270.8 g of copper nitrate trihydrate, 95.1 g of zinc nitrate hexahydrate, and 10.8 g of cerium nitrate were dissolved in 1600 mL of deionized water to form a third solution. Under stirring, this third solution was added to the reaction system containing the first base solution in parallel with the sodium carbonate precipitant solution. The reaction temperature was maintained at 75 °C, and the pH was maintained at 6.5 by controlling the dropping rate. After the third solution was completely added, the reaction temperature was kept constant, and the mixed solution was transferred to a microwave reactor for aging treatment for 20 min to obtain the second precipitate.
[0058] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 15 μS / cm, and then dried in a 110℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0059] S5, after calcining the dried catalyst precursor at 330℃ for 4 hours, 1 w%t of graphite was added to the calcined decomposition product and mixed evenly. Finally, the methanol synthesis catalyst was obtained by pressing the product into tablets.
[0060] Example 4 A method for preparing a methanol synthesis catalyst, comprising: S1, 89.1g of aluminum nitrate nonahydrate and 12.2g of nickel sulfate hexahydrate were dissolved in 220mL of deionized water to form a first mixed metal salt solution. 1mol / L potassium carbonate was dissolved in deionized water to form a second alkaline solution. The first and second solutions were added concurrently to a reaction vessel preheated to 75℃ with stirring. The dropping rate was controlled to maintain the pH at 7.0. After the first solution was completely added, the feeding of the second solution was stopped, and the first precipitate was collected.
[0061] S2, after filtration, the first precipitate was washed with deionized water and dried in a 100℃ forced-air drying oven for 12 hours to obtain dried nickel aluminate. The nickel aluminate catalyst precursor was then calcined at 500℃ for 4 hours to obtain spinel-type nickel aluminate.
[0062] S3. Spinel-type nickel aluminate was redispersed in the first base solution. 250.8 g of copper nitrate trihydrate, 90.1 g of zinc nitrate hexahydrate, and 11.9 g of magnesium nitrate were dissolved in 1700 mL of deionized water to form a third solution. Under stirring, this third solution was added to the reaction system containing the first base solution in parallel with the potassium carbonate precipitant solution. The reaction temperature was maintained at 70 °C, and the pH was maintained at 7 by controlling the dropping rate. After the third solution was added, the reaction temperature was kept constant, and the mixed solution was transferred to a microwave reactor for aging treatment for 30 min to obtain the second precipitate.
[0063] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 20 μS / cm, and then dried in a 100℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0064] S5. After calcining the dried catalyst precursor at 340℃ for 4 hours, 2wt% of graphite was added to the calcined decomposition product and mixed evenly. Finally, the product was shaped into a tablet by a tablet press to obtain the methanol synthesis catalyst.
[0065] Example 5 A method for preparing a methanol synthesis catalyst, comprising: S1, 88.2g of aluminum nitrate nonahydrate and 15.2g of magnesium nitrate hexahydrate were dissolved in 290mL of deionized water to form a first mixed metal salt solution. 1mol / L sodium carbonate was dissolved in deionized water to form a second alkaline solution. The first and second solutions were added concurrently to a reaction vessel preheated to 70℃ with stirring. The dropping rate was controlled to maintain the pH at 8.0. After the first solution was completely added, the feeding of the second solution was stopped, and the first precipitate was collected.
[0066] S2, after filtration, the first precipitate is washed with deionized water.
[0067] S3, the first precipitate is redispersed in the first base solution. 270.8 g of copper nitrate trihydrate, 95.1 g of zinc nitrate hexahydrate, and 11.9 g of cerium nitrate are dissolved in 1600 mL of deionized water to form a third solution. Under stirring, this third solution is added in parallel with the sodium carbonate precipitant solution to the reaction system containing the first base solution. The reaction temperature is maintained at 75°C, and the dropping rate is controlled to maintain the pH at 6.5. After the third solution is completely added, the reaction temperature is kept constant, and the precipitate is aged for 2 hours to obtain the second precipitate.
[0068] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 15 μS / cm, and then dried in a 110℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0069] S5. After calcining the dried catalyst precursor at 330℃ for 4 hours, 1 wt% of graphite was added to the calcined decomposition product and mixed evenly. Finally, the product was shaped into a tablet by a tablet press to obtain the methanol synthesis catalyst.
[0070] Comparative Example 1 differs from Example 1 in that zinc aluminate is not added; A method for preparing a methanol synthesis catalyst, comprising: S3, 280.8 g of copper nitrate trihydrate, 89.1 g of zinc nitrate hexahydrate, 92.2 g of aluminum nitrate nonahydrate, and 10.8 g of magnesium nitrate were dissolved in 1800 mL of deionized water to form a third solution. Under stirring, this third solution was added in parallel with the sodium carbonate precipitant solution to the reaction system containing the first base solution. The reaction temperature was maintained at 70 °C, and the pH was maintained at 7 by controlling the dropping rate. After the third solution was completely added, the reaction temperature was kept constant, and the mixed solution was transferred to a microwave reactor for aging treatment for 30 min to obtain the second precipitate.
[0071] S4. The second precipitate was washed with deionized water until the conductivity was less than or equal to 5 μS / cm, and then dried in a 110℃ forced-air drying oven for 12 h to obtain the catalyst precursor.
[0072] S5. After calcining the dried catalyst precursor at 350℃ for 3 hours, 2wt% of graphite was added to the calcined decomposition product and mixed evenly. Finally, the product was shaped into a tablet by a tablet press to obtain the methanol synthesis catalyst.
[0073] Comparative Example 2 differs from Example 1 in that step S3 does not involve microwave heating for aging; S3, spinel-type zinc aluminate is redispersed in the first base solution. 280.8g of copper nitrate trihydrate, 89.1g of zinc nitrate hexahydrate, and 10.8g of magnesium nitrate are dissolved in 1800mL of deionized water to form a third solution. Under stirring, this third solution is added in parallel with the sodium carbonate precipitant solution to the reaction system containing the first base solution. The reaction temperature is maintained at 70℃ using ordinary heating, and the pH is maintained at 7 by controlling the dropping rate. After the third solution is completely added, the reaction temperature is kept constant, and the precipitate is left to age for 3 hours to obtain the second precipitate.
[0074] Performance / Data Testing: The methanol synthesis catalysts of Examples 1 to 5 and Comparative Examples 1 and 2 were tested for methanol synthesis. The methanol synthesis catalyst particles were crushed and screened to 40-60 mesh, and the loading amount was 3 mL (1.5 mL catalyst + 1.5 mL inert support). The samples were activated. Before the activity and heat resistance tests, the composition of the reducing gas (by volume fraction) was 5% hydrogen, ≤0.2% oxygen, and the remainder nitrogen. The reduction temperature was 220℃. For the activity test, the feed gas H2:CO:CO2:N2 contained CO = 13.0-14.0%, CO2 = 4.0-5.0%, N2 = 17%, and the remainder was H2. The reaction pressure was 5.0 MPa, and the space velocity was 10000 h⁻¹. -1 The reaction temperature was 230℃. The CO conversion rate and CH3OH space-time yield were measured before the reaction under heat resistance. Activity test after heat resistance: After initial activity testing, the pressure was reduced to 0.1 MPa, the reaction temperature was increased to 400℃, and the space velocity was reduced to 3000 h⁻¹. -1After a 10-hour heat treatment, the conditions were returned to the above activity test conditions, and the CO conversion rate and CH3OH space-time yield were measured after heat resistance. Figure 3 This is a schematic diagram of the performance / data testing process for the methanol synthesis catalysts prepared in each embodiment, wherein, Figure 3 The attached diagrams are labeled as follows: 1. Pressure controller; 2. Gas mass flow controller (MFC); 3. Integrated process control station; 4. Online gas purifier (i.e., gas purification tank); 5. Temperature measurement probe; 6. Fixed-bed flow reactor; 7. Multi-stage electric heating furnace; 8. Quartz sand packing layer (40-60 mesh); 9. Quartz fiber filter; 10. Activated reaction bed (40-60 mesh); 11. Heating tape; 12. Product condensate trap; 13. Water cooling circulation device; 14. Overpressure relief valve; 15. Gas phase analysis system (GC); 16. Ritter rotor gas flow meter; 17. Experimental data recording station. The thermal stability of the catalyst is represented by the ratio of the methanol space-time yield after the heat resistance test to the initial methanol space-time yield. The test comparison data are shown in Table 1.
[0075] Table 1. Comparative data on methanol synthesis using the methanol synthesis catalysts of each embodiment and comparative example.
[0076] The embodiments showed better thermal stability due to the addition of aluminate, which improved heat resistance. As shown in Table 1, these embodiments were superior to Comparative Example 1. Comparative Example 1, however, showed poorer heat resistance because it did not contain aluminate.
[0077] The catalysts in each embodiment improved their activity due to microwave heating aging, as shown in Table 1, outperforming Comparative Example 2. Comparative Example 2, lacking microwave heating, initially showed lower activity, but its performance improved compared to Comparative Example 1 after the addition of heat-resistant aluminate.
[0078] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0079] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions of the first aspect mentioned above, and will not be repeated here.
[0080] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.
[0081] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.
Claims
1. A method for preparing a methanol synthesis catalyst, characterized in that, include: S1, aluminum salt and metal salt M are co-dissolved in deionized water at a preset molar ratio to form a first solution, and a precipitant is dissolved in deionized water to form a second solution. The first solution and the second solution are added to the reaction vessel in parallel under stirring, and the reaction temperature and pH are maintained within a first preset range to form a first precipitate. The metal salt M is any one or more combinations of Zn, Mg, Mn, Ni or Fe. S2, the first precipitate is filtered, washed, dried and calcined to obtain spinel-type aluminate, with the formula MAl2O4; S3, the spinel aluminate particles are redispersed to form the first base liquid, and the copper salt, zinc salt and auxiliary salt are dissolved together in water to form the third solution. Under stirring, the third solution is added to the reaction system with the first base liquid in parallel flow with the precipitant. The reaction temperature and pH are maintained within the second preset range. After the third solution is added dropwise, the addition of the precipitant is stopped. The mixed solution is aged by microwave to obtain the second precipitate. S4, the second precipitate is filtered, washed and dried to obtain the catalyst precursor; S5, after calcining the catalyst precursor in air, graphite is added to the calcined decomposition products, mixed evenly, and the mixture is shaped to obtain the methanol synthesis catalyst.
2. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, Aluminum salts include any one or a combination of aluminum chloride, aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum isopropoxide, boehmite, or boehmite. Metal salts include any one or a combination of zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, magnesium nitrate, magnesium chloride, magnesium sulfate, manganese nitrate, manganese sulfate, nickel nitrate, nickel chloride, ferric nitrate, ferric sulfate, and ferric chloride.
3. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, The precipitant includes any one or more combinations of sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonia, potassium carbonate, potassium bicarbonate, and potassium hydroxide.
4. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, In step S1, the preset molar ratio of aluminum salt to metal salt is (9~2):1, the reaction temperature in the first preset range is 50~80℃, and the pH value is 6.0~8.
0.
5. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, In step S2, the calcination temperature is 400℃~800℃, the calcination time is 2~6h, the calcination atmosphere is air or nitrogen, and the heating rate is 2℃ / min~5℃ / min.
6. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, In step S3, the molar ratio of copper salt, zinc salt, and auxiliary salt is 1:(0.5~1):(0.1~0.5). Among them, copper salts include any one or a combination of copper nitrate, copper chloride, and copper acetate; Zinc salts include any one or a combination of zinc nitrate, zinc sulfate, or zinc acetate; The auxiliary salts include any one or more combinations of magnesium salts, zirconium salts, cerium salts, manganese salts, strontium salts, lanthanum salts, niobium salts, barium salts, and yttrium salts.
7. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, The second preset reaction range is 60℃~85℃, pH value is 6.0~8.5, and aging time is 0.5~3h.
8. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, In step S4, the conductivity of the second precipitate after washing is less than or equal to 50 μS / cm, the drying temperature is 80℃~120℃, and the drying time is 6h~12h. In step S5, the roasting temperature is 300℃~600℃, and the holding time is 2h~6h.
9. The method for preparing the methanol synthesis catalyst according to claim 1, characterized in that, In the methanol synthesis catalyst, copper exists in the form of CuO, accounting for 50% to 70% by mass; zinc exists in the form of ZnO, accounting for 20% to 35% by mass; aluminum exists in the form of Al2O3, accounting for 5% to 15% by mass; and the auxiliary salts contain auxiliary oxides, accounting for 0.5% to 3% by mass.
10. A methanol synthesis catalyst, characterized in that, It is prepared by the method for preparing the methanol synthesis catalyst according to any one of claims 1 to 9.