A method for preparing a copper-based catalyst for methanol synthesis
By combining gradient dropping rate and silicon source, the deactivation problem of copper-based catalysts caused by Cu particle agglomeration and water molecule adsorption in methanol synthesis reaction was solved, achieving high stability and high activity of the catalyst, with a significant improvement in activity retention rate and specific surface area.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGKE CATALYSIS NEW TECH (DALIAN) CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-06-19
AI Technical Summary
Copper-based catalysts are prone to deactivation in methanol synthesis reactions due to Cu particle agglomeration and water molecule adsorption, especially in the presence of CO2, where the catalysts exhibit poor stability.
By employing a gradient dropping rate in synergy with a silicon source, the Cu-Zn co-precipitation process is controlled, forming a special structure that inhibits Cu particle agglomeration and oxidation, thereby increasing the specific surface area and hydrophobicity of the catalyst.
The thermal stability and activity retention of the catalyst were significantly improved, with the activity retention rate increasing from 79.6% to over 94%, and the specific surface area of the catalyst increasing to 149.8-162.4 m2/g.
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Abstract
Description
Technical Field
[0001] This application relates to a method for preparing a copper-based catalyst for methanol synthesis, belonging to the field of catalyst preparation. Background Technology
[0002] Methanol is one of the most important organic raw materials in the chemical industry, with wide applications in fuels and chemicals, and is a crucial platform molecule. Currently, among the many catalysts used in methanol synthesis, copper-based catalysts are widely used due to their advantages such as high activity at low temperatures and low cost. However, during the reaction, Cu particles in copper-based catalysts are very prone to agglomeration, leading to catalyst deactivation and significantly reducing the stability of copper-based catalysts. Especially when CO2 is present in the reaction gas, water molecules, a byproduct, are inevitably generated during the reaction. These water molecules readily adsorb onto the active sites on the catalyst surface, accelerating the oxidation of copper species and the growth of copper particles, thus causing deactivation of the copper-based catalyst. Summary of the Invention
[0003] To overcome the problems of Cu particle agglomeration in copper-based catalysts caused by high temperatures during the reaction, and water generated from CO2 reduction adsorption on the catalyst surface accelerating Cu species oxidation and leading to catalyst deactivation, this application achieves further dispersion of Cu active species through the synergistic effect of gradient dropping rate and the introduction of a silicon source, significantly improving the specific surface area and surface hydrophobicity of the catalyst. Compared with existing technologies, the catalyst of this application achieves unexpected technical effects in terms of thermal stability, with an activity retention rate increased to over 94%, at least 14 percentage points higher than the 79.6% in existing technologies. This synergistic effect is not a simple combination, but rather involves controlling the Cu-Zn co-precipitation process through gradient dropping rate, while simultaneously introducing a silicon source to form a special structure, effectively suppressing Cu particle agglomeration and oxidation, thereby improving the thermal stability of the catalyst.
[0004] According to one aspect of this application, a method for preparing a copper-based catalyst for methanol synthesis is provided.
[0005] A method for preparing a copper-based catalyst for methanol synthesis, the method comprising: S1 dissolves and mixes copper and zinc sources in water to obtain a Cu-Zn mixture. The Cu-Zn mixture is then added dropwise to an alkaline solution at a gradient dropping rate to obtain a first suspension, which is then aged. S2 dissolves the aluminum source and silicon source in the first suspension after aging to obtain the second suspension, and then ages it. S3 washes, dries, and calcines the aged second suspension to obtain the copper-based catalyst; The components and their weight percentages in the copper-based catalyst are as follows: CuO: 55~65%; ZnO: 20~30%; Al2O3: 5~15%; SiO2: 0.1~3.0%.
[0006] Optionally, the weight percentage of SiO2 is selected from any value of 0.1%, 0.5%, 1.0%, 1.5%, 3.0% or any range between two.
[0007] Optionally, in S1, the dropping rate is divided into four gradients, namely 7~11, 4~8, 2~4, and 0.5~1.5 mL / min, respectively. Based on the volume of the Cu-Zn mixture, the dropping amounts corresponding to each gradient are 30~40%, 45~55%, 6~10%, and 1~6%.
[0008] Optionally, the dropping rate of the first gradient is selected from any value of 7, 8, 9, 10, 11 mL / min or any range between the two.
[0009] Optionally, the dropping rate of the second gradient is selected from any value of 4, 5, 6, 7, 8 mL / min or any range between two values.
[0010] Optionally, the dropping rate of the third gradient is selected from any value of 2, 2.5, 3, 3.5, 4 mL / min or any range between two.
[0011] Optionally, the dropping rate of the fourth gradient is selected from any value of 0.5, 0.8, 1, 1.2, 1.5 mL / min or any range between two values.
[0012] Optionally, the amount of liquid added corresponding to the first gradient is selected from any value of 30%, 32%, 35%, 38%, 40% or any range between two.
[0013] Optionally, the amount of liquid added corresponding to the second gradient is selected from any value of 45%, 48%, 50%, 52%, 55% or any range between two.
[0014] Optionally, the amount of liquid added corresponding to the third gradient is selected from any value of 6%, 7%, 8%, 9%, 10% or any range between two.
[0015] Optionally, the amount of liquid added corresponding to the fourth gradient is selected from any value of 1%, 2%, 3%, 4%, 5%, 6% or any range between two.
[0016] Optionally, the weight percentages of each component in the copper-based catalyst are as follows: CuO: 57~62%; ZnO: 22~26%; Al2O3: 8~12%; SiO2: 0.5~1.5%.
[0017] Optionally, the specific surface area of the copper-based catalyst is 149.8-162.4 m². 2 / g.
[0018] Optionally, in S1, the temperature at which the copper source and the zinc source are dissolved in water and mixed is 40~70°C, and the time is 10~20 min.
[0019] Optionally, in step S1, the Cu-Zn mixture is added to the alkaline solution at a gradient dropping rate at a temperature of 60-80°C for 18-20 minutes.
[0020] Optionally, in S1, the pH value at the endpoint of the droplet addition is 7-8.
[0021] Optionally, in S1, the copper source is at least one of Cu(NO3)2, CuSO4, and CuCl2.
[0022] Optionally, in S1, the zinc source is at least one of Zn(NO3)2, ZnSO4, and ZnCl2.
[0023] Optionally, in S1, the mass of the copper source is calculated as copper element, the mass of the zinc source is calculated as zinc element, and the mass ratio of the copper source, the zinc source, and water is (5.5~6.5):(2.0~3.0):(90~110).
[0024] Optionally, in S1, the alkaline solution is an aqueous solution of at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.
[0025] Optionally, in S1, the mass ratio of the Cu-Zn mixture to the alkaline solution is (0.6~1.0):(0.7~1.0).
[0026] Optionally, the alkali content is (9~11)% based on the mass of the alkali solution.
[0027] Optionally, in S1, the aging temperature is 75~85℃ and the time is 20~60min.
[0028] Optionally, in S1, the temperature is reduced to 40~60°C after aging.
[0029] Optionally, in S2, the aluminum source is at least one of Al(NO3)3, Al2(SO4)3, AlCl3, and boehmite.
[0030] Optionally, in S2, the silicon source is at least one of tetraethyl orthosilicate, silica sol, and sodium silicate.
[0031] Optionally, in S2, the mass of the aluminum source is measured in terms of aluminum element, the mass of the silicon source is measured in terms of silicon element, and the mass ratio of the copper source, the aluminum source, and the silicon source is (5.5~6.5):(0.3~0.5):(0.025~0.25).
[0032] Optionally, in S2, the aging temperature is 40~60℃ and the time is 10~40min.
[0033] Optionally, in step S3, the drying temperature is 80~120℃ and the time is 6~24h.
[0034] Optionally, in step S3, the calcination temperature is 350~450℃ and the time is 2~4h.
[0035] The preparation method described in this application increases the catalyst activity retention rate from 79.6% in the prior art to 95.1%, demonstrating an unexpected technical effect resulting from the synergistic effect of gradient dropping rate and silicon source introduction. In particular, when the SiO2 content is 1.43%, the catalyst activity retention rate reaches 95.1%, which is at least 10 percentage points higher than using gradient dropping rate alone (77.4%) or silicon source alone (85.0%), proving the synergistic effect of the combination. Detailed Implementation
[0036] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0037] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0038] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0039] The method for calculating the catalyst activity retention rate was adopted as described in CN120094589A (Comparative Example 3).
[0040] Example 1 Weigh 23g of copper nitrate and 11.5g of zinc nitrate, dissolve them in 100g of deionized water, and heat to 60℃ for later use; weigh 21.3g of baking soda, dissolve it in 175g of deionized water, and place it in a beaker under a 70℃ water bath for later use; carry out the co-precipitation reaction by adding the salt solution dropwise to the alkali solution using a metering pump, controlling the flow rate in four gradients: 8, 6, 3, and 1 mL / min, with the volume ratios of the Cu-Zn salt solution being 35%, 50%, 10%, and 5%, respectively; after the addition is complete, age for 30 min. The temperature was raised to 80℃ and aged for another 20 min. The system was then cooled to 55℃, and 1.39 g of boehmite and 1 g of Na2SiO3 were added. The system was aged for 15 min. After filtration and washing, the catalyst was dried at 100℃ for 12 h and then calcined at 350℃ for 3 h to obtain catalyst powder, denoted as catalyst S-1. The components and their weight percentages in the catalyst are as follows: CuO: 62.64%; ZnO: 23.82%; Al2O3: 12.08%; SiO2: 1.43%.
[0041] Example 2 The preparation method is the same as in Example 1, except that the flow rates of the four gradients are set to 7, 4, 2 and 0.5 mL / min, respectively, and are denoted as catalyst S-2. The components in the catalyst and their weight percentages are as follows: CuO: 61.17%; ZnO: 23.36%; Al2O3: 13.97%; SiO2: 1.38%.
[0042] Example 3 The preparation method is the same as in Example 1, except that the flow rates of the four gradients are set to 11, 8, 4 and 1.5 mL / min, respectively, and are denoted as catalyst S-3. The components in the catalyst and their weight percentages are as follows: CuO: 62.11%; ZnO: 23.49%; Al2O3: 12.06%; SiO2: 1.55%.
[0043] Example 4 The preparation method is the same as in Example 1, except that the amount of Na2SiO3 added is 2g, which is designated as catalyst S-4. The components and their weight percentages in the catalyst are as follows: CuO: 61.68%; ZnO: 23.51%; Al2O3: 12.15%; SiO2: 2.27%.
[0044] Example 5 The preparation method is the same as in Example 1, except that the amount of Na2SiO3 added is 0.25g, which is designated as catalyst S-5. The components and their weight percentages in the catalyst are as follows: CuO: 61.72%; ZnO: 23.37%; Al2O3: 13.11%; SiO2: 0.45%.
[0045] Comparative Example 1 The preparation method is the same as in Example 1, except that the salt solution is added dropwise to the alkali solution at a rate of 8 mL / min to obtain catalyst D-1. The components and their weight percentages in the catalyst are as follows: CuO: 62.34%; ZnO: 24.38%; Al2O3: 10.79%; SiO2: 1.52%.
[0046] Comparative Example 2 The preparation method is the same as in Example 1, except that Na2SiO3 is not added. It is designated as catalyst D-2. The components and their weight percentages in the catalyst are as follows: CuO: 62.15%; ZnO: 24.58%; Al2O3: 13.17%.
[0047] Comparative Example 3 The preparation method of the embodiment in Chinese patent CN120094589A is adopted and is referred to as catalyst D-3. The components of the catalyst and their weight percentages are as follows: CuO: 61.68%; ZnO: 32.02%; Al2O3: 6.30%.
[0048] Comparative Example 4 The preparation method of the embodiment in Chinese patent CN104174404A is referred to as catalyst D-4. The components and their weight percentages in the catalyst are as follows: CuO: 72.16%; ZnO: 22.68%; Al2O3: 2.54%; ZrO2: 2.01%.
[0049] Test case The above catalyst was evaluated using a micro fixed-bed reactor for the synthesis of methanol from syngas, under the following evaluation conditions: Catalyst particle size: 20~40 mesh; Reaction pressure: 5 MPa; Reaction temperature: 230°C; Airspeed: 10000h -1 Syngas composition: CO: 14%; CO2: 4%; H2: 60%; Ar: 22%; Heat treatment conditions: 400℃, 5h.
[0050] Test Result Table
[0051] Test results show that the activity retention rate of this application (93.7-95.1%) is significantly higher than that of comparative example 1 (85.0%), comparative example 2 (77.4%), comparative example 3 (79.6%) and comparative example 4 (76.0%). The specific surface area of this application is 149.8-162.4 m². 2 The concentration ( / g) was significantly higher than that of the comparative sample (125.3-145.2m). 2 / g).
[0052] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing a copper-based catalyst for methanol synthesis, characterized in that, The preparation method includes: S1 dissolves and mixes copper and zinc sources in water to obtain a Cu-Zn mixture. The Cu-Zn mixture is then added dropwise to an alkaline solution at a gradient dropping rate to obtain a first suspension, which is then aged. S2 dissolves the aluminum source and silicon source in the first suspension after aging to obtain the second suspension, and then ages it. S3 washes, dries, and calcines the aged second suspension to obtain the copper-based catalyst; The components and their weight percentages in the copper-based catalyst are as follows: CuO: 55~65%; ZnO: 20~30%; Al2O3: 5~15%; SiO2: 0.1~3.0%.
2. The preparation method according to claim 1, characterized in that, In S1, the dropping rate is divided into four gradients, namely 7~11, 4~8, 2~4, and 0.5~1.5 mL / min. Based on the volume of the Cu-Zn mixture, the dropping amounts corresponding to each gradient are 30~40%, 45~55%, 6~10%, and 1~6%, respectively.
3. The preparation method according to claim 1, characterized in that, The weight percentages of each component in the copper-based catalyst are as follows: CuO: 57~62%; ZnO: 22~26%; Al2O3: 8~12%; SiO2: 0.5~1.5%; Preferably, the copper-based catalyst has a specific surface area of 149.8-162.4 m². 2 / g.
4. The preparation method according to claim 1, characterized in that, In S1, the temperature at which the copper source and the zinc source are dissolved in water and mixed is 40~70℃, and the time is 10~20min; Preferably, in step S1, the Cu-Zn mixture is added to the alkaline solution at a gradient dropping rate at a temperature of 60-80°C for 18-20 minutes. Preferably, in S1, the pH value at the endpoint of the drop addition is 7-8.
5. The preparation method according to claim 1, characterized in that, In S1, the copper source is at least one of Cu(NO3)2, CuSO4, and CuCl2; Preferably, in S1, the zinc source is at least one of Zn(NO3)2, ZnSO4, and ZnCl2; Preferably, in S1, the mass of the copper source is calculated as copper element, the mass of the zinc source is calculated as zinc element, and the mass ratio of the copper source, the zinc source and water is (5.5~6.5):(2.0~3.0):(90~110).
6. The preparation method according to claim 1, characterized in that, In S1, the alkaline solution is an aqueous solution of at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. Preferably, in step S1, the mass ratio of the Cu-Zn mixture to the alkaline solution is (0.6~1.0):(0.7~1.0). Preferably, the alkali content is (9~11)% based on the mass of the alkali solution.
7. The preparation method according to claim 1, characterized in that, In S1, the aging temperature is 75~85℃ and the time is 20~60min; Preferably, in step S1, the temperature is reduced to 40-60°C after aging.
8. The preparation method according to claim 1, characterized in that, In S2, the aluminum source is at least one of Al(NO3)3, Al2(SO4)3, AlCl3, and boehmite. Preferably, in step S2, the silicon source is at least one of tetraethyl orthosilicate, silica sol, and sodium silicate; Preferably, in step S2, the mass of the aluminum source is measured in terms of aluminum element, the mass of the silicon source is measured in terms of silicon element, and the mass ratio of the copper source, the aluminum source, and the silicon source is (5.5~6.5):(0.3~0.5):(0.025~0.25).
9. The preparation method according to claim 1, characterized in that, In step S2, the aging temperature is 40~60℃ and the time is 10~40min.
10. The preparation method according to claim 1, characterized in that, In step S3, the drying temperature is 80~120℃ and the drying time is 6~24h; Preferably, in step S3, the calcination temperature is 350~450℃ and the time is 2~4h.