Preparation method of low-sodium high-activity copper-based methanol synthesis catalyst
By improving the preparation method of copper-based methanol synthesis catalyst, and by using low-sodium alkaline precipitant and pressure washing steps, the problem of high sodium content in the catalyst was solved, achieving higher activity and selectivity in catalytic effect, which is suitable for low-temperature and low-pressure methanol synthesis units.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2023-10-20
- Publication Date
- 2026-06-23
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology and relates to a novel preparation method for a low-sodium, high-activity copper-based methanol synthesis catalyst. Background Technology
[0002] Methanol, as a basic chemical raw material and environmentally friendly power fuel, is widely used in formaldehyde, ethanol, acetic acid, methyl tert-butyl ether, pharmaceuticals, pesticides, and vehicle fuels. By the end of 2022, my country's methanol production capacity had exceeded 100 million tons per year. Industrial methanol is generally produced by reacting syngas containing H2, CO, and CO2 under certain pressure and temperature conditions in the presence of a catalyst. The catalyst adopts a Cu-Zn-Al system, in which copper and zinc oxides are referred to as active precursors, and alumina is used as the support. This catalyst system not only has good low-temperature methanol synthesis activity at relatively low operating pressures, but also produces methanol with low impurity content, which is beneficial for energy conservation. Therefore, this system is widely used.
[0003] Methanol synthesis catalysts are mainly composed of oxides of copper, zinc, and aluminum. The typical catalyst preparation method involves first preparing a copper-zinc precursor (i.e., reacting a mixed solution of soluble copper and zinc salts with an alkaline precipitant to obtain copper and zinc precipitates), then loading it onto an alumina support, followed by washing, filtration, drying, calcination, and molding to obtain the catalyst. Currently, one or more sodium-containing bases (such as sodium bicarbonate, sodium hydroxide, or sodium carbonate) are used as the precipitant for the precursor, resulting in a precursor solution containing a large amount of soluble sodium. + Ions. Literature studies have found that thermal stability increases with decreasing Na content in the catalyst; however, a Na₂O content >0.5% in the catalyst can also affect its initial activity. The main reason for this is Na... + It tends to segregate on the catalyst surface, covering the active sites and clogging the pores. Additionally, excessive Na... + It is also prone to producing side reactions. Summary of the Invention
[0004] The purpose of this invention is to propose a new method for preparing a low-sodium, highly active copper-based methanol synthesis catalyst.
[0005] The copper-based methanol synthesis catalyst prepared by the method of this invention has a lower sodium impurity content than catalysts prepared by conventional methods, and the catalyst has better performance and can meet higher requirements.
[0006] This invention is implemented as follows: It mainly includes the following steps:
[0007] (1) Prepare a mixed solution (1) of Cu(NO3)2 and Zn(NO3)2, heat it, and set it aside for later use;
[0008] (2) Prepare a mixed solution of Cu(NO3)2, Zn(NO3)2 and Zr(NO3)4 (2), heat it, and set it aside for later use;
[0009] (3) Adjust the mixed solution (1) and mixed solution (2) with ammonia water to remove free acid from the solution;
[0010] (4) Prepare a 1-2 mol / L alkaline precipitant solution (3), heat it to 65℃-85℃, and set aside for use;
[0011] (5) Pour the above alkaline precipitant solution (3) into the neutralization tank, and slowly add the above copper-zinc mixture (1) into the neutralization tank under strong stirring. The pH value at the precipitation endpoint is 7.5 to 8.5, and the binary parent precursor of the precipitate is obtained.
[0012] (6) The sediment obtained in step (5) is washed by natural sedimentation-drainage method. The washing water temperature is 50℃~70℃, and the washing is repeated 5 times.
[0013] (7) A mixed solution (2) and an alkaline precipitant solution (3) are simultaneously pumped into the precipitate slurry described in step 6) using a co-current sedimentation method. The process pH is controlled to be 8-9, the amount of alkaline precipitant solution (3) added is 1.5L, and the final pH is 6.8-7.2 to obtain a binary parent material.
[0014] (8) Use pressure washing to remove excess impurities. The water temperature is 65℃~85℃. Wash until the conductivity of the solution is less than 200μs / cm to obtain the catalyst matrix.
[0015] (9) Add 10% to 15% of the total mass of copper and zinc to a low-sodium alumina support, and then wash, filter, dry and calcine to obtain a catalyst precursor.
[0016] (10) Wash the catalyst precursor with a mixed solution of 20% water and 80% anhydrous ethanol and anhydrous ethanol, respectively. The liquid volume V 液 V 固 =1:1 to 2:1;
[0017] (11) Dry the catalyst precursor at 85℃ under N2 protection for 12 h, with an N2 space velocity of 50–100 h⁻¹. -1 ;
[0018] (12) The dried catalyst is shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst.
[0019] The mixed solution (1) mentioned in step (1) has a Cu(NO3)2 concentration of 120-200 g / L and a Zn(NO3)2 concentration of 40-70 g / L.
[0020] The heating temperature of the mixed solution (1) in step (1) is 65℃~85℃.
[0021] In step (2), the concentration of Cu(NO3)2 in the mixed solution (2) is 60-100 g / L, the concentration of Zn(NO3)2 is 20-40 g / L, and the mass of Zr(NO3)4 is 3-15% of the mass of Zn(NO3)2 in the mixed solution.
[0022] The mixed solution (1) described in step (2) does not contain free acid and contains trace amounts of flocculated precipitate.
[0023] The heating temperature of the mixed solution (2) described in step (2) is 65℃~85℃.
[0024] The alkaline precipitant is one or more of sodium hydroxide, sodium oxalate, sodium acetate, sodium carbonate, or sodium bicarbonate;
[0025] The pressure for pressure washing in step (8) is 0.5 to 0.8 MPa.
[0026] The sodium content in the low-sodium alumina described in step (9) should be less than or equal to 0.05 wt%.
[0027] In step (9), the drying temperature is 90-110℃ and the calcination temperature is 330-360℃.
[0028] The methanol synthesis catalyst prepared by the method of this invention has a lower sodium impurity content than catalysts prepared by conventional methods. The catalyst has high activity, better selectivity and physicochemical properties, and can meet the requirements of large-scale methanol production plants. Detailed Implementation
[0029] The following examples are used to further illustrate the content of this invention:
[0030] Example 1
[0031] Prepare a solution (1) containing 120g Cu(NO3)2 and 70g Zn(NO3)2 in 1L, heat it to 65℃ and set aside. Prepare a solution (2) containing 100g Cu(NO3)2, 20g Zn(NO3)2 and 13.5g Zr(NO3)4 in 1L, heat it to 65℃ and set aside. Dissolve 252g NaHCO3 in 3L deionized water to prepare an alkaline precipitant solution (3), heat it to 65℃ and set aside.
[0032] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 65-67℃, and the final pH value was 8. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 60℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 8.5, and the final pH value was 7.1 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The water temperature was 65℃, the pressure was 0.5MPa, and the conductivity of the washing endpoint solution was 192μs / cm to obtain the catalyst precursor.
[0033] Add 11.5g of low-sodium alumina support, and after washing, filtering, drying, and calcining, obtain the catalyst precursor; wash the catalyst precursor with a mixed solution of 20% water + 80% anhydrous ethanol and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =1:1;
[0034] The catalyst precursor was dried at 85℃ under N2 protection for 12 hours, with an N2 space velocity of 50 h⁻¹. -1 ;
[0035] The catalyst, after being dried at 100℃ and calcined at 330℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.1.
[0036] Example 2
[0037] Prepare a solution (1) containing 200g Cu(NO3)2 and 40g Zn(NO3)2 in 1L, heat it to 70℃ and set aside. Prepare a solution (2) containing 60g Cu(NO3)2, 40g Zn(NO3)2 and 8g Zr(NO3)4 in 1L, heat it to 70℃ and set aside. Dissolve 636g Na2CO3 in 3L deionized water to prepare an alkaline precipitant solution (3), heat it to 70℃ and set aside.
[0038] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 70-72℃, and the final pH value was 7.5. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 70℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 9.0, and the final pH value was 7.2 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The pressure was 0.6MPa, the water temperature was 75℃, and the conductivity of the washing endpoint solution was 187μs / cm to obtain the catalyst precursor.
[0039] Add 12.7g of low-sodium alumina support, and after washing, filtering, drying, and calcining, obtain the catalyst precursor; wash the catalyst precursor with a mixed solution of 20% water + 80% anhydrous ethanol and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =1.5:1;
[0040] The catalyst precursor was dried at 90℃ under N2 protection for 12 hours, with an N2 space velocity of 100 h⁻¹. -1 ;
[0041] The catalyst, dried at 90℃ and calcined at 340℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.2.
[0042] Example 3
[0043] Prepare a solution (1) containing 160g Cu(NO3)2 and 55g Zn(NO3)2 in 1L, heat it to 75℃ and set aside for use. Prepare a solution (2) containing 80g Cu(NO3)2, 30g Zn(NO3)2 and 4.25g Zr(NO3)4 in 1L, heat it to 75℃ and set aside for use. Dissolve 180g NaOH in 3L deionized water to prepare an alkaline precipitant solution (3), heat it to 75℃ and set aside for use.
[0044] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 75-77℃, and the final pH value was 7.0. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 65℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 8.0, and the final pH value was 7.0 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The pressure was 0.7MPa, the water temperature was 70℃, and the conductivity of the washing endpoint solution was 168μs / cm to obtain the catalyst precursor.
[0045] Add 13.3g of low-sodium alumina support, and after washing, filtering, drying, and calcining, obtain the catalyst precursor; wash the catalyst precursor with a mixed solution of 20% water + 80% anhydrous ethanol and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =2:1;
[0046] The catalyst precursor was dried at 80℃ under N2 protection for 12 hours, with an N2 space velocity of 90 h⁻¹. -1 ;
[0047] The catalyst, dried at 110℃ and calcined at 350℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.3.
[0048] Example 4
[0049] Prepare a solution (1) containing 180g Cu(NO3)2 and 50g Zn(NO3)2 in 1L, heat it to 80℃ and set aside for use. Prepare a solution (2) containing 70g Cu(NO3)2, 35g Zn(NO3)2 and 3.45g Zr(NO3)4 in 1L, heat it to 80℃ and set aside for use. Dissolve 402g Na2C2O4 in 3L deionized water to prepare an alkaline precipitant solution (3), heat it to 80℃ and set aside for use.
[0050] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 79-81℃, and the final pH value was 8.1. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 50℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 8.1, and the final pH value was 6.8 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The pressure was 0.8MPa, the water temperature was 85℃, and the conductivity of the washing endpoint solution was 174μs / cm to obtain the catalyst precursor.
[0051] Add 14.8g of low-sodium alumina support, and after washing, filtering, drying, and calcining, obtain the catalyst precursor; wash the catalyst precursor with a 20% water + 80% anhydrous ethanol mixed solution and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =1.4:1;
[0052] The catalyst precursor was dried at 84℃ under N2 protection for 12 hours, with an N2 space velocity of 70 h⁻¹. -1 ;
[0053] The catalyst, dried at 100℃ and calcined at 360℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.4.
[0054] Example 5
[0055] Prepare a solution (1) containing 140g Cu(NO3)2 and 60g Zn(NO3)2 in 1L, heat it to 85℃ and set aside for use. Prepare a solution (2) containing 90g Cu(NO3)2, 25g Zn(NO3)2 and 8.5g Zr(NO3)4 in 1L, heat it to 85℃ and set aside for use. Dissolve 492g CH3COONa in 3L of deionized water to prepare an alkaline precipitant solution (3), heat it to 85℃ and set aside for use.
[0056] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 83-85℃, and the final pH value was 7.6. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 60℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 8.8, and the final pH value was 6.9 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The pressure was 0.8MPa, the water temperature was 80℃, and the conductivity of the washing endpoint solution was 181μs / cm to obtain the catalyst precursor.
[0057] A catalyst precursor was prepared by adding 15.0g low-sodium alumina support, followed by washing, filtration, drying, and calcination. The catalyst precursor was then washed with a 20% water + 80% anhydrous ethanol mixed solution and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =2:1;
[0058] The catalyst precursor was dried at 90℃ under N2 protection for 12 hours, with an N2 space velocity of 100 h⁻¹. -1 ;
[0059] The catalyst, dried at 110℃ and calcined at 340℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.5.
[0060] Example 6
[0061] Prepare a solution (1) containing 150g Cu(NO3)2 and 50g Zn(NO3)2 in 1L, heat it to 65℃ and set aside. Prepare a solution (2) containing 80g Cu(NO3)2, 30g Zn(NO3)2 and 6.4g Zr(NO3)4 in 1L, heat it to 65℃ and set aside. Dissolve 252g NaHCO3 and 318g Na2CO3 in 3L deionized water to prepare an alkaline precipitant solution (3), heat it to 65℃ and set aside.
[0062] The mixed solution (1) was added to 1.5L of alkaline precipitant solution (3) under stirring. The process temperature was 65-67℃, and the final pH value was 7.2. The above precipitate was washed by natural sedimentation-drainage method. The washing water temperature was 60℃, and the washing was repeated 5 times. The mixed solution (2) and 1.5L of alkaline precipitant solution (3) were added to the above binary precursor slurry by co-current method. The process pH value was controlled at 8.0, and the final pH value was 7.0 to obtain the binary precursor. The binary precursor was washed by pressure washing method to remove excess impurities. The pressure was 0.7MPa, the water temperature was 65℃, and the conductivity of the washing endpoint solution was 173μs / cm to obtain the catalyst precursor.
[0063] Add 15.8g of low-sodium alumina support, and after washing, filtering, drying, and calcining, obtain the catalyst precursor; wash the catalyst precursor with a 20% water + 80% anhydrous ethanol mixed solution and anhydrous ethanol, respectively, with a liquid volume of V. 液 V 固 =1.7:1;
[0064] The catalyst precursor was dried at 85℃ under N2 protection for 12 hours, with an N2 space velocity of 90 h⁻¹. -1 ;
[0065] The catalyst, dried at 100℃ and calcined at 350℃, was shaped to obtain the finished low-sodium, high-activity copper-based methanol synthesis catalyst cat.6.
[0066] Comparative Example
[0067] A 1L mixed solution containing 180g Cu(NO3)2 and 60g Zn(NO3)2 was heated to 70℃ and set aside. 252g NaHCO3 was dissolved in 3L deionized water to prepare an alkaline precipitant solution, which was also heated to 70℃ and set aside. The copper-zinc mixed solution was added to the alkaline precipitant solution with stirring, the process temperature was maintained at 69–71℃, and the final pH value was 7.0. The binary precursor was washed 5 times, and 19.9g alumina support was added to the binary precursor. The mixture was then washed, filtered, dried at 100℃, calcined at 360℃, and shaped to prepare the comparative catalyst cat.0.
[0068] Sample testing
[0069] Catalyst samples: particle size 0.425–1.180 mm.
[0070] Activity testing: A micro fixed-bed continuous flow reactor was used. The catalyst loading was 4 mL, with a particle size of 16-40 mesh. Catalyst reduction was performed in a low-hydrogen atmosphere (H2:N2 = 5:95) with a programmed temperature increase (20℃ / h) for 10 hours, reaching a temperature of 230℃. The reducing gas was then switched to the feed gas for activity testing. The activity testing conditions were a reaction pressure of 5.0 MPa and a space velocity of 10000 h⁻¹. -1 The temperature was 230℃, and the synthesis gas composition was H2∶CO∶CO2∶N2=65∶14∶4∶17 (v / v). After heat treatment at 400℃ for 5 h, the catalyst's activity was measured under the above conditions. The activity value was expressed as the space-time yield (g / ml) of methanol production. -1 h -1 The ratio of activity after heat resistance to initial activity is used to compare the thermal stability of the samples.
[0071] Sodium content was determined using a DIONX ICS-900 inductively coupled plasma atomic emission spectrometer.
[0072] The surface area, pore volume, and pore size distribution of the catalyst were determined using a Quantachrome Nova 2200e pore structure analyzer and a CHEMBET-3000 fully automated specific surface area analyzer.
[0073] The catalyst phase was determined using a Rigaku DmaxⅢA X-ray diffractometer (Japan), with a scanning range of 2θ = 10° to 60°, a voltage of 40 kV, a current of 30 mA, and a Cu target. The grain size was calculated using the broadening method.
[0074] The performance test results are listed in Tables 1 to 3, where samples cat.1, cat.2, cat.3, cat.4, cat.5, and cat.6 were prepared by the method of this invention, and cat.0 is a comparative sample prepared by the conventional method. Table 1 shows the Na2O content detection results of the catalyst bulk, Table 2 shows the catalyst activity test results, Table 3 shows the catalyst selectivity test results, and Table 4 shows the BET test results.
[0075] Table 1. Results of Impurity Content Test
[0076] catalyst cat.1 cat.2 cat.3 cat.4 cat.5 cat.6 cat.0 <![CDATA[Na2O content / ppm]]> 95 90 90 93 98 89 320
[0077] Table 2 Activity test results
[0078]
[0079] Table 3 Selectivity Test Results
[0080]
[0081] Table 4 BET Detection Results
[0082]
[0083] As can be seen from Tables 1 to 4 above, the sodium content of the low-sodium, high-activity copper-based methanol synthesis catalyst prepared by the method of the present invention is significantly reduced. Its initial activity and post-heat-resistant activity are both higher than those of the comparative catalyst. The methanol selectivity in the prepared crude methanol is higher than that of the comparative catalyst, while the ethanol content and total impurity content are lower. The specific surface area, pore volume, and average pore diameter of the catalyst are greater than those of the comparative catalyst. The crystallite size of CuO and ZnO is comparable to that of the comparative catalyst. This indicates that the catalyst prepared by the method of the present invention has superior performance, and the present invention represents a significant improvement over existing methods.
[0084] The catalyst prepared by the method of the present invention is suitable for methanol production from syngas containing CO, CO2 and H2, and is especially suitable for low-temperature and low-pressure methanol synthesis plants.
Claims
1. A method for preparing a low-sodium high-activity copper-based methanol synthesis catalyst, comprising the following steps: (1) preparing a mixed solution (1) of Cu(NO3)2 and Zn(NO3)2, heating, and waiting; (2) preparing a mixed solution (2) of Cu(NO3)2, Zn(NO3)2 and Zr(NO3)4, heating, and waiting; (3) adjusting the mixed solution (1) and the mixed solution (2) with ammonia water to remove free acid in the solution; (4) preparing a 1-2 mol / L alkaline precipitant solution (3), heating to 65-85 ℃, and waiting; (5) pouring the alkaline precipitant solution (3) into a neutralization barrel, slowly adding the copper-zinc mixed solution (1) to the neutralization barrel under strong stirring, and obtaining a precipitate binary matrix precursor with a pH value of 7.5-8.5 at the end of precipitation; (6) washing the precipitate obtained in step (5) by using a natural sedimentation-tilting method, with the washing water temperature being 50-70 ℃, and washing for 5 times; (7) pumping the mixed solution (2) and the alkaline precipitant solution (3) into the slurry of the precipitate material in step 6) by using a parallel flow precipitation method, controlling the process pH value to be 8-9, the addition amount of the alkaline precipitant solution (3) being 1.5 L, and the end point pH value being 6.8-7.2, to obtain a binary matrix; (8) removing excess impurities by using a pressurized washing method, with the water temperature being 65-85 ℃, and washing until the conductivity of the solution is less than 200 μs / cm, to prepare a catalyst matrix; (9) adding a low-sodium alumina carrier with a total mass of 10%-15% of copper and zinc, and washing, filtering, drying, and calcining to prepare a catalyst precursor; (10) The catalyst precursor is washed with 20% water + 80% anhydrous ethanol mixed solution and anhydrous ethanol respectively, the liquid amount V 液 : V 固 = 1:1~2:1; (11) Dry the catalyst precursor at 85 °C under N2protection for 12 h, N2space velocity is 50-100 h -1 ; (12) forming the dried catalyst to obtain a finished low-sodium high-activity copper-based methanol synthesis catalyst; In step (1), the concentration of Cu(NO3)2 in the mixed solution (1) is 120-200 g / L, and the concentration of Zn(NO3)2 is 40-70 g / L; In step (2), the concentration of Cu(NO3)2 in the mixed solution (2) is 60-100 g / L, the concentration of Zn(NO3)2 is 20-40 g / L, and the mass of Zr(NO3)4 is 3-15% of the mass of Zn(NO3)2 in the mixed solution; In step (2), the mixed solution (1) does not contain free acid and contains a small amount of flocculation precipitate; In step (9), the sodium content in the low-sodium alumina is less than or equal to 0.05wt%.
2. The method of claim 1, wherein In step (1), the heating temperature of the mixed solution (1) is 65-85 ℃.
3. The method of claim 1, wherein In step (2), the heating temperature of the mixed solution (2) is 65-85 ℃.
4. The method of claim 1, wherein The alkaline precipitant is one or more of sodium hydroxide, sodium oxalate, sodium acetate, sodium carbonate, or sodium bicarbonate.
5. The method of claim 1, wherein In step (8), the pressure of the pressurized washing is 0.5-0.8 MPa.
6. The method of claim 1, wherein In step (9), the drying temperature is 90-110 ℃, and the calcination temperature is 330-360 ℃.