A process for the preparation of a methanol synthesis catalyst with stable precipitation

Abstract

The present application relates to the technical field of catalyst production, in particular to a preparation method of methanol synthesis catalyst with stable precipitation process, comprising the following steps: step 1: dissolving zirconium nitrate, zinc nitrate and aluminum nitrate in water to form a zirconium-zinc-aluminum mixed salt solution A, dissolving zinc nitrate, aluminum nitrate and copper nitrate in water to form a copper-zinc-aluminum mixed salt solution B, dissolving sodium carbonate in water to form alkali solution C and alkali solution D, and adding a small amount of alkali solution C into deionized water to form deionized water E; step 2: using the salt solution A, the alkali solution C and the deionized water E to form a precipitate 1, and then aging the precipitate 1; step 3: after aging, filtering and washing the precipitate 1, adding the precipitate 1 into the mixed solution B to form a highly dispersed suspension slurry F; step 4: using the suspension slurry F and the alkali solution D to perform an emulsification reaction to form a precipitate 2, and aging the precipitate 2.

Description

Technical Field

[0001] This invention relates to the field of catalyst production technology, and specifically to a method for preparing a methanol synthesis catalyst that is stable during the precipitation process. Background Technology

[0002] Methanol is an important basic chemical raw material with wide applications in traditional chemical industries. It is an upstream raw material for a series of chemical products such as formaldehyde, dimethyl ether, and acetic acid. As of the end of 2022, my country had a total methanol production capacity of 113.06 million tons, with an effective capacity of 100 million tons, an increase of 5.7% year-on-year.

[0003] Currently, methanol synthesis catalysts are often prepared by co-precipitation. During the preparation process, the volume of metal cations per unit volume in the precipitate fluctuates with the continuous addition of salt and alkali solutions. Furthermore, the salt and alkali solutions diffuse and precipitate when dripped into the parent precipitate. These unfavorable factors are detrimental to the complete stability of the pH value during the precipitation process, ultimately affecting the low-temperature activity and high-temperature selectivity of the catalyst. Previous experiments have shown that when the catalyst has excellent low-temperature activity, its high-temperature selectivity is poor. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a methanol synthesis catalyst with a stable precipitation process, thereby solving the technical problem of unstable precipitation process in existing methanol synthesis catalysts.

[0005] This invention discloses a method for preparing a methanol synthesis catalyst that is stable during precipitation, comprising the following steps:

[0006] Step 1: Dissolve zirconium nitrate, zinc nitrate, and aluminum nitrate in water to form zirconium-zinc-aluminum mixed salt solution A; dissolve zinc nitrate, aluminum nitrate, and copper nitrate in water to form copper-zinc-aluminum mixed salt solution B; dissolve sodium carbonate in water to form alkaline solutions C and D; add a small amount of alkaline solution C to deionized water to form deionized water E.

[0007] Step 2: Using salt solution A, alkaline solution C and deionized water E, precipitate 1 is formed, and then precipitate 1 is aged.

[0008] Step 3: After aging is complete, filter and wash precipitate 1, and add precipitate 1 to mixed solution B to form a highly dispersed suspension slurry F;

[0009] Step 4: Use suspension slurry F and alkaline solution D to carry out an emulsification reaction to form precipitate 2, and then age precipitate 2;

[0010] Step 5: After the aging of precipitate 2 is complete, precipitate 2 is filtered and washed. The filter cake obtained by filtration is dried and then calcined. Graphite is added to the calcined product, and after mixing evenly and forming, methanol synthesis catalyst is obtained.

[0011] Furthermore, the salt solution A and the alkaline solution C are introduced into the reaction via spray.

[0012] Furthermore, the Zn in salt solution A in step 1 2+ The molar amount of Zn in salt solution A and salt solution B accounts for a certain percentage of the total Zn content. 2+ 10% to 20%.

[0013] Furthermore, the Al in salt solution A in step 1 3+ The molar amount of Al in salt solution A and salt solution B accounts for a certain percentage of the total Al content. 3+ More than 90%.

[0014] Furthermore, the pH value of the deionized water E mentioned in step 1 is 7.0 to 9.0, preferably 8.0.

[0015] Furthermore, in step 2, the temperature is preheated to 70–90°C, preferably 80°C.

[0016] Furthermore, in step 2, when precipitate 1 is formed, the total amount of metal cations per unit volume is kept constant. Specifically, after a portion of the salt solution A is consumed, deionized water is atomized and sprayed downwards from the top of the reactor, controlling the flow rate of the sprayed deionized water to ensure that the total amount of metal cations per unit volume remains constant.

[0017] Furthermore, in step 2, while precipitate 1 is being formed, precipitate 1 is transferred to another container with stirring and temperature control, the liquid level in the reactor is kept constant, and the pH value of precipitate 1 transferred to the other container with stirring and temperature control is kept the same as that of deionized water E.

[0018] Furthermore, in step 2, after the salt solution A is completely sprayed in, the spraying of the alkali solution C and deionized water is stopped. After the precipitate 1 is completely entered into the reaction container, stirring is continued for 30 min to 120 min. After stirring is completed, the temperature is lowered, preferably by stirring for 60 min.

[0019] Furthermore, in step 4, the pH of precipitate 2 is controlled to be 6.5–8.0, preferably 7.2.

[0020] Furthermore, in step 4, the pumping of alkaline solution D is stopped when the suspension slurry F is completely added.

[0021] Furthermore, the aging temperature in steps 3 and 4 is 60–80°C, preferably 70°C, and stirring is continued at this temperature for 1–3 hours, preferably 90 minutes.

[0022] Furthermore, the calcination is carried out at 300-400°C for 3-5 hours, preferably at 350°C for 4 hours.

[0023] Furthermore, the graphite accounts for 2% of the total mass of the catalyst.

[0024] A methanol synthesis catalyst with a precipitation process stability includes graphite, wherein the graphite accounts for 1-3% of the total mass of the catalyst, and the remaining components, excluding graphite, are, by mass percentage, 55-60% CuO, 18-23% ZnO, 20-25% Al2O3 and 0.5%-3% ZrO2.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Salt solution A and alkaline solution C are atomized into extremely fine droplets by spraying and fall into the bottom of the reaction vessel where the pH value has been adjusted by alkaline solution C. This allows salt solution A and alkaline solution C to diffuse and react more quickly, resulting in smaller and more stable pH fluctuations during precipitation. This is beneficial for the formation and stability of the support structure, and ultimately helps to improve the stability of the catalyst.

[0027] 2. By atomizing and spraying deionized water into the reactor during the reaction process, the total amount of metal cations per unit volume remains constant. By transferring the precipitate 1 generated by the reaction to another container with stirring and temperature control, the liquid level in the reactor is kept constant. These operations make the precipitation process more stable and less volatile. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] Example 1

[0030] This embodiment discloses a method for preparing a methanol synthesis catalyst that is stable during the precipitation process, comprising the following steps:

[0031] Dissolve 19.94g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O, and 250.85g Al(NO3)3·9H2O in deionized water and bring the volume to 750ml to form salt solution A; dissolve 253.12g Cu(NO3)2·3H2O, 79.75g Zn(NO3)2·6H2O, and 27.87g Al(NO3)3·9H2O in deionized water and bring the volume to 1380ml to form salt solution B; dissolve 107.06g NaCO3 in deionized water and bring the volume to 1000ml to form the alkaline solution C required for precipitation; dissolve 214.12g NaCO3 in deionized water and bring the volume to 2000ml to form the alkaline solution D required for precipitation; add a small amount of alkaline solution C to the deionized water to form deionized water E with a pH of 8.0.

[0032] After preheating salt solution A, alkali solution C, and deionized water E to 80°C, add an appropriate amount of deionized water E into the reactor. Then, start stirring. Simultaneously, atomize and spray salt solution A and alkali solution C from the top of the reactor downwards. The fine droplets formed by salt solution A and alkali solution C fall into the bottom of the reactor and react to form precipitate 1. After a portion of salt solution A is consumed, atomize and spray deionized water at the same temperature as the preheating temperature from the top of the reactor downwards. Control the flow rate of the sprayed deionized water to keep the total amount of metal cations per unit volume constant. At the same time, transfer precipitate 1 to another container with stirring and temperature control. Keep the liquid level in the reactor constant, and control the pH value of precipitate 1 to be the same as that of deionized water E and the temperature to be the same as the preheating temperature. After salt solution A is completely sprayed in, stop spraying alkali solution C and deionized water. After precipitate 1 has completely entered the reaction container, continue to age at a constant temperature with stirring for 60 minutes.

[0033] After aging is complete, filter and wash precipitate 1, and add precipitate 1 to mixed solution B to form a highly dispersed suspension slurry F.

[0034] Suspension slurry F and alkaline solution D are simultaneously pumped into an emulsification reactor to react and form precipitate 2. Precipitate 2 enters a container with stirring and temperature control through a reaction extension tube. The pH value of precipitate 2 is controlled at 7.2. After suspension slurry F is completely pumped in, the pumping of alkaline solution D is stopped. Then, the temperature of precipitate 2 is raised to 70°C, and stirring and aging are continued at this temperature for 90 minutes.

[0035] After aging, the precipitate 2 was filtered and washed, the filter cake was dried, and the dried material was calcined at 350°C for 4 hours. 2% of graphite by mass was added to the calcined material, and after mixing and molding, the methanol synthesis catalyst was obtained and numbered as sample 1.

[0036] Example 2

[0037] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is modified from Example 1 by dissolving 25.48g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O and 222.98g Al(NO3)3·9H2O in deionized water and making up to 700ml to form salt solution A, and dissolving 253.12g Cu(NO3)2·3H2O and 101.9g Zn(NO3)2·6H2O in deionized water and making up to 1380ml to form salt solution B. The methanol synthesis catalyst sample obtained by this method is numbered Sample 2.

[0038] Example 3

[0039] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is modified from Example 1 only by the following changes: Salt solution A consists of 9.97g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O, and 222.98g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 645ml; Salt solution B consists of 276.13g Cu(NO3)2·3H2O and 89.72g Zn(NO3)2·6H2O dissolved in deionized water and diluted to a volume of 1430ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 3.

[0040] Example 4

[0041] In this embodiment, a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is described. The only difference from Example 1 is that salt solution A consists of 19.94g Zn(NO3)2·6H2O, 15.67g Zr(NO3)4·5H2O, and 240.82g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 740ml; and salt solution B consists of 253.12g Cu(NO3)2·3H2O, 79.75g Zn(NO3)2·6H2O, and 26.76g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 1380ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 4.

[0042] Example 5

[0043] In this embodiment, a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is described. The only difference from Example 1 is that salt solution A consists of 9.97g Zn(NO3)2·6H2O, 2.61g Zr(NO3)4·5H2O, and 227.72g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 640ml; salt solution B consists of 276.13g Cu(NO3)2·3H2O, 89.72g Zn(NO3)2·6H2O, and 11.99g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 1460ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 5.

[0044] Example 6

[0045] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is described. The only changes are based on Example 1: the preheating temperature is controlled at 70°C, the pH value of deionized water E is 7.0, the constant temperature stirring time of precipitate 1 is 120 min, the pH value of precipitate 2 is 6.5, the constant temperature stirring time of precipitate 2 after reaching 80°C is 60 min, the dried material is calcined at 300°C for 5 h, and 1% of graphite by mass is added to the calcined material. The methanol synthesis catalyst sample obtained by this method is numbered Sample 6.

[0046] Example 7

[0047] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a methanol synthesis catalyst with a stable precipitation process is based on Example 1. The only changes are controlling the preheating temperature to 90°C, the pH value of deionized water E to 9.0, the constant temperature stirring time of precipitate 1 to 30 min, the pH value of precipitate 2 to 8.0, the constant temperature stirring time of precipitate 2 after reaching 60°C to 2 h, the dried material to be calcined at 400°C for 3 h, and the addition of 3% graphite by mass to the calcined material. The methanol synthesis catalyst sample obtained by this method is numbered Sample 7.

[0048] Comparative Example 1

[0049] To highlight the beneficial effects of the present invention, Comparative Example 1 is provided, comparing the methanol catalyst prepared in Examples 1-7 of the present invention with a catalyst prepared by conventional spray precipitation followed by dispersion and then emulsification precipitation. This visually demonstrates the effect of the method of the present invention on the methanol catalyst. The preparation method of Comparative Example 1 is as follows:

[0050] Dissolve 19.94g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O, and 250.85g Al(NO3)3·9H2O in deionized water and bring the volume to 750ml to form salt solution A; dissolve 253.12g Cu(NO3)2·3H2O, 79.75g Zn(NO3)2·6H2O, and 27.87g Al(NO3)3·9H2O in deionized water and bring the volume to 1380ml to form salt solution B; dissolve 321.18g... NaCO3 was dissolved in deionized water and brought to a final volume of 3000 ml to form the alkali solution C required for precipitation. Salt solutions A and B, and alkali solution C were preheated to 80°C. An appropriate amount of deionized water was added to the reactor, and stirring was started. Then, salt solution A and alkali solution C were simultaneously atomized and sprayed into the reactor from the top. The fine droplets formed by salt solution A and alkali solution C collided directly to form precipitate 1, which fell to the bottom of the reactor. The pH of precipitate 1 was controlled at 8.0, and the temperature at 80°C. After salt solution A was completely sprayed in, the spraying of alkali solution C was stopped, and the mixture was stirred at a constant temperature for 60 minutes to age. After aging, precipitate 1 was filtered and washed, and then added to a mixture... In solution B, a highly dispersed suspension slurry F is formed. The suspension slurry F and the alkaline solution D are simultaneously pumped into an emulsification reactor to react and form precipitate 2. The precipitate 2 is then introduced into a container with stirring and temperature control through a reaction extension tube. The pH of the precipitate 2 is controlled at 7.2 and the temperature at 70°C. After the suspension slurry F is completely injected, the injection of alkaline solution C is stopped, and stirring and aging continue at this temperature for 90 minutes. After aging, the precipitate 2 is filtered and washed, and the resulting filter cake is dried. The dried product is then calcined at 350°C for 4 hours. 2% of graphite by mass is added to the calcined product, and after uniform mixing and molding, a methanol synthesis catalyst is obtained, designated as control sample 1.

[0051] Comparative Example 2

[0052] To highlight the beneficial effects of the present invention, Comparative Example 2 is provided, comparing the methanol catalyst prepared in Examples 1-7 of the present invention with the catalyst prepared by dispersing the catalyst after co-current precipitation and then re-co-current precipitation, so as to intuitively reflect the effect of the method of the present invention on the methanol catalyst. The preparation method of Comparative Example 2 is as follows:

[0053] Dissolve 19.94g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O, and 250.85g Al(NO3)3·9H2O in deionized water and bring the volume to 750ml to form salt solution A; dissolve 253.12g Cu(NO3)2·3H2O, 79.75g Zn(NO3)2·6H2O, and 27.87g Al(NO3)3·9H2O in deionized water and bring the volume to 1380ml to form salt solution B; dissolve 321.18g... NaCO3 was dissolved in deionized water and brought to a final volume of 3000 ml to form the alkali solution C required for precipitation. Salt solutions A and B, and alkali solution C were preheated to 80°C. An appropriate amount of deionized water was added to the reactor, and stirring was started. Then, salt solution A and alkali solution C were simultaneously pumped into the reactor. Salt solution A and alkali solution C reacted at the bottom of the reactor to form precipitate 1. The pH of precipitate 1 was controlled at 8.0, and the temperature at 80°C. After salt solution A was completely pumped in, the pumping of alkali solution C was stopped, and the mixture was stirred at a constant temperature for 60 minutes to age. After aging, precipitate 1 was filtered and washed, and then added to mixed solution B. A highly dispersed suspension slurry F was formed. Then, the suspension slurry F and the alkaline solution C were pumped into the reactor. The suspension slurry F and the alkaline solution C fell to the bottom of the reactor to form precipitate 2. The pH value of precipitate 2 was controlled at 7.2 and the temperature at 70℃. After the suspension slurry F was completely pumped in, the pumping of alkaline solution C was stopped. The mixture was stirred and aged at this temperature for 90 minutes. After aging, precipitate 2 was filtered and washed. The filter cake obtained was dried and calcined at 350℃ for 4 hours. 2% of graphite by mass was added to the calcined product. After mixing and molding, the methanol synthesis catalyst was obtained and numbered as control sample 2.

[0054] Comparative Example 3

[0055] To highlight the beneficial effects of the present invention, Comparative Example 3 is provided, which compares the methanol catalysts prepared in Examples 1-7 of the present invention with those prepared by spray method, to intuitively reflect the effect of the method of the present invention on methanol catalysts. The preparation method of Comparative Example 3 is as follows:

[0056] Dissolve 19.94g Zn(NO3)2·6H2O, 10.44g Zr(NO3)4·5H2O, and 250.85g Al(NO3)3·9H2O in deionized water and bring the volume to 750ml to form salt solution A; dissolve 253.12g Cu(NO3)2·3H2O, 79.75g Zn(NO3)2·6H2O, and 27.87g Al(NO3)3·9H2O in deionized water and bring the volume to 1380ml to form salt solution B; dissolve 321.18g... NaCO3 was dissolved in deionized water and the volume was adjusted to 3000 ml to form the alkali solution C required for precipitation. Salt solution A, salt solution B, and alkali solution C were preheated to 80°C. An appropriate amount of deionized water was added to the reactor, and stirring was started. Then, salt solution A and alkali solution C were simultaneously sprayed into the reactor from the top in an anti-collision atomization manner. The fine droplets formed by salt solution A and alkali solution C directly collided to form precipitate 1, which fell to the bottom of the reactor. The pH of precipitate 1 was controlled at 8.0, and the temperature was controlled at 80°C. After salt solution A was completely sprayed in, the spraying of alkali solution C was stopped, and the mixture was kept at a constant temperature and stirred for 60 minutes for aging. Then, salt solution B and alkali solution C were simultaneously sprayed into the reactor from the bottom. The upper part of the reactor is atomized and sprayed with salt solution B and alkali solution C. The fine droplets formed by the salt solution B and alkali solution C directly collide to form precipitate 2, which falls to the bottom of the reactor and mixes with precipitate 1 to form precipitate 3. The pH value of precipitate 3 is controlled at 7.2 and the temperature is 70℃. After the salt solution B is completely pumped in, the pumping of alkali solution C is stopped, and the mixture is stirred and aged at this temperature for 90 minutes. After aging, precipitate 3 is filtered and washed, and the filter cake is dried. The dried product is calcined at 350℃ for 4 hours. 2% of graphite by mass is added to the calcined product, and after mixing and molding, the methanol synthesis catalyst is obtained and numbered as control sample 3.

[0057] Comparative Example 4

[0058] To highlight Zr in this invention 4+ The beneficial effect of adding it during the first precipitation step is provided in Comparative Example 4, which involves mixing the methanol catalyst prepared in Examples 1-7 of this invention with Zr. 4+ In the second step, a catalyst was prepared for comparison to visually demonstrate the effect of the method of the present invention on methanol catalysts. The preparation method of Comparative Example 4 is as follows:

[0059] The preparation method was the same as in Example 1, except that salt solution A was prepared by dissolving 19.94g Zn(NO3)2·6H2O and 250.85g Al(NO3)3·9H2O in deionized water and making up to a volume of 750ml; salt solution B was prepared by dissolving 253.12g Cu(NO3)2·3H2O, 10.44g Zr(NO3)4·5H2O, 79.75g Zn(NO3)2·6H2O and 27.87g Al(NO3)3·9H2O in deionized water and making up to a volume of 1380ml. The methanol synthesis catalyst sample obtained by this method was designated as Comparative Sample 4.

[0060] Comparative Example 5

[0061] To highlight Zr in this invention 4+ The added beneficial effects will be Zr 4+ Replace with Mg 2+ Comparative Example 5 is provided, in which the methanol catalyst prepared in Examples 1-7 of this invention is reacted with Mg. 2+ The preparation method of the catalyst in Comparative Example 4 is as follows: The catalyst prepared in Comparative Example 4 is compared with that prepared in Comparative Example 4 to visually demonstrate the effect of the method of the present invention on methanol catalysts.

[0062] The preparation method is the same as in Example 1, except that 10.44g Zr(NO3)4·5H2O in salt solution A is replaced with 19.23g Mg(NO3)2·6H2O. The methanol synthesis catalyst sample obtained by this method is numbered as Comparative Sample 5.

[0063] Comparative Example 6

[0064] To highlight Zr in this invention 4+ The beneficial effects of adding it are achieved without adding Zr during the preparation process. 4+ Comparative Example 6 is provided, which compares the methanol catalyst prepared in Examples 1-7 of this invention with one without the addition of Zr. 4+ The preparation method of Comparative Example 6 is as follows: The catalyst prepared in Comparative Example 6 is compared with that prepared in Comparative Example 6 to visually demonstrate the effect of the method of the present invention on methanol catalysts.

[0065] The preparation method is the same as in Example 1, except that the Zr in salt solution A is removed. 4+ Remove the reference number; the methanol synthesis catalyst sample obtained by this method is designated as Comparative Sample 6.

[0066] Example: Catalyst evaluation method:

[0067] This embodiment provides evaluation methods for the catalysts of Examples 1-7 and Comparative Examples 1-6, as detailed below:

[0068] Sample particle size: 16-40 mesh. Filling volume: 4 mL (2 mL catalyst + 2 mL inert support).

[0069] Sample activation: Before activation and heat resistance tests, the sample is reduced for 10-12 hours with a hydrogen-nitrogen mixture of low concentration hydrogen (H2 / N2 = 5 / 95 (volume ratio)), with the highest reduction temperature being 220℃.

[0070] Activity test: The feed gas composition was: CO = 7%, CO2 = 1.2%, N2 = 12.5%, with the remainder being H2. The reaction pressure was 5.0 MPa, and the space velocity was 20,000 h⁻¹. -1 The reaction temperature was 220±2℃. The CO conversion rate and CH3OH space-time yield (the amount of methanol produced per mL of catalyst per hour) were measured before the reaction was heated.

[0071] High-temperature selectivity test: After determining the initial activity, the reaction temperature is raised to 310±2℃, and the content of major impurities in the liquid phase product is determined.

[0072] Post-heat resistance activity test: After determining the high-temperature selectivity, the atmosphere was switched to a reducing atmosphere, the pressure was reduced to 0.1 MPa, the reaction temperature was increased to 450℃, and the space velocity was reduced to 3000 h⁻¹. -1 After heat treatment for 10 hours, the conditions were restored to the above-mentioned activity test conditions, and the CO conversion rate and CH3OH space-time yield were measured after heat resistance.

[0073] The catalysts of Examples 1-7 and Comparative Examples 1-6 were evaluated for their activity before and after heat resistance using the above test methods. The results are shown in Table 1. The higher the CH3OH space-time yield of the catalyst after heat resistance, the higher the stability of the catalyst. Using the impurity content of Comparative Sample 6 as a baseline, the impurity content of other samples was divided by the corresponding impurity content of Comparative Sample 6 and multiplied by the baseline value to obtain the relative values ​​of the impurity content of each sample. This provides a direct reflection of the difference in impurity content between different samples. The results are shown in Table 2.

[0074] Table 1. Catalyst activity data before and after heat resistance

[0075]

[0076] Table 2 High-temperature selectivity of catalysts

[0077]

[0078]

[0079] As shown in Table 1, the catalyst samples 1-7 prepared using the present invention exhibit better fresh activity and activity after heat resistance than the comparative samples 1-3. Combined with Table 2, it can be seen that although the present invention improves the low-temperature activity and stability of the catalyst, its high-temperature selectivity is not reduced. Compared with comparative sample 4, sample 1 shows that Zr... 4+When added to salt solution B for precipitation, it reduces the stability and high-temperature selectivity of the catalyst; compared with control sample 5, sample 1 showed that adding Zr in solution A reduced the catalyst's stability and high-temperature selectivity. 4+ Replace with Mg 2+ Precipitation reduces the stability and high-temperature selectivity of the catalyst, indicating that Zr... 4+ Superior to Mg 2+ The sample was added to salt solution A for precipitation. Compared to control sample 6, sample 1 showed that solution A did not contain Zr. 4+ Precipitation reduces the catalyst's stability and high-temperature selectivity; therefore, Zr... 4+ Superior to Mg 2+ Zr is used to precipitate the precipitate in solution A. 4+ It is more suitable to add it to solution A for precipitation.

[0080] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A method for preparing a methanol synthesis catalyst with a precipitation process stability, characterized in that: Includes the following steps: Step 1: Dissolve zirconium nitrate, zinc nitrate, and aluminum nitrate in water to form zirconium-zinc-aluminum mixed salt solution A; dissolve zinc nitrate, aluminum nitrate, and copper nitrate in water to form copper-zinc-aluminum mixed salt solution B; dissolve sodium carbonate in water to form alkaline solutions C and D; add a small amount of alkaline solution C to deionized water to form solution E. Step 2: Using salt solution A, alkaline solution C, and solution E, precipitate 1 is formed, and then precipitate 1 is aged; Step 3: After aging is complete, filter and wash precipitate 1, and add precipitate 1 to mixed solution B to form a highly dispersed suspension slurry F; Step 4: Use suspension slurry F and alkaline solution D to carry out an emulsification reaction to form precipitate 2, and then age precipitate 2; Step 5: After the aging of precipitate 2 is complete, filter and wash precipitate 2, dry the filter cake obtained by filtration and calcine it, add graphite to the obtained calcined product, mix it evenly and shape it to obtain methanol synthesis catalyst. The salt solution A and the alkali solution C are introduced into the reaction in the form of a spray. Specifically, the salt solution A and the alkali solution C are simultaneously atomized and sprayed downwards from the top of the reaction vessel. The fine droplets formed by the salt solution A and the alkali solution C fall into the bottom of the reaction vessel and react to form precipitate 1. Zn in salt solution A in step 1 2+ The molar amount of Zn in salt solution A and salt solution B accounts for a certain percentage of the total Zn content. 2+ 10%~20%; Al in salt solution A in step 1 3+ The molar amount of Al in salt solution A and salt solution B accounts for a certain percentage of the total Al content. 3+ More than 90%; In step 2, when precipitate 1 is formed, the total amount of metal cations per unit volume is kept constant; In step 2, while precipitate 1 is being formed, precipitate 1 is transferred to another container with stirring and temperature control. The liquid level in the reactor is kept constant, and the pH value of precipitate 1 transferred to the other container with stirring and temperature control is kept the same as that of solution E.

2. The method for preparing a precipitation-stable methanol synthesis catalyst according to claim 1, characterized in that: The aging temperature described in steps 2 and 4 is 60~80℃, and stirring is continued at this temperature for 1~3 h.

3. The method for preparing a precipitation-stable methanol synthesis catalyst according to claim 2, characterized in that: The aging temperature described in steps 2 and 4 is 70°C, and stirring is continued at this temperature for 2 hours.

4. The method for preparing a precipitation-stable methanol synthesis catalyst according to claim 1, characterized in that: The roasting is carried out at 300~400℃ for 3~5 hours.

5. The method for preparing a precipitation-stable methanol synthesis catalyst according to claim 4, characterized in that: The roasting was carried out at 350°C for 4 hours.

6. The methanol synthesis catalyst prepared by the method for preparing a precipitation-stable methanol synthesis catalyst according to any one of claims 1-5, characterized in that: The catalyst includes graphite, which accounts for 1-3% of the total mass of the catalyst. Excluding graphite, the remaining components, in terms of the sum of their mass percentages of 100%, include CuO 55-60%, ZnO 18-23%, Al2O3 20-25%, and ZrO2 0.5-3%.

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