Preparation method of high-selectivity and high-stability methanol synthesis catalyst

Abstract

The present application relates to the technical field of catalyst production, in particular to a preparation method of a high-selectivity and high-stability methanol synthesis catalyst, 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; 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, then using the salt solution B, the alkali solution D and the precipitate 1 to react to form a precipitate 2, then heating the precipitate 2, and aging the precipitate 2; step 3: after aging, filtering and washing the precipitate 2, drying the filter cake obtained by filtering, and then calcining and molding to obtain the methanol synthesis catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst production technology, and specifically to a method for preparing a highly selective and highly stable methanol synthesis catalyst. 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.

[0003] Currently, my country's new methanol plants are trending towards large-scale operations, with the vast majority being 1 million tons / year or more. In these plants, the average catalyst bed temperature consistently exceeds 280℃, with some hotspots surpassing 300℃. Preliminary experiments have shown that when operating temperatures exceed 280℃, the content of liquid-phase byproducts increases dramatically, not only increasing the distillation load but also negatively impacting product quality and feedstock utilization. Therefore, methanol synthesis catalysts must possess excellent thermal stability and high-temperature selectivity. Previous experiments have also indicated that while catalysts exhibit excellent low-temperature activity, their high-temperature selectivity is poor. Therefore, there is an urgent need to develop a methanol synthesis catalyst that balances low-temperature activity, thermal stability, and high-temperature selectivity. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a highly selective and stable methanol synthesis catalyst, which solves the technical problems in the prior art, such as low heat exchange efficiency of the liquid in the reactor, uneven heat distribution, slow temperature adjustment and control, low product yield, and difficulty in achieving automation.

[0005] This invention discloses a method for preparing a highly selective and stable methanol synthesis catalyst, 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. Then, salt solution B, alkaline solution D and precipitate 1 react to form precipitate 2. Next, precipitate 2 is heated to age it.

[0008] Step 3: After aging is complete, filter and wash the precipitate 2, and dry the resulting filter cake;

[0009] Step 4: Calcine the dried product, add graphite to the calcined product, mix evenly and shape to obtain the methanol synthesis catalyst.

[0010] Furthermore, the salt solution A and the alkaline solution C are introduced into the reaction via spray.

[0011] 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%.

[0012] 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%.

[0013] Furthermore, the pH value of the deionized water E mentioned in step 1 is 6.5~8.0, preferably 7.2.

[0014] Furthermore, in step 2, the temperature is preheated to 60-80°C, preferably 70°C.

[0015] 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.

[0016] 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.

[0017] Furthermore, in step 2, after the salt solution A is completely sprayed in, stop spraying the alkali solution C and deionized water. After the precipitate 1 has completely entered the reaction container, continue stirring for 30 min to 120 min. After stirring is completed, cool down, preferably stirring for 80 min.

[0018] Furthermore, the precipitate 2 formed in step 2 enters a container with stirring and temperature control through a reaction extension tube, and the pH value of the precipitate 2 is controlled to be the same as that of deionized water E.

[0019] Furthermore, in step 2, the salt solution B and precipitate 1 are added simultaneously. After the salt solution B is completely pumped in, the pumping of the alkaline solution D is stopped.

[0020] Furthermore, the aging temperature is 60~80℃, preferably 70℃, and stirring is continued at this temperature for 1~3 hours, preferably 2 hours.

[0021] Furthermore, the calcination is carried out at 300~400℃ for 3~5 hours, preferably at 350℃ for 4 hours.

[0022] Furthermore, the graphite accounts for 2% of the total mass of the catalyst.

[0023] A high-temperature selective methanol synthesis catalyst 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% ZrO.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. 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 less volatile, which is beneficial to the stability of the catalyst precursor structure and ultimately helps to improve the stability of the catalyst.

[0026] 2. Salt solution B, alkaline solution D and precipitate 1 are emulsified to generate precipitate 2. In this process, the precipitate generated by the reaction of salt solution B and alkaline solution D is mixed more evenly with precipitate 1, thus making precipitate 2 more uniform. This is beneficial to the stability of the catalyst precursor structure and ultimately helps to improve the stability and low-temperature activity of the catalyst.

[0027] 3. The present invention involves a two-step precipitation process. The first step uses a mixed salt solution of zirconium, zinc, and aluminum, replacing the magnesium used in the traditional process with zirconium, forming zirconium and zinc modified alumina. Combined with the method of the present invention, this effectively improves the high-temperature selectivity of the catalyst. 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 highly selective and stable methanol synthesis catalyst, 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 750 ml 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 1380 ml to form salt solution B; dissolve 107.06g NaCO3 in deionized water and bring the volume to 1000 ml to form the alkaline solution C required for precipitation; dissolve 214.12g NaCO3 in deionized water and bring the volume to 2000 ml to form the alkaline solution D required for precipitation.

[0032] Preheat salt solution A, salt solution B, and alkali solution C to 70°C. Add an appropriate amount of deionized water E, whose pH value is adjusted to 7.2 by alkali solution C, into the reactor. Start stirring. Then, simultaneously atomize and spray salt solution A and alkali solution C from the top of the reactor downwards to form precipitate 1.

[0033] After a portion of salt solution A is consumed, deionized water at the same temperature as salt solution A is atomized and sprayed downwards from the top of the reactor. The flow rate of the sprayed deionized water is controlled to keep the total amount of metal cations per unit volume constant. At the same time, 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 is controlled to be the same as that of deionized water E, and the temperature is the same as the preheating temperature. After salt solution A is completely sprayed in, the spraying of alkali solution C and deionized water is stopped. After precipitate 1 has completely entered the container, the constant temperature stirring is continued for 80 minutes. After stirring is completed, the temperature is lowered, and salt solution B, alkali solution D and precipitate 1 are simultaneously atomized and sprayed downwards from the top of the reactor, which has been pre-stirred and contains an appropriate amount of deionized water E, to form precipitate 2.

[0034] After a portion of the salt solution B is consumed, deionized water is atomized and sprayed downwards from the top of the reactor. The flow rate of the sprayed deionized water is controlled to keep the total amount of metal cations per unit volume constant. At the same time, precipitate 2 is transferred to another container with stirring and temperature control. The liquid level in the reactor is kept constant, and precipitate 1 and salt solution B are completed simultaneously. The pH value of precipitate 2 is controlled to be the same as that of deionized water E. After salt solution B is completely sprayed in, the spraying of alkaline solution D and deionized water is stopped. After precipitate 2 has completely entered the container, the temperature of precipitate 2 is raised to 70°C. Stirring and aging are continued at this temperature for 2 hours. After aging, precipitate 2 is filtered and washed. The filter cake obtained from filtration is dried and calcined at 350°C for 4 hours. 2% graphite by mass is added to the calcined product. After mixing and molding, the methanol synthesis catalyst is obtained and numbered as sample 1.

[0035] Example 2

[0036] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst is modified from Example 1 by dissolving 25.48 g Zn(NO3)2·6H2O, 10.44 g Zr(NO3)4·5H2O and 222.98 g Al(NO3)3·9H2O in deionized water and making up to 700 ml to form salt solution A, and dissolving 253.12 g Cu(NO3)2·3H2O and 101.9 g Zn(NO3)2·6H2O in deionized water and making up to 1380 ml to form salt solution B. The methanol synthesis catalyst sample obtained by this method is numbered Sample 2.

[0037] Example 3

[0038] In this embodiment, a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst is described. The only difference from Example 1 is that salt solution A consists of 9.97 g Zn(NO3)2·6H2O, 10.44 g Zr(NO3)4·5H2O, and 222.98 g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 645 ml; and salt solution B consists of 276.13 g Cu(NO3)2·3H2O and 89.72 g Zn(NO3)2·6H2O dissolved in deionized water and diluted to a volume of 1430 ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 3.

[0039] Example 4

[0040] In this embodiment, a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst is described. The only difference from Example 1 is that salt solution A consists of 19.94 g Zn(NO3)2·6H2O, 15.67 g Zr(NO3)4·5H2O, and 240.82 g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 740 ml; salt solution B consists of 253.12 g Cu(NO3)2·3H2O, 79.75 g Zn(NO3)2·6H2O, and 26.76 g Al(NO3)3·9H2O dissolved in deionized water and diluted to a volume of 1380 ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 4.

[0041] Example 5

[0042] In this embodiment, a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst 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 640 ml; 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 1460 ml. The methanol synthesis catalyst sample obtained by this method is designated as Sample 5.

[0043] Example 6

[0044] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst is modified from Example 1 by controlling the preheating temperature to 60°C, the pH value of deionized water E to 6.5, the constant temperature stirring time of precipitate 1 to 120 min, the constant temperature stirring of precipitate 2 to 60°C for 3 h, the dried material to be calcined at 300°C for 5 h, and the addition of 1% graphite by mass to the calcined material. The methanol synthesis catalyst sample obtained by this method is numbered Sample 6.

[0045] Example 7

[0046] In this embodiment, which is a preferred embodiment of the present invention, a method for preparing a highly selective and highly stable methanol synthesis catalyst is modified from Example 1 by controlling the preheating temperature to 80°C, the pH value of deionized water E to 8.0, the constant temperature stirring time of precipitate 1 to 30 min, the constant temperature stirring of precipitate 2 to 80°C for 1 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.

[0047] Comparative Example 1

[0048] To highlight the beneficial effects of the present invention, Comparative Example 1 is provided, which compares the methanol catalyst prepared in Examples 1-7 of the present invention with the catalyst prepared by conventional spray 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 1 is as follows:

[0049] 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 750 ml 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 1380 ml to form salt solution B; dissolve 321.18g NaCO3 in deionized water and bring the volume to 3000 ml. ml, forming the alkaline solution C required for precipitation; preheat salt solution A, salt solution B, and alkaline solution C to 70℃, add an appropriate amount of deionized water to the reactor, start stirring, then simultaneously spray salt solution A and alkaline solution C from the top of the reactor in an anti-collision atomization manner. The fine droplets formed by salt solution A and alkaline solution C directly collide to form precipitate 1, which falls to the bottom of the reactor. Control the pH value of precipitate 1 to 7.2 and the temperature to 70℃. After salt solution A is completely sprayed in, stop spraying alkaline solution C, and continue stirring at a constant temperature for 80 min. Then, spray salt solution B and alkaline solution C from the top of the reactor in an anti-collision atomization manner. The fine droplets formed by salt solution B and alkaline solution C directly collide to form precipitate, which falls to the bottom of the reactor and mixes with precipitate 1 to form precipitate 2. Control the pH value of precipitate 2 to 7.2 and the temperature to 70℃. After salt solution B is completely sprayed in, stop spraying alkaline solution C, and continue stirring and aging at this temperature for 2 minutes. h, after aging is complete, filter and wash precipitate 2, dry the filter cake obtained by filtration, calcine the dried product at 350℃ for 4 h, add 2% of graphite by mass to the calcined product, mix evenly and form to obtain methanol synthesis catalyst, numbered as control sample 1.

[0050] Comparative Example 2

[0051] To highlight the beneficial effects of the present invention, Comparative Example 2 is provided, which compares the methanol catalyst prepared in Examples 1-7 of the present invention with the catalyst prepared by 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:

[0052] 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 750 ml 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 1380 ml to form salt solution B; dissolve 321.18g NaCO3 in deionized water and bring the volume to 3000 ml. ml, forming the alkaline solution C required for precipitation, preheat salt solution A, salt solution B and alkaline solution C to 70℃, add an appropriate amount of deionized water to the reactor, start stirring, then pump salt solution A and alkaline solution C into the reactor simultaneously. Salt solution A and alkaline solution C react at the bottom of the reactor to form precipitate 1. Control the pH of precipitate 1 to 7.2 and the temperature to 70℃. After salt solution A is completely pumped in, stop pumping alkaline solution C and continue stirring at a constant temperature for 80 min. Then pump salt solution B and alkaline solution C into the reactor. Salt solution B and alkaline solution C fall to the bottom of the reactor and mix with precipitate 1 to form precipitate 2. Control the pH of precipitate 2 to 7.2 and the temperature to 70℃. After salt solution B is completely pumped in, stop pumping alkaline solution C and continue stirring and aging at this temperature for 2 h. After aging, filter and wash precipitate 2, dry the filter cake obtained by filtration, and calcine the dried product at 350℃ for 4 hours. h, 2% graphite by mass was added to the obtained calcined product, and after mixing and molding, a methanol synthesis catalyst was obtained, which was numbered as control sample 2.

[0053] Comparative Example 3

[0054] To highlight the beneficial effects of the present invention, Comparative Example 3 is provided, which compares the methanol catalyst prepared in Examples 1-7 of the present invention with the catalyst prepared by three-stage emulsification, so as to intuitively reflect the effect of the method of the present invention on the methanol catalyst. The preparation method of Comparative Example 3 is as follows:

[0055] 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 750 ml 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 1380 ml to form salt solution B; dissolve 107.06g NaCO3 in deionized water and bring the volume to 1000 ml to form the alkaline solution C required for precipitation; dissolve 214.12g NaCO3 in deionized water and bring the volume to 2000 ml to form the alkaline solution D required for precipitation; preheat salt solutions A, B, C, and D to 70°C. After reaching a certain temperature, salt solution A and alkali solution C were atomized and sprayed into the vicinity of the first rotor of the three-stage emulsifying reactor through the inlet, forming precipitate 1. At the same time, salt solution B and alkali solution D were atomized and sprayed into the vicinity of the second rotor of the three-stage emulsifying reactor through another inlet, forming precipitate 2. Precipitate 2 was further reacted and mixed near the third rotor of the three-stage emulsifying reactor before flowing out of the three-stage emulsifying reactor, forming precipitate 3. The pH of precipitate 3 was controlled to be 7.2 when flowing out of the three-stage emulsifying reactor. Precipitate 3 was further stirred and aged at 70℃ for 120 min. After aging, precipitate 3 was filtered and washed, and the filter cake obtained was dried. The dried product was calcined at 350℃ for 4 h. 2% of graphite by mass was added to the calcined product, and after uniform mixing and molding, methanol synthesis catalyst was obtained, which was numbered as control sample 3.

[0056] Comparative Example 4

[0057] To highlight the beneficial effects of the present invention, Comparative Example 4 is provided, which compares the methanol catalyst prepared in Examples 1-7 of the present invention with the catalyst prepared using three emulsifiers, to intuitively reflect the effect of the method of the present invention on the methanol catalyst. The preparation method of Comparative Example 4 is as follows:

[0058] 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 750 ml 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 1380 ml to form salt solution B; dissolve 107.06g NaCO3 in deionized water and bring the volume to 1000 ml to form the alkaline solution C required for precipitation; dissolve 214.12g NaCO3 in deionized water and bring the volume to 2000 ml. ml, the alkaline solution D required to form the precipitate is prepared. Salt solutions A and B, as well as alkaline solutions C and D, are preheated. After the preheating temperature reaches the reaction temperature of 70℃, salt solution A and alkaline solution C are fed into the first emulsification reactor in parallel to react and obtain precipitate 1. The pH value of precipitate 1 is controlled at 7.2. Precipitate 1 is fed into the third emulsification reactor through the reaction extension tube. At the same time, salt solution B and alkaline solution D are fed into the second emulsification reactor in parallel to react and obtain precipitate 2. The pH value of precipitate 2 is controlled at 7.2. Precipitate 2 is fed into the third emulsification reactor through the reaction extension tube. Precipitates 1 and 2 continue to emulsify and mix in the third emulsification reactor to obtain precipitate 3. After precipitate 3 flows out of emulsification reactor 3, it is stirred and aged at 70℃ for 120 min. After aging, precipitate 3 is filtered and washed. The filter cake obtained from filtration is dried. The dried product is calcined at 350℃ for 4 minutes. h, 2% graphite by mass was added to the obtained calcined product, and after mixing and molding, a methanol synthesis catalyst was obtained, which was numbered as control sample 4.

[0059] Comparative Example 5

[0060] To highlight the beneficial effects of the present invention, Comparative Example 5 is provided, which compares the methanol catalyst prepared in Examples 1-7 of the present invention with a catalyst prepared using a combination of conventional spray and emulsification reactors. This visually demonstrates the effect of the method of the present invention on the methanol catalyst. The preparation method of Comparative Example 5 is as follows:

[0061] 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 750 ml 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 1380 ml to form salt solution B; dissolve 321.18g NaCO3 in deionized water and bring the volume to 3000 ml. ml, forming the alkali solution C required for precipitation; preheat salt solution A, salt solution B, and alkali solution C to 70℃, add an appropriate amount of deionized water to the reactor, start stirring, then simultaneously spray salt solution A and alkali solution C from the top of the reactor in an opposing atomized manner. The fine droplets formed by salt solution A and alkali solution C directly collide to form precipitate 1, which falls to the bottom of the reactor. Control the pH value of precipitate 1 to 7.2 and the temperature to 70℃. After salt solution A is completely sprayed in, stop spraying alkali solution C, and continue constant temperature stirring for 80 min. Then, feed salt solution B and alkali solution D into the emulsification reactor in parallel to react and obtain precipitate 2. Precipitate 2 enters the reactor containing precipitate 1 through the reaction extension tube. Control the pH value of precipitate 2 to 7.2. Precipitate 1 and precipitate 2 are mixed in the reactor to obtain precipitate 3. After salt solution B is consumed, stop adding alkali solution D, and continue stirring and aging precipitate 3 at 70℃ for 120 minutes. After aging for 3 minutes, the precipitate 3 was filtered and washed. The filter cake was dried and the dried product was calcined at 350°C for 4 hours. 2% of graphite was added to the calcined product. After mixing and molding, the methanol synthesis catalyst was obtained and numbered as control sample 5.

[0062] Comparative Example 6

[0063] To highlight Zr in this invention 4+ The beneficial effect of adding it during the first precipitation step is provided in Comparative Example 6, which involves mixing the methanol catalyst prepared in Examples 1-7 of this invention with Zr. 4+ The catalyst was prepared in the second step for comparison, visually reflecting the effect of the method of the present invention on methanol catalysts. The preparation method of Comparative Example 6 is as follows:

[0064] The preparation method is the same as in Example 1, except that salt solution A is formed 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 750 ml; salt solution B is formed 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 1380 ml. The methanol synthesis catalyst sample obtained by this method is numbered as Comparative Sample 6.

[0065] Comparative Example 7

[0066] To highlight Zr in this invention 4+ The added beneficial effects will be Zr 4+ Replace with Mg 2+ Comparative Example 7 is provided, in which the methanol catalyst prepared in Examples 1-7 of this invention is reacted with Mg. 2+ The catalysts prepared in the same manner were compared to those prepared in the present invention to visually demonstrate the effect of the method of the present invention on methanol catalysts. The preparation method of Comparative Example 7 is as follows:

[0067] 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 7.

[0068] Comparative Example 8

[0069] 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 8 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 8 is as follows: The catalyst prepared in Comparative Example 8 is compared with that prepared in Comparative Example 8 to visually demonstrate the effect of the method of the present invention on methanol catalysts.

[0070] 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 8.

[0071] Example: Catalyst evaluation method:

[0072] This embodiment provides evaluation methods for the catalysts of Examples 1-7 and Comparative Examples 1-8, as detailed below:

[0073] Sample particle size: 16-40 mesh. Filling volume: 4 mL (2 mL catalyst + 2 mL inert support).

[0074] 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℃.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] The catalysts of Examples 1-7 and Comparative Examples 1-8 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 8 as a baseline, the impurity content of other samples was divided by the corresponding impurity content of Comparative Sample 8 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.

[0079] Table 1. Catalyst activity data before and after heat resistance

[0080]

[0081] Table 2. High-temperature selectivity of catalysts

[0082]

[0083] As shown in Table 1, the catalyst samples 1-7 prepared using this invention exhibit better fresh activity and activity after heat resistance than the comparative samples 1-5. Combined with Table 2, it can be seen that although this invention improves the low-temperature activity and stability of the catalyst, the high-temperature selectivity is not reduced. Compared with comparative sample 6, it can be observed that Zr... 4+When Zr is added to salt solution B for precipitation, although the fresh activity does not decrease, the stability and high-temperature selectivity of the catalyst are reduced. Compared with control sample 7, it can be seen that adding Zr to solution A... 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. Comparing sample 1 and control sample 8, it can be observed that solution A did not contain Zr. 4+ Precipitation reduces the stability and high-temperature selectivity of the catalyst; therefore, it can be concluded that 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.

[0084] 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 highly selective and highly stable methanol synthesis catalyst, 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 deionized water E; Step 2: Using salt solution A, alkaline solution C and deionized water E, precipitate 1 is formed. Then, salt solution B, alkaline solution D and precipitate 1 react to form precipitate 2. Next, precipitate 2 is heated to age it. Step 3: After aging is complete, filter and wash the precipitate 2, and dry the resulting filter cake; Step 4: Calcine the dried product, add graphite to the calcined product, mix evenly and shape to obtain the methanol synthesis catalyst; 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. The salt solution A and the alkaline solution C are introduced into the reaction via spray; 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%.

2. The method for preparing a highly selective and highly stable methanol synthesis catalyst according to claim 1, characterized in that: The pH value of the deionized water E mentioned in step 1 is 6.5~8.

0.

3. The method for preparing a highly selective and highly stable methanol synthesis catalyst according to claim 1, characterized in that: In step 2, when precipitate 1 is formed, the total amount of metal cations per unit volume is kept constant.

4. The method for preparing a highly selective and highly stable methanol synthesis catalyst according to claim 1, characterized in that: The aging temperature is 60~80℃, and stirring continues at this temperature for 1~3 hours.

5. The method for preparing a highly selective and highly stable methanol synthesis catalyst according to claim 4, characterized in that: The aging temperature is 70°C, and stirring continues at this temperature for 2 hours.

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

7. The method for preparing a highly selective and highly stable methanol synthesis catalyst according to claim 6, characterized in that: The roasting was carried out at 350°C for 4 hours.

8. A high-temperature selective methanol synthesis catalyst, characterized in that: The catalyst is prepared according to any one of claims 1-7, comprising graphite, wherein the graphite accounts for 1-3% of the total mass of the catalyst, and excluding the graphite, the remaining components, based on a total mass percentage of 100%, include CuO 55-60%, ZnO 18-23%, Al2O3 20-25%, and ZrO 20.5%-3%.

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