Methanol synthesis catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of methanol synthesis catalysts, and particularly relates to a methanol synthesis catalyst and a preparation method and application thereof. The preparation method comprises the following steps: (1) carrying out a first precipitation reaction on an Al source and a first precipitant to obtain a first turbid liquid; (2) contacting the first turbid liquid with a Cu source, a Zn source and a second precipitant to carry out coprecipitation reaction to obtain a second turbid liquid; and (3) adding a seed crystal inducer into the second turbid liquid, heating and aging, and filtering, washing, drying and roasting the obtained product to obtain the methanol synthesis catalyst, wherein the first precipitant and the second precipitant are the same or different and are independently selected from carbonate and / or bicarbonate. The precursor prepared by the method is small in crystal grain and short in crystallization time, and the obtained catalyst has better activity and thermal stability.

Description

Technical Field

[0001] The invention belongs to the field of methanol synthesis catalysts, and in particular relates to a methanol synthesis catalyst and a preparation method and application thereof. Background Art

[0002] Industrial methanol is mainly synthesized by catalytic synthesis of synthesis gas, and Cu / ZnO / Al is mainly used in the synthesis process. 2 O 3 Catalyst. In Cu-ZnO-A1 2 O 3 In the catalyst, Cu-ZnO is the main active component. The copper and zinc elements work synergistically to form the active center of the catalytic reaction. Improving its precursor structure is beneficial to improving the catalyst activity and thermal stability.

[0003] Cu-ZnO-A1 2 O 3 During the catalyst preparation process, although low-temperature precipitation of copper and zinc elements is beneficial to the formation of small-grain precursors, there is a problem of too long crystallization time.

[0004] In addition, after the precipitation is completed, the properties of the precipitate are not completely fixed, and a process of particle growth and crystal formation is required. After the formation of the crystal nucleus, the solute is continuously deposited on the crystal nucleus, and the grains continue to grow. In this process, the molecules may not have time to arrange in an orderly manner, thus generating amorphous particles. The crystallization process is the process of the precipitate gradually transforming from amorphous particles to orderly arranged crystals.

[0005] Patent document CN112169800A discloses a methanol synthesis catalyst and a preparation method thereof, which performs precipitation reaction under ultrasound to solve the problems of slow molecular interaction and long crystallization time. However, the ultrasonic precipitation process still has technical and cost problems in industrial application.

[0006] Patent document CN109420501A discloses a method for preparing a catalyst for synthesizing methanol, using (Zn, Cu) 5 (CO 3 ) 2 (OH) 6 Adding it into the system as a crystallizing agent shortens the crystallization time of the precursor; however, the problem is that (Zn, Cu) 5 (CO 3 ) 2 (OH) 6 The crystallization agent is not an effective precursor of the active component. At the same time, adding the crystallization agent after precipitation at a higher temperature will promote the increase of the precursor grain size, which will have an adverse effect on the catalyst performance.

[0007] Patent document CN103480377A discloses a method for preparing a copper-based methanol synthesis catalyst, wherein a Cu-Zn binary matrix slurry is prepared by using a seed Cu 2 CO 3 (OH) 2 The induced precipitation method reduces the aging time of the parent slurry. 2 CO 3 (OH) 2 The crystallization agent is not an effective precursor of the active component. Its addition will lead to a decrease in the proportion of the effective active component precursor, which will have an adverse effect on the catalyst performance.

[0008] In view of this, it is worthwhile to continue exploring how to obtain catalysts with better activity and thermal stability. Summary of the invention

[0009] In view of the problems existing in the prior art for preparing methanol synthesis catalysts, a methanol synthesis catalyst and a preparation method and application thereof are provided. The synergistic effect of low-temperature precipitation, high-temperature aging and the addition of a seed crystal inducer is adopted to make the precursor of the active component of the catalyst have small grains and a short crystallization time. The obtained catalyst has better activity and thermal stability and can also reduce production costs.

[0010] In order to achieve the above object, the present invention provides the following technical solutions:

[0011] In a first aspect, a method for preparing a methanol synthesis catalyst is provided, comprising the following steps:

[0012] (1) contacting an Al source with a first precipitant to perform a first precipitation reaction to obtain a first suspension;

[0013] (2) contacting the first suspension with a Cu source, a Zn source and a second precipitant to perform a coprecipitation reaction to obtain a second suspension;

[0014] (3) adding a seed crystal inducing agent to the second suspension and heating the suspension for aging, filtering, washing, drying and calcining the obtained product to obtain a methanol synthesis catalyst;

[0015] Wherein, the first precipitant and the second precipitant are the same or different, and are independently selected from carbonates and / or bicarbonates.

[0016] In some embodiments, the first precipitant and the second precipitant are each independently selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

[0017] In some embodiments, the Al source is a water-soluble compound containing Al element, preferably selected from Al(NO 3 ) 3、Al 2 (SO 4 ) 3 and AlCl 3 At least one of .

[0018] In some embodiments, the Cu source is a water-soluble compound containing the Cu element, preferably selected from Cu(NO 3 ) 2 ,CuSO 4 and CuCl 2 At least one of .

[0019] In some embodiments, the Zn source is a water-soluble compound containing Zn element, preferably selected from Zn(NO 3 ) 2 、ZnSO 4 and ZnCl 2 At least one of .

[0020] In some embodiments, in step (1), the conditions of the first precipitation reaction include: a temperature of 5-40°C (e.g., 6°C, 8°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 38°C), preferably 5-30°C; a system pH of 5-10 (e.g., 5.5, 6, 7, 8, 9, 9.5), preferably 6-9.

[0021] The reaction time of the first reaction in step (1) can be adjusted according to the amount of the reaction raw materials used. Generally, if the amount of the reaction raw materials used is large, the reaction time can be appropriately extended.

[0022] In step (1), the Al source and the first precipitant are dripped into a co-precipitation container. During the dripping process, the amount of the first precipitant added can be controlled to ensure that the endpoint pH value of the mixture I (i.e., the mixture of the Al source and the first precipitant) system is within the range of 5-10, for example.

[0023] In some embodiments, in step (2), the conditions of the coprecipitation reaction include: a temperature of 5-40°C (e.g., 6°C, 8°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 38°C), preferably 5-30°C; a system pH of 6-9 (e.g., 6.5, 7, 7.5, 8, 8.5), preferably 7-8.

[0024] The reaction time of the co-precipitation reaction in step (2) can be adjusted according to the amount of the reaction raw materials used. Generally, when the amount of the reaction raw materials used is large, the reaction time can be appropriately extended.

[0025] In step (2), the Cu source, the Zn source and the second precipitant are added to the first suspension at the same time. During the addition, the amount of the second precipitant added can be controlled to ensure that the endpoint pH of the mixture II (a mixture of the first suspension, the Cu source, the Zn source and the second precipitant) system is, for example, 7-8.

[0026] In some embodiments, in step (3), the conditions of the aging reaction include: temperature of 40-90°C (e.g., 50°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C), preferably 65-90°C; time of 1-12h (e.g., 2.5h, 4h, 5h, 8h, 10h), preferably 2-8h.

[0027] In some embodiments, in step (3), the seed inducing agent is (Zn, Cu) 5 (CO 3 ) 2 (OH) 6 .

[0028] In some embodiments, the amount of the seed inducer is calculated based on the divalent metal ions contained therein, and the ratio of the molar amount of divalent metal ions in the seed inducer to the total molar amount of copper and zinc ions in the system is 0.5:10 to 5:10 (for example, 0.55:10, 0.6:10, 0.8:10, 1:10, 1.2:10, 1.5:10, 1.8:10, 2:10, 3:10, 4:10), preferably 0.5:10 to 2:10.

[0029] In some embodiments, in step (3), the drying conditions include: a temperature of 90-120°C (e.g., 100°C, 110°C, 115°C) and a time of 6-18h (e.g., 7h, 8h, 10h, 12h, 15h).

[0030] In some embodiments, in step (3), the calcination conditions include: a temperature of 300-390°C (e.g., 310°C, 320°C, 340°C, 350°C, 380°C), and a time of 2-18h (e.g., 3h, 4h, 5h, 8h, 10h, 12h, 15h).

[0031] In some embodiments, the molar ratio of the Cu source, Zn source and Al source, calculated on an element basis, is (40-65):(20-40):(3-30), for example, 40:35:25, 40:40:20, 50:40:10, 50:35:15, 60:30:10, 60:25:15, 45:40:15, 45:35:20, 50:30:20, 65:30:5, 65:20:15, 62:30:8, preferably (45-65):(20-35):(8-20).

[0032] In a second aspect, a methanol synthesis catalyst prepared by the preparation method as described above is provided, wherein the methanol synthesis catalyst comprises the following components in the following amounts based on the total weight of the catalyst:

[0033] Al 2 O 3 1.5wt%-25wt% (e.g., 2wt%, 4wt%, 5wt%, 6wt%, 8wt%, 10wt%, 15wt%, 18wt%, 20wt%) of aluminum component, preferably 1.93wt%-21.44wt%,

[0034] 40wt%-70wt% (e.g., 41wt%, 43wt%, 45wt%, 50wt%, 55wt%, 60wt%, 62wt%, 65wt%) of copper component, preferably 42.67wt%-68.37wt%, calculated as CuO,

[0035] The zinc component is 20 wt% to 45 wt% (e.g., 22 wt%, 24 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 42 wt%), preferably 21.94 wt% to 43.66 wt%, calculated as ZnO.

[0036] In a third aspect, a methanol synthesis catalyst prepared by the preparation method described above or the use of the methanol synthesis catalyst described above is provided.

[0037] Herein, the application of the prepared catalyst in the catalytic synthesis of methanol from synthesis gas can be achieved by conventional means in the art, which will not be described in detail here.

[0038] The inventors have found that the formation and growth of active component precursor grains in methanol synthesis catalysts are closely related to precipitation temperature. Low-temperature precipitation is conducive to the formation of small grains, but is not conducive to the transformation of amorphous particles into orderly arranged crystals during the aging process, and the aging time will be greatly extended. In order to solve this technical obstacle, the present invention selects the temperature range of each precipitation reaction and the aging temperature range. Through the synergistic effect of low-temperature precipitation, high-temperature aging and the addition of seed inducers, "low-temperature precipitation" is conducive to the formation of small-sized precursor grains, which is conducive to increasing the copper specific surface area in the catalyst and thus improving the catalytic activity; at the same time, adding seed crystals during aging and raising the temperature (such as in the range of 70 to 90°C) can form small-sized active component precursor grains on the one hand, improve the performance of the catalyst, and on the other hand, shorten the aging time and reduce the production cost of the catalyst.

[0039] Compared with the prior art, the excellent effect of the technical solution of the present invention lies at least in that: the present invention adopts low-temperature precipitation, high-temperature aging and the addition of a seed crystal inducer for synergistic effect, the active component precursor in the prepared catalyst has small grains, and the precursor crystallization time is short, and the degree of copper-zinc substitution in the precursor structure is high, so that the obtained catalyst has a larger specific surface area, better catalytic activity and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The XRD schematic spectra of the catalysts prepared in Example 1 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0041] In order to understand the technical features and contents of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described here.

[0042] Unless otherwise specified, the experimental procedures used in the following examples are all conventional methods.

[0043] The raw materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0044] Embodiment 1:

[0045] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0046] The preparation method of a methanol synthesis catalyst comprises the following steps:

[0047] (1) First, use a peristaltic pump to mix the prepared aluminum salt solution with Na 2 CO 3 The aqueous solution was added dropwise to a water bath flask for reaction. The water bath temperature was 5°C. The addition process was accompanied by stirring. By adjusting the first precipitant (Na 2 CO 3 The dropping speed of the mixture I (aluminum salt solution and Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 8, and a first suspension is obtained;

[0048] (2) adding the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 The aqueous solution (second precipitant) was coprecipitated at a water bath temperature of 5°C. During the addition, the Na 2 CO 3 The dripping speed of the aqueous solution ensures that the endpoint pH value of the mixture II (a mixture of the first suspension, the copper-zinc salt mixed salt solution and the second precipitant) is 7.5, thereby obtaining a second suspension;

[0049] In this process, the molar ratio of Cu and Zn in the copper-zinc salt mixed salt solution and Al in the aluminum salt solution is 60:30:10;

[0050] (3) Adding a seed inducing agent (Cu, Zn) to the second suspension obtained in step (2) 2 CO 3 (OH) 2 , where (Cu, Zn) 2 CO 3 (OH) 2 The molar ratio of the divalent metal ions in the solution to the total divalent metal ions in the copper-zinc salt mixed salt solution is 0.5:10, and at the same time, the temperature of the system is raised to 65°C and an aging treatment is performed for 2 hours;

[0051] The obtained product was filtered and washed until the conductivity of the filtrate was less than 30 μs / cm, and the obtained filter residue was dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h. After that, the catalyst particles of 60 to 100 mesh were obtained through tableting, crushing and sieving.

[0052] Embodiment 2:

[0053] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0054] The preparation method of a methanol synthesis catalyst comprises the following steps:

[0055] (1) First, use a peristaltic pump to mix the prepared aluminum salt solution with Na 2 CO 3 The aqueous solution was added dropwise to a water bath flask for reaction. The water bath temperature was 30°C. The addition process was accompanied by stirring. By adjusting the first precipitant (Na 2 CO 3 The dropping speed of the mixture I (aluminum salt solution and Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 7, and a first suspension is obtained;

[0056] (2) adding the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 The aqueous solution (second precipitant) was coprecipitated at a water bath temperature of 30°C. During the addition, the Na 2 CO 3 The dripping speed of the aqueous solution ensures that the endpoint pH value of the mixture II (a mixture of the first suspension, the copper-zinc salt mixed salt solution and the second precipitant) is 7.5, thereby obtaining a second suspension;

[0057] In this process, the molar ratio of Cu and Zn in the copper-zinc salt mixed salt solution and Al in the aluminum salt solution is 60:30:10;

[0058] (3) Adding a seed inducing agent (Cu, Zn) to the second suspension obtained in step (2) 2 CO 3 (OH) 2 , where (Cu, Zn) 2 CO 3 (OH) 2 The molar ratio of the divalent metal ions in the solution to the total divalent metal ions in the copper-zinc salt mixed salt solution is 1:10, and at the same time, the temperature of the system is raised to 80°C and an aging treatment is performed for 2 hours;

[0059] The obtained product was filtered and washed until the conductivity of the filtrate was less than 30 μs / cm, and the obtained filter residue was dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h. After that, the catalyst particles of 60 to 100 mesh were obtained through tableting, crushing and sieving.

[0060] Embodiment 3:

[0061] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0062] The preparation method of the methanol synthesis catalyst is as described in Example 1, except that: in step (1), the water bath temperature is controlled to be 40° C., and the pH value of the system is controlled to be 6.5; and, in step (2), the water bath temperature is controlled to be 40° C., and the pH value of the system is controlled to be 7.5;

[0063] The remaining steps are the same as those in Example 1. Finally, catalyst particles with a size of 60 to 100 meshes are obtained.

[0064] Embodiment 4:

[0065] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0066] The preparation method of the methanol synthesis catalyst is similar to that of Example 1, except that: a seed inducer (Cu, Zn) is added in step (3). 2 CO 3 (OH) 2 , where (Cu, Zn) 2 CO 3 (OH) 2 The molar ratio of the divalent metal ions in the copper-zinc salt mixed salt solution to the total divalent metal ions in the copper-zinc salt mixed salt solution is 2:10;

[0067] The remaining steps are the same as those in Example 1. Finally, catalyst particles with a size of 60 to 100 meshes are obtained.

[0068] Embodiment 5:

[0069] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution.

[0070] The preparation method of the methanol synthesis catalyst is similar to that of Example 1, except that: in step (2), the molar ratio of Cu, Zn in the copper-zinc salt mixed salt solution and Al in the aluminum salt solution is controlled to be 48:22:30;

[0071] The remaining steps are the same as those in Example 1. Finally, catalyst particles with a size of 60 to 100 meshes are obtained.

[0072] Comparative Example 1:

[0073] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0074] The method for preparing the catalyst comprises the following steps:

[0075] (1) First, use a peristaltic pump to mix the prepared aluminum salt solution with Na 2 CO 3 The aqueous solution was added dropwise to a water bath flask for reaction at a temperature of 65°C. The addition process was accompanied by stirring. By adjusting the first precipitant Na 2 CO 3 The dripping speed of the aqueous solution controls the mixture I (aluminum salt solution and Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 8, and a first suspension is obtained;

[0076] (2) adding the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 The aqueous solution (second precipitant) was coprecipitated at a water bath temperature of 65°C. During the addition, the Na 2 CO 3 The dripping speed of the aqueous solution ensures that the mixture II (the first suspension, the copper-zinc salt mixed salt solution and the Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 7.5, and a second suspension is obtained;

[0077] In this process, the molar ratio of Cu and Zn in the copper-zinc salt mixed salt solution and Al in the aluminum salt solution is 60:30:10;

[0078] (3) The second suspension obtained in step (2) is aged at 70° C. for 2 h, and the obtained product is filtered and washed until the conductivity of the filtrate is less than 30 μs / cm. The obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h. After that, the catalyst particles of 60 to 100 mesh are obtained by tableting, crushing and sieving.

[0079] Comparative Example 2:

[0080] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution.

[0081] The method for preparing the catalyst comprises the following steps:

[0082] (1) First, use a peristaltic pump to mix the prepared aluminum salt solution with Na 2 CO 3 The aqueous solution was added dropwise to a water bath flask for reaction at a temperature of 65°C. The addition process was accompanied by stirring. By adjusting the first precipitant Na 2 CO 3 The dripping speed of the aqueous solution controls the mixture I (aluminum salt solution and Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 8, and a first suspension is obtained;

[0083] (2) adding the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 The aqueous solution (second precipitant) was coprecipitated at a water bath temperature of 65°C. During the addition, the Na 2 CO 3 The dripping speed of the aqueous solution ensures that the mixture II (the first suspension, the copper-zinc salt mixed salt solution and the Na 2 CO 3 The endpoint pH value of the mixture of the aqueous solution is 7.5, and a second suspension is obtained;

[0084] In this process, the molar ratio of Cu and Zn in the copper-zinc salt mixed salt solution and Al in the aluminum salt solution is 60:30:10;

[0085] (3) Adding a seed inducing agent (Cu, Zn) to the second suspension obtained in step (2) 2 CO 3 (OH) 2 , and among them, (Cu, Zn) 2 CO 3 (OH) 2 The molar ratio of the divalent metal ions in the solution to the total divalent metal ions in the copper-zinc salt mixed salt solution is 0.5:10; at the same time, the system is aged for 2 hours;

[0086] The obtained product was filtered and washed until the conductivity of the filtrate was less than 30 μs / cm, and the obtained filter residue was dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h. After that, the catalyst particles of 60 to 100 mesh were obtained through tableting, crushing and sieving.

[0087] Comparative Example 3:

[0088] The raw materials used are Cu(NO 3 ) 2 ·3H 2 O、Zn(NO 3 ) 2 6H 2 O、Al(NO 3 ) 3 9H 2 O and Na 2 CO 3 , prepare 1 mol / L copper-zinc salt mixed salt solution, 1 mol / L aluminum salt solution and 1 mol / L Na 2 CO 3 Aqueous solution (as the first precipitant and the second precipitant).

[0089] The steps for preparing the catalyst are as in Example 1, except that in step (3), no seed inducer (Cu, Zn) is added to the second suspension. 2 CO 3 (OH) 2 The remaining steps are the same as those in Example 1. The final catalyst particles are 60 to 100 meshes.

[0090] Table 1 Composition of the catalysts prepared in each embodiment and comparative example

[0091] serial number <![CDATA[Al 2 O 3 Content (wt%)]]> CuO content (wt%) ZnO content (wt%) Example 1 6.30 61.49 32.21 Example 2 6.04 62.16 31.80 Example 3 6.30 61.49 32.21 Example 4 5.56 62.48 31.96 Example 5 21.43 53.49 25.08 Comparative Example 1 6.60 61.79 31.61 Comparative Example 2 6.30 61.49 32.21 Comparative Example 3 6.60 61.79 31.61

[0092] The precursors prepared in Example 1 and Comparative Example 1 were subjected to X-ray diffraction analysis on a Bruker D8 X-ray diffractometer under the following conditions: 40 kV / 40 mA, using Cu K-ray The main signal peak positions of the copper-zinc coprecipitate are 14.637°, 17.467°, 24.075°, and 29.591°. The XRD results of the precursors prepared in Example 1 and Comparative Example 1 are shown in FIG. Figure 1 As shown, it can be seen that the crystal grains of the active component precursor in the catalyst prepared by the method of the present invention are small. At the same time, compared with the conventional preparation method, the method of the present invention can effectively promote the degree of copper-zinc substitution in the catalyst.

[0093] Catalyst performance evaluation

[0094] The catalyst performance evaluation experiment was conducted using a 16-channel micro multi-tube combined reaction device produced by HTE, Germany. The device evenly splits one channel of raw gas into 16 channels through a capillary splitting system and distributes them to 16 tubular reactors. The raw gas flow rate in each reaction tube is the same, and the components have good consistency. The experimental pressure is 4MPa, the reaction temperature is 230℃, the loading amount of the catalyst to be tested is 0.8g, and the space velocity is 8000h -1 The designed raw gas volume composition is: CO 13%, CO 2 1.2%, H 2 The raw gas is provided by Beijing Helium Gas Industry Co., Ltd. The particle size of each catalyst to be tested is 60-100 mesh, and quartz sand of the same particle size is mixed with the catalyst during filling. Among them, the No. 6 reaction tube is filled with quartz sand of the same particle size for online detection of the raw gas composition.

[0095] The initial activity test process of the catalyst is as follows: after the catalyst to be tested is reduced, the raw gas introduced reacts under the action of the catalyst, and after reacting at 230°C for 48 hours, the gas product (including methanol) after the reaction is obtained, and it is introduced into the gas chromatograph to analyze the composition of the gas product. Before the gas product is introduced into the gas chromatograph, it is heated by a heating belt to stabilize the temperature of the gas product at 120°C, and then introduced into the gas chromatograph. The gas product samples at the outlet of each reaction tube are sampled in turn by the GC analysis system and tested and analyzed for their composition. The activity test process of the catalyst after heat treatment is as follows: after the catalyst to be tested is reduced, the introduced raw gas reacts under the action of the catalyst, and after reacting at 230°C for 48 hours, the temperature is raised to 320°C, and the catalyst is heat-treated at the constant temperature for 24 hours; then the temperature is lowered to 230°C and the raw gas is reacted at this temperature in the presence of the catalyst after the heat treatment for 24 hours, the gas product obtained by the reaction is introduced into a gas chromatograph, and the gas product samples at the outlet of each reaction tube are sampled in turn through the GC analysis system and the composition is detected and analyzed, that is, the activity of the catalyst after heat treatment is evaluated.

[0096] The performance evaluation results of each catalyst are shown in Table 2.

[0097] Table 2 Evaluation results of catalyst performance obtained in each example

[0098]

[0099]

[0100] Table 3 Evaluation results of catalyst performance obtained in each comparative example

[0101] Sample No. Initial activity / % Activity after heat treatment / % Activity retention rate / % Methanol selectivity / % Example 1 72.59 68.71 94.65 99.01 Comparative Example 1 65.03 55.83 85.85 96.24 Comparative Example 2 63.34 51.78 81.75 95.45 Comparative Example 3 52.40 33.41 63.76 74.95

[0102] In the table, activity retention rate % = (activity after heat treatment / initial activity)*100%.

[0103] Table 1 shows the components and contents of the catalysts prepared in the examples and comparative examples.

[0104] It can be seen from Table 2 that the catalyst prepared by the preparation method of the present invention has high initial activity and high activity retention rate, which indicates that its thermal stability is also significantly improved.

[0105] As can be seen from Table 3, since Comparative Examples 1 and 2 adopt high-temperature precipitation to prepare the catalyst, the active component precursors formed therein have large grains, and the initial activity and thermal stability of the catalysts are lower than those of Example 1. Since Comparative Example 2 adopts high-temperature precipitation and adds a seeding agent, the grains grow too fast, and the initial activity of the obtained catalyst is lower than that of Example 1 and Comparative Example 1. Although Comparative Example 3 adopts low-temperature precipitation, no seeding agent is added during the aging process, resulting in insufficient morphological transformation of the active component precursors, and the initial activity and thermal stability of the catalyst are greatly reduced.

[0106] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing a methanol synthesis catalyst, It is characterized in that The steps include: (1) contacting an Al source with a first precipitant to perform a first precipitation reaction to obtain a first suspension; (2) contacting the first suspension with a Cu source, a Zn source and a second precipitant to perform a coprecipitation reaction to obtain a second suspension; (3) adding a seed crystal inducing agent to the second suspension and heating the suspension for aging, filtering, washing, drying and calcining the obtained product to obtain a methanol synthesis catalyst; Wherein, the first precipitant and the second precipitant are the same or different, and are independently selected from carbonates and / or bicarbonates.

2. The preparation method according to claim 1, It is characterized in that The Al source is a water-soluble compound containing Al element, preferably selected from Al(NO 3 ) 3 、Al 2 (SO 4 ) 3 and AlCl 3 At least one of; and / or The Cu source is a water-soluble compound containing the Cu element, preferably selected from Cu(NO 3 ) 2 ,CuSO 4 and CuCl 2 At least one of; and / or The Zn source is a water-soluble compound containing Zn element, preferably selected from Zn(NO 3 ) 2 、ZnSO 4 and ZnCl 2 At least one of; and / or The first precipitant and the second precipitant are each independently selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

3. The preparation method according to claim 1 or 2, It is characterized in that In step (1), the conditions of the first precipitation reaction include: a temperature of 5-40°C, preferably 5-30°C; and a system pH of 5-10, preferably 6-9.

4. The preparation method according to any one of claims 1 to 3, It is characterized in that In step (2), the conditions of the coprecipitation reaction include: a temperature of 5-40° C., preferably 5-30° C.; and a system pH of 6-9, preferably 7-8.

5. The preparation method according to any one of claims 1 to 4, It is characterized in that In step (3), the conditions of the aging reaction include: temperature of 40-90°C, preferably 65-90°C; time of 1-12h, preferably 2-8h.

6. The preparation method according to any one of claims 1 to 5, It is characterized in that In step (3), the seed inducer is (Zn, Cu) 5 (CO 3 ) 2 (OH) 6 ; The dosage of the seed crystal inducer is calculated based on the divalent metal ions contained therein, and the ratio of the molar amount of the divalent metal ions in the seed crystal inducer to the total molar amount of copper and zinc ions in the system is 0.5:10 to 5:10, preferably 0.5:10 to 2:

10.

7. The preparation method according to any one of claims 1 to 6, It is characterized in that In step (3), The drying conditions include: a temperature of 90-120°C and a time of 6-18 hours; and / or The calcination conditions include: temperature of 300-390° C. and time of 2-18 hours.

8. The preparation method according to any one of claims 1 to 7, It is characterized in that Calculated by elements, the molar ratio of the Cu source, Zn source and Al source is (40-65):(20-40):(3-30), preferably (45-65):(20-35):(8-20).

9. A methanol synthesis catalyst obtained by the preparation method according to any one of claims 1 to 8, It is characterized in that Based on the total weight of the catalyst, the methanol synthesis catalyst comprises the following components: Al 2 O 3 1.5wt%-25wt% of aluminum component, 40wt%-70wt% of copper component, calculated as CuO, Calculated as ZnO, 20wt%-45wt% of the zinc component.

10. Use of the methanol synthesis catalyst obtained by the preparation method according to any one of claims 1 to 8 or the methanol synthesis catalyst according to claim 9.

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