Methanol synthesis catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical 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 parallel flow contact on an aluminum source and a first precipitant, and carrying out a first precipitation reaction under a pH value reciprocating swing condition to obtain a first turbid liquid; (2) carrying out parallel flow contact on the first turbid liquid, a copper source, a zinc source and a second precipitant, and carrying out a co-precipitation reaction to obtain a second turbid liquid; and (3) aging and filtering the second suspension, and sequentially washing, drying and roasting the obtained filter residue to prepare 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 thermal stability of the catalyst prepared by the method is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical 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 syngas, mainly using Cu / ZnO / Al 2 O 3 Catalyst. Copper and zinc elements work together to form the active center of the catalytic reaction. 2 O 3 It not only acts as a skeleton in the catalyst, but also disperses the active components in the catalyst.

[0003] Cu-ZnO-A1 2 O 3 Among methanol synthesis catalysts, A1 2 O 3 The carrier plays a role in fixing the active components and maintaining the catalyst structure. However, the catalyst obtained by the traditional co-precipitation method has a 2 O 3 The support is usually amorphous and has limited effect in spacing the active components of the catalyst and preventing the migration of the active components.

[0004] For example, patent document CN115999551A discloses a high-temperature resistant copper-based methanol synthesis catalyst and a preparation method. Pseudo-boehmite is prepared by an acid precipitation method. During the precipitation process, the pH of the solution gradually changes from acidic to alkaline, which easily leads to the production of amorphous colloids in the later stage.

[0005] In view of this, it is worth exploring further how to inhibit the formation of amorphous alumina and reduce the agglomeration of alumina carriers to achieve uniform isolation of copper and zinc active components. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a methanol synthesis catalyst and a preparation method and application thereof, by controlling the crystallinity and particle size of pseudo-boehmite in a co-current precipitation mode with pH swing during aluminum precipitation, inhibiting the formation of amorphous alumina, reducing the agglomeration of alumina carriers, making alumina form a suitable steric hindrance effect, achieving uniform isolation of copper and zinc active components, and preventing them from agglomerating during heating, thereby improving the thermal stability of the copper-based catalyst.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] In a first aspect, a method for preparing a methanol synthesis catalyst is provided, comprising the following steps:

[0009] (1) contacting an aluminum source with a first precipitant in parallel, performing a first precipitation reaction under a condition where the pH value swings back and forth, and obtaining a first suspension;

[0010] (2) contacting the first suspension with a copper source, a zinc source and a second precipitant in parallel to perform a coprecipitation reaction to obtain a second suspension;

[0011] (3) aging the second suspension, filtering, and sequentially washing, drying, and calcining the resulting filter residue to obtain a methanol synthesis catalyst;

[0012] Wherein, the first precipitant and the second precipitant are the same or different, and are independently selected from carbonates and / or bicarbonates.

[0013] According to the preparation method of the present invention, 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.

[0014] In step (1) of the present invention, the "carrying out the first precipitation reaction under the condition of reciprocating pH swing" can be understood as adjusting the dripping speed of the first precipitant to control the pH value of the mixture I (a mixture of the aluminum salt solution and the first precipitant) to complete one swing within a certain period of time (that is, the pH value swings from acidic-neutral-alkaline, and then from alkaline-neutral-acidic, which is one alternating swing). According to this swinging mode, multiple reciprocating pH swings can be performed, and the endpoint pH value of the last reciprocating swing is neutral or alkaline, thereby obtaining a first suspension.

[0015] In some embodiments, the aluminum source is a water-soluble compound containing the Al element, preferably selected from Al(NO 3 ) 3 、Al 2 (SO 4 ) 3 and AlCl 3 At least one of .

[0016] In some embodiments, the copper 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 .

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

[0018] In some embodiments, in step (1), the conditions of the first precipitation reaction include: a reaction temperature of 40-90°C (e.g., 50°C, 55°C, 65°C, 70°C, 80°C), preferably 60-75°C; a pH value fluctuates between 2 and 11, with the number of reciprocating fluctuations being 2 to 20 times; preferably, (to promote the formation of high crystalline purity pseudo-boehmite), the pH fluctuates between 3 and 10, with the number of reciprocating fluctuations being 3 to 8 times.

[0019] In the present invention, the reaction time of the first reaction 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.

[0020] In step (1), the aluminum source and the first precipitant are dripped into a co-precipitation container together, and the pH value of the mixture I (which can be understood as a mixture of the Al source and the first precipitant) in the mixed system is controlled to fluctuate back and forth in the range of 2-11 by adjusting the dripping speed of the first precipitant, that is, within the pH range of 2-11, the pH value changes from pH = 2 as a starting point to neutral and then to alkaline, and then changes from alkaline to neutral and then to acidic, ...; the endpoint pH value of the reciprocating fluctuation is in the range of 7-9.

[0021] In some embodiments, in step (2), the conditions of the coprecipitation reaction include: a temperature of 60-90°C (e.g., 62°C, 65°C, 70°C, 80°C, 85°C), preferably 60-75°C; a pH of 6-9 (e.g., 6.5, 7, 7.5, 8, 8.5), preferably 7-8.5.

[0022] In the present invention, the reaction time of the coprecipitation reaction 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.

[0023] In step (2), the Cu source, Zn source and coprecipitant are added to the first suspension simultaneously, and during the addition, the pH of the mixture II (which can be understood as a mixture of the first suspension, the Cu source, the Zn source and the coprecipitant) is ensured to be, for example, 7-8.5.

[0024] In some embodiments, in step (3), the aging conditions include: a temperature of 70-90°C (e.g., 72°C, 75°C, 80°C, 85°C) and a time of 1-12h (e.g., 2h, 4h, 5h, 8h, 10h).

[0025] In some embodiments, in step (3), the drying conditions include: a temperature of 90-120°C (e.g., 95°C, 100°C, 110°C, 115°C), and a time of 6-18h (e.g., 8h, 10h, 12h, 15h, 16h); the roasting 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).

[0026] In some embodiments, the molar ratio of the copper source, zinc source and aluminum source, calculated on an element basis, is (40-65):(20-40):(3-30), for example, 40:30:30, 50:20:30, 60:20:20, 45:25:30, 50:30:20, 60:30:10, 65:30:5, 40:40:20, 50:40:10, 60:35:5, preferably (45-65):(20-35):(8-20).

[0027] 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 methanol synthesis catalyst:

[0028] 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%,

[0029] 40wt%-70wt% (e.g., 41wt%, 43wt%, 45wt%, 50wt%, 55wt%, 60wt%, 62wt%, 65wt%) of copper component, preferably 42.67wt%-68.37wt%, calculated as CuO,

[0030] 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.

[0031] Wherein, at least part of the aluminum component exists in the form of nano-crystals.

[0032] In a third aspect, there is provided a methanol synthesis catalyst prepared by the preparation method as described above or use of the methanol synthesis catalyst as described above in catalytic synthesis of methanol from synthesis gas.

[0033] 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.

[0034] The present invention selects the acid-base alternation method to precipitate aluminum in the co-current precipitation process of the Al source and the precipitant. The pH swings toward the acid side, which can dissolve the fine colloid particles and amorphous aluminum hydroxide generated in the gel, while retaining the pseudo-boehmite that has been generated; the pH swings toward the alkaline side, which can cause a large amount of pseudo-boehmite to precipitate. As the number of reciprocating pH swings increases during the precipitation of the aluminum element, the pseudo-boehmite content increases, the crystallinity increases, and the particle size becomes more consistent. In addition, during the precipitation process in which the pH swing is controlled, aluminum and copper-zinc are precipitated step by step (i.e., copper-zinc precipitation is performed in the next step). In this way, the interference of copper-zinc ions in the formation of pseudo-boehmite can be eliminated, and the formation of hydrotalcite structure can be effectively avoided. Al with a certain degree of crystallinity is obtained by the co-precipitation method in which the pH swing is controlled in the Al source precipitation step. 2 O 3 The carrier can reduce the agglomeration of the alumina carrier, form a suitable steric hindrance effect, realize the uniform isolation of the copper and zinc active components, make the active components less likely to aggregate during the heating process, and thus improve the thermal stability of the copper-based catalyst.

[0035] Compared with the prior art, the excellent effect of the technical solution of the present invention lies at least in that: in the catalyst preparation method of the present invention, the reaction is first carried out under the reciprocating swing of the pH of the system in the Al source precipitation step, and then the Cu source and the Zn source are added to the obtained first suspension for co-precipitation, which is beneficial to promote the formation of pseudo-boehmite with high crystalline purity. The aluminum-containing nanoparticles in the catalyst prepared by this method have limited isolation ability, can form a suitable steric hindrance effect, realize uniform isolation of copper and zinc active components, make the copper component not easy to aggregate and sinter during the heating process, thereby improving the thermal stability of the copper-based catalyst. DETAILED DESCRIPTION

[0036] 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.

[0037] Unless otherwise specified, the experimental procedures used in the following examples are all conventional methods.

[0038] The raw materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0039] Embodiment 1:

[0040] The raw materials used are Cu(NO3 ) 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).

[0041] The preparation method of the methanol synthesis catalyst comprises the following steps:

[0042] (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 in parallel over 12 minutes at a water bath temperature of 70°C. The addition process was accompanied by stirring. 2 CO 3 The dropping speed of the mixture I (aluminum salt solution and Na 2 CO 3 The pH value of the mixture of the aqueous solution) increased from 3 to 9 within 4 minutes, and then decreased from 9 to 3, that is, one swing was completed; according to this swinging mode, three reciprocating swings of the pH value were completed within 12 minutes, and the end point pH value of the reciprocating swing was 8, thereby obtaining a first suspension;

[0043] (2) Add the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 During the addition of aqueous solution (second precipitant), ensure that the mixture II (first suspension, copper-zinc mixed salt solution and Na 2 CO 3 The temperature of the mixture of the aqueous solution is 70° C. and the pH is 7.5 to obtain a second suspension;

[0044] In this process, the molar ratio of Cu and Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is 60:30:10;

[0045] (3) The obtained second suspension is aged at 80° C. for 2 h and filtered, and the obtained filter residue is washed until the conductivity of the filtrate is less than 30 μs / cm, and then the obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h; the obtained product is tableted, crushed, and sieved to obtain catalyst particles of 60 to 100 mesh.

[0046] Embodiment 2:

[0047] 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).

[0048] The preparation method of the methanol synthesis catalyst comprises the following steps:

[0049] (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 in parallel over 12 minutes at a water bath temperature of 70°C. The addition process was accompanied by stirring. 2 CO 3 The dropping speed of the mixture I (aluminum salt solution and Na 2 CO 3 The pH value of the mixture of the aqueous solution) increases from 4 to 8 within 3 minutes, and then decreases from 8 to 4, that is, one swing is completed; according to this swinging mode, four reciprocating swings of the pH value are completed within 12 minutes, and the end point pH value of the reciprocating swing is 8, thereby obtaining a first suspension;

[0050] (2) Add the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 During the addition of aqueous solution (second precipitant), ensure that the mixture II (first suspension, copper-zinc mixed salt solution and Na 2 CO 3 The temperature of the mixture of the aqueous solution is 65° C. and the pH is 7.5 to obtain a second suspension;

[0051] In this process, the molar ratio of Cu and Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is 56:28:16;

[0052] (3) The obtained second suspension is aged at 70° C. for 2 h and filtered, and the obtained filter residue is washed until the conductivity of the filtrate is less than 30 μs / cm, and then the obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h; the obtained product is tableted, crushed, and sieved to obtain catalyst particles of 60 to 100 mesh.

[0053] Embodiment 3:

[0054] The preparation process of the methanol synthesis catalyst refers to Example 1, except that the molar ratio of Cu, Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is changed to 45:25:30.

[0055] Embodiment 4:

[0056] The preparation process of the methanol synthesis catalyst refers to Example 1, except that the molar ratio of Cu, Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is changed to 50:20:30.

[0057] Embodiment 5:

[0058] The preparation process of the methanol synthesis catalyst is as described in Example 1, except that: in step (1), the addition rate of the first precipitant is adjusted to control the mixture I (aluminum salt solution and Na 2 CO 3 The pH value of the mixture of the aqueous solution) increased from 3 to 9 within 4 minutes, and then decreased from 9 to 3, that is, one swing was completed; according to this swinging mode, 8 reciprocating swings of the pH value were completed within 32 minutes, and the end point pH value of the reciprocating swing was 8, to obtain the first suspension.

[0059] The rest of the contents were the same as those in Example 1, and finally catalyst particles of 60 to 100 meshes were obtained.

[0060] Comparative Example 1:

[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.

[0062] The preparation method of the catalyst comprises the following steps:

[0063] (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 in parallel over 12 minutes at a water bath temperature of 70°C. The addition process was accompanied by stirring. 2 CO 3 The dropping speed of the mixture I (aluminum salt solution and Na 2 CO 3 The pH value of the mixture of the aqueous solution is stabilized at about 8 to obtain a first suspension;

[0064] (2) Add the prepared copper-zinc salt mixed salt solution, Na 2 CO 3 During the addition of aqueous solution (second precipitant), ensure that the mixture II (first suspension, copper-zinc mixed salt solution and Na 2 CO 3 The temperature of the mixture of the aqueous solution is 70° C. and the pH is 7.5 to obtain a second suspension;

[0065] In this process, the molar ratio of Cu and Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is 60:30:10;

[0066] (3) The obtained second suspension is aged at 80° C. for 2 h and filtered, and the obtained filter residue is washed until the conductivity of the filtrate is less than 30 μs / cm, and then the obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h; the obtained product is tableted, crushed, and sieved to obtain catalyst particles of 60 to 100 mesh.

[0067] Comparative Example 2

[0068] 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.

[0069] The preparation method of the catalyst comprises the following steps:

[0070] (1) Use a peristaltic pump to mix the prepared copper-zinc salt mixed salt solution, aluminum salt solution and Na 2 CO 3 The aqueous solution was added alternately and concurrently into a water bath flask at a water bath temperature of 70°C. The dropping process was accompanied by stirring. The pH value of the mixture in the reaction system was controlled to increase from 3 to 9 within 4 minutes and then decrease from 9 to 3 by adjusting the dropping speed of the precipitant, thus completing one swing. According to this swinging mode, the pH value was swung back and forth three times within 12 minutes, and the end point pH value of the reciprocating swing was 8, thereby obtaining a suspension.

[0071] In this process, the molar ratio of Cu and Zn contained in the copper-zinc salt mixed salt solution and Al contained in the aluminum salt solution is 60:30:10;

[0072] (2) The obtained suspension is aged at 80° C. for 2 h and filtered, and the obtained filter residue is washed until the conductivity of the filtrate is less than 30 μs / cm, and then the obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h; the obtained product is tableted, crushed, and sieved to obtain catalyst particles of 60 to 100 mesh.

[0073] Comparative Example 3

[0074] 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).

[0075] The preparation method of the catalyst comprises the following steps:

[0076] (1) Use a peristaltic pump to mix the prepared copper-zinc salt mixed salt solution, aluminum salt solution and Na 2 CO 3 The aqueous solution is added alternately and concurrently into a water bath flask, the water bath temperature is 70° C., the dropping process is accompanied by stirring, and the pH value of the mixture in the system is controlled to alternately change between 3 and 9 within 4 minutes by adjusting the dropping speed of the precipitant, and the changing rule is neutral→alkaline→acidic→neutral or neutral→acidic→alkaline→neutral, that is, one swing is completed; according to this swing mode, the pH value is swung back and forth three times within 12 minutes, and the end point pH value of the reciprocating swing is 7, thereby obtaining a suspension;

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

[0078] (2) The obtained suspension is aged at 80° C. for 2 h and filtered, and the obtained filter residue is washed until the conductivity of the filtrate is less than 30 μs / cm, and then the obtained filter residue is dried at 110° C. for 12 h, and then calcined at 350° C. for 4 h; the obtained product is tableted, crushed, and sieved to obtain catalyst particles of 60 to 100 mesh.

[0079] Table 1 Composition of the catalysts prepared in each embodiment and comparative example

[0080] serial number <![CDATA[Al 2 O 3 Content (wt%)]]> CuO content (wt%) ZnO content (wt%) Example 1 6.60 61.79 31.61 Example 2 10.80 59.01 30.19 Example 3 21.41 50.11 28.48 Example 4 21.44 55.75 22.81 Example 5 6.60 61.79 31.61 Comparative Example 1 6.60 61.79 31.61 Comparative Example 2 6.60 61.79 31.61 Comparative Example 3 6.60 61.79 31.61

[0081] The methanol synthesis reaction performance of the catalysts prepared in the examples and comparative examples was evaluated using a 16-channel micro multi-tube combined reaction device produced by HTE of 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.

[0082] In the methanol synthesis reaction, the reaction pressure is 4MPa, the reaction temperature is 230℃, the catalyst loading is 0.8g, and the space velocity is 8000h -1 The designed raw gas volume composition is: CO content is 13%, CO 2 The content is 1.2%, H 2 The content is 80%, the Ar content is 5.8%, and the raw gas is provided by Beijing Helium Gas Industry Co., Ltd. The catalyst particle size 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.

[0083] 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 a 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.

[0084] The catalytic performance evaluation results are shown in Tables 2 and 3.

[0085] Table 2 Catalytic performance evaluation results of the catalysts prepared in each example

[0086]

[0087]

[0088] Table 3 Catalytic performance evaluation results of the catalysts prepared in each comparative example

[0089] Sample No. Initial activity / % Activity after heat treatment / % Activity retention rate / % Methanol selectivity / % Example 1 73.98 69.70 94.21 99.23 Comparative Example 1 65.36 55.50 84.91 96.18 Comparative Example 2 62.67 51.47 82.13 95.91 Comparative Example 3 63.72 53.06 83.27 95.73

[0090] In the table, activity retention rate % = (activity after heat treatment / initial activity)*100%.

[0091] Table 1 shows the components and contents of the catalysts prepared in various examples and comparative examples.

[0092] It can be seen from Table 2 that the catalyst prepared by the present invention has high initial activity and the activity retention rate is also greatly improved.

[0093] As can be seen from Table 3, the aluminum element precipitation in Comparative Example 1 adopts the conventional pH constant titration method, and the thermal stability of the obtained catalyst is lower than the catalyst prepared by the pH swing method in Example 1. Comparative Examples 2 and 3 adopt pH swing or alternating co-current to co-precipitate copper, zinc and aluminum ions, resulting in the generation of talc-like in the catalyst, and the catalytic activity and thermal stability are lower than the catalyst prepared in Example 1.

[0094] 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 aluminum source with a first precipitant in parallel, performing a first precipitation reaction under a condition where the pH value swings back and forth, and obtaining a first suspension; (2) contacting the first suspension with a copper source, a zinc source and a second precipitant in parallel to perform a coprecipitation reaction to obtain a second suspension; (3) aging the second suspension, filtering, and sequentially washing, drying, and calcining the resulting filter residue 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 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 The aluminum source is a water-soluble compound containing the Al element, preferably selected from Al(NO 3 ) 3 、Al 2 (SO 4 ) 3 and AlCl 3 At least one of; and / or The copper 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 zinc source is a water-soluble compound containing the Zn element, preferably selected from Zn(NO 3 ) 2 、ZnSO 4 and ZnCl 2 At least one of .

4. The preparation method according to any one of claims 1 to 3, It is characterized in that In step (1), the conditions of the first precipitation reaction include: the reaction temperature is 40-90°C, preferably 60-75°C; the pH value fluctuates between 2-11, and the number of reciprocating fluctuations is 2 to 20 times; preferably, the pH value fluctuates between 3-10, and the number of reciprocating fluctuations is 3 to 8 times.

5. The preparation method according to any one of claims 1 to 4, It is characterized in that In step (2), the conditions of the coprecipitation reaction include: temperature of 60-90°C, preferably 60-75°C; pH of 6-9, preferably 7-8.

5.

6. The preparation method according to any one of claims 1 to 5, It is characterized in that In step (3), the aging conditions include: temperature of 70-90° C. and time of 1-12 h.

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 h; 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 copper source, zinc source and aluminum 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 methanol synthesis catalyst, the methanol synthesis catalyst includes 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 in catalytic synthesis of methanol from synthesis gas.

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