A preparation method for a photoreduction deposition in-situ etching methanol synthesis catalyst

Abstract

This invention discloses a method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching, comprising the following steps: (1) a salt solution containing Cu, Zn, Al and Ti is neutralized and precipitated with a precipitant to obtain a precursor, and the precursor is calcined to obtain a mixed oxide of Cu, Zn, Al and Ti; (2) the mixed oxide obtained in step (1) is etched with a noble metal acid solution under light-shielding conditions; (3) the mixed oxide etched in step (2) is placed under light conditions for in-situ reaction for 1-6 hours, and then filtered, washed and dried to obtain the methanol synthesis catalyst. This invention uses a noble metal acid solution to etch the calcined mixed oxide to form more mesoporous channels in the system; then, the noble metal ions are reduced to metal nanoparticles in situ in the channels by photoreduction deposition to increase the amount of noble metal introduced, thereby improving the low-temperature activity of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst. Background Technology

[0002] Currently, numerous catalysts are used industrially for methanol synthesis, with Cu-ZnO-Al2O3 catalysts being the most widely applied. This catalyst typically requires operation at 230–250℃ to fully realize its catalytic effect. However, the active component Cu in Cu-ZnO-Al2O3 catalysts undergoes surface atomic migration at 134℃ and lattice migration at 405℃. Therefore, in practical applications, the lifespan of Cu-ZnO-Al2O3 catalysts is generally short. The conventional solution is to add a small amount of noble metal to the Cu-ZnO-Al2O3 catalyst to improve its low-temperature activity, enabling it to exert its catalytic effect at lower operating temperatures and thus extending its lifespan. In existing technologies, precious metals are introduced into catalysts through impregnation. However, in practical applications, it has been found that this method easily leads to uneven distribution of the introduced precious metals. Furthermore, since the mixed oxides of Cu, Zn, and Al have few pores, it is difficult for precious metal ions to enter the oxide pores. As a result, it is difficult to ensure the amount of precious metals introduced, which seriously affects the low-temperature activity of the catalyst and its low-temperature catalytic effect. Summary of the Invention

[0003] In order to solve the technical problem of low low-temperature activity of methanol synthesis catalysts in the prior art, this invention proposes a method for preparing methanol synthesis catalysts by photoreduction deposition in situ etching, so as to effectively improve the low-temperature activity of the catalyst.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0006] (1) A salt solution containing Cu, Zn, Al and Ti is neutralized and precipitated with a precipitant to obtain a precursor. The precursor is then calcined to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0007] (2) The mixed oxide obtained in step (1) is etched using a noble metal acid solution under light-shielding conditions;

[0008] (3) After the etched mixed oxide in step (2) is placed under light conditions for in-situ reaction for 1-6 hours, it is filtered, washed and dried to obtain methanol synthesis catalyst.

[0009] Furthermore, the salt solution in step (1) is any one of nitrate, sulfate or chloride.

[0010] Furthermore, the molar ratio of Cu, Zn, Al and Ti in the salt solution of step (1) is (6-15):(4-10):(1-5):(1-5).

[0011] Furthermore, the precipitant in step (1) is any one of sodium hydroxide, ammonia, sodium carbonate, and sodium bicarbonate.

[0012] Furthermore, the temperature of the neutralization precipitation reaction in step (1) is 20-60℃; the endpoint pH of the neutralization precipitation reaction is 5-9.

[0013] Furthermore, the roasting temperature in step (1) is 200-300℃.

[0014] Furthermore, in step (2), the noble metal acid solution is any one of ruthenium acid solution, rhodium acid solution, palladium acid solution, osmium acid solution, iridium acid solution or platinum acid solution.

[0015] Furthermore, the concentration of the noble metal acid solution in step (2) is 1-500 mmol / L.

[0016] Furthermore, in step (2), the etching temperature is 20-100℃ and the etching time is 30-300min.

[0017] Furthermore, the illumination in step (3) is irradiation using a 360nm laser.

[0018] The beneficial effects of this invention are:

[0019] This invention utilizes a noble metal acid solution to etch a mixed oxide of Cu, Zn, Al, and Ti obtained after calcination, thereby forming more mesoporous channels within the mixed oxide system. This facilitates the full and uniform diffusion of noble metal ions into the catalyst interior. The noble metal ions uniformly diffused into the catalyst interior then grow in situ into metal nanoparticles under the photoreduction precipitation of titanium, achieving a large and uniform dispersion of noble metals within the catalyst structure. Traditional impregnation methods for introducing noble metal ions often only adhere to the catalyst surface, making it difficult to reach the interior. However, the preparation method employed in this invention can uniformly disperse a large number of nano-noble metal particles both inside and outside the catalyst, thus improving the low-temperature activity of the catalyst. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in various embodiments of this application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0023] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0024] Example 1

[0025] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0026] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0027] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0028] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0029] Example 2

[0030] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0031] (1) 53.8 g of copper chloride, 40.9 g of zinc chloride, 33.4 g of aluminum chloride, and 9.5 g of titanium chloride were dissolved in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution was 8:6:5:1. The obtained salt solution and 1 M sodium hydroxide aqueous solution were simultaneously added to a continuous neutralization reactor using a metering pump, and the mixture was continuously stirred at room temperature until the pH reached 5 to obtain a mixed reactant. The precipitate in the mixed reactant was filtered, washed with deionized water, and dried in an oven to obtain a precursor. The precursor was calcined at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0032] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0033] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0034] Example 3

[0035] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0036] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti. Add the obtained salt solution and 1 M sodium bicarbonate aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0037] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0038] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0039] Example 4

[0040] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0041] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at 60 °C until the pH reaches 9 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcinate the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0042] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0043] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0044] Example 5

[0045] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0046] (1) Dissolve 72.5g of copper nitrate trihydrate, 59.5g of zinc nitrate hexahydrate, 93.8g of aluminum nitrate nonahydrate, and 75.0g of titanium nitrate in 1L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 6:4:5:5. Add the obtained salt solution and 1M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcinate the precursor at 200℃ for 30min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0047] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0048] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0049] Example 6

[0050] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0051] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 300 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0052] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0053] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0054] Example 7

[0055] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0056] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0057] (2) Immerse the mixed oxide obtained in step (1) in a 1 mmol / L aqueous solution of platinum acid under light-shielding conditions and continuously stir and etch for 30 min at room temperature.

[0058] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0059] Example 8

[0060] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0061] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0062] (2) The mixed oxide obtained in step (1) was immersed in a 500 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at 100°C for 300 min.

[0063] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0064] Example 9

[0065] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0066] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0067] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions and continuously stirred and etched at room temperature for 30 min.

[0068] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 6 hours. After filtration, washing and drying, methanol synthesis catalyst can be obtained.

[0069] Comparative Example 1

[0070] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0071] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0072] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium chloride aqueous solution under light-shielding conditions and stirred continuously at room temperature for 30 min.

[0073] (3) The mixed oxide etched in step (2) is placed under the condition of 360nm laser irradiation for in-situ reaction for 1 hour, and then filtered, washed and dried to obtain methanol synthesis catalyst.

[0074] The difference between this comparative example and Example 1 above is that the ruthenium acid aqueous solution is replaced with ruthenium chloride aqueous solution.

[0075] Comparative Example 2

[0076] A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching includes the following steps:

[0077] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0078] (2) The mixed oxide obtained in step (1) was immersed in a 1 mmol / L ruthenium acid aqueous solution under light-shielding conditions, and after continuous stirring and etching at room temperature for 30 min, the methanol synthesis catalyst was obtained by filtration, washing and drying.

[0079] The difference between Comparative Example 2 and Example 1 above is that the in-situ reaction was not carried out under laser irradiation.

[0080] Comparative Example 3

[0081] A method for preparing a methanol synthesis catalyst includes the following steps:

[0082] (1) Dissolve 96.6 g of copper nitrate trihydrate, 89.3 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate, and 15.0 g of titanium nitrate in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al, and Ti, wherein the molar ratio of Cu, Zn, Al, and Ti in the salt solution is 8:6:5:1. Add the obtained salt solution and 1 M sodium hydroxide aqueous solution simultaneously to a continuous neutralization reactor using a metering pump, and stir continuously at room temperature until the pH reaches 5 to obtain a mixed reactant. Filter the precipitate from the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor. Calcine the precursor at 200 °C for 30 min to obtain a mixed oxide of Cu, Zn, Al, and Ti.

[0083] (2) The methanol synthesis catalyst is obtained by soaking the mixed oxide obtained in step (1) in a 1 mmol / L ruthenium chloride aqueous solution and stirring continuously for 30 min at room temperature and then drying directly.

[0084] The difference between this Comparative Example 3 and Comparative Example 1 above is that the in-situ reaction was not carried out under laser irradiation.

[0085] Performance testing

[0086] The pore size and activity of the methanol synthesis catalysts obtained in the above embodiments and comparative examples of this application were tested. Specifically, to verify the catalytic activity of the methanol synthesis catalysts obtained in the above embodiments and comparative examples of this application, the methanol synthesis catalysts obtained in the above embodiments and comparative examples were applied to a micro fixed-bed continuous flow reactor to prepare methanol. The catalytic reaction conditions for methanol synthesis were as follows: catalyst loading was 4 mL, synthesis gas composition was: CO (13–15%), CO2 (3–5%), H2 (55–65%), balance N2, and space velocity was 10000 h⁻¹. -1 The reaction pressure is 5.0 MPa and the reaction temperature is 130℃.

[0087] The pore size analysis and activity evaluation results of the above embodiments and comparative examples are shown in Table 1:

[0088] Table 1: Results of pore size analysis and activity evaluation of products obtained in each example and comparative example

[0089]

[0090]

[0091] As can be clearly seen from the experimental data in Table 1, the methanol synthesis catalyst prepared by the method of this embodiment has a pore size range of 13.4-14.3 nm, which is significantly improved compared with the pore size of Comparative Example 1 and Comparative Example 3 without etching, proving that the ruthenium acid aqueous etching method effectively improves the pore size of the catalyst.

[0092] The methanol synthesis catalyst prepared by the method of this embodiment has a methanol yield ranging from 0.98 to 1.04 g / (mL-Cat·h), which is significantly improved compared to the comparative example. This demonstrates that uniformly dispersing noble metal active sites through in-situ photoreduction deposition is an effective way to improve the low-temperature activity of the catalyst.

[0093] Furthermore, the experimental data from Example 1 and Comparative Example 1 show that without etching with ruthenium acid aqueous solution, the catalyst pore size is only 9.2 nm. Even with photoreduction applied to the catalyst at this point, the dispersion of the reduced noble metal is still insufficient, resulting in a methanol yield of only 0.80 g / (mL-Cat·h). This result demonstrates that pore enlargement helps improve the low-temperature activity of the catalyst.

[0094] The experimental data from Example 1 and Comparative Example 2 show that the catalyst pores expanded to 13.3 nm after etching with ruthenium acid aqueous solution. However, since no subsequent photoreduction etching treatment was performed on the noble metal ions, the noble metal ions were rapidly lost after washing, and the catalyst had almost no activity at 130°C, demonstrating the importance of the photoreduction deposition process.

[0095] As can be seen from the experimental data of Example 1 and Comparative Example 3, the catalyst that has not undergone etching and photoreduction is significantly lower than that of Example 1 in terms of pore size and activity.

[0096] Finally, it should be noted that these embodiments are for illustrative purposes only and do not limit the scope of the invention. Furthermore, those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a methanol synthesis catalyst by photoreduction deposition in situ etching, characterized in that, Includes the following steps: (1) A salt solution containing Cu, Zn, Al and Ti is neutralized and precipitated with a precipitant to obtain a precursor. The precursor is then calcined to obtain a mixed oxide of Cu, Zn, Al and Ti. (2) The mixed oxide obtained in step (1) is etched using a noble metal acid solution under light-shielding conditions; (3) After the etched mixed oxide in step (2) is placed under light conditions for in-situ reaction for 1-6 hours, it is filtered, washed and dried to obtain methanol synthesis catalyst; In step (2), the noble metal acid solution can be either ruthenium acid solution or osmium acid solution.

2. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: In step (1), the salt solution is any one of nitrate, sulfate, or chloride.

3. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: The molar ratio of Cu, Zn, Al and Ti in the salt solution of step (1) is (6-15):(4-10):(1-5):(1-5).

4. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: In step (1), the precipitant is any one of sodium hydroxide, ammonia, sodium carbonate, or sodium bicarbonate.

5. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: The temperature of the neutralization precipitation reaction in step (1) is 20-60℃; the endpoint pH of the neutralization precipitation reaction is 5-9.

6. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: The roasting temperature in step (1) is 200-300℃.

7. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: The concentration of the noble metal acid solution in step (2) is 1-500 mmol / L.

8. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: In step (2), the etching temperature is 20-100℃ and the etching time is 30-300min.

9. The method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst according to claim 1, characterized in that: The illumination in step (3) is irradiation using a 360nm laser.

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