Preparation method of methanol synthesis catalyst through photo-reduction deposition in-situ etching

Abstract

The invention discloses a preparation method of a photo-reduction deposition in-situ etching methanol synthesis catalyst, which comprises the following steps: (1) carrying out neutralization precipitation reaction on a salt solution containing Cu, Zn, Al and Ti and a precipitator to obtain a precursor, and roasting the precursor to obtain a mixed oxide of Cu, Zn, Al and Ti; (2) etching the mixed oxide obtained in the step (1) by adopting a noble metal acid solution under a shading condition; and (3) placing the etched mixed oxide in the step (2) under an illumination condition, carrying out an in-situ reaction for 1-6 hours, filtering, washing, and drying to obtain the methanol synthesis catalyst. According to the invention, the mixed oxide obtained after roasting is etched by using the noble metal acid solution, so that more mesoporous channels are formed in the system; noble metal ions are reduced into metal nanoparticles in situ in the pore channels through a photo-reduction precipitation method, so that the introduction amount of noble metal is increased, and the effect of improving the low-temperature activity of the catalyst is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a method for preparing a photoreduction deposition in-situ etching methanol synthesis catalyst. Background Art

[0002] At present, there are many types of catalysts used in industry for methanol synthesis, among which Cu-ZnO-Al2O3 catalyst is the most widely used. This catalyst generally needs to be used under 230-250℃ to fully exert its catalytic effect. However, the active component Cu of the Cu-ZnO-Al2O3 catalyst will undergo surface atomic migration at 134℃ and lattice migration at 405℃. Therefore, in actual application, the service life of the Cu-ZnO-Al2O3 catalyst is generally short. In this regard, the current conventional solution is to add a small amount of precious metal to the Cu-ZnO-Al2O3 catalyst to improve the low-temperature activity of the catalyst so that it can fully exert its catalytic effect at a lower operating temperature, thereby extending the service life of the catalyst. In the prior art, precious metals are introduced into the catalyst by an impregnation method. However, in actual application, it is found that such an impregnation method easily causes uneven distribution of the introduced precious metals. At the same time, since the Cu, Zn, and Al mixed oxides themselves have fewer 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 in turn seriously affects the low-temperature activity of the catalyst and its low-temperature catalytic effect. Summary of the invention

[0003] The present invention aims to solve the technical problem of low low-temperature activity of methanol synthesis catalyst in the prior art; a preparation method of a methanol synthesis catalyst by photoreduction deposition in-situ etching is proposed to achieve the technical effect of effectively improving the low-temperature activity of the catalyst.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

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

[0006] (1) neutralizing and precipitating a salt solution containing Cu, Zn, Al and Ti with a precipitant to obtain a precursor, and calcining the precursor to obtain a mixed oxide of Cu, Zn, Al and Ti;

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

[0008] (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 a 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, in step (1), the precipitant is any one of sodium hydroxide, ammonia water, sodium carbonate and sodium bicarbonate.

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

[0013] Furthermore, the calcination temperature in step (1) is 200-300°C.

[0014] Furthermore, the noble metal acid solution in step (2) 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° C., and the etching time is 30-300 min.

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

[0018] The beneficial effects of the present invention are:

[0019] The present invention etches the mixed oxide of Cu, Zn, Al and Ti obtained after calcination by using a noble metal acid solution, so that more mesoporous channels are formed in the mixed oxide system, which is conducive to the sufficient and uniform diffusion of noble metal ions into the interior of the catalyst; the noble metal ions uniformly diffused into the interior of the catalyst grow in situ into metal nanoparticles under the photoreduction precipitation of titanium, so that the purpose of dispersing a large amount of noble metals uniformly in the catalyst structure can be achieved. The traditional impregnation method of introducing noble metal ions can often only attach noble metal ions to the surface of the catalyst, and it is difficult to reach the inside, while the preparation method adopted by the present invention can evenly disperse a large number of nano noble metal particles inside and outside the catalyst. Thereby achieving the effect of improving the low-temperature activity of the catalyst. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in each embodiment of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present 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 understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined.

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

[0023] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate 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, comprising the following steps:

[0026] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0027] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0029] Example 2

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

[0031] (1) Dissolve 53.8g of copper chloride, 40.9g of zinc chloride, 33.4g of aluminum chloride and 9.5g of titanium chloride 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 8:6:5:1. Add the obtained salt solution and 1M sodium hydroxide aqueous solution into a continuous neutralization reactor through a metering pump, and continue stirring at room temperature until the pH is 5 to obtain a mixed reactant. Filter the precipitate in the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor, and calcine the precursor at 200°C for 30 minutes to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0032] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0034] Example 3

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

[0036] (1) 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 were dissolved in 1 L of deionized water to obtain a salt solution containing Cu, Zn, Al and Ti. The obtained salt solution and 1 M sodium bicarbonate aqueous solution were simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously 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, and the precursor was calcined at 200° C. for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0037] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0039] Example 4

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

[0041] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at 60° C. until the pH is 9 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200° C. for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0042] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0044] Example 5

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

[0046] (1) Dissolve 72.5 g of copper nitrate trihydrate, 59.5 g of zinc nitrate hexahydrate, 93.8 g of aluminum nitrate nonahydrate and 75.0 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 6:4:5:5. Add the obtained salt solution and 1M sodium hydroxide aqueous solution into a continuous neutralization reactor through a metering pump, and continue stirring at room temperature until the pH is 5 to obtain a mixed reactant. Filter the precipitate in the mixed reactant, wash with deionized water, and dry in an oven to obtain a precursor, and calcine the precursor at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0047] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0049] Example 6

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

[0051] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 300°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0052] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

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

[0054] Example 7

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

[0056] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0057] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L platinum acid aqueous solution, and is continuously etched with stirring for 30 minutes at room temperature.

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

[0059] Example 8

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

[0061] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0062] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) was immersed in a 500 mmol / L aqueous solution of ruthenic acid, and etched at 100° C. with continuous stirring for 300 min.

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

[0064] Example 9

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

[0066] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0067] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the etching is continued for 30 minutes under room temperature with continuous stirring.

[0068] (3) The mixed oxide etched in step (2) is placed under 360 nm laser irradiation to react in situ for 6 hours, and then filtered, washed, and dried to obtain a methanol synthesis catalyst.

[0069] Comparative Example 1

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

[0071] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0072] (2) Immerse the mixed oxide obtained in step (1) in a 1 mmol / L ruthenium chloride aqueous solution under light-shielding conditions, and continue stirring at room temperature for 30 minutes.

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

[0074] The difference between this comparative example and the above-mentioned Example 1 is that the ruthenic acid aqueous solution is replaced by a ruthenium chloride aqueous solution.

[0075] Comparative Example 2

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

[0077] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0078] (2) Under light-shielding conditions, the mixed oxide obtained in step (1) is immersed in a 1 mmol / L aqueous solution of ruthenic acid, and the mixture is continuously stirred and etched for 30 min at room temperature, and then filtered, washed, and dried to obtain a methanol synthesis catalyst.

[0079] The difference between this comparative example 2 and the above-mentioned example 1 is that the in-situ reaction is not carried out under laser irradiation.

[0080] Comparative Example 3

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

[0082] (1) 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 are 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 is 8:6:5:1. The obtained salt solution and 1M sodium hydroxide aqueous solution are simultaneously added to a continuous neutralization reactor through a metering pump, and stirred continuously at room temperature until the pH is 5 to obtain a mixed reactant. The precipitate in the mixed reactant is filtered, washed with deionized water, and dried in an oven to obtain a precursor, and the precursor is calcined at 200°C for 30 min to obtain a mixed oxide of Cu, Zn, Al and Ti.

[0083] (2) The mixed oxide obtained in step (1) is immersed in a 1 mmol / L ruthenium chloride aqueous solution, and stirred continuously for 30 min at room temperature, and then directly dried to obtain a methanol synthesis catalyst.

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

[0085] Performance testing

[0086] The pore size and activity of the methanol synthesis catalyst obtained in the above-mentioned embodiments and comparative examples of the present application were tested. In order to verify the catalytic activity of the methanol synthesis catalyst obtained in the above-mentioned embodiments and comparative examples of the present application, the methanol synthesis catalyst obtained in the above-mentioned embodiments and comparative examples was applied to a micro-fixed bed continuous flow reactor to prepare methanol. The catalytic reaction conditions for the synthesis of methanol are as follows: the catalyst loading is 4 mL, the composition of the synthesis gas is: CO (13-15%), CO2 (3-5%), H2 (55-65%), the balance is N2, and the space velocity is 10000h -1 , the reaction pressure is 5.0MPa, 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: Pore size analysis and activity evaluation results of products obtained in various examples and comparative examples

[0089]

[0090]

[0091] It can be clearly seen from the experimental data in Table 1 that the pore size range of the methanol synthesis catalyst prepared by the method of this embodiment is 13.4-14.3nm, which is significantly improved compared with the pore size of Comparative Example 1 and Comparative Example 3 that have not been etched, proving that the ruthenic acid aqueous solution etching method effectively improves the pore size of the catalyst.

[0092] The methanol yield of the methanol synthesis catalyst prepared by the method of this embodiment ranges from 0.98 to 1.04 g / (mL-Cat·h), which is significantly higher than that of the comparative example. This proves that the introduction of noble metal active sites uniformly dispersed by in-situ photoreduction deposition is an effective way to improve the low-temperature activity of the catalyst.

[0093] It can be seen from the test data of Example 1 and Comparative Example 1 that without etching with ruthenic acid aqueous solution, the catalyst pores are only 9.2 nm. Even if the catalyst is subjected to photoreduction operation, the dispersion of the noble metal after reduction is still insufficient, so the methanol yield is only 0.80 g / (mL-Cat·h). This result proves that the expansion of the pores helps to improve the low-temperature activity of the catalyst.

[0094] It can be seen from the test data of Example 1 and Comparative Example 2 that after etching with ruthenic acid aqueous solution, the pores of the catalyst expanded to 13.3 nm. However, since the noble metal ions were not subsequently subjected to photoreduction etching, the noble metal ions were quickly lost after washing, and the catalyst had almost no activity at 130°C, proving the importance of the photoreduction deposition process.

[0095] It can be seen from the test data of Example 1 and Comparative Example 3 that the catalyst that has not been etched and photoreduced is significantly lower than that of Example 1 in terms of pores and activity.

[0096] Finally, it should be noted that these embodiments are only used to illustrate the present invention and do not limit the scope of the present invention. In addition, for those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the scope of protection of the present invention.

Claims

1. A method for preparing a methanol synthesis catalyst by photoreduction deposition in-situ etching, characterized in that: The steps include: (1) neutralizing and precipitating a salt solution containing Cu, Zn, Al and Ti with a precipitant to obtain a precursor, and calcining the precursor to obtain a mixed oxide of Cu, Zn, Al and Ti; (2) etching the mixed oxide obtained in step (1) using 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 a methanol synthesis catalyst.

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

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

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

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

7. The method for preparing a methanol synthesis catalyst by photoreduction deposition in-situ etching according to claim 1, characterized in that: The noble metal acid solution in step (2) is any one of ruthenium acid solution, rhodium acid solution, palladium acid solution, osmium acid solution, iridium acid solution or platinum acid solution.

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

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

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

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