A catalyst for preparing glyoxal from ethylene glycol, its preparation method and application

Abstract

The present application discloses a catalyst for preparing glyoxal from ethylene glycol. By weight, its raw material composition includes: 45-55 parts of a porous carrier, 8.2-9.5 parts of copper phosphate, 7.5-8 parts of silver phosphate, 0.5-1 part of selenium dioxide, and 100 parts of hydrofluoric acid; the mass fraction of hydrogen fluoride in the hydrofluoric acid is 5.2-7.5%. The preparation method of the catalyst includes the following steps: S1, adding the porous carrier, copper phosphate, silver phosphate, and selenium dioxide into the hydrofluoric acid, mixing evenly to obtain a mixed solution; S2, adjusting the pH of the mixed solution to 1.5-3.5; S3, performing heat treatment on the mixed solution to obtain an intermediate; S4, performing heat treatment on the intermediate to obtain the catalyst. The catalyst is used for catalytic oxidation to prepare glyoxal. The copper, silver, phosphorus, and selenium composite catalyst prepared in the present application helps to improve the conversion rate and selectivity of glyoxal, reduce the activation energy required for the reaction, and thus reduce the temperature required for the reaction.

Description

Technical Field

[0001] The present application relates to the technical field of glyoxal preparation, and in particular to a catalyst for preparing glyoxal from ethylene glycol, and a preparation method and application thereof. Background Art

[0002] Glyoxal, with its two adjacent carbonyl groups, possesses the general properties of aldehydes and ketones and is capable of undergoing many specialized reactions. Consequently, it is widely used in fields such as organic synthesis, medicine, and biochemistry. Currently, the main processes for producing glyoxal include the ethylene glycol-catalyzed method and the nitric acid oxidation method. While the nitric acid oxidation method consumes less energy than the ethylene glycol-catalyzed method, the use of strong acids, strong bases, and certain extractants can easily generate large amounts of contaminated wastewater, making the ethylene glycol-catalyzed method more popular.

[0003] The ethylene glycol method involves introducing a mixture of air, inert gas, and ethylene glycol gas into a catalyst-loaded reaction tower for a catalytic oxidation reaction to produce glyoxal. Currently, the catalysts used are silver-phosphorus or silver-phosphorus-selenium composites, and the reaction temperature is relatively high at 600±10°C. Furthermore, the conversion rate of glyoxal is less than 85%, and the selectivity of glyoxal is less than 75%. Summary of the Invention

[0004] In order to solve at least one of the above technical problems, a method for preparing glyoxal with a reaction temperature below 500°C, a glyoxal conversion rate higher than 95%, and a selectivity higher than 85% is developed. The present application provides a catalyst for preparing glyoxal from ethylene glycol, a preparation method thereof, and an application thereof.

[0005] On the one hand, the present application provides a catalyst for preparing glyoxal from ethylene glycol, the raw material composition of which, by weight, includes:

[0006]

[0007] Wherein, the porous carrier comprises silica A with a particle size of 52 to 55 nm, silica B with a particle size of 55.5 to 70 nm, and silica C with a particle size of 70.5 to 100 nm, and the weight ratio of the silica A, the silica B, and the silica C is (4.7 to 5.2): (3.2 to 3.4): (2.3 to 2.9);

[0008] The mass fraction of hydrogen fluoride in the hydrofluoric acid is 5.2-7.5%.

[0009] By adopting the above technical solution, the composite system formed by copper, silver, phosphorus and selenium can be stably attached to the porous support, which helps to improve the conversion rate and selectivity of glyoxal, reduce the activation energy and temperature required for the reaction, and further reduce the temperature required for the reaction; the porous support formed by silica with different particle sizes in a specific proportion can provide more sites for attaching the catalyst, thereby further improving the conversion rate and selectivity of glyoxal.

[0010] Optionally, the weight ratio of the silica A, the silica B and the silica C is 5.2:3.4:2.9.

[0011] Optionally, the particle size of the silica A is 53.5 nm, the particle size of the silica B is 57 nm, and the particle size of the silica C is 81 nm.

[0012] By adopting the above technical solution, ethylene glycol in the reaction process can be adsorbed more fully, effectively improving the catalytic effect of the catalyst.

[0013] Optionally, there are 50 parts of the porous support, 8.2 parts of copper phosphate, 7.6 parts of silver phosphate, 0.5 part of selenium dioxide and 100 parts of hydrofluoric acid.

[0014] In a second aspect, the present application provides a method for preparing the catalyst for preparing glyoxal from the above ethylene glycol, including the following steps: S1. Add the porous support, copper phosphate, silver phosphate and selenium dioxide into the hydrofluoric acid, mix evenly to obtain a mixed solution;

[0015] S2. Adjust the pH of the mixed solution to 1.5 - 3.5;

[0016] S3. Heat-treat the mixed solution to obtain an intermediate with a particle size of 7 - 10 μm;

[0017] S4. Heat-treat the intermediate to obtain the catalyst for preparing glyoxal from ethylene glycol.

[0018] By adopting the above technical solution, the catalyst is prepared by heating the solution, which can make silver, copper, phosphorus and selenium disperse more evenly on the porous support, thus ensuring the catalytic effect of the prepared catalyst.

[0019] Optionally, in step S2, the pH of the mixed solution is adjusted by using one of formic acid, lactic acid and salicylic acid.

[0020] By adopting the above technical solution, the dispersibility of the catalytic system can be further improved, which helps to improve the catalytic effect of the catalyst.

[0021] Optionally, in step S3, the heat treatment method is: heating at a heating rate of 20 to 40 °C / min to 320 to 380 °C, and maintaining at this temperature for 1.5 to 2 hours.

[0022] Optionally, in step S4, the heat treatment method is: in an oxygen atmosphere, the heating temperature is 350 to 450 °C, and the heating time is 4 to 6 hours.

[0023] By adopting the above technical solution, the composite system formed by silver, copper, phosphorus, and selenium can be stably attached to the carrier, so as to improve the conversion rate and selectivity of glyoxal.

[0024] In a third aspect, the present application provides the use of the above catalyst for preparing glyoxal from ethylene glycol in the field of preparing glyoxal.

[0025] The preparation method for preparing glyoxal by using the above catalyst includes the following steps:

[0026] Step 1: Heat ethylene glycol to obtain ethylene glycol gas;

[0027] Step 2: Mix ethylene glycol gas, air, and inert gas;

[0028] Step 3: Pass the mixed gas into a reaction tower loaded with the catalyst for preparing glyoxal from ethylene glycol for catalytic oxidation reaction, control the temperature of the reaction tower to be 275 °C, and the pressure to be 0.75 Mpa;

[0029] Step 4: The gas generated by the reaction is quickly cooled and then sent to an absorption tower for repeated absorption to obtain an aqueous solution of glyoxal.

[0030] By adopting the above technical solution, the reaction temperature is lower than 500 °C, the conversion rate of glyoxal is higher than 95%, and the selectivity is higher than 85%.

[0031] In summary, the present invention includes at least one of the following beneficial technical effects:

[0032] 1. The copper, silver, phosphorus, and selenium composite catalyst prepared in the present application helps to improve the conversion rate and selectivity of glyoxal, reduce the activation energy required for the reaction, and thus reduce the temperature required for the reaction.

[0033] 2. The porous carrier formed by mixing silica with different particle sizes in a specific ratio can provide more sites for attaching the catalyst, thereby further improving the conversion rate and selectivity of glyoxal.

[0034] 3. The present application prepares the catalyst by heating the solution, which can make silver, copper, phosphorus, and selenium more evenly dispersed on the porous carrier, thus ensuring the catalytic effect of the prepared catalyst. Description of the Drawings

[0035] Figure 1 The preparation flow chart of the catalyst for preparing glyoxal from ethylene glycol provided by this application. Specific embodiments

[0036] The following further elaborates on this application in conjunction with the accompanying drawings and examples.

[0037] This application designs a catalyst for preparing glyoxal from ethylene glycol. By weight, its raw material composition includes:

[0038]

[0039] Among them, the porous carrier includes silica A with a particle size of 52 - 55 nm, silica B with a particle size of 55.5 - 70 nm, and silica C with a particle size of 70.5 - 100 nm. The weight ratio of silica A, silica B, and silica C is (4.7 - 5.2):(3.2 - 3.4):(2.3 - 2.9);

[0040] The mass fraction of hydrogen fluoride in the hydrofluoric acid is 5.2 - 7.5%.

[0041] The catalyst for preparing glyoxal from ethylene glycol of this application is prepared by the following method, including the following steps:

[0042] S1. Add the porous carrier, copper phosphate, silver phosphate, and selenium dioxide into the hydrofluoric acid, mix evenly to obtain a mixed solution;

[0043] S2. Adjust the pH of the mixed solution to 1.5 - 3.5;

[0044] S3. Heat-treat the mixed solution to obtain an intermediate with a particle size of 7 - 10 μm;

[0045] S4. Heat-treat the intermediate to obtain the catalyst for preparing glyoxal from ethylene glycol.

[0046] The application of the catalyst for preparing glyoxal from ethylene glycol of this application in the field of preparing glyoxal.

[0047] The copper, silver, phosphorus, and selenium composite catalyst prepared by this application helps to improve the conversion rate and selectivity of glyoxal, reduce the activation energy required for the reaction, and thus lower the temperature required for the reaction. The porous carrier formed by combining silica with different particle sizes in a specific ratio can provide more sites for attaching the catalyst, thereby further improving the conversion rate and selectivity of glyoxal. This application prepares the catalyst by heating the solution, which can make silver, copper, phosphorus, and selenium disperse more evenly on the porous carrier, thus ensuring the catalytic effect of the prepared catalyst. Specific examples

[0049] Example 1

[0050] A method for preparing a catalyst for preparing glyoxal from ethylene glycol comprises the following steps:

[0051] S1. Add 50 g of the porous support, 8.2 g of copper phosphate, 7.6 g of silver phosphate, and 0.5 g of selenium dioxide to 100 g of hydrofluoric acid, mix well, and prepare a mixed solution;

[0052] S2, adjusting the pH of the mixed solution to 2 using formic acid;

[0053] S3, heat-treating the mixed solution to obtain an intermediate with a particle size of 10 μm;

[0054] S4, heat-treating the intermediate to obtain the catalyst for preparing glyoxal from ethylene glycol.

[0055] In step S1, the porous carrier includes silica A with an average particle size of 52 nm, silica B with an average particle size of 60 nm, and silica C with an average particle size of 75 nm, and the weight ratio of silica A, silica B, and silica C is 4.7:3.3:2.6; copper phosphate is purchased from Chengdu Borite Chemical Technology Co., Ltd., silver phosphate is purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd., and selenium dioxide is purchased from Beijing Bailingwei Technology Co., Ltd.; the mass fraction of hydrogen fluoride in hydrofluoric acid is 6.1%.

[0056] In step S2, the formic acid (Shanghai Aladdin Biochemical Technology Co., Ltd.) has a concentration of 85%.

[0057] In step S3, the heat treatment method is: heating to 350°C at a heating rate of 30°C / min and maintaining this temperature for 1.5 hours.

[0058] In step S4, the heat treatment method is: in an oxygen atmosphere, the heating temperature is 400° C., and the heating time is 5 hours.

[0059] Examples 2 to 6

[0060] The difference between Examples 2 to 6 and Example 1 is that in step S1, the ratio of the raw materials is different, as shown in Table 1 below.

[0061] Table 1

[0062]

[0063] The catalysts prepared in Examples 1 to 6 were used in the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275° C. were measured. The test results are shown in Table 2 below. The process flow is as follows:

[0064] Step 1: heating ethylene glycol to obtain ethylene glycol gas;

[0065] Step 2: Mix ethylene glycol gas, air, and inert gas in a volume ratio of 0.85:4.5:7.3;

[0066] Step 3: The mixed gas is passed into a reaction tower loaded with a catalyst with a service life of 20 hours to carry out a catalytic oxidation reaction. The temperature of the reaction tower is controlled at 275° C. and the pressure is controlled at 0.75 MPa.

[0067] Step 4: The gas generated by the reaction is rapidly cooled and then sent to an absorption tower for repeated absorption to obtain a glyoxal aqueous solution.

[0068] Table 2

[0069]

[0070] From the test results in Table 2, it can be seen that the temperature for preparing glyoxal in Examples 1 to 6 is relatively mild, and the conversion rate of glyoxal is above 97%, and the selectivity is above 85%.

[0071] Examples 7 to 11

[0072] The difference between Examples 7 to 11 and Example 1 is that in step S1, the average particle sizes of silicon dioxide A, silicon dioxide B, and silicon dioxide C are different, as shown in Table 3 below.

[0073] Table 3

[0074]

[0075] The catalysts prepared in Examples 7 to 11 were used in the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275° C. were measured. The test results are shown in Table 4 below.

[0076] Table 4

[0077]

[0078] From the test results in Table 4, it can be seen that the temperature for preparing glyoxal in Examples 7 to 11 is relatively mild, and the conversion rate of glyoxal is above 97.5%, and the selectivity is above 87%.

[0079] Examples 12 to 16

[0080] The difference between Examples 12 to 16 and Example 1 is that in step S1, the weight ratios of silicon dioxide A, silicon dioxide B, and silicon dioxide C are different, as shown in Table 5 below.

[0081] Table 5

[0082]

[0083]

[0084] The catalysts prepared in Examples 12 to 16 were subjected to the process flow for preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 6 below.

[0085] Table 6

[0086]

[0087] From the test results in Table 6, it can be seen that the temperature for preparing glyoxal in Examples 12 to 16 is relatively mild, and the conversion rate of glyoxal is above 97%, and the selectivity is above 85%.

[0088] Examples 17 to 21

[0089] The difference between Examples 17 to 21 and Example 1 is that in step S1, the mass fraction of hydrogen fluoride in hydrofluoric acid is different, as shown in Table 7 below.

[0090] Table 7

[0091] Mass fraction of hydrogen fluoride (%) Example 1 6.1 Example 17 5.2 Example 18 7.5 Example 19 5.8 Example 20 6.4 Example 21 7.1

[0092] The catalysts prepared in Examples 17 to 21 were subjected to the process flow for preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 8 below.

[0093] Table 8

[0094]

[0095]

[0096] From the test results in Table 8, it can be seen that the temperature for preparing glyoxal in Examples 17 to 21 is relatively mild, and the conversion rate of glyoxal is above 97%, and the selectivity is above 85%.

[0097] Examples 22 to 26

[0098] The difference between Examples 22 to 26 and Example 1 is that in step S2, the acid for adjusting pH and / or the pH are different, as shown in Table 9 below.

[0099] Table 9

[0100] Acid pH Example 1 Formic acid 2 Example 22 Formic acid 1.5 Example 23 Lactic acid 1.75 Example 24 Lactic acid 3.5 Example 25 Salicylic acid 3.1 Example 26 Formic acid 2.6

[0101] The lactic acid in Examples 23 and 24 was purchased from Tianjin Xiens Biochemical Technology Co., Ltd., the salicylic acid in Example 25 was purchased from Shanghai Haohong Biomedicine Technology Co., Ltd., and the salicylic acid in Examples 22 and 26 had the same source as that in Example 1.

[0102] The catalysts prepared in Examples 22 to 26 were used in the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275° C. were measured. The test results are shown in Table 10 below.

[0103] Table 10

[0104]

[0105]

[0106] From the test results in Table 10, it can be seen that the temperature for preparing glyoxal in Examples 22 to 26 is relatively mild, and the conversion rate of glyoxal is above 97.5%, and the selectivity is above 86%.

[0107] Examples 27 to 32

[0108] The difference between Examples 27 to 32 and Example 1 is that in step S3, the heat treatment methods are different, and the average particle sizes of the intermediates obtained are different, as shown in Table 11 below.

[0109] Table 11

[0110]

[0111] The catalysts prepared in Examples 27 to 32 were used in the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275° C. were measured. The test results are shown in Table 12 below.

[0112] Table 12

[0113]

[0114] From the test results in Table 12, it can be seen that the conditions for preparing glyoxal in Examples 27 to 32 are relatively mild, and the conversion rate of glyoxal is above 97.5%, and the selectivity is above 85%.

[0115] Examples 33 to 38

[0116] The difference between Examples 33 to 38 and Example 1 is that in step S4, the heat treatment method is different, as shown in Table 13 below.

[0117] Table 13

[0118]

[0119] The catalysts prepared in Examples 33 to 38 were subjected to the process flow for preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275°C were measured. The test results are shown in Table 14 below.

[0120] Table 14

[0121]

[0122] From the test results in Table 14, it can be seen that the conditions for preparing glyoxal in Examples 33 to 38 are mild, and the conversion rate of glyoxal is above 97.5%, and the selectivity is above 85.5%.

[0123] Comparative Examples 1 to 5

[0124] The differences between Comparative Examples 1 to 5 and Example 1 are as follows: the weight fractions of the porous carrier are different, as shown in Table 15 below.

[0125] Table 15

[0126]

[0127]

[0128] The catalysts prepared in Comparative Examples 1 to 5 were subjected to the process flow for preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275°C were measured. The test results are shown in Table 16 below.

[0129] Table 16

[0130]

[0131] From the test results in Table 16, it can be seen that in Comparative Examples 1 to 3, due to the weight fraction of the porous carrier being lower than 45%, the catalytic active components loaded on the prepared catalyst are relatively low, resulting in the conversion rate of the prepared glyoxal being lower than 87% and the selectivity being lower than 76%; in Comparative Examples 4 and 5, due to the weight fraction of the porous carrier being higher than 55%, the catalytic active components cannot be fully loaded on the porous carrier, resulting in the conversion rate of the prepared glyoxal being lower than 89% and the selectivity being lower than 80%.

[0132] Comparative Examples 6 to 11

[0133] The differences between Comparative Examples 6 to 11 and Example 1 are as follows: the average particle sizes of silica A, silica B, and silica C are different, as shown in Table 17 below.

[0134] Table 17

[0135]

[0136]

[0137] The catalysts prepared in Comparative Examples 6-11 were subjected to the process flow of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 18 below.

[0138] Table 18

[0139]

[0140] From the test results in Table 18, it can be seen that in Comparative Examples 6-11, due to the improper selection of the average particle size of silica A, silica B, and silica C, the prepared catalyst was used for catalytic oxidation to prepare glyoxal, and the conversion rate of glyoxal was lower than 90%, and the selectivity was lower than 80%.

[0141] Comparative Examples 12-17

[0142] The differences between Comparative Examples 12-17 and Example 1 are as follows: the weight ratios of silica A, silica B, and silica C are different, as shown in Table 19 below.

[0143] Table 19

[0144] Silica A Silica B Silica C Example 1 4.7 3.3 2.6 Comparative Example 12 4.5 3.3 2.6 Comparative Example 13 4.7 3 2.6 Comparative Example 14 4.7 3.3 2 Comparative Example 15 5.5 3.3 2.6 Comparative Example 16 4.7 3.6 2.6 Comparative Example 17 4.7 3.3 3.2

[0145] The catalysts prepared in Comparative Examples 12-17 were subjected to the process flow of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 20 below.

[0146] Table 20

[0147]

[0148] From the test results in Table 20, it can be seen that in Comparative Examples 12-17, since the weight ratios of silica A, silica B, and silica C did not fall within the range of (4.7-5.2):(3.2-3.4):(2.3-2.9), the prepared catalyst was used for catalytic oxidation to prepare glyoxal, and the conversion rate of glyoxal was lower than 90%, and the selectivity was lower than 80.5%.

[0149] Comparative Examples 18-21

[0150] The difference between Comparative Example 18 and Example 1 is that copper nitrate was used to replace copper phosphate, and the copper nitrate was purchased from Hubei Chengfeng Chemical Co., Ltd.

[0151] The difference between Comparative Example 19 and Example 1 is that silver chloride was used to replace silver phosphate, and the silver chloride was purchased from Shanghai Macklin Biochemical Co., Ltd.

[0152] The difference between Comparative Example 20 and Example 1 is that it does not contain copper phosphate.

[0153] The difference between Comparative Example 21 and Example 1 is that it does not contain silver phosphate.

[0154] The catalysts prepared in Comparative Examples 18 to 21 were subjected to the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 21 below.

[0155] Table 21

[0156]

[0157]

[0158] From the test results in Table 21, it can be seen that in Comparative Examples 18 and 19, due to the lack of phosphorus element, the conversion rate of glyoxal was lower than 92% and the selectivity was lower than 82% when the prepared catalysts were used for catalytic oxidation to prepare glyoxal; in Comparative Examples 20 and 21, due to the lack of copper phosphate or silver phosphate, the conversion rate of glyoxal was lower than 80% and the selectivity was lower than 70%.

[0159] Comparative Examples 22 - 25

[0160] The difference between Comparative Examples 22 - 25 and Example 1 is that the weight fraction of copper phosphate is different, as shown in Table 22 below.

[0161] Table 22

[0162]

[0163] The catalysts prepared in Comparative Examples 22 - 25 were subjected to the process of preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 23 below.

[0164] Table 23

[0165]

[0166] From the test results in Table 23, it can be seen that in Comparative Examples 22 and 23, due to the weight fraction of copper phosphate being lower than 8.2, the conversion rate of glyoxal was lower than 93.5% and the selectivity was lower than 83% when the prepared catalysts were used for catalytic oxidation to prepare glyoxal; in Comparative Examples 24 and 25, due to the weight fraction of copper phosphate being higher than 9.5, the conversion rate of glyoxal did not exceed 93% and the selectivity did not exceed 83% when the prepared catalysts were used for catalytic oxidation to prepare glyoxal.

[0167] Comparative Examples 26 - 29

[0168] The difference between Comparative Examples 26 - 29 and Example 1 is that the weight fraction of silver phosphate is different, as shown in Table 24 below.

[0169] Table 24

[0170]

[0171] The catalysts prepared in Comparative Examples 26 to 29 were subjected to the process flow for preparing glyoxal from ethylene glycol, and the conversion rate and selectivity of ethylene glycol at 275 °C were measured. The test results are shown in Table 25 below.

[0172] Table 25

[0173]

[0174] From the test results in Table 25, it can be seen that in Comparative Examples 26 and 27, since the weight fraction of silver phosphate was less than 7.5, the conversion rate of glyoxal prepared by catalytic oxidation of the prepared catalyst did not exceed 92.5%, and the selectivity was less than 83%; in Comparative Examples 28 and 29, since the weight fraction of silver phosphate was higher than 8, the conversion rate of glyoxal prepared by catalytic oxidation of the prepared catalyst did not exceed 92.5%, and the selectivity did not exceed 83%.

[0175] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. Use of a catalyst in the catalytic oxidation of ethylene glycol to prepare glyoxal, characterized in that, By weight parts, the catalyst raw material composition includes: 45 - 55 parts of porous carrier, 8.2 - 9.5 parts of copper phosphate, 7.5 - 8 parts of silver phosphate, 0.5 - 1 part of selenium dioxide, 100 parts of hydrofluoric acid, Wherein, the porous carrier includes silica A with a particle size of 52 - 55 nm, silica B with a particle size of 55.5 - 70 nm, and silica C with a particle size of 70.5 - 100 nm. The weight ratio of silica A, silica B, and silica C is (4.7 - 5.2):(3.2 - 3.4):(2.3 - 2.9); The mass fraction of hydrogen fluoride in the hydrofluoric acid is 5.2 - 7.5%.

2. The application according to claim 1, wherein The weight ratio of silica A, silica B, and silica C is 5.2:3.4:2.

9.

3. The application according to claim 1, wherein The particle size of silica A is 53.5 nm, the particle size of silica B is 57 nm, and the particle size of silica C is 81 nm.

4. The application according to claim 1, wherein 50 parts of the porous carrier, 8.2 parts of copper phosphate, 7.6 parts of silver phosphate, 0.5 part of selenium dioxide, and 100 parts of hydrofluoric acid.

5. The application according to claim 1, wherein The preparation method of the catalyst includes the following steps: S1. Add the porous carrier, copper phosphate, silver phosphate, and selenium dioxide into the hydrofluoric acid, mix evenly to obtain a mixed solution; S2. Adjust the pH of the mixed solution to 1.5 - 3.5; S3. Heat-treat the mixed solution to obtain an intermediate with a particle size of 7 - 10 μm; S4. Heat-treat the intermediate to obtain the catalyst.

6. The application according to claim 5, wherein In step S2, the pH of the mixed solution is adjusted by using one of formic acid, lactic acid, and salicylic acid.

7. The application according to claim 5, characterized in that In step S3, the heat treatment method is: heat up to 320 - 380 °C at a heating rate of 20 - 40 °C / min and maintain at this temperature for 1.5 - 2 hours.

8. The application according to claim 5, characterized in that In step S4, the heat treatment method is: in an oxygen atmosphere, the heating temperature is 350 - 450 °C and the heating time is 4 - 6 hours.

9. The application according to claim 8, wherein The method for preparing glyoxal includes the following steps: Step 1. Heat ethylene glycol to obtain ethylene glycol gas; ​ ​ ​

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