Preparation and application of adjustable spherical silicon-aluminum compound containing two acids
The spherical silicon-aluminum composite was prepared by hydrolyzing aluminum alcohol and silicate composite, which solved the problem of insufficient activity of the phthalothic alumina catalyst, achieved efficient catalytic acetone glycerol reaction and had the ability to reuse.
Patent Information
- Application Number
- CN202510386054.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-30
- Publication Date
- 2025-08-01
AI Technical Summary
The existing pseudo-thin water-thin catalysts are insufficient in catalytic activity in the catalytic glycerol acetone ketalization reaction and cannot be recycled. The preparation method for low-silicon spherical pseudo-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin water-thin catalysts are not suitable for the preparation of high-silicon aluminum composite spheres.
After hydrolyzing C3-C6 aluminum alcohol and adding acid additives, silicate ester is added for composite, a spherical silicon-aluminum composite sol containing two acids was prepared, and the balls were dripped with an oil ammonia column and heat treatment was performed to adjust the SiO2 content to adjust the acidity and pore structure.
The prepared spherical silicon-aluminum composite has both B acid and L acid, and its acidity and pore structure are adjustable, with high catalytic activity and good wear resistance, and can be reused and suitable for the preparation of acetone glycerol.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the chemical production process, and particularly relates to the preparation and application of a spherical silicon-aluminum composite with adjustable two acids. Background Art
[0002] The present invention relates to a method for preparing a catalyst with high purity, thermal stability and adjustable acidity by mixing an aluminum alkoxide hydrolyzate with a silicon ester compound in an aqueous medium, and then dropping the obtained sol through an oil-ammonia column, drying and calcining. The ratio of Bronsted acid and Lewis acid of the catalyst can be adjusted, and the pore volume and pore diameter can be adjusted. It is used for the preparation of acetone glycerol ketal, and has the advantages of high conversion rate and high selectivity.
[0003] Pseudoboehmite has the advantages of narrow pore size distribution, good mechanical strength, suitable isoelectric point and high physicochemical stability, etc., and is the most commonly used catalyst carrier in the catalytic field. However, it only contains Lewis acid itself and is difficult to catalyze the ketalization of glycerol and acetone. Therefore, it needs to be modified to improve its performance. Doping with silica can change the pore structure of alumina and form a material with both Bronsted acid and Lewis acid, which is beneficial to the preparation of acetone glycerol ketal. We have found that spherical low-silicon modified pseudoboehmite has certain catalytic activity, but the catalyst cannot be recycled, and the preparation method of low-silicon spherical pseudoboehmite is not suitable for the preparation of high-silicon content silicon-aluminum composite spheres. Therefore, a new method needs to be developed to prepare spherical silicon-aluminum composites with high silicon content. Summary of the Invention
[0004] The object of the present invention is to prepare a spherical silicon-aluminum composite containing two acids. Only silicon and alcohol are introduced during the preparation process, no other impurities are introduced, and no waste is discharged. The obtained spherical silicon-aluminum composite has adjustable pore structure, specific surface area and acidity. The technical solution of the present invention is to adjust by the way of adding silicon, prepare a silicon-aluminum composite sol, and obtain a spherical silicon-aluminum composite by using an oil-ammonia column. The method adopted is to add an acid assistant after hydrolyzing the aluminum alkoxide, then add a silicate ester for compounding, and the obtained sol is dropped into spheres and subjected to heat treatment to obtain a spherical silicon-aluminum composite containing two acids.
[0005] The technical solution of the present invention is as follows: A method for preparing a spherical silicon-aluminum composite containing two acids, characterized in that first hydrolyze C3-C6 aluminum alkoxide, then carry out acidolysis and then add a silicate ester to continue hydrolysis and aging, and drop the spheres through an oil-ammonia column. By changing the SiO2 content, a spherical silicon-aluminum composite containing two acids and having an adjustable ratio is obtained.
[0006] According to the above method, when hydrolyzing C3-C6 aluminum alkoxide, aluminum isopropoxide is preferably used.
[0007] According to the above method, it is characterized in that the water used for hydrolysis is high-purity water, the hydrolysis is carried out during stirring, the hydrolysis temperature is 80-95 °C, and the hydrolysis time is 0.5-4 h.
[0008] According to the above method, it is characterized in that the mixture obtained after hydrolysis is subjected to acid peptization, and the acid used can be HCl, HNO3, acetic acid or citric acid, preferably HNO3.
[0009] According to the above method, it is characterized in that a silicate alcohol solution is added, and the addition amount of SiO2 can be 15-70%.
[0010] According to the above method, it is characterized in that the temperature for adding the silicate solution is 80-95 °C, and the reaction time is 0.5-4 h.
[0011] According to the above method, it is characterized in that the prepared silicon-aluminum composite is subjected to alcohol-water separation to obtain a sol, and a spherical silicon-aluminum composite is obtained by using an oil-ammonia column dropping ball.
[0012] Compared with the existing acid catalysts, the spherical silicon-aluminum composite can have both Bronsted acid and Lewis acid at the same time, does not need to load other components, has a simple composition, adjustable acidity and pore structure, can be directly used as an acid catalyst for reactions, and the spherical particles have good wear resistance, can be reused, and are easy to separate from the products. Description of the Drawings
[0013] Figure 1 is the XRD diffraction pattern of the spherical silicon-aluminum composite in Examples 1-5 Figure 2 is the infrared spectrum of pyridine adsorption of the spherical silicon-aluminum composite in Examples 1-5 Figure 3 is the NH3-TPD pattern of the spherical silicon-aluminum composite in Examples 1-5 Figure 4 is the catalytic activity and selectivity of acetone glycerol ketal of the samples in Examples 1-5 Detailed Description of the Invention
[0014] Example 1: First, 10 g of aluminum isopropoxide is dissolved in isopropanol in a four-necked flask. 22 mL of deionized water is added at 85 °C. After hydrolysis for 2 h, 5 mL of HNO3 (0.1 mol / L) is added, and after peptization at 95 °C to prepare an aluminum sol, a mixed solution of 3.41 g of TEOS and isopropanol is added to the above sol solution, and the reaction continues for 3 h. The alcohol is evaporated at 110 °C to obtain a silicon-aluminum sol. Spheroidization and curing are carried out in an oil-ammonia column with paraffin oil on the upper layer and ammonia water (concentration about 10%) on the lower layer. The obtained spherical particles are naturally dried in a fume hood overnight and then placed in an oven at 110 °C for 7 h, and calcined in a muffle furnace at 550 °C to obtain the sample.
[0015] Example 2: First, add 10 g of aluminum isopropoxide dissolved in isopropanol into a four-necked flask, then add 22 mL of deionized water and hydrolyze at 85 °C. After 2 h of hydrolysis, add 5 mL of HNO3 (0.1 mol / L). After peptizing at 95 °C to prepare an aluminum sol, add a mixed solution of 5.62 g of TEOS and isopropanol to the above sol and react for 3 h. Distill off the alcohol at 110 °C to obtain a silica-alumina sol. Spherify and solidify in an oil-ammonia column with paraffin oil on the upper layer and ammonia water (concentration about 10%) on the lower layer. Place the obtained spherical particles in a fume hood and dry naturally overnight, then put them in an oven at 110 °C for 7 h, and calcine in a muffle furnace at 550 °C to obtain the sample.
[0016] Example 3: First, add 10 g of aluminum isopropoxide dissolved in isopropanol into a four-necked flask, then add 22 mL of deionized water and hydrolyze at 85 °C. After 2 h of hydrolysis, add 5 mL of HNO3 (0.1 mol / L). After peptizing at 95 °C to prepare an aluminum sol, add a mixed solution of 8.72 g of TEOS and isopropanol to the above sol and react for 3 h. Distill off the alcohol at 110 °C to obtain a silica-alumina sol. Spherify and solidify in an oil-ammonia column with paraffin oil on the upper layer and ammonia water (concentration about 10%) on the lower layer. Place the obtained spherical particles in a fume hood and dry naturally overnight, then put them in an oven at 110 °C for 7 h, and calcine in a muffle furnace at 550 °C to obtain the sample.
[0017] Example 4: First, add 10 g of aluminum isopropoxide dissolved in isopropanol into a four-necked flask, then add 22 mL of deionized water and hydrolyze at 85 °C. After 2 h of hydrolysis, add 5 mL of HNO3 (0.1 mol / L). After peptizing at 95 °C to prepare an aluminum sol, add a mixed solution of 13.33 g of TEOS and isopropanol to the above sol and react for 3 h. Distill off the alcohol at 110 °C to obtain a silica-alumina sol. Spherify and solidify in an oil-ammonia column with paraffin oil on the upper layer and ammonia water (concentration about 10%) on the lower layer. Place the obtained spherical particles in a fume hood and dry naturally overnight, then put them in an oven at 110 °C for 7 h, and calcine in a muffle furnace at 550 °C to obtain the sample.
[0018] Example 5: First, add 10 g of aluminum isopropoxide dissolved in isopropanol into a four-necked flask, then add 22 mL of deionized water and hydrolyze at 85 °C. After 2 h of hydrolysis, add 5 mL of HNO3 (0.1 mol / L). After peptizing at 95 °C to prepare an aluminum sol, add a mixed solution of 19.89 g of TEOS and isopropanol to the above sol and react for 3 h. Distill off the alcohol at 110 °C to obtain a silica-alumina sol. Spherify and solidify in an oil-ammonia column with paraffin oil on the upper layer and ammonia water (concentration about 10%) on the lower layer. Place the obtained spherical particles in a fume hood and dry naturally overnight, then put them in an oven at 110 °C for 7 h, and calcine in a muffle furnace at 550 °C to obtain the sample.
[0019] The spherical silica-alumina composite obtained by the present invention has a relatively high specific surface area, adjustable pore volume and pore diameter, variable Bronsted acid and Lewis acid, and the catalyst has a composite Bronsted + Lewis acid. The catalyst with such a structure has practical significance for the preparation of acetone glycerol ketal and can promote the deep application of biomass resources.
[0020] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the creative concept of the present invention, several improvements and transformations are made, and these all belong to the protection scope of the present invention.
Claims
1. Preparation and application of a spherical silica-alumina composite with adjustable two acids, characterized in that Hydrolyze the C3-C6 aluminum alkoxide first, then carry out acidolysis and then add silicate ester to continue hydrolysis and aging, and drip through an oil-ammonia column. By changing the SiO2 content, spherical silica-alumina composites containing two acids with adjustable ratios are obtained.
2. The method according to claim 1, wherein When hydrolyzing the C3-C6 aluminum alkoxide, aluminum isopropoxide is preferred.
3. The method according to claim 1, characterized in that The water used for hydrolysis is ultrapure water, the hydrolysis temperature is 80-95 °C, and the hydrolysis time is 0.5-4 h.
4. The method according to claim 1, wherein Carry out acid peptization on the mixture obtained after hydrolysis. The acid used can be HCl, HNO3, acetic acid or citric acid, and HNO3 is preferred.
5. The method according to claim 1, characterized in that Add the silicate ester alcohol solution, and the addition amount of SiO2 can be 15-70%.
6. The method according to claim 1, wherein The temperature for adding the silicate ester solution is 80-95 °C, and the reaction time is 0.5-4 h.
7. The method according to claim 1, characterized in that After the silica-alumina composite is separated by alcohol and water, use an oil-ammonia column to drip and obtain a spherical silica-alumina composite.