CN104492487A - Silica composite ionic liquid solid acid material catalyst and preparation method thereof - Google Patents

Abstract

The invention provides a silica composite ionic liquid solid acid material catalyst and a preparation method thereof. The catalyst uses aminoalkyl trialkoxysilane to react with propane sultone or butane sultone to obtain trialkoxy silicon-containing ylide, which is then acidified with acid, and finally mixed with ethyl orthosilicate Perform hydrolysis and condensation to form a silica composite ionic liquid solid acid material catalyst. The material has high thermal stability, high acid value above 2.5mmol/g, large surface area, good catalytic effect and can be used repeatedly.

Description

A kind of silicon dioxide composite ionic liquid solid acid material catalyst and preparation method thereof

technical field

The invention relates to the technical field of organic chemical synthesis, in particular to a silica composite ionic liquid solid acid material catalyst and a preparation method thereof.

Background technique

In today's crisis of energy problems and environmental problems, it has become the goal of modern chemical industry to efficiently generate target products with a small amount of energy without producing unnecessary by-products. Acid catalysts are indispensable in the modern chemical industry and are widely used in the manufacture of various products such as pharmaceuticals, petrochemical products, and polymer products. However, most of the currently used liquid acid catalysts are hydrochloric acid and sulfuric acid. . The liquid catalyst used in the production process needs to be neutralized by alkali, and separated and recovered from the product by removing the salt generated by neutralization. However, a considerable amount of energy is consumed in the above neutralization and salt removal steps. In addition, there is a surplus of recovered salt on the market, mostly a by-product with little availability and thus often difficult to dispose of.

Compared with the above situation, since the solid acid catalyst does not need the above-mentioned neutralization or salt removal process during separation and recovery, unnecessary by-products can not be generated, and the target product can be produced in an energy-saving manner. Therefore, research in this area has been subject to scientific work. concerns of researchers (Ishihara, K; Hasegawa, A; Yamamoto, H. Angew. Chem. Int. Ed. 2001, 40, 4077.). In the research and development of solid acid catalysts, solid acid catalysts such as zeolite, silica-alumina, and hydrous niobium have become great achievements in the chemical industry and have made great contributions to society. In addition, as a strong acid polymer, a material obtained by sulfonating polystyrene is considered to be a solid acid, and it has been conventionally used as a cation exchange resin having acidity. In addition, it is known that Nafion (registered trademark of DuPont) having a sulfo group in the polytetrafluoroethylene skeleton is also an extremely strong solid acid (solid superacid) having hydrophilicity, and they are known as acids having a larger Strong super acid works. However, there is a problem that it is unstable to heat and the price is too high for industrial use. In view of the above, the use of solid acid catalysts is more difficult to design advantageous industrial processes in terms of performance and cost than the use of the above-mentioned liquid acids, and almost all chemical industries today rely on liquid acid catalysts. As a kind of green catalyst and reaction solvent, ionic liquid has been paid attention by scholars at home and abroad.

However, the recovery of ionic liquids during use, especially after reacting with more polar alcohols and carboxylic acids, cannot be recovered because they will dissolve in organic matter and are difficult to separate.

Contents of the invention

In order to solve the above problems, the present invention provides a silica composite ionic liquid solid acid material catalyst, which introduces hydrolyzable alkoxy silicon into the traditional ionic liquid structure, and synthesizes silica by mixing with ethyl orthosilicate for hydrolysis. The silicon composite ionic liquid solid acid material simplifies the recovery process of the material on the basis of maintaining the high catalytic activity of the ionic liquid.

To achieve the above object, the present invention adopts the following technical solutions:

A silica composite ionic liquid solid acid material catalyst, the catalyst adopts aminoalkyltrialkoxysilane to react with propane sultone or butane sultone to obtain an ylide containing trialkoxy silicon, Then acidify with acid to obtain sulfonic acid group functionalized ionic liquid monomer with anion as acid group, and finally carry out hydrolysis and condensation of ionic liquid monomer and ethyl orthosilicate in ethanol water mixed solvent to form silica composite ionic liquid Solid acid material catalyst.

Further, the aminoalkyltrialkoxysilane is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminoethyltriethoxysilane or 2-aminoethyl One of 3-aminopropyltrimethoxysilane and the like, preferably 3-aminopropyltrimethoxysilane.

Further, the acid is one of sulfuric acid, hydrochloric acid, phosphoric acid, and p-toluenesulfonic acid, preferably sulfuric acid.

Another object of the present invention is to provide a method for preparing a silica composite ionic liquid solid acid material, which has simple operation and high yield.

To achieve the above object, the present invention adopts the following technical solutions:

A preparation method of the silica composite ionic liquid solid acid material catalyst as claimed in claim 1, comprising the following steps:

Step a, preparation of ylide, using aminoalkyltrialkoxysilane as raw material, tetrahydrofuran as solvent, adding propane sultone or butane sultone and mixing, heating and stirring to obtain ylide; wherein aminoalkyl The molar ratio of trialkoxysilane to propane sultone or butane sultone is 1:1;

Step b, acidification, after dissolving the ylide in a mixed solvent of ethanol and water, adding an equal amount of acid and stirring at room temperature to obtain a homogeneous ionic liquid solution in which the anion is an acid radical;

Step c, the synthesis of solid acid material

Add tetraethyl orthosilicate with a molar ratio of 1:0.5 to 1:5.0 into the ionic liquid solution, continue to heat, stir, hydrolyze and condense, then pour it into an evaporating dish, evaporate the solvent in an oven, and react overnight , and then washed with hot water for 3 times, and dried the solid in an oven for 12 hours to obtain a silica composite ionic liquid solid acid material catalyst.

Further, the amount of tetrahydrofuran solvent used in step a is 4 to 10 times the mass of aminoalkyltrialkoxysilane.

Further, the heating temperature in step a is 70°C.

Further, the ylide obtained in step a is a white solid, which is filtered by suction, washed 3 times with diethyl ether or ethyl acetate with a concentration greater than 99%, and vacuum-dried at 60°C to obtain the ylide;

Further, the volume ratio of ethanol and water in the ethanol-water mixed solvent in step b is 1:1.

Further, during the hydrolysis and condensation reaction in step c, the heating temperature is 80°C.

Further, in step c, the solvent volatilization temperature, hot water temperature and drying temperature are all 80°C.

The acidic ionic liquid silica composite solid acid prepared above can be used as a catalyst for esterification, condensation, alkylation, etherification and other reactions.

The catalyst is recovered by filtration, washed with acetone, dried, and can be directly used in the next reaction.

Compared with the prior art, the advantages of the present invention are: the catalyst of the present invention has high thermal stability and qualitative properties, and the thermal decomposition temperature is above 180°C; the acid value is high, above 2.5mmol/g; it has a large surface area; and the catalytic effect is good , has high catalytic activity for general acid-catalyzed reactions such as: esterification, condensation, alkylation, etherification, etc.; the catalyst is easy to recover, can be separated by simple filtration, and can be reused many times. The silicon dioxide composite ionic liquid solid acid material synthesized by the invention has wide application prospects.

Further, the preparation method of the catalyst of the present invention is simple in operation and high in yield.

Detailed ways

The present invention will be further elaborated below by specific embodiment:

Example 1

Preparation of Silica Composite 3-Aminopropyltrimethoxysilyl Ionic Liquid Solid Acid Material

Preparation of step 1 ylide

Take 3-aminopropyltrimethoxysilane and 1,4-butane sultone as raw materials, add tetrahydrofuran solvent, the amount is 6 times the mass of 3-aminopropyltrimethoxysilane, at 70 ℃ After heating and stirring for 2 hours, a white solid was obtained, which was then suction-filtered, washed three times with 99% diethyl ether, and vacuum-dried at 60°C to obtain the ylide;

Step 2 Acidification

Dissolve 1 g of ylide in 5 g of a mixed solvent of ethanol and water at a volume ratio of 1:1, add sulfuric acid equal to the substance of the ylide, and stir and mix at room temperature for 4 hours to obtain the corresponding anion as hydrogen sulfate. Ionic liquid solution;

The third step is the synthesis of silica composite ionic liquid solid acid material

Add orthosilicate ethyl ester with a molar ratio of 1:1.0 to the ionic liquid monomer to the above ionic liquid solution, continue heating and stirring at 80°C for 12 hours, pour it into an evaporating dish, and carry out the solvent in an oven at 80°C Volatilize and react overnight, then wash with hot water at 80°C for 3 times, and dry the solid in an oven at 80°C for 12 hours to obtain a silica composite ionic liquid solid acid material catalyst with an acid value of 4.2mmol/g and a pyrolysis temperature of 220°C .

Example 2-4

Except for the following differences, the rest are the same as in Example 1, and the aminoalkyltrialkoxysilane is shown in Table 1 to obtain the following ionic liquid solid acid material catalyst.

Aminoalkyltrialkoxysilane used in Table 1 Embodiment 2-4 and the catalyst parameters obtained

Example 5-6

Except following difference, all the other are with embodiment 1, and acid is shown in table 2 respectively, and the catalyst result that different acids obtain is as table 2.

The acid used in table 2 embodiment 5-6 and the catalyst parameter that obtains

Example 7

Catalyzed esterification reaction: equipped with electromagnetic stirrer, thermometer, reflux condenser, the catalyzer that the embodiment 1 that adds 0.1mol acetic acid, 0.15mol n-butanol, 0.05g makes in the 100mL three-necked flask of water trap carries out 70 Heated and stirred at ℃, reacted for 4 hours, and the calculated yield was 95.1%. The catalyst was reused 5 times, but the catalytic activity did not change.

Example 8

Catalyzed condensation reaction: in the 100mL three-necked bottle that is equipped with electromagnetic stirring, reflux condenser, water trap, add the catalyst that 0.1mol cyclohexanone, 0.12mol ethylene glycol, 10ml cyclohexane and 0.05g embodiment 6 make , heated to reflux and stirred to azeotropically distill the water produced by the reaction and the entrainer. The reaction took about 1.5 hours, and the yield was 99.5%. The catalyst was reused 5 times, and the catalytic activity did not change.

Example 9

Catalyzed alkylation reaction: in the 100mL three-necked bottle that is equipped with electromagnetic stirring, reflux condenser, water trap, add the catalyst that 0.1mol catechol, 0.2mol tert-butanol and 0.1g embodiment 6 make, heat Reflux and stir, react for about 5 hours, the yield is 94%. The catalyst was reused 5 times, but the catalytic activity did not change.

Example 10

Catalyzed etherification reaction: in the 100mL three-necked bottle that is equipped with electromagnetic stirring, reflux condenser, water trap, add the catalyst that 0.1mol2-naphthol, 0.3mol methyl alcohol and 0.1g embodiment 6 make, carry out heating and reflux stirring, The reaction was about 6h, and the yield was 90%. The catalyst was reused 5 times, but the catalytic activity did not change.

Claims (10)

1. a silica compound ion liquid solid-acid material catalyst, it is characterized in that: described catalyst adopts aminoalkyl trialkoxy silane and propane sultone or butane sultone to react, obtain the inner salt containing tri-alkoxy silicon, acidifying is carried out again with acid, obtain the sulfonic functional ion liquid monomer that anion is acid group, finally be hydrolyzed ionic liquid monomer and ethyl orthosilicate in ethanol water mixed solvent condensation, forms silica compound ion liquid solid-acid material catalyst.

2. catalyst according to claim 1, is characterized in that: described aminoalkyl trialkoxy silane is the one in 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 2-aminoethyl triethoxysilane or 2-aminoethyl trimethoxy silane.

3. catalyst according to claim 1, is characterized in that: described acid is sulfuric acid, hydrochloric acid, phosphoric acid, the one in p-methyl benzenesulfonic acid.

4. a preparation method for silica compound ion liquid solid-acid material catalyst as claimed in claim 1, is characterized in that, comprise the following steps:

Step a, the preparation of inner salt, with aminoalkyl trialkoxy silane for raw material, oxolane is solvent, after adding propane sultone or butane sultone mixing, adds thermal agitation and obtains inner salt; Wherein the mol ratio of aminoalkyl trialkoxy silane and propane sultone or butane sultone is 1:1;

Step b, acidifying, after inner salt being dissolved in ethanol water mixed solvent, the acid amount of substance such as adding is stirred in room temperature, and the anion obtaining homogeneous phase is the ionic liquid solution of acid group;

Step c, the synthesis of solid-acid material

To in described ionic liquid solution, add the ethyl orthosilicate that mol ratio is 1:0.5 ~ 1:5.0, after proceeding to add thermal agitation hydrolytic condensation, further solvent volatiling reaction in an oven, reusable heat water washing, solid is dry in an oven, obtain silica compound ion liquid solid-acid material catalyst.

5. preparation method according to claim 4, is characterized in that: the consumption of tetrahydrofuran solvent described in step a is 4 ~ 10 times of aminoalkyl trialkoxy silane quality.

6. preparation method according to claim 4, is characterized in that: in step a, heating-up temperature is 70 DEG C.

7. preparation method according to claim 4, is characterized in that: the inner salt obtained in step a is white solid, after suction filtration, with concentration be greater than 99% ether or ethyl acetate washing after, carry out vacuum drying, obtain inner salt.

8. preparation method according to claim 4, is characterized in that: the volume ratio 1:1 of second alcohol and water in ethanol water mixed solvent in step b.

9. preparation method according to claim 4, is characterized in that: in step c during hydrolysis-condensation reaction, and heating-up temperature is 80 DEG C.

10. preparation method according to claim 4, is characterized in that: in step c, solvent volatilization temperature and hot water temperature and bake out temperature are 80 DEG C.