阅读说明：本技术 一种介孔固体酸催化剂制备方法及其在抗氧剂bht合成中的应用 (Preparation method of mesoporous solid acid catalyst and application of mesoporous solid acid catalyst in antioxidant BHT synthesis ) 是由 刘定华 郑鑫 居海军 于 2020-06-16 设计创作，主要内容包括：本发明涉及介孔固体酸催化剂制备方法及其用于抗氧剂BHT的合成,该方法包括第一步：利用溶胶凝胶法,选择合适原料及助剂制得二氧化硅溶胶,再向溶胶中逐滴加入配置好的盐溶液,继续搅拌至完全形成凝胶；第二步：得到的凝胶老化24h后在恒温干燥箱中干燥,干燥结束后将其于100~600℃焙烧活化,使之产生酸性位,即得催化剂成品。该方法制得催化剂可用于催化合成抗氧剂BHT。本发明催化剂制备过程简单高效,使用过程中无明显腐蚀性,避免了该抗氧剂工业化合成使用传统液体酸催化剂所带来的环境污染、后处理工艺复杂等问题,且具有很高的烷基化反应效率,反应条件温和,工艺简单、有望工业化应用。(The invention relates to a preparation method of a mesoporous solid acid catalyst and application of the mesoporous solid acid catalyst in synthesis of antioxidant BHT, wherein the method comprises the following steps: selecting proper raw materials and auxiliaries to prepare silicon dioxide sol by a sol-gel method, dropwise adding prepared salt solution into the sol, and continuously stirring until gel is completely formed; the second step is that: and (3) aging the obtained gel for 24 hours, drying the gel in a constant-temperature drying oven, and roasting and activating the gel at 100-600 ℃ after drying to generate an acid site, thus obtaining a catalyst finished product. The catalyst prepared by the method can be used for catalytically synthesizing antioxidant BHT. The catalyst has the advantages of simple and high-efficiency preparation process, no obvious corrosivity in the using process, high alkylation reaction efficiency, mild reaction conditions, simple process and hopeful industrial application, and avoids the problems of environmental pollution, complex post-treatment process and the like caused by the use of the traditional liquid acid catalyst in the industrial synthesis of the antioxidant.)

1. A preparation method of a mesoporous solid acid catalyst is characterized by comprising the following steps:

the first step is as follows: selecting proper raw materials and auxiliaries to prepare silicon dioxide sol by a sol-gel method, dropwise adding prepared salt solution into the sol, and continuously stirring until gel is completely formed;

the second step is that: and (3) drying the obtained gel in a constant-temperature drying oven after aging, and roasting and activating the gel at 150-350 ℃ after complete drying to generate an acid site, thus obtaining a catalyst finished product.

2. The method for preparing the mesoporous solid acid catalyst according to claim 1, wherein the sol-gel method comprises the following steps: mixing an auxiliary agent and deionized water in a flask, sequentially adding an acid solution and silicate ester under a stirring state, stirring for 10-50 min, dropwise adding a prepared salt solution, and continuously stirring for 2-5 h until gel is formed; and in the second step, the obtained gel is aged for 12-24 h, and is roasted and activated for 3-10 h at the temperature of 100-600 ℃ after the aging is finished, so that an acid site is generated, and a catalyst finished product is obtained.

3. The preparation method of the mesoporous solid acid catalyst and the use of the mesoporous solid acid catalyst in the synthesis of antioxidant BHT according to claim 1 are characterized in that, in the first step, the auxiliary agent is at least one of methyl cellulose, ethyl cellulose, cetyl trimethyl ammonium bromide, sesbania powder, polyvinyl alcohol and N, N-dimethylaniline hydrochloride; the acid is at least one of formic acid, acetic acid, nitric acid, hydrochloric acid and sulfuric acid; the salt is at least one of antimony sulfate, sodium sulfate, lithium sulfate, titanium sulfate, zirconium sulfate, cerium sulfate, strontium sulfate and barium sulfate.

4. The preparation method of the mesoporous solid acid catalyst according to claim 1 and the use of the mesoporous solid acid catalyst in the synthesis of antioxidant BHT are characterized in that, in the first step, the molar ratio of the acid, silicate, salt and auxiliary raw materials is 1: 0.5-1: 0.001-0.01: 0.0001 to 0.00001.

5. The use of the mesoporous solid acid catalyst of claims 1-4 in antioxidant BHT synthesis, characterized in that: and (3) putting a catalyst finished product into a high-pressure kettle, adding p-cresol serving as a raw material, heating to 60-100 ℃, introducing isobutene, stabilizing airflow, reacting at a constant temperature for 3.5-7.5 hours, and removing the catalyst after the reaction is finished to obtain the BHT-containing alkylation solution.

6. The use of the mesoporous solid acid catalyst according to claim 5 in antioxidant BHT synthesis, characterized in that: the feeding mass ratio of the catalyst and the p-cresol used in the alkylation reaction is 1: 3.5 to 5.5.

Technical Field

The invention relates to the technical field of catalyst preparation, in particular to a preparation method of a mesoporous solid acid catalyst and application of the mesoporous solid acid catalyst in antioxidant BHT synthesis.

Background

2, 6-di-tert-butyl-4-methylphenol, BHT for short, English name of Butylated hydroxytolyuene, molecular formula C15H24O, relative molecular mass 220.36, and chemical structure as follows:

BHT is a phenol antioxidant with the widest use and the largest dosage in the world, is nontoxic, not easy to corrode, has good storage stability, and can effectively delay the oxidative degradation of plastics or rubber and prolong the service life. The appearance is white or light yellow crystal powder, which is dissolved in benzene, toluene, methanol, ethanol, acetone and other solvents and is insoluble in water. It is an excellent antioxidant additive for various petroleum products, and can be widely used for lubricating oil, gasoline, paraffin and various raw oil, and can prevent the acid value or viscosity of lubricating oil and fuel oil from increasing. The antioxidant and the stabilizer can delay the rancidity of food as food antioxidant and stabilizer in food-grade plastics and packaged food. It can also be used in polyethylene, polystyrene, polypropylene, polyvinyl chloride, resin, polyvinyl acetate, cellulose resin and foamed plastic, food grade plastic, natural rubber, synthetic rubber, animal and vegetable oil and fat, food containing animal and vegetable oil and fat, cosmetic, etc.

The synthesis of BHT is mainly achieved by reacting p-cresol with an alkylating agent, which may be generally selected from isobutylene and isopropanol.

(1) An isopropanol method:

patent (CN 103694085B) discloses a method for synthesizing BHT, which uses p-cresol as raw material, isopropanol as alkylating agent, concentrated sulfuric acid as catalyst, and alumina as dehydrating agent to react to generate BHT. The method can not only produce a large amount of waste water, but also has low synthesis efficiency, and equipment can be seriously corroded due to the use of concentrated sulfuric acid in the reaction process.

(2) An isobutylene method:

the patent (CN 201310284145) discloses a synthesis method for synthesizing 2, 6-di-tert-butyl-4-methylphenol, which takes p-cresol as a raw material, isobutene as an alkylating agent and p-toluenesulfonic acid as a catalyst to react and synthesize BHT. Although the method avoids the problem of subsequent separation of a large amount of wastewater, the intermittent reaction can reduce the production efficiency; the use of p-toluenesulfonic acid can also corrode equipment and pollute the environment.

The mesoporous solid acid material has wide application in petrochemical industry and fine organic synthesis. In the aspect of structure, the mesoporous solid acid material has a good pore diameter structure, and reactant molecules can enter a pore channel in the reaction process, so that the reaction mass transfer rate is improved, and the mass transfer resistance is reduced. In addition, the mesoporous solid acid material has the advantages of simple preparation, mild reaction conditions and the like, has good catalytic efficiency when used for catalytic reaction, has little corrosion to equipment, is easier to separate products, has little three wastes, and belongs to an environment-friendly catalyst. Therefore, the mesoporous solid acid material has been attracting attention from development to application.

Therefore, it is urgently needed to develop a novel solid acid catalyst and a corresponding green process for catalytically synthesizing BHT, so as to replace sulfuric acid or p-toluenesulfonic acid catalyst used in the prior art and avoid a plurality of defects in the prior art; liquid acids such as sulfuric acid or p-toluenesulfonic acid and the like have strong corrosivity and have high requirements on corrosion resistance of equipment materials, and meanwhile, the inevitable corrosion of the equipment can increase the content of heavy metals such as chromium, nickel and the like in products, so that hidden troubles exist in the safety production of food-grade and feed-grade antioxidant additives BHT. Therefore, the development of the novel solid acid green catalytic synthesis BHT has important epoch significance and theoretical application value. .

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an automatic cleaning and disinfecting device for a test tube for gene detection, which has the following specific technical scheme:

the technical problem to be solved by the invention is as follows: aiming at the problems in the prior art, a preparation method of a mesoporous solid acid catalyst, the prepared catalyst and application thereof are provided. The preparation process is simple, only needs to be roasted once, and the catalyst efficiency of the prepared catalyst can be ensured.

Therefore, the invention provides the following technical scheme: the reaction equation is as follows: the method comprises the steps of taking p-cresol and isobutene as raw materials, preparing a mesoporous silica solid acid catalyst taking load sulfate as an active center by a sol-gel method under the action of a surfactant, adding the active center sulfate with the mass ratio of 25-35% into a reaction kettle, starting stirring for preheating, introducing isobutene for reaction after the temperature of a reaction system is raised to a target value, and opening the reaction kettle after the reaction is finished to obtain an alkylated liquid containing a BHT crude product.

The reaction mechanism of the method is that after isobutene is introduced, paracresol and isobutene molecules are diffused to the surface of the catalyst and then are internally diffused to pore channels of the catalyst. The mesoporous silica solid acid catalyst contains a large amount of L acid and B acid sites and a complex electronic layer structure. The p-cresol as the raw material loses the combination of proton and L acid position, isobutene enters pores to form isobutyl carbonium ions, and then the isobutyl carbonium ions and the p-cresol combined with the L acid position are subjected to electrophilic reaction to generate BHT.

In the method, the surfactant is methyl cellulose, ethyl cellulose, polyvinyl alcohol and hexadecyl trimethyl ammonium bromide.

According to the method, in the preparation process of the solid acid catalyst, formic acid and tetraethyl orthosilicate are mixed and stirred for 10-60 minutes, and sulfate is prepared into a solution and then is dropwise added into the mixed liquid.

In the method, the preferable reaction temperature of alkylation is 60-100 ℃.

In the method, the preferable reaction time for alkylation is 3.5-5.5 h.

The invention has the beneficial effects that: 1. the sulfate is loaded on the mesoporous silica and can be synthesized in one step by a sol-gel method, so that the defects of high equipment corrosion, more byproducts and low product purity existing in the traditional liquid acid serving as a catalyst are overcome, the using amount of the catalyst is reduced to a certain extent, the generation of water is avoided in the reaction process, and the reaction is promoted. 2. The reaction is a heterogeneous reaction system, and the catalyst can be completely removed from the alkylation solution through filtration, washing and centrifugation, so that the purity of the product is improved.

The specific implementation mode is as follows:

for the purpose of enhancing an understanding of the present invention, the following detailed description will be given of the present invention with reference to examples.