阅读说明：本技术 一种负载型杂多酸催化剂的制备方法 (Preparation method of supported heteropolyacid catalyst ) 是由 徐林 黄杰军 丁克鸿 徐志斌 徐文轩 钱赟 庞诗卉 于 2019-04-10 设计创作，主要内容包括：本发明的目的是提供一种负载型杂多酸的制备方法,并用于催化氯丙烯环氧化制备环氧树脂关键中间体环氧氯丙烷的方法。该催化剂具有制备收率高、催化活性和选择性好和稳定性强的特点。常温常压下,将一定比例的钨酸钠和磷酸溶于一定的水中,加入一定量的盐酸,此时在酸性条件下生成磷钨酸溶液,加入一定量的双氧水氧化后生成过氧钨酸溶液；再将一定量事先配置好的季铵盐有机溶液加入过氧磷钨酸的溶液中,在一定温度下反应一段时间,反应后,产物经离心、洗涤、干燥,得到杂多酸单体。(The invention aims to provide a preparation method of a supported heteropoly acid, and a method for preparing epoxy chloropropane which is a key intermediate of epoxy resin by catalyzing the epoxidation of chloropropene. The catalyst has the characteristics of high preparation yield, good catalytic activity and selectivity and strong stability. Dissolving sodium tungstate and phosphoric acid in a certain proportion in certain water at normal temperature and normal pressure, adding a certain amount of hydrochloric acid to generate a phosphotungstic acid solution under an acidic condition, and adding a certain amount of hydrogen peroxide to oxidize the solution to generate a peroxytungstic acid solution; adding a certain amount of quaternary ammonium salt organic solution prepared in advance into the solution of the peroxyphosphotungstic acid, reacting for a period of time at a certain temperature, and centrifuging, washing and drying a product after reaction to obtain the heteropoly acid monomer.)

1. A supported heteropolyacid catalyst, characterized in that its structural general formula is:

in the structural general formula: a is 250 to 300, b is 10 to 50; n is an integer of 3 to 20, preferably an integer of 7 to 14; said R₁、R₂And R₃Are alkyl groups of 4 carbons which are the same or different from each other.

2. A process for the preparation of a supported heteropolyacid according to claim 1, comprising the steps of:

(1) Preparing heteropoly acid monomer: dissolving sodium tungstate and phosphoric acid in a certain proportion in certain water at normal temperature and normal pressure, adding a certain amount of hydrochloric acid to generate a phosphotungstic acid solution under an acidic condition, and adding a certain amount of hydrogen peroxide to oxidize the solution to generate a peroxytungstic acid solution; adding a certain amount of quaternary ammonium salt organic solution prepared in advance into a solution of peroxyphosphotungstic acid, reacting for a period of time at a certain temperature, and centrifuging, washing and drying a product after reaction to obtain a heteropoly acid monomer;

(2) and (3) heteropoly acid monomer polymerization: sequentially adding N-isopropyl acrylamide, a heteropoly acid monomer, a free radical initiator Azobisisobutyronitrile (AIBN) and a solvent N, N-dimethylformamide into a pressure-resistant reaction bottle, stirring for dissolving, deoxidizing, carrying out polymerization reaction for 4 hours at 70 ℃, and after the reaction is finished, precipitating, centrifuging and drying a product to obtain the supported heteropoly acid catalyst.

3. The method for preparing a supported heteropolyacid according to claim 2, wherein the molar ratio of the sodium tungstate to the phosphoric acid in the step (1) is 3.0 to 5.0:1, preferably 3.5 to 4.5: 1.

4. The method of claim 2, wherein the amount of water in step (1) is 3 to 10 times, preferably 5 to 8 times, the weight of sodium tungstate.

5. the preparation method of the supported heteropoly acid according to claim 2, wherein the molar ratio of the hydrochloric acid to the sodium tungstate in the step (1) is 1.5-3.0: 1, preferably 2.0-2.5: 1;

6. The preparation method of the supported heteropolyacid according to claim 2, wherein the molar ratio of the hydrogen peroxide to the sodium tungstate in the step (1) is 1-10: 1, preferably 3-8: 1;

7. The preparation method of the supported heteropoly acid according to claim 2, wherein the molar ratio of the quaternary ammonium salt to the sodium tungstate in the step (1) is 2.8-3.3: 4, preferably 3.0-3.2: 4, and the molecular formula of the quaternary ammonium salt is C_n+3H_{2n+ 5}NR₁R₂R₃N is an integer of 3-20, preferably an integer of 7-14; said R₁、R₂and R₃Are alkyl groups of 4 carbons which are the same or different from each other.

8. The preparation method of the supported heteropoly acid according to claim 2, wherein the reaction temperature in the step (1) is 10-60 ℃, preferably 20-40 ℃; the reaction time is 1-10 h, preferably 3-5 h.

9. The preparation method of the supported heteropoly acid according to claim 2, wherein the molar ratio of the N-isopropyl acrylamide, the heteropoly acid monomer and the radical initiator Azobisisobutyronitrile (AIBN) in the step (2) is 2-8: 1: 0.001-0.005, preferably 3-6: 1: 0.002-0.004; the weight ratio of the N-isopropyl acrylamide to the solvent N, N-dimethylformamide is 1-10: 100.

10. the use of a supported heteropolyacid according to claim 1, wherein the reaction is as follows: adding 309.0g of chloropropene and 15.0g of supported heteropolyacid catalyst into a 500mL four-neck flask, heating to reflux, dropwise adding 69.6g of 49.1% hydrogen peroxide within 2.0h under a stirring state, and reacting for 4-6h at the reflux temperature; and (3) after the reaction is finished, carrying out secretion and standing layering to obtain an epichlorohydrin oil layer and a water layer, carrying out GC (gas chromatography) quantitative analysis on the epichlorohydrin and the 3-chloro-1, 2-propanediol content in the oil layer and the water layer, and measuring the residual hydrogen peroxide content in the water layer.

Technical Field

The invention belongs to the technical field of heteropoly acid preparation, and particularly relates to a preparation method of a supported heteropoly acid and a method for preparing epoxy chloropropane, a key intermediate of epoxy resin, by catalytic epoxidation of the supported heteropoly acid.

Background

The heteropoly acid is a kind of oxygen-containing polyacid which is formed by the coordination and bridging of heteroatoms (such as P, Si, Fe, Co and the like) and polyatomic atoms (such as Mo, W, V, Nb, Ta and the like) through oxygen atoms according to a certain structure. It not only has acidity, but also has oxidation-reduction property, and is a multifunctional novel catalyst; can be used for catalyzing homogeneous phase, heterogeneous phase, phase transfer and other reactions. The catalyst has good stability and no pollution to the environment, and is a promising green catalyst. The existing methods for preparing heteropoly acid mainly comprise an ether acidification extraction method, an ion exchange method and the like. The ether acidification extraction method has the advantages of harsh technological process requirement, high acidification pH requirement, completely different product structures even if the difference is 0.01, low boiling point, toxicity, flammability and easy volatilization of ether, dangerous use process and environmental pollution. The ion exchange method avoids the use of ether, has high production safety, but has long production period, great energy consumption and limited production capacity, and becomes the bottleneck of industrial production.

CN102744088 discloses a preparation method of phosphotungstic heteropoly acid: dissolving sodium tungstate and disodium hydrogen phosphate in water, and producing phosphotungstic acid under heating and acidic conditionsAnd sodium phosphotungstate, and then adding C_nH_2n+1N⁺Cl^-Adding the organic solution into a mixed solution of phosphotungstic acid and sodium phosphotungstate, reacting, and centrifuging, washing, drying and roasting a product to obtain the phosphotungstic heteropoly acid.

CN104282106 discloses a preparation method and application of a weak water-soluble load type phosphotungstic heteropoly acid: dissolving sodium tungstate in water, and dropwise adding the solution into dilute hydrochloric acid to obtain a yellow-green solid; adding a small amount of the yellow-green solid into the phosphoric acid solution for multiple times, and stirring to obtain water-soluble phosphotungstic heteropoly acid; adding citric acid, titanium-silicon molecular sieve (TS-1 for short) and potassium chloride solution; and centrifuging and drying the precipitate to obtain the supported TS-1 phosphotungstic heteropoly acid with the yield of 79.85 percent.

the heteropoly acid has good water solubility, poor solubility in an organic phase, causes difficult catalyst recovery, and has unstable catalytic activity caused by uneven distribution in the practical application process; compared with other acid catalysts, the catalyst has higher price and cannot be applied to industrial production. Therefore, the research on the heteropolyacid loading method is developed, the recovery rate of the catalyst is improved, and the method has very important significance for promoting petrochemical production and the like.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a preparation method of a supported heteropoly acid, and a method for preparing epoxy chloropropane which is a key intermediate of epoxy resin by catalyzing the epoxidation of chloropropene. The catalyst has the characteristics of high preparation yield, good catalytic activity and selectivity and strong stability.

In order to achieve the purpose of the invention, the invention adopts the following method:

(1) Preparing heteropoly acid monomer: dissolving sodium tungstate and phosphoric acid in a certain proportion in certain water at normal temperature and normal pressure, adding a certain amount of hydrochloric acid to generate a phosphotungstic acid solution under an acidic condition, and adding a certain amount of hydrogen peroxide to oxidize the solution to generate a peroxytungstic acid solution; adding a certain amount of quaternary ammonium salt organic solution prepared in advance into a solution of peroxyphosphotungstic acid, reacting for a period of time at a certain temperature, and centrifuging, washing and drying a product after reaction to obtain a heteropoly acid monomer;

The molar ratio of sodium tungstate to phosphoric acid is 3.0-5.0: 1, preferably 3.5-4.5: 1;

The water amount is 3-10 times, preferably 5-8 times of the weight of the sodium tungstate;

The molar ratio of the hydrochloric acid to the sodium tungstate is 1.5-3.0: 1, preferably 2.0-2.5: 1;

The molar ratio of hydrogen peroxide to sodium tungstate is 1-10: 1, preferably 3-8: 1;

the quaternary ammonium salt organic solution refers to organic solutions of quaternary ammonium salt such as chloromethane, dichloromethane, chloroform, carbon tetrachloride, dichloroethane and the like;

The molecular formula of the quaternary ammonium salt is C_n+3H_2n+5NR₁R₂R₃(structural formula is) N is an integer of 3-20, preferably an integer of 7-14; said R₁、R₂and R₃Are alkyl radicals of 4 carbons which are identical or different from one another;

The molar ratio of the quaternary ammonium salt to the sodium tungstate is 2.8-3.3: 4, preferably 3.0-3.2: 4;

The reaction temperature is 10-60 ℃, and preferably 20-40 ℃; the reaction time is 1-10 h, preferably 3-5 h.

(2) And (3) heteropoly acid monomer polymerization: sequentially adding N-isopropyl acrylamide, a heteropoly acid monomer, a free radical initiator Azobisisobutyronitrile (AIBN) and a solvent N, N-dimethylformamide into a pressure-resistant reaction bottle, stirring for dissolving, deoxidizing, carrying out polymerization reaction for 4 hours at 70 ℃, and after the reaction is finished, precipitating, centrifuging and drying a product to obtain the supported heteropoly acid catalyst.

the reaction equation is:

A supported heteropolyacid catalyst, its general structural formula is:

The meanings of each letter in the structural general formula are as follows: a represents the number of N-propyl acrylamide branched chains, the range is 250-300, b represents the number of quaternary ammonium salt branched chains, the range is 10-50;

The molar ratio of the N-isopropyl acrylamide to the heteropoly acid monomer to the free radical initiator Azobisisobutyronitrile (AIBN) is 2-8: 1: 0.001-0.005, preferably 3-6: 1: 0.002-0.004;

The weight ratio of the N-isopropyl acrylamide to the solvent N, N-dimethylformamide is 1-10: 100.

(3) and (3) ECH synthesis: the high molecular catalyst is applied to olefin epoxidation reaction, and more specifically is used for catalyzing hydrogen peroxide chloropropene to epoxidize and synthesize epichlorohydrin. The reaction process is as follows: 309.0g of chloropropene and 15.0g of catalyst are added into a 500mL four-neck flask, the temperature is raised to reflux, 69.6g of 49.1% hydrogen peroxide is dripped into the flask within 2.0h under the stirring state, and the mixture reacts for 4 to 6h at the reflux temperature; and (3) after the reaction is finished, carrying out secretion and standing layering to obtain an epichlorohydrin oil layer and a water layer, carrying out GC (gas chromatography) quantitative analysis on the epichlorohydrin and the 3-chloro-1, 2-propanediol content in the oil layer and the water layer, and measuring the residual hydrogen peroxide content in the water layer.

Detailed Description

the following examples illustrate the preparation and use of the present catalyst. The examples are not intended to limit the practical scope of the present invention to the conditions described in the examples.