阅读说明：本技术 光高效催化异构化制备山梨酸的方法 (Method for preparing sorbic acid by virtue of efficient photocatalytic isomerization ) 是由 付强 陈艳艳 熊新国 官凤钢 刘宗飞 于 2020-05-06 设计创作，主要内容包括：本发明属于山梨酸的制备技术领域,具体涉及一种光高效催化异构化制备山梨酸的方法,包括以下步骤：(1)将山梨酸聚酯投入反应釜中,加入去离子水,打开光源,投入固体碱催化剂,搅拌升温进行反应；(2)反应完毕后,趁热过滤,得到山梨酸水溶液；(3)冷却结晶,洗涤,干燥,得山梨酸；其中,所述的固体碱催化剂为负载型阴离子交换树脂,以大孔阴离子树脂为载体,EDTA为络合媒介物,负载钯、铂、锌或铜离子,负载量为0.1-1wt％。本发明采用光催化技术操作简便,绿色环保,采用的负载型离子交换树脂碱性较强,催化反应时间短,提高生产效率,同时负载的金属离子与光源对异构化有协同促进作用,能够进一步降低副产焦油量。(The invention belongs to the technical field of sorbic acid preparation, and particularly relates to a method for preparing sorbic acid by virtue of photocatalytic isomerization, which comprises the following steps: (1) putting the sorbic acid polyester into a reaction kettle, adding deionized water, turning on a light source, putting a solid base catalyst, stirring and heating to react; (2) after the reaction is finished, filtering while the reaction is hot to obtain sorbic acid aqueous solution; (3) cooling, crystallizing, washing and drying to obtain sorbic acid; wherein the solid base catalyst is a load type anion exchange resin, macroporous anion resin is used as a carrier, EDTA is used as a complexing vector, palladium, platinum, zinc or copper ions are loaded, and the load capacity is 0.1-1 wt%. The method adopts the photocatalysis technology, is simple and convenient to operate, is green and environment-friendly, adopts the supported ion exchange resin with stronger alkalinity and short catalytic reaction time, improves the production efficiency, simultaneously has the synergistic promotion effect of the supported metal ions and the light source on isomerization, and can further reduce the byproduct tar amount.)

1. A method for preparing sorbic acid by high-efficiency photocatalytic isomerization is characterized by comprising the following steps: the method comprises the following steps:

(1) putting the sorbic acid polyester into a reaction kettle, adding deionized water, turning on a light source, putting a solid base catalyst, stirring and heating to react;

(2) after the reaction is finished, filtering while the reaction is hot to obtain sorbic acid aqueous solution;

(3) cooling, crystallizing, washing and drying to obtain sorbic acid;

wherein the solid base catalyst is a load type anion exchange resin, macroporous anion resin is used as a carrier, EDTA is used as a complexing vector, palladium, platinum, zinc or copper ions are loaded, and the load capacity is 0.1-1 wt%.

2. The process for preparing sorbic acid by photocatalytic isomerization with high efficiency according to claim 1, wherein: the preparation method of the solid base catalyst comprises the following steps:

(1) ion exchange resin pretreatment

Washing macroporous anion resin, soaking in 0.01-0.05 mol/L EDTA solution, standing for 5-24 hr, filtering, and drying;

(2) preparing raw materials containing palladium, platinum, zinc or copper ions into 0.1-1 wt% solution, then soaking pretreated ion exchange resin in the solution for 5-24h, and drying to obtain the catalyst.

3. The process for preparing sorbic acid by photocatalytic isomerization with high efficiency according to claim 2, wherein: drying at constant temperature of 30-60 ℃ for 2-12h in the step (1).

4. The process for preparing sorbic acid by photocatalytic isomerization with high efficiency according to claim 2, wherein: and (3) drying at constant temperature of 30-60 ℃ for 2-12h in the step (2).

5. The process for preparing sorbic acid by photocatalytic isomerization with high efficiency according to claim 1, wherein: the mass ratio of the sorbic acid polyester to the solid base catalyst in the step (1) is 150-200: 5-20.

6. The process for preparing sorbic acid by photocatalytic isomerization with high efficiency according to claim 1, wherein: in the step (1), the reaction temperature is 40-70 ℃, and the reaction time is 10-30 min.

7. The method for preparing sorbic acid by efficient photocatalytic isomerization as claimed in claim 1, wherein the light intensity of the light source is 600-1500L ux.

8. The method for preparing sorbic acid by high-efficiency catalytic isomerization according to claim 1 or 7, wherein the light source is an ultraviolet lamp, a red L ED lamp, a yellow L ED lamp, a blue L ED lamp, a green L ED lamp or a white L ED lamp.

Technical Field

The invention belongs to the technical field of sorbic acid preparation, and particularly relates to a method for preparing sorbic acid by virtue of efficient photocatalytic isomerization.

Background

Sorbic acid (Sorbic acid) with the chemical formula C₆H₈O₂Also called as cool tea acid, 2, 4-hexadienoic acid and 2-propenyl acrylic acid. It is a food additive, and has inhibitory effect on yeast, mold, etc. It can also be used in animal feed, cosmetics, medicines, packaging materials, rubber adjuvants, etc.

Sorbic acid has 4 isomers, namely trans-trans isomer (E-E), cis isomer (Z-Z), trans-cis isomer (E-Z) and cis-trans isomer (Z-E), wherein the trans-trans isomer is the active ingredient of sorbic acid. The other three isomers account for 8-20%, are sensitive to oxygen in air, are easy to oxidize, gel and discolor into byproduct tar, and reduce the yield and quality of sorbic acid.

At present, the preparation process of sorbic acid by depolymerizing sorbic acid polyester is common, and the modes for converting sorbic acid from sorbic acid polyester are generally an alkali-acidolysis method and an acidolysis method.

The alkali-acidolysis method is to convert sorbic acid polyester into sorbic acid in two steps, the first step is to saponify the polyester with alkali solution and depolymerize the polyester into sorbate, and the second step is to neutralize the sorbate with acid and dehydrate the sorbate into sorbic acid product. In the first step of saponification and depolymerization reaction, an alkali solution is used as a depolymerization catalyst and an isomerization reagent, and in the second step of reaction, an excessive acid solution is used for neutralizing the alkali in the first step to be acidic. Therefore, the alkali-acid hydrolysis method needs to consume a large amount of alkali and acid solution, and a large amount of high-salinity wastewater is generated through neutralization reaction.

The acidolysis process is currently the most common process, where polyester is depolymerized to sorbic acid by adding an acid solution to the polyester. The method can not depolymerize polyester completely, and has long reaction time, high reaction temperature and large acid-containing wastewater amount.

Patent CN110642698A discloses a method for preparing sorbic acid by acid hydrolysis of sorbic acid polyester, wherein the method for preparing sorbic acid by acid hydrolysis still has high byproduct rate of final tar, long preparation time and low yield in unit time.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method for preparing sorbic acid by photocatalytic isomerization with high efficiency overcomes the defects of the prior art, and the prepared sorbic acid has high yield, low tar content, simple operation and environmental protection by the synergistic action of a light source and a catalyst.

The invention is realized by adopting the following technical scheme:

the method for preparing sorbic acid by virtue of photocatalytic isomerization comprises the following steps:

(1) putting the sorbic acid polyester into a reaction kettle, adding deionized water, turning on a light source, putting a solid base catalyst, stirring and heating to react;

(2) after the reaction is finished, filtering while the reaction is hot to obtain sorbic acid aqueous solution;

(3) cooling, crystallizing, washing and drying to obtain sorbic acid;

wherein the solid base catalyst is a load type anion exchange resin, macroporous anion resin is used as a carrier, EDTA is used as a complexing vector, palladium, platinum, zinc or copper ions are loaded, and the load capacity is 0.1-1 wt%.

Preferably, the mass ratio of the sorbic acid polyester to the solid base catalyst in the step (1) is 150-200: 5-20.

Preferably, the reaction temperature in the step (1) is 40-70 ℃, and the reaction time is 10-30 min.

Preferably, the light intensity of the light source is 600-1500L ux, and the light source can be selected from an ultraviolet lamp, a red L ED lamp, a yellow L ED lamp, a blue L ED lamp, a green L ED lamp or a white L ED lamp.

The wavelengths corresponding to the ultraviolet lamp, the red L ED lamp, the yellow L ED lamp, the blue L ED lamp, the green L ED lamp and the white L ED lamp are respectively less than 400nm, 615-650nm, 580-595nm, 450-480nm, 495-530nm and 450-465nm, light with various wavelengths can cooperate with the solid base catalyst to improve the isomerization of the sorbic acid polyester, photoinduced intermolecular electron transfer, the reaction energy barrier is reduced, the conversion of cis-trans isomers is promoted, and the side yield of tar is further reduced.

The preparation method of the solid base catalyst comprises the following steps:

(1) ion exchange resin pretreatment

Washing macroporous anion resin, soaking in 0.01-0.05 mol/L EDTA solution, standing for 5-24 hr, filtering, and drying at 30-60 deg.C for 2-12 hr;

(2) dissolving raw materials containing palladium, platinum, zinc or copper ions in 5-75% ethanol mixed solvent to prepare 0.1-1 wt% solution, then soaking pretreated ion exchange resin therein for 5-24h, and drying at constant temperature of 30-60 deg.C for 2-12h to obtain the final product.

Compared with the prior art, the invention has the following beneficial effects:

1. the method adopts the photocatalysis technology, is simple and convenient to operate, and is green and environment-friendly.

2. The invention has high isomerization efficiency in the photocatalytic production process, reduces the tar yield and improves the sorbic acid yield.

3. The load type ion exchange resin adopted by the invention has stronger alkalinity and short catalytic reaction time, improves the production efficiency, and simultaneously, the loaded metal ions and the light source have a synergistic promotion effect on isomerization, and can further reduce the byproduct tar amount.

Detailed Description

The present invention will be further described with reference to the following examples.