阅读说明：本技术 一种淀粉基固体酸、其制备方法和在水相体系中降解壳聚糖制备氨基葡萄糖盐酸盐中的应用 (Starch-based solid acid, preparation method thereof and application of starch-based solid acid in preparation of glucosamine hydrochloride by degrading chitosan in water phase system ) 是由 汪源浩 韩金山 赵丽娜 谭凤芝 李沅 刘兆丽 曹亚峰 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种淀粉基固体酸、其制备方法和在水相体系中降解壳聚糖制备氨基葡萄糖盐酸盐中的应用。首先以淀粉为碳源的多孔碳,再用浓H<Sub>2</Sub>SO<Sub>4</Sub>磺化多孔碳,制备酸密度高、热稳定性好的淀粉基固体酸。并利用淀粉基固体酸作为催化剂,降解壳聚糖制备D-氨基葡萄糖盐酸盐,原料价廉,方法简单、环保、D-氨基葡萄糖盐酸盐的产率高,且固体酸催化剂可循环利用,碳基固体酸催化剂与降解的反应液容易分离,能很好地避免液体酸降解壳聚糖制备氨基葡萄糖盐酸盐存在的问题。(The invention discloses a starch-based solid acid, a preparation method thereof and application thereof in preparing glucosamine hydrochloride by degrading chitosan in a water phase system. Firstly, porous carbon with starch as carbon source is used, and then concentrated H is used 2 SO 4 The starch-based solid acid with high acid density and good thermal stability is prepared by sulfonating porous carbon. The starch-based solid acid is used as a catalyst to degrade chitosan to prepare D-glucosamine hydrochloride, the raw material is low in price, the method is simple and environment-friendly, the yield of the D-glucosamine hydrochloride is high, the solid acid catalyst can be recycled, the carbon-based solid acid catalyst is easy to separate from degraded reaction liquid, and the method can well separate the carbon-based solid acid catalyst from the degraded reaction liquidThe problem of preparing glucosamine hydrochloride by degrading chitosan with liquid acid is avoided.)

1. The preparation method of the starch-based solid acid catalyst is characterized by comprising the following steps of:

(1) preparing porous carbon with starch as a carbon source: mixing starch with KOH or NaOH, carbonizing at 400 ℃ for 30-40min by using nitrogen as a carrier gas, and activating at 800 ℃ for 40-120min by using 500-; washing the product after carbonization and activation with HCl, washing with water, filtering and drying to obtain porous carbon;

wherein the mass ratio of the KOH or NaOH to the starch is 1-2: 1;

(2) with concentrated H₂SO₄Sulfonated porous carbon: adding concentrated H into the porous carbon obtained in the step (1)₂SO₄Reacting at 100-140 ℃ for 8-12 h; washing, filtering and drying a product obtained by sulfonation with water to obtain a starch-based solid acid catalyst;

the porous carbon and concentrated H₂SO₄The proportion of (A) is 1-2g to 100 ml.

2. The method for preparing a starch-based solid acid catalyst according to claim 1, wherein the concentration of HCl in the step (1) is 0.5-1.0 mol/L.

3. The method for preparing a starch-based solid acid catalyst according to claim 1, wherein in the step (1), the drying conditions are as follows: drying at 75-100 deg.C for 8-10 h.

4. The method for preparing a starch-based solid acid catalyst according to claim 1, wherein in the step (2), the water for washing the product obtained by sulfonation with water is water at 80-90 ℃; in the steps (1) and (2), filtering is carried out until the pH value of the filtrate is neutral.

5. The method for preparing a starch-based solid acid catalyst according to claim 1, wherein in the step (2), the drying conditions in the step (2) are as follows: drying at 70-100 deg.C for 8-10 hr.

6. A starch-based solid acid catalyst prepared by the method of any one of claims 1 to 6.

7. The starch-based solid acid catalyst according to claim 6, wherein the starch-based solid acid catalyst has an acid density of 0.352 to 2.607 mmol/g.

8. Use of the starch-based solid acid catalyst according to claim 6 or 7 for the degradation of chitosan in an aqueous system to produce glucosamine hydrochloride.

9. The use of claim 8, wherein the hydrochloric acid and chitosan are dissolved in water, and then a starch-based solid acid catalyst is added, and the degradation is carried out for 5-10h at the reaction condition of 50-100 ℃.

10. Use according to claim 8, wherein the molar ratio of hydrochloric acid to chitosan is 1.1: 1.0.

Technical Field

The invention relates to the technical field of catalysts, and particularly relates to a starch-based solid acid, a preparation method thereof and application thereof in preparation of glucosamine hydrochloride by degrading chitosan in a water phase system.

Background

Chitosan is an N-deacetylated product of chitin, and its chemical name is (1,4) -2-amino-2-deoxy- β -D-glucan, because of its excellent properties such as biocompatibility, film-forming property, non-toxicity, antioxidation and antibacterial property, it has received great attention [ in Mary, Lilimei, Guojiazhi, etc. ], the application of chitosan in tissue engineering [ J]The high technology of China, 2019(3), 103-; chitosan fiber [ J ] with functions of health in chidren, bacteriostasis and beauty treatment]Textile science research, 2019,173(05):68-69.]. However, chitosan has a molecular weight varying from tens of thousands to millions, and contains a large amount of-NH-in its molecule₂and-OH, strong hydrogen bonds are easily formed, so that the chitosan is only dissolved in solutions of certain organic acids and inorganic acids and is not dissolved in common solvents, water and dilute alkali, and the utilization of the chitosan is greatly limited. However, some degradation products of chitosan, such as low molecular weight chitosan (LWCS), chitosan oligosaccharides and D-glucosamine, have great potential for use in the pharmaceutical and food industries. The D-glucosamine is monosaccharide degraded by chitosan, and has effects of inhibiting growth of tumor cells, treating enteritis, and improving injection effect of antibiotics. Glucosamine hydrochloride (GAH) has good bioactivity, and can be widely applied in the fields of biological and medical engineering, such as anti-inflammatory and liver protection in the process of liver and kidney detoxification; when being applied to medicines, the composition has antibacterial and anti-inflammatory properties; when used together with antibiotics, the composition has the properties of reducing side reactions, promoting the absorption of antibiotics and the like. However, GAH is difficult to carry out chemicallySynthesis, usually prepared from chitosan or chitin by hydrolysis of glycosidic bonds. The current methods for chitosan degradation are chemical degradation [ Huang Q Z, Zhuo L H, Guo Y C₂O₂catalysed by phosphotungstate[J].Carbohydrate Polymers,2008,72(3):500-505.]The research progress of chitosan degradation [ Li Zhi, Liu Xiao Fei, Yang Dong Zhi, etc. ]]Chemical development, 2000,19(6): 20-23; development of application of edible chitosan in Chinese Uisan province [ J]Guangxi chemical fiber communication, 2003(1):25-30]And biodegradation [ Jinxinrong, Chaiping, Zhang Wen Qing, preparation method and research progress [ J ] of oligomeric water-soluble chitosan]Chemical evolution, 1998,17(2):17-21.]. For example, glucosamine hydrochloride is prepared by degradation using a concentration of hydrochloric acid. Research on preparation of glucosamine hydrochloride by acid hydrolysis of chitosan [ J]Light journal, 2010,25(1):36-38.]Degrading chitosan with hydrochloric acid with the concentration of 36%, wherein the yield of glucosamine hydrochloride is 55.1% under the conditions that chitosan/hydrochloric acid is 1/6, the reaction temperature is 95 ℃ and the reaction time is 7 h; preparation of D-glucosamine hydrochloride and optimization of technological conditions [ J ] of Wang Yan pine, Li hong Xia, Zhanghui ]]Jiangsu pharmaceutical and clinical research, 2005,13(5):22-24.]The yield of the glucosamine hydrochloride is 60 percent by using 30 percent hydrochloric acid under the conditions of the reaction temperature of 95 ℃ and the reaction time of 5 hours; preparation of Chen-Xiang-Yan, et al (Chen-Xiang-Yan, Wang Lin Chuan, Cen Jianjun, et al.) D-glucosamine hydrochloride]Jiangsu agricultural science, 2008(4) 232-.]Dissolving chitosan with 1% acetic acid, and reacting with 15% hydrochloric acid at 100 deg.C for 3 hr to obtain 4.6mg/mL glucosamine hydrochloride solution; optimization and component analysis of D-glucosamine sulfate hydrolysis conditions [ J]Biological processing, 2018(4) 92-98.]The yield of the D-glucosamine sulfate is 43.86 percent under the conditions that the mass fraction of sulfuric acid is 53.29 percent, the reaction temperature is 88.31 ℃ and the reaction time is 6 hours.

Although the degradation method can be used for preparing D-glucosamine, a large amount of acid and alkali are consumed in the production process, equipment is seriously corroded in the degradation process, products are difficult to separate in the separation process, reagents are difficult to recover, the cost is high, the environment is polluted in the post-treatment process, and the like. Therefore, due to various disadvantages in the chemical and enzymatic methods for degrading chitosan, better methods for degrading chitosan have to be found. At present, no relevant patent and foreign literature reports about a method for preparing D-glucosamine hydrochloride by degrading chitosan by using a starch-based solid acid catalyst.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of a starch-based solid acid catalyst and application of the starch-based solid acid catalyst in preparation of glucosamine hydrochloride by degrading chitosan in an aqueous phase system. The D-glucosamine hydrochloride is prepared by degrading chitosan by using starch-based solid acid with high acid density (2.607mmol/g) and good thermal stability as a catalyst, and the method has the advantages of low raw material price, simple method, environmental protection and high yield of the D-glucosamine hydrochloride.

The purpose of the invention is realized by the following technical scheme: a preparation method of a starch-based solid acid catalyst comprises the following steps:

(1) preparing porous carbon with starch as a carbon source: mixing starch with KOH or NaOH, carbonizing at 400 ℃ for 30-40min by using nitrogen as a carrier gas, and activating at 800 ℃ for 40-120min by using 500-; washing the product after carbonization and activation with HCl to remove inorganic salt, washing with water, filtering and drying to obtain porous carbon;

wherein the mass ratio of the alkali (KOH or NaOH) to the carbon (starch) is (1-2) to 1;

(2) with concentrated H₂SO₄Sulfonated porous carbon: adding concentrated H into the porous carbon obtained in the step (1)₂SO₄Reacting at 100-140 ℃ for 8-12 h; washing, filtering and drying a product obtained by sulfonation with water to obtain a starch-based solid acid catalyst;

wherein the porous carbon is mixed with concentrated H₂SO₄The proportion of (1-2g) to 100 ml.

Based on the technical scheme, preferably, in the step (1), the concentration of HCl is 0.5-1.0 mol/L.

Based on the above technical solution, preferably, in the step (1), the drying conditions are as follows: drying at 75-100 deg.C for 8-10 h.

Based on the technical scheme, in the step (1), the filtration is preferably carried out until the pH value of the filtrate is neutral.

Based on the technical scheme, in the step (2), the water for washing the product obtained by sulfonation with water is preferably 80-90 ℃; filtering until the pH value of the filtrate is neutral.

Based on the above technical solution, preferably, in the step (2), the drying conditions are as follows: drying at 70-100 deg.C for 8-10 hr.

The present invention also relates to the protection of starch-based solid acid catalysts prepared by the above-described process, said starch-based solid acid catalysts having an acid density in the range of 0.352 to 2.607 mmol/g.

The invention also relates to an application of the starch-based solid acid catalyst in preparing glucosamine hydrochloride by degrading chitosan in an aqueous phase system, wherein the route flow is as follows:

the method specifically comprises the following steps: dissolving hydrochloric acid and chitosan in water, adding starch-based solid acid catalyst, and degrading at 50-100 deg.C for 5-10 hr.

Based on the technical scheme, the molar ratio of the hydrochloric acid to the chitosan is preferably 1.1: 1.0.

Based on the technical scheme, preferably, the proportion relation of the starch-based solid acid catalyst, the hydrochloric acid and the chitosan is as follows: the proportion relation of the solid acid and the chitosan is (0.1-0.2g) 1.1mol:1.0 mol.

The invention has the beneficial effects that: the invention takes starch with wide source and low price as raw material to prepare novel porous starch-based solid acid, the density of the solid acid can reach 2.607mmol/g, and the thermal stability is good (25-430 ℃, the mass loss is less than or equal to 15%); the solid acid is used as the catalyst in an aqueous phase system after the protonation of the chitosan to degrade the chitosan to prepare the glucosamine, and the method has the advantages of mild reaction conditions, environmental friendliness, simple method, simple post-treatment and the like, and the yield of the D-glucosamine hydrochloride is high, the solid acid catalyst can be recycled, the carbon-based solid acid catalyst is easy to separate from degraded reaction liquid, and the problem of preparing the glucosamine hydrochloride by degrading the chitosan with liquid acid can be well avoided.

Drawings

FIG. 1 is an IR spectrum of a starch-based solid acid catalyst of example 5.

FIG. 2 is a scanning electron micrograph of a starch-based solid acid catalyst according to example 5.

FIG. 3 is a thermogravimetric plot of the starch-based solid acid catalyst of example 5.

FIG. 4 is a liquid chromatogram of D-glucosamine and the product (in the figure, D-glucosamine is the standard, the sample is the D-glucosamine product prepared by the method, and the reaction conditions are that 1.0g of chitosan is dissolved in 12.4mL of 0.5mol/L dilute hydrochloric acid, the density of starch-based solid acid is 1.27mmol/g, the density of starch-based solid acid is 0.1g, the temperature is 90 ℃, and the reaction time is 8 h).

Detailed Description

The following non-limiting examples will allow one of ordinary skill in the art to more fully understand the present invention, but are not intended to limit the invention in any way.