A kind of preparation method of high acid density celluloid enzyme resin solid acid catalyst

Abstract

A preparation method of a high-acid-density celluloid-like resin solid acid catalyst is to use the polyphenolic substance tannic acid rich in plants as a raw material, modify it with an acidic amino acid to prepare a tannin-acidic amino acid salt, and then A tannin-amino acid resin-based solid acid catalyst was synthesized by formaldehyde cross-linking. The tannin-amino acid resin prepared by this method has a high acid density and a catalytic active site similar to cellulase, and can effectively hydrolyze cellulose into reducing sugars. It provides an effective new method for converting cellulose into platform compounds.

Description

technical field [0001] The invention relates to a preparation method of a high-acid-density celluloid-like resin solid acid catalyst. First, the polyphenolic substance tannic acid rich in plants is used as a raw material, and the tannin-acidic acid catalyst is prepared by modifying it with acidic amino acids. Amino acid salts are then cross-linked with formaldehyde to synthesize a tannin-acidic amino acid resin-based solid acid catalyst. Background technique [0002] At present, the use of traditional fossil energy not only brings various environmental problems, such as air pollution, global warming, etc., but also due to its non-renewable nature, fossil resources will not be able to meet the energy needs of mankind in the future, and we are looking for new energy to replace fossil resources At present, biomass, as the only renewable organic carbon source on the earth, is regarded as the best substitute for the production of energy and chemicals. In biomass, glucose can be o...

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Problems solved by technology

[0002] At present, the use of traditional fossil energy not only brings various environmental problems, such as air pollution, global warming, etc., but also due to its non-renewable nature, fossil resources will not be able to meet the energy needs of mankind in the future, and we are looking for new energy to replace fossil resources At present, biomass, as the only renewable organic carbon source on the earth, is regarded as the best substitute for the production of energy and chemicals. In biomass, glucose can be obtained after depolymerization of cellulose, and then can be obtained by fermentation Ethanol, or platform compounds such as 5-hydroxymethylfurfural (HMF) by dehydration

[0003] Cellulose is a high polymer in which glucose units are connected by β-1,4-glucosidic bonds, and there are many hydrogen bonds in the molecule and between molecules, which brings great difficulties to the hydrolysis of cellulose into glucose. Acids and biological enzymes are often used to hydrolyze cellulose. For example, concentrated sulfuric acid can effectively expand crystalline cellulose and hydrolyze it into glucose by breaking the strong hydrogen bonds in crystalline cellulose, but there are many types of by-products and corrosion of equipment. , product and catalyst are difficult to separate, waste water treatment and other issues, the study found that the main reason why cellulase can hydrolyze efficiently is that there are binding groups and catalytic groups on its structure, and the binding group is responsible for the binding of the cellulase and cellulose chains. Hydroxyl groups form hydrogen bonds, shortening the distance between cellulase and cellulose. The catalytic group is responsible for hydrolyzing the glycosidic bonds on the cellulose chain. In cellulase, acid groups such as carboxyl and phenolic hydroxyl groups of amino acids are used as proton sources. Used to cleave glycosidic bonds, cellulase can selectively hydrolyze cellulose under mild conditions, however, due to the thermal instability of cellulase, the hydrolysis rate cannot be accelerated by increasing the temperature, resulting in long enzymatic hydrolysis reaction time, Cellulase itself is expensive and difficult to recycle. The high cost is the bottleneck of the enzymatic hydrolysis process. The above shortcomings limit the application of liquid acid and cellulase to hydrolyze cellulose. In order to make the process of hydrolyzing cellulose green and efficient, solid acid is used as a catalyst , especially the method of resin solid acid catalyzed hydrolysis of cellulose has been extensively studied. Compared with traditional methods, the use of solid acid in the process of hydrolysis of cellulose has the advantages of easy separation of products, recyclable utilization, and less corrosion to equipment. The literature reports

[0004] The sulfonated chloromethyl polystyrene resin is prepared by using chloromethyl polystyrene resin as a catalyst carrier. The chlorine groups on the resin are expected to be used as cellulose binders, and the sulfonic acid groups partially replace the chlorine groups after sulfonation. As a catalyst domain introduced into the resin, the solid acid catalyst has good stability and can be recycled without loss of activity, although the sulfonated chloromethyl polystyrene resin has good catalytic performance in cellulose hydrolysis because of its low acid density (0.0033 mmol / g), resulting in a lower rate of cellulose hydrolysis

[0005] Most of the existing solid acids are -SO 3 H acts as a catalytic group, however, the sulfonic acid group releases the H + post-formed-SO 3 -It will be hydrolyzed and shed in acidic medium, resulting in the loss of sulfonic acid group; secondly, -SO 3 H will further degrade glucose at high temperature, and the sulfonating agents such as concentrated sulfuric acid and chlorosulfonic acid used in the sulfonation process of the catalyst will cause great environmental pollution, which is not in line with the environmental friendliness of today's green chemistry. Suganuma et al. The carbon source synthesis sulfonation catalyst catalyzes the hydrolysis of cellobiose. Since the catalyst does not contain -OH, it is difficult to adsorb cellobiose, the catalytic activity is low, and the glucose yield is only 30.1%.

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