Process for Separation of Mild Acid Catalyzed Lignin Depolymerization Products and Its Extraction Products

Abstract

The invention discloses a process for separating a product of mild acid-catalyzed depolymerization of lignin. The process comprises the following steps: (1) with phenol as a solvent, adding main and auxiliary acidic catalysts under the conditions of stirring and normal pressure heating or normal pressure, wherein the usage amount of the acidic catalysts is 1 to 6 wt% of the total amount of phenol and lignin, adding lignin in batch, wherein a mass ratio of lignin to phenol is 4: 1-20, carrying out a catalytic reaction at a constant temperature of 90 to 150 DEG C for a period of time and selectively acquiring the product of mild acid-catalyzed depolymerization of lignin; and (2) extracting the depolymerization product of lignin by using a continuous solvent extraction method or simultaneous distillation and extraction method so as to obtain extraction products. Moreover, the invention also discloses the extraction products prepared by using the process. The process is low in separating temperature, so no damage is posed to the structure of the extraction products; the process is convenient to operate, low in cost, green, environment-friendly; an extraction agent can be continuously used; and compounds which can be extracted by the extraction agent can be thoroughly extracted by using a small amount of the extraction agent.

Description

technical field [0001] The invention belongs to the field of natural organic polymer chemical industry; it relates to a process for separating lignin depolymerization products and its products; more specifically, it relates to a process for separating mild acid-catalyzed lignin depolymerization products and its extraction products. Background technique [0002] Lignin is an amorphous, three-dimensional natural polymer, which accounts for about 10-35% of the total cell wall content, about 30% of the earth's organic carbon content, and about 40% of bio-based energy. The macromolecular structure of lignin is complex and has not been fully clarified so far. It is generally believed that lignin is composed of syringyl (3,5-dimethoxy-4-hydroxyphenylpropane), guaiacyl (3-methoxy -4-hydroxyphenylpropane) and p-hydroxyphenyl-(4-hydroxyphenylpropane) unit structures are complex organic polymers formed by C-O-C or C-C bonds, most of which are β-O-4 linkages. The molecular structure of...

AI Technical Summary

Problems solved by technology

[0006] However, for industrial-grade lignin, it usually contains more sugars, inorganic substances and insoluble impurities. After acid-catalyzed oxidation, the reaction products are more complex, and it is particularly difficult to separate and screen its depolymerization products.

Images