Method for improving amination modification efficiency or phenolic hydroxyl group content of alkali lignin

Abstract

The invention belongs to the field of improvement of reaction activity of alkali lignin, and discloses a method for improving the amination modification efficiency or phenolic hydroxyl group content of alkali lignin, which comprises the following preparation steps: adding lignin into a deep eutectic solvent system (a choline chloride / urea system, a choline chloride / glycerol system and a choline chloride / acetic acid system), uniformly mixing, carrying out heating treatment, adjusting the pretreatment temperature, adding deionized water to terminate the reaction after stirring treatment is conducted for a period of time, then performing centrifugation and freeze drying to obtain the pretreated alkali lignin, carrying out reduced pressure distillation to recover the deep-eutectic solvent system, or transferring the reaction system treated by the deep-eutectic solvent system into a dilute acid solution, continuing to mechanically stir for a period of time, and then centrifuging and vacuum drying to obtain the pretreated industrial alkali lignin. The solvent used in the pretreatment method is green and environment-friendly, can be recycled, and is free of pollution, and the method is simple in process, is easy to operate, is suitable for industrial production, and has a good application prospect.

Description

technical field [0001] The invention belongs to the field of improving the reaction activity of alkali lignin, and specifically relates to a method for increasing the amination yield or phenolic hydroxyl content of alkali lignin. Background technique [0002] The information disclosed in this background section is only intended to increase the understanding of the general background of the present invention, and is not necessarily taken as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. [0003] Lignin, as one of the most abundant natural polymers on earth, ranks second only to cellulose in reserves. Worldwide, approximately 30 million tons of lignin waste are obtained annually by various chemical pulping methods. As a by-product of the biomass refining process, most lignin is burned as fuel in the alkali recovery process, but the calorific value of lignin is low, and the combustion of a l...

AI Technical Summary

Problems solved by technology

However, the use of the above chemical reagents has caused an increase in the pressure of water pollution treatment, which is not a green and environmentally friendly method

[0005] On the other hand, there are a variety of chemical connections between the molecular structural units of lignin, presenting a complex and tight three-dimensional network structure, with low reactivity. In order to increase the content of phenolic hydroxyl groups in lignin and increase its reactivity, research Scholars use sulfuric acid to activate lignin

However, the use of the above-mentioned chemical reagents brings great pollution to the environment and does not meet the requirements of green environmental protection.

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