Method for preparing microcrystalline celluloses by acid hydrolysis after pretreatment through high shear machinery

Abstract

The invention discloses a method for preparing microcrystalline celluloses by acid hydrolysis after pretreatment through high shear machinery. The method comprises the following steps: firstly, pulping and filtering wood dissolving pulp or refined cotton by high shear machinery to obtain pretreated pulp; mixing the pretreated slurry with acid liquor, and carrying out acid hydrolysis reaction to obtain an acid hydrolysis reaction product; finally, filtering the acid hydrolysis reaction product to obtain hydrolyzed celluloses; and washing the hydrolyzed celluloses to be neutral, and carrying outspray drying to obtain microcrystalline celluloses. According to the invention, the wood dissolving pulp or refined cotton is subjected to pulping pretreatment by the high shear machinery, the actingforce of the high shear machinery is used for cutting off fibers in the pretreatment process, so that the porosity and the specific surface area inside the fibers are increased, the accessibility ofacid liquor to the celluloses is improved, the penetration speed of the acid liquor into the celluloses is increased, the acid hydrolysis rate of the acid liquor to a cellulose amorphous region is increased, and the dosage of chemicals is reduced or the reaction time is shortened. The particle size of the microcrystalline cellulose product is regulated and controlled.

Description

technical field [0001] The invention belongs to the technical field of lignocellulose utilization, in particular to a method for preparing microcrystalline cellulose by acid hydrolysis after high-shear mechanical pretreatment. Background technique [0002] Microcrystalline cellulose is an important cellulose-based functional material, widely used in medicine, food, cosmetics, leather and other industrial fields; in the prior art, the preparation of microcrystalline cellulose mostly uses inorganic acids to directly acid hydrolyze cellulose fibers The raw material destroys the amorphous region of its aggregated structure and retains the crystalline region; and causes the cellulose fibers to break in the radial direction, thereby obtaining rod-shaped or Granular microcrystalline cellulose powder product. [0003] Because the crystalline regions and amorphous regions of the cellulose fiber aggregate structure are alternately arranged and wrapped with each other; while the cryst...

AI Technical Summary

Problems solved by technology

[0003] Because the crystalline regions and amorphous regions of the cellulose fiber aggregate structure are alternately arranged and wrapped with each other; while the crystalline region has a regular and compact structure, and in addition, the microfibers in the biological structure of the cellulose fiber raw material are tightly entwined, and the microfibers are closely combined; The above-mentioned structural features lead to low accessibility and poor selectivity of the acid solution to the amorphous region of cellulose when the acid hydrolysis process is used to prepare microcrystalline cellulose, slow penetration of the acid solution and slow acid hydrolysis reaction; in the prior art, in order to improve the penetration effect and reaction rate, the use of prolonging the reaction time and increasing the concentration of acid solution leads to higher preparation cost of microcrystalline cellulose, harsh preparation conditions and longer production cycle; at the same time, concentrated acid solution increases the environmental burden, which is not conducive to industrial production

Images