High-efficiency pretreatment separation of hemicellulose from fiber-based biomass raw material and comprehensive utilization method

Abstract

The invention provides high-efficiency pretreatment separation of hemicellulose from a fiber-based biomass raw material and a comprehensive utilization method. The method comprises the following steps: the forest biomass resource fiber-based biomass raw material is used as a raw material, and the fiber-based biomass raw material is firstly subjected to slurry method pretreatment: the fiber-based biomass raw material is ground by a ball mill, sieving is performed to obtain fiber-based biomass raw material powder with a certain mesh, and the powder and water are mixed according to a ratio at a room temperature to obtain a fiber-based biomass raw material powder slurry premixed liquid; through regulation and control of the reaction temperature, time and water quantity, high-efficiency hydrothermal removal of the hemicellulose in the fiber-based biomass raw material powder in the slurry fiber-based biomass raw material powder premixed liquid system is realized; after the mixed liquid is filtered, the filtrate is subjected to gradient precipitation to separate low-dispersion hemicellulose, the precipitate is dried, and the dried material is stored; after the filter residues, a polar aprotic solvent and water are mixed, the mixture is heated and stirred in a pressurized reaction kettle for a certain period of time, filtering separation is performed to obtain high-purity cellulose, the high-purity cellulose is washed by using water, drying is performed, and the dried high-purity cellulose is stored; the filtrate and water are mixed, the mixture is allowed to stand, the precipitated powder is filtered, drying is performed, and the dried material is stored; and the filtrate is subjected to reduced-pressure distillation to recover water, the solvent and a small amount of small-molecular chemicals, and recycling is performed. The method provided by the invention adopts the fast-growing forest fiber-based biomass raw material unique in China as the raw material, and has a green and environmentally-friendly process and low costs, the hemicellulose has a low dispersion degree and a high yield, the solvent used in the method can be efficiently recycled, and the method is friendly to the environment, and suitable for industrial production.

Description

technical field [0001] The invention belongs to the pretreatment technology of lignocellulosic biomass, in particular a method for separating low-dispersion hemicellulose from fibrous biomass by hydrothermal method, and then directional liquefaction to separate high-purity cellulose and dissociate lignin polyphenols. Background technique [0002] In recent years, with the depletion of non-renewable fossil resources on the earth and the increasing environmental pollution worldwide, people are paying more and more attention to the use of renewable resources to produce energy or chemicals to meet the needs of human society. Biomass is rich in reserves and is a renewable and cheap resource. Biomass resources are playing an increasingly important role in the progress of human society. It is considered to be the most effective renewable resource to partially replace petroleum resources. Cellulosic biomass is an abundant biomass resource that can be directly converted into liquid f...

AI Technical Summary

Problems solved by technology

The reaction mechanisms of the three are similar, the difference is the type and content of the product, the content of oligosaccharides in the sugar produced by ultra-low acid and acid-free hydrolysis is much higher than that of dilute acid hydrolysis, and there are more degradation products, but the production efficiency is not high

However, due to cognitive limitations, most scholars are currently focusing on the main factors affecting the pretreatment results in the conditions of supercritical carbon dioxide pretreatment, and no specific research on the removal effect of hemicellulose has appeared.

[0010] The acid hydrolysis process is mature, but there are equipment corrosion problems, and the reaction waste liquid pollutes the environment, and the post-treatment steps are complicated

Alkaline hydrolysis is not as widely used as acid hydrolysis. Enzymatic hydrolysis has attracted more and more attention because of its advantages such as good selectivity, mild reaction conditions, environmental friendliness, and simple equipment. However, its reaction cycle is too long and cellulase preparation Purification is difficult and expensive, so it is still difficult to achieve large-scale industrial application

[0011] Although there are many methods for removing hemicellulose, especially acid hydrolysis, there are still unresolved problems or aspects that need to be improved in the current mature technology:

[0012] (1) Acid hydrolysis and alkali hydrolysis are highly corrosive, the post-treatment of waste liquid and waste residue is complicated, and the process cost is high

[0013] (2) The reaction time of enzymatic hydrolysis is long, the purification of cellulase is difficult, and the price is expensive

[0014] (3) Process conditions such as supercritical pretreatment are harsh, and equipment investment is large

[0015] (4) Most of the existing pretreatment methods hydrolyze hemicellulose into small molecular substances such as furfural and acetic acid while depolymerizing lignin or cellulose, which has low added value and is difficult to achieve for biomass with high hemicellulose content. High value-added full-quality utilization

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