A kind of high-efficiency pretreatment of fibrous biomass to separate hemicellulose and its comprehensive utilization method

Abstract

The present invention proposes a high-efficiency pretreatment of fibrous biomass raw materials to separate hemicellulose and its comprehensive utilization method. Using fibrous biomass raw materials such as forestry biomass resources as raw materials, the fibrous biomass raw materials are firstly subjected to slurry method Pretreatment: The fibrous biomass raw material is ground by a ball mill and then sieved to obtain a certain mesh of fibrous biomass raw material powder, which is mixed with water in proportion at room temperature to obtain a premixed fibrous biomass raw material powder slurry. By adjusting the reaction temperature, time and water volume, the hydrothermal and efficient removal of hemicellulose in the fibrous biomass raw material powder premixed liquid system in the slurry state is realized. After the mixture is filtered, the filtrate is separated from low-dispersion hemicellulose by a gradient precipitation method, dried and precipitated, and stored. After the filter residue is mixed with a polar aprotic solvent and water, heated and stirred in a pressurized reaction kettle for a certain period of time, filtered and separated to obtain high-purity cellulose, washed with water, dried and stored. The filtrate is mixed with water and left to stand, and the precipitated powder is filtered and dried for storage. The filtrate is distilled under reduced pressure to recover water, solvent and a small amount of small molecule chemicals, and recycled. The invention uses my country's unique fast-growing forest fiber biomass raw material as raw material, the process is green and environmentally friendly, the cost is low, the dispersion degree of hemicellulose is low, the yield is high, and the solvent used can be recycled efficiently, the environment is friendly, and it is 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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