Process for efficiently preprocessing lignocellulose

Abstract

The invention relates to a process for efficiently preprocessing lignocellulose. The process adopts the following procedures of stepwise optimizing and hydrolyzing: firstly, boiling the lignocellulose in overheated water to ensure that most hemicellulose is dissolved into oligosaccharide; continuously reacting the boiled mixture in a special flash evaporation reactor; and gradually changing reaction temperatures in the process of reaction to slow down xylose decomposition as far as possible and ensure that the hemicellulose is more completely transformed into xylose. The process has the advantages of simpleness, low cost, reasonable energy utilization, no solid-liquid separation in stepwise process, direct hydrolysis on the hot mixture, energy saving and high hydrolysis efficiency of processed cellulose on enzyme.

Description

technical field [0001] The invention belongs to the field of biomass pretreatment, in particular to a process for pretreating lignocellulose with high efficiency. Background technique [0002] my country has a large amount of renewable straw resources, and the annual output can reach more than 600 million tons. Lignocellulose such as straw contains a large number of polymer compounds (cellulose and hemicellulose) composed of some sugar units. These sugar units are separated from the dense and complex structure of lignocellulose by chemical and biological methods. Producing environment-friendly fuel ethanol will become an effective way to solve the country's energy problems under the circumstances of high international oil prices and grain ethanol not meeting the national conditions. Cellulose, an important component of the cell wall, has an unconventional crystal structure, and is surrounded by denser lignin and hemicellulose, forming a shield and not easily hydrolyzed. It...

AI Technical Summary

Problems solved by technology

[0005] At present, the common pretreatment methods are roughly divided into four categories: ①Physical methods, mainly to reduce the size and mechanically change the microstructure of cellulose, including crushing, high temperature / low temperature cycle, microwave, ultrasonic, etc., these methods are either very effective Limited, or the cost is too high, not suitable for industrial use

②Biodegradation, some microorganisms such as soft rot fungi can degrade lignin, although it is a good choice in terms of saving energy, pretreatment costs and the environment; but as far as the fungi discovered and studied are concerned, their degradation speed Too slow, also consumes some cellulose and hemicellulose to a certain extent, therefore, it is not suitable as the main industrial treatment method

③Chemical treatment methods, including the use of acid, alkali, oxidant, etc., but most of the methods, such as lime treatment and ammonia fiber blasting treatment, can mainly dissolve lignin, but cannot dissolve hemicellulose, and additional methods are still required to use hemicellulose. Cellulose; using acid as a catalyst can accelerate the hydrolysis of hemicellulose, and using concentrated acid can effectively dissolve almost all hemicellulose and most of the cellulose, but since sulfuric acid must be recovered in the process, otherwise the cost is too high, and The recycling operation itself also adds a series of additional steps and costs

[0006] It is difficult for any single existing pretreatment method to simultaneously achieve: ① obtain xylose, the hydrolyzed product of hemicellulose, with high efficiency; ② produce less inhibitors of xylose degradation;

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