High-yield preparation method for high-purity low-molecular-weight lignin

Abstract

The invention discloses a high-yield preparation method for high-purity low-molecular-weight lignin and belongs to the field of biochemical engineering. According to the method, non-grain crops or bioethanol wood fiber waste is adopted as raw materials, the raw materials are pretreated through dilute acid steam explosion, and steam explosion materials with hemicellulose removed are obtained; the steam explosion materials and an ethanol water solution are added to a high-pressure reactor, temperature rises to 100 DEG C to 300 DEG C, and reacting is carried out for 0.5 h to 5 h at the temperature; after reacting is finished, cooling is carried out, products are dissolved in a reaction solution, pH is adjusted to be 1-7, and the high-purity low-molecular-weight lignin is obtained. The method has the advantages of being economical and feasible, environmentally friendly and high in yield and efficiency, and has wide prospects in the high-valued utilization direction of the lignin in agricultural waste.

Description

technical field [0001] The invention belongs to the field of biochemical industry, and relates to a method for preparing high-purity low-molecular-weight lignin with high yield by utilizing non-grain crops or bioethanol lignocellulosic waste. Background technique [0002] Lignin is the second most abundant renewable biopolymer in nature, and it is also the only renewable aromatic biopolymer in nature. Lignin molecules are based on p-hydroxyphenylpropane, guaiacylphenylpropane, syringylphenylpropane and their structural derivatives, and become an aromatic polymer with a three-dimensional space network structure through C-O bonds and C-C links . Lignin has not been efficiently utilized so far, and a large amount of lignin resources are usually used for combustion for heating. [0003] High-purity low-molecular-weight lignin can be used to replace petroleum-based aromatic compounds and to prepare bio-based renewable functional polymer materials. The molecular weight of raw l...

AI Technical Summary

Problems solved by technology

The molecular weight of raw lignin in nature is as high as hundreds of thousands. The molecular weight of lignin obtained by different preparation methods is generally several thousand to tens of thousands, and the yield is low and the preparation conditions are harsh.

The traditional process uses the alkaline method to prepare lignin. This method uses a large amount of high-concentration alkaline solution, which causes serious environmental pollution and difficult water treatment in the later stage. The lignin prepared by this method is usually mixed with impurities such as cellulose and hemicellulose. The yield Usually less than 20%, lignin molecular weight is higher (usually Mw greater than 10000)

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