CN111979819A - Method for separating lignocellulosic biomass components - Google Patents

Abstract

The invention discloses a method for separating wood fiber biomass components, and belongs to the field of biomass refining. The method is characterized in that the lignocellulose raw material is separated at high temperature by using a cooking liquor formed by blending a methanesulfonic acid solution and a small molecular organic matter according to a certain ratio. Compared with the prior art, the method disclosed by the invention can improve the separation efficiency of each component, obtain cellulose pulp, hemicellulose sugars and lignin products, is easy to recycle methanesulfonic acid, is simple in operation process, is short in cooking time, and can effectively reduce the production energy consumption and the operation cost.

Description

Method for separating lignocellulosic biomass components

technical field

The invention relates to the field of biomass refining, and in particular provides a method for separating lignocellulosic biomass components.

Background technique

In recent years, research on biomass-based materials, energy and chemicals has gradually attracted widespread attention. The concept of "biomass refining" has been proposed for "petroleum refining", which aims to use wood fiber as raw material and utilize sustainable and environmentally friendly The technology produces high value-added products and realizes the high-value utilization of all components of wood fiber. The pulp and paper industry is a huge consumer of lignocellulosic raw materials. The traditional pulping process mainly utilizes cellulose in lignocellulosic raw materials, while the other two main components, hemicellulose and lignin, are not fully utilized. Based on the concept of biomass refining, exploring the efficient separation technology of all components of lignocellulosic raw materials is not only a severe challenge but also a rare development opportunity for the traditional pulp and paper industry. Therefore, the comprehensive, effective and high-value utilization of lignocellulosic biomass and the development of new separation technologies are of great significance for the comprehensive utilization of resources and the ecological environment of nature.

Chinese invention patent ZL99805811.4 relates to a method for producing pulp by using a mixture of formic acid and acetic acid as a cooking chemical agent. The method includes the following steps: (1) using a mixture of formic acid and acetic acid as a cooking medicine, wherein the content of formic acid is 80-40%, the content of acetic acid is 10-30%, the cooking temperature is 110-140 DEG C, and the time is 20-80min; (2) evaporation The used cooking liquor is brought to a solid content of 50-80%, and then a mixture of formic acid and acetic acid is obtained by distillation for cooking.

Chinese invention patent CN103924470A relates to a natural pulp production method for improving pulp whiteness. The method includes pre-treating plant fiber raw materials with sodium percarbonate, cooking with a mixed organic solvent of formic acid, acetic acid and acetone, and washing the cooked pulp with formic acid and hot water to prepare uncolored pulp.

Chinese invention patent ZL02813978.x relates to a method for preparing pulp by cooking using organic acids containing furfural including formic acid and acetic acid. The main steps of the method are: (1) a mixture containing an organic acid such as formic acid, acetic acid, a mixture thereof and furfural as a cooking reagent is subjected to cooking at 105-160° C.; (2) the recovery of the cooking reagent, the cooking reagent including the recovery step furfural obtained in . The pulp is finally obtained.

The above organic acid cooking technology mainly involves the use of organic acid to prepare traditional pulp, which has poor removal effect on lignin in raw materials, and a considerable amount of lignin remains in the pulp, which increases the consumption of subsequent bleaching chemicals; more Most importantly, since organic acids dissolve lignin and hemicellulose during the cooking process, the above patents do not involve the subsequent recycling of the dissolved lignin and hemicellulose resources, resulting in waste of biomass resources. adversely affect the ecological environment.

In order to improve the removal rate of lignin during the separation of lignocellulose by organic acids, small molecular compounds such as hydrogen peroxide and inorganic acids were added as catalysts to the separation system for catalytic cooking.

Chinese invention patent CN103898786A relates to a method for comprehensive utilization of biomass raw materials. The method mainly comprises the following steps: (1) under the catalysis of hydrogen peroxide, using an organic acid solution formed by formic acid and acetic acid (total acid concentration is 70-85%) to cook the pulverized biomass, and control the cooking The temperature is 90-120°C, the solid-liquid mass ratio is 1:5-1:15, the reaction time is 30-90min, and the solid-liquid separation is performed after the reaction is completed; (2) in the mixed solution formed by hydrogen peroxide, formic acid and acetic acid, the residual The solid is pickled, then washed with water, and the obtained solid is screened to obtain fine pulp cellulose; (3) the cooking waste liquid and the pickling waste liquid are evaporated and concentrated to obtain formic acid and acetic acid vapor and concentrated solution, and the concentrated solution is diluted with water and stirred. , the obtained solid is washed with water to obtain the desired lignin, and the obtained liquid is subjected to decolorization, filtration and concentrated crystallization to obtain xylose.

Chinese invention patent CN103122594A relates to a production method of dissolving pulp. The method mainly comprises the following steps: (1) using water, steam or dilute acid to pre-hydrolyze the fiber raw material; (2) using hydrogen peroxide and formic acid or acetic acid to form peroxy acid for cooking, and the cooking waste liquid is distilled and reused; (3) The pulp is treated with hemicellulase; (4) The pulp is bleached. Finally, a dissolving pulp with a brightness greater than 90% ISO, a content of α-cellulose greater than 92%, and a content of pentose polysaccharide less than 2.0% is obtained.

The consumption of hydrogen peroxide in the organic acid cooking process using hydrogen peroxide as a catalyst is relatively high, and hydrogen peroxide is easily decomposed in a high temperature environment and loses its catalytic performance. This process is only suitable for mild conditions, and the expected effect can be achieved by increasing the number of reaction sections and increasing the reaction time, which undoubtedly increases the investment and operating costs of the equipment. The addition of sulfuric acid during the separation of biomass by organic acid method increases the reaction intensity of the separation system, which will result in partial degradation of cellulose, a decrease in pulp yield, and a significant decrease in pulp strength. Sulphur in the element.

To sum up, in the existing research on the separation of biomass by organic acid method, the removal efficiency of lignin is low, and in the process of separation of lignocellulosic biomass by organic acid, the lignin structure is depolymerized at the same time. Condensation reaction occurs, which not only reduces the efficiency of delignification, but also increases the difficulty of subsequent depolymerization and reuse of lignin. Therefore, by developing a new technology for separating lignocellulose with organic acids, while improving the removal rate of lignin, pulp, hemicellulose sugars and lignin products with excellent performance can be obtained, which is very important for realizing high utilization of biomass resources. Value and industrialization are of great significance.

SUMMARY OF THE INVENTION

The present invention is aimed at the shortcomings of the above-mentioned prior art, and provides a method for separating lignocellulosic biomass components with simple operation process and short cooking time.

The technical scheme adopted by the present invention to solve the technical problem is: a method for separating lignocellulosic biomass components, which is characterized by the use of a cooking liquid composed of a certain proportion of methanesulfonic acid solution and small molecular organic matter blended to separate the lignocellulose. The raw materials are separated at high temperature.

The purpose of the above-mentioned high-temperature separation can be pulping for papermaking, or it can be used for biomass refining.

The small molecular organic matter of the present invention is used to synergistically separate biomass raw materials, preferably one or two of formic acid, acetic acid, oxalic acid, oxalic acid, benzoic acid, formaldehyde, acetaldehyde, propionaldehyde, glyoxal and benzaldehyde a mixture of more than one substance.

As a preference, the mass ratio of the methanesulfonic acid solution to the pure small molecular organic matter in the cooking liquid can be (5-95): (95-5), preferably (1-15): 1, more preferably (1- 9): 1. The mass percentage concentration of the methanesulfonic acid solution may be 10-95%, preferably 80-90%.

Further, the process conditions of high temperature separation in the method of the present invention include:

The mass ratio of material to liquid is 1:4-1:20, preferably 1:7-1:13, more preferably 1:7-1:10;

The cooking temperature is 40-200°C, preferably 80-170°C, more preferably 120-130°C;

Cooking time 5-900min, preferably 10-120min, more preferably 15-20min;

The heating rate is 1-5°C/min, preferably 5°C/min.

Further, after the high-temperature separation reaction in the papermaking and pulping process is completed, solid-liquid separation can obtain solids and black liquor, and the solids are used to prepare pulp; the black liquor can be used to extract lignin and/or hemicellulose. sugars, and recover methanesulfonic acid and small organics.

The extraction method of lignin and/or hemicellulose saccharides can adopt the existing conventional extraction methods, such as evaporation and concentration under reduced pressure, adding water to form precipitation to obtain lignin, and the hemicellulose saccharides dissolved in the water phase can be obtained after drying .

The recovery method of methanesulfonic acid and small molecular organics is as follows: after evaporation under reduced pressure, they are respectively obtained by multi-effect extraction and rectification.

The lignocellulosic feedstocks include wood (eg, poplar, eucalyptus, and acacia) and non-wood fibrous feedstocks (eg, bamboo, straw, wheat straw, and corn stover).

Compared with the prior art, the method for separating lignocellulosic biomass components of the present invention has the following outstanding beneficial effects:

(1) It is easy to obtain lignin and hemicellulose products, which is conducive to the subsequent comprehensive and effective high-value utilization of lignocellulosic biomass;

(2) The extraction rate of lignin in the raw material is improved, and the dosage of chemicals is reduced;

(3) Methanesulfonic acid can realize one-stage separation, and the small molecular organic matter is easy to recycle, and has the characteristics of simple operation process and low production cost;

(4) No other inorganic acids, inorganic salts and metal ions are introduced, and the obtained product is relatively pure.

Detailed ways

The present invention will be further described below with reference to specific embodiments, but it is not intended to limit the present invention.

Unless otherwise specified, the content of each component used in the following is a mass percentage content.

[Example 1]

Wood fiber raw material: Cizhu bamboo chips, length and width 2.0-4.0 cm, thickness 0.5-1.0 cm;

Cooking vessel: Hastelloy C reactor, heated by a program-controlled heating mantle.

Material ratio:

Cooking process:

A. the methanesulfonic acid solution and/or the cooking reagent of the above-mentioned formula amount are loaded into the reaction kettle with the Bamboo serrata, and the cooking time is 15min after being heated to 130 °C, and the heating rate of the heating process is 5.0 °C/min.

b. After the cooking is completed, solid and liquid are separated to obtain solid and black liquor. The solids were washed and screened to obtain pulp.

c. Recover chemical products such as cooking reagents, small molecular phenols, sugars and lignin in the black liquor. The recovery method of lignin and hemicellulose sugars can be concentrated by evaporation under reduced pressure, adding water to form precipitation to obtain lignin, and dissolved The hemicellulose saccharides in the aqueous phase can be obtained after drying.

Methanesulfonic acid and small-molecule organic compounds are obtained by multi-effect extraction and rectification after vacuum evaporation and reused.

Detection and analysis of the isolated product:

It can be seen from the above detection data that methanesulfonic acid can effectively separate the main components of lignocellulose, and can obtain a higher yield. By adjusting the ratio of methanesulfonic acid and organic medium, a better yield of lignin and hemicellulose can be achieved. With the increase of the ratio of formic acid in the organic medium, the yield of hemicellulose gradually decreases, indicating that in the case of higher formic acid At the concentration, the hemicellulose undergoes a severe degradation reaction.

Claims (7)

1. the method for separating lignocellulosic biomass components is characterized in that: the lignocellulosic raw material is separated at high temperature with the cooking liquid of certain proportioning methanesulfonic acid solution and small molecular organic matter blending. 2. The method for separating lignocellulosic biomass components according to claim 1, wherein the small molecular organic matter is formic acid, acetic acid, oxalic acid, oxalic acid, benzoic acid, formaldehyde, acetaldehyde, propionaldehyde, One or a mixture of two or more of glyoxal and benzaldehyde. 3. the method for separating lignocellulosic biomass components according to claim 1, is characterized in that: in the cooking liquid, the mass ratio of methanesulfonic acid solution and small molecular organic matter is (5-95): (95-5) . 4. The method for separating lignocellulosic biomass components according to claim 3, wherein the mass percentage concentration of the methanesulfonic acid solution is 10-95%. 5 . The method for separating lignocellulosic biomass components according to claim 1 , wherein the process conditions for high temperature separation include: a material-to-liquid mass ratio of 1:4-1:20, a cooking temperature of 40-200° C., and a cooking temperature of 40-200° C. 6 . Time 5-900min. 6. the method for separating lignocellulosic biomass components according to claim 1, is characterized in that: after high temperature separation reaction is completed, solid-liquid separation obtains solid matter and black liquor, The solids are used to prepare pulp; The black liquor is used to extract lignin and/or hemicellulose sugars, and to recover methanesulfonic acid and small molecular organics. 7. The method for separating lignocellulosic biomass components according to claim 1, wherein the lignocellulosic raw materials include wood and non-wood fiber raw materials.