CN104988783B - Pulping method and product of reed organic solvent pulp with hemicellulose pre-extracted - Google Patents

Abstract

The present invention relates to pulping process of phragmites communiss organic solvent slurry of preextraction hemicellulose and products thereof.Method includes：Phragmites communiss are got the raw materials ready；Prehydrolysis；Solid-liquor separation and washing；Residue high boiling alcohol method prepares paper pulp.Said method obtains reed pulp and the phragmites communiss extracting solution that can prepare saccharide compound or ethanol.Compared with not hydrolyzing the phragmites communiss raw material extracting hemicellulose, after prehydrolysis, under identical Pulping conditions, the Kappa number of gained slurry reduces 58 units to phragmites communiss.Carry out prehydrolysis and extract hemicellulose before slurrying, the high difficult point of sugared content in high boiling solvent (hbs) recovery system can be reduced, can achieve each component effectively utilizes of Wooden Biomass raw material again, improve the added value of side-product, the Financial cost of balance high boiling solvent (hbs) slurrying.

Description

Pulping method and product of reed organic solvent pulp with hemicellulose pre-extracted

technical field

The invention relates to the fields of chemical engineering and reed pulping technology, in particular to a reed organic solvent pulping method and a product thereof by pre-extracting hemicellulose.

Background technique

my country's timber resources are very scarce, and the bottleneck of papermaking raw materials is prominent. Reed is an important non-wood papermaking raw material with high cost performance. Therefore, the scientific and rational use of non-timber raw materials such as reeds can solve the problem of insufficient raw materials for papermaking in my country.

Organic solvent pulping is a pollution-free and clean pulping method, and high-boiling alcohol solvent pulping belongs to the category of organic solvent pulping methods. Document 1 Preliminary Study on Bagasse Pulping with High Boiling Alcohol Solvent Method -- "China Papermaking", Issue 06, 2008, Document 2 Preparation of Straw Pulp and Lignin by High Boiling Alcohol Method (HBS Method) -- "Journal of Minjiang University" 2003 02 A high-boiling alcohol pulping method using 1,4-butanediol as a cooking solvent for bagasse and rice straw was reported in the period. Although reed, bagasse and rice straw belong to non-wood raw materials, their growth characteristics and raw material structure are different, so their pulping behaviors are quite different. Especially after pre-hydrolysis and extraction of hemicellulose from reeds, the lignin structure and reactivity of reed residues have changed greatly compared with reed raw materials, which also affects the pulping behavior of reed residues after pre-extraction of hemicellulose and reed residues. Properties of pulp.

During the cooking process of high-boiling alcohol solvent, the hemicellulose of the plant raw material is degraded under the heating of the solvent, and the residual sugar produced is dissolved in the raffinate. The cooking raffinate contains high boiling alcohol, low molecular weight lignin, hemicellulose sugars and sugar derivatives, etc. It is relatively easy to separate high-molecular-weight lignin from the raffinate of high-boiling alcohol solvent pulping and cooking, but the separation of low-molecular-weight lignin and sugars is a major difficulty.

The dissolution of hemicellulose into the pulping raffinate is not only unfavorable to the treatment of the raffinate, but also increases the viscosity of the raffinate due to the dissolution of sugar, which increases the energy consumption of the high-boiling alcohol solvent separation and recovery system.

In recent years, the State University of New York in the United States has proposed the technology of an integrated forestry biomass refinery plant. Its core technology is to transform the traditional kraft pulp mill, pre-hydrolyze the wood chips with a near-neutral, acidic or alkaline aqueous solution before pulping, extract part of the hemicellulose and convert it into ethanol and sugar compounds, Various chemicals are further produced, and the pretreated wood chips are chemically pulped to obtain pulp and paper products, which realizes the effective utilization of various components of lignocellulosic raw materials, and the economic and social benefits are better than pure pulping.

The hemicellulose content of reed is 20%-25%, and the main component is polypentose, which is one of the best raw materials for xylose, xylooligosaccharides, xylitol, arabinose and ethanol. Currently, reeds are either purely pulped or simply extracted from sugars to produce carbohydrates or ethanol. The target products of these two production methods are single, and the economic benefits are poor. At present, there is no technical scheme for the comprehensive utilization of reeds that fully considers the extraction of hemicellulose and the preparation of organic solvent pulp.

Contents of the invention

One of the technical problems to be solved by the present invention is to provide a process for extracting hemicellulose by prehydrolysis of reeds. The pre-hydrolyzate can be used reasonably without affecting the performance of the subsequent reed pulp.

The second technical problem to be solved by the present invention is to provide a high-boiling alcohol pulping process from reed residues for pre-extracting hemicellulose.

The third technical problem to be solved by the present invention is to provide products obtained by using the reed organic solvent pulping method for pre-extracting hemicellulose, including reed extract and reed pulp.

The fourth technical problem to be solved by the present invention is to provide the above-mentioned reed extract and reed organic solvent slurry products.

The technical scheme adopted by the present invention to solve the above-mentioned technical problems is: a kind of reed high boiling alcohol method pulping technology of pre-extracting hemicellulose, comprises the following steps:

(1) The reeds are prepared by dry and wet methods. The reeds are evenly cut off, and the light dust is removed by a winnowing machine, and then fine impurities such as sediment and reed pith are screened out by a round sieve, and finally the reed leaves and reed film are removed by a dust collector. Provide reed pieces with a length of 20-40mm and a pass rate of more than 85% after washing with water to further remove impurities, and the dryness of the reed after dehydration is not less than 35%;

(2) Pre-hydrolysis: carried out in a cooking pot, water is used as the extraction solvent of hemicellulose. The process conditions are as follows: for clean dry reed raw materials, the solid-liquid ratio is 1:3-7, the temperature is raised to 150-190°C, and the temperature is kept at this temperature for 30-240 minutes. The pH value of the hydrolysis end point is 2.5-4.5. Process and hydrolyzate to extract pentose concentration ≤ 40%;

(3) Liquid-solid separation and washing, collecting the filtrate to obtain the extract, and collecting the residue for subsequent use;

(4) paper pulp is prepared by reed residue high boiling alcohol method;

(5) Wash the reed pulp after cooking.

On the basis of the above scheme, in step (3), the hydrolyzate of step (2) is subjected to liquid-solid separation and multi-stage countercurrent washing (multi-stage countercurrent washing with filtrate and clear water) by means of continuous pressing, and the concentrated filtrate is collected to obtain extract, and collect the residue for later use.

The continuous pressing method and multi-stage countercurrent washing technology adopt known and published technical solutions, which can be screw extrusion, roller pressing or vacuum filtration, etc. The first stage uses the second stage filtrate to wash and press, and the second stage uses the third stage filtrate Washing and pressing, and so on, the last section is washed and pressed with clean water, the first section of concentrated filtrate is collected to obtain the extract, and the last section of residue is collected for later use.

On the basis of the above scheme, in step (4), the reed residue is put into a cooking pot for cooking, and the butanediol amount adopted is butanediol: water=40%～60% (volume percentage), and the liquid ratio is the reed residue : Liquid = 1: 4-10 (kg/l), the cooking temperature is 160-200° C., and the holding time is 60-180 minutes, so that the reeds are fully dissolved to obtain pulp.

On the basis of the above scheme, the reed pulp is washed after cooking in step (4). First wash with butanediol, the washing solution is 50%～60% (volume ratio) of butanediol prepared according to the liquid ratio of 1:7～9, and the washing temperature is 50°C-60°C. Then wash it with clean water under normal temperature and pressure.

The product obtained by the reed organic solvent pulping method using the above-mentioned pre-extracted hemicellulose is the reed extract obtained through steps (1) to (3) of reed preparation, prehydrolysis and liquid-solid separation. Dried reed raw material, the extraction rate of reed pentose is 20%~40%, the pH value of the extract is 2.5~4.5, and the components include xylooligosaccharides, xylose, arabinose, glucose, lignin, furfural, uronic acid and acetic acid.

For the purposes of the above-mentioned reed extract product, the further treatment and subsequent processing of the extract can adopt known and published technologies, such as acid hydrolysis, decolorization, deacidification, concentration, purification, ion exchange, dehydration, hydrogenation synthesis, biological fermentation , enzymatic hydrolysis, chromatographic separation, ultrafiltration, crystallization and spray drying, etc., to further produce xylose, xylooligosaccharides, xylitol, arabinose and other products, or through acid hydrolysis, concentration, purification, biological fermentation, Distilled to produce ethanol and other fermentation products.

The product obtained by the reed organic solvent pulp pulping method using the above-mentioned pre-extracted hemicellulose is the reed coarse pulp obtained through steps (1) to (5), and the absolute dry reed raw material has a coarse pulp yield of 48 ~55%, brown pulp kappa value is 29~35.

For the purposes of the above-mentioned brown stock products, the brown stock is further processed to obtain bleached chemical pulp by using well-known and disclosed techniques, such as washing, screening and bleaching.

The beneficial effect of the invention is: compared with the reed raw material that has not been hydrolyzed to extract the hemicellulose, the kappa number of the slurry obtained under the same pulping conditions is reduced by 5-8 units after the reed is pre-hydrolyzed. Prehydrolysis treatment significantly improved the pulping efficiency afterward.

The components of hemicellulose extract include xylooligosaccharides, xylose, arabinose, glucose, lignin, furfural, uronic acid and acetic acid, etc., but the content of non-sugar organic impurities such as furfural and lignin in the extract Low, the extract can be used in the preparation of food additives and chemical products such as xylooligosaccharides, xylose, xylitol, arabinose and ethanol.

The hemicellulose is extracted by prehydrolysis before pulping, and the extracted hemicellulose can be used to prepare sugar compounds or ethanol, and the pretreated reed residue is used for pulp production. This technical route can not only reduce the difficulty of high sugar content in the recovery of high-boiling alcohol solvents, but also realize the effective utilization of multi-component woody biomass raw materials in the pulping process, increase the added value of by-products, and balance the production of high-boiling alcohol solvents. Pulp economic cost.

detailed description

The present invention will be further described below in conjunction with the examples. It should be understood that these examples are only for the purpose of illustration, and in no way limit the protection scope of the present invention.

Example 1

(1) The reeds are prepared by dry and wet methods. The reeds are evenly cut off, and the light dust is removed by a winnowing machine, and then fine impurities such as sediment and reed pith are screened out by a round sieve, and finally the reed leaves and reed film are removed by a dust collector. Reed pieces with a length of 20-40mm and a pass rate of more than 85% are washed with water to further remove impurities, and the dryness of the reed after dehydration is not less than 35%.

(2) Pre-hydrolysis: carried out in a cooking pot, the process conditions are: for the absolute dry reed raw material, the solid-to-liquid ratio is 1:4, the hydrolysis temperature is 160°C, the pressure is the saturated steam pressure at the corresponding temperature, and the holding time is 180°C. Minutes, the final pH of hydrolysis was 4.3.

(3) Liquid-solid separation and washing, the filtrate was collected to obtain an extract, and the extraction rate of reed pentose was 35.6%. Use a three-stage vacuum filter to separate the liquid from the solid and countercurrent wash the hydrolyzate. The first stage is washed and squeezed with the second stage filtrate, the second stage is washed and pressed with the third stage filtrate, and the third stage is washed and squeezed with water. The concentrated filtrate of the first stage is used to obtain an extract, and the residue of the third stage is collected for cooking and pulping, and the dryness of the residue is not less than 35%.

(4) Reed residue high-boiling alcohol method cooking and pulping: for absolute dry reed residue, the amount of butanediol used is butanediol: water=60% (volume percentage), and the liquid ratio is reed raw material: liquid=1:6 , rapid heating, cooking temperature 190°C, holding time 60min, so that reeds are fully dissolved to obtain pulp.

(5) Washing: First wash with butanediol, then wash with 50% (volume ratio) butanediol solution, the liquid ratio is 1:7, and the washing temperature is 60°C. Then wash it with clean water under normal temperature and pressure. The yield of reed coarse pulp is 53%, and the kappa value is 33.

Example 2

(1) dry and wet method of reed is prepared, with embodiment 1.

(2) Pre-hydrolysis: carried out in a cooking pot, the process conditions are: for the absolute dry reed raw material, the solid-liquid ratio is 1:5, the hydrolysis temperature is 170°C, the pressure is the saturated steam pressure at the corresponding temperature, and the holding time is 60°C. Minutes, the final pH of hydrolysis was 4.1.

(3) Liquid-solid separation and washing, collecting the filtrate to obtain an extract: the extraction rate of reed pentose is 36.5%, and the operation method is the same as that in Example 1.

(4) Cooking and pulping of reed residue: for the absolute dry reed residue, the amount of butanediol used is butanediol: water=60% (volume percentage), and the liquid ratio is reed raw material: liquid=1: 5 (kg/l ), rapid heating, cooking temperature of 180°C, and holding time of 80 minutes, so that the reeds are fully dissolved to obtain pulp.

(5) Washing: first wash with butanediol, then wash with 60% (volume ratio) butanediol solution. The washing temperature is 60°C, and the liquid ratio is 1:8. Then wash it with clean water under normal temperature and pressure. The yield of reed coarse pulp is 52%, and the kappa value is 31.

Example 3

(1) dry and wet method of reed is prepared, with embodiment 1.

(2) Pre-hydrolysis: carried out in a cooking pot, the process conditions are: for the absolute dry reed raw material, the solid-liquid ratio is 1:6, the hydrolysis temperature is 180°C, the pressure is the saturated steam pressure at the corresponding temperature, and the holding time is 40°C. Minutes, the final pH of hydrolysis was 3.8.

(3) Liquid-solid separation and washing, collecting the filtrate to obtain an extract, the extraction rate of reed pentose is 37.3%, and the specific operation method is the same as that in Example 1.

(4) Cooking and pulping of reed residue: for the absolute dry reed residue, the amount of butanediol used is butanediol: water=50% (volume percentage), and the liquid ratio is reed raw material: liquid=1: 5 (kg/l ), rapid heating, cooking temperature 180 ° C, holding time 60 min, so that reeds are fully dissolved to obtain pulp.

(5) Washing: first wash with butanediol, then wash with 50% (volume ratio) butanediol solution. The washing temperature is 50°C, and the liquid ratio is 1:8. Then wash it with clean water under normal temperature and pressure. The yield of reed coarse pulp is 51%, and the kappa value is 32.

Claims (6)

1. the pulping method of the reed organic solvent pulp of pre-extracting hemicellulose, it is characterized in that: comprise the following steps in order: (1) Dry and wet preparation of reeds, providing reed pieces with a length of 20-40mm, a pass rate of ≥85%, and a dryness of not less than 35%; (2) Pre-hydrolysis: carried out in a cooking pot, water is used as the extraction solvent of hemicellulose, and the process conditions are: for clean dry reed raw materials, the solid-to-liquid ratio is 1:3-7, and the temperature is raised to 150-190°C. Incubate at this temperature for 30 to 240 minutes, and the pH value at the end of hydrolysis is 2.5 to 4.5; (3) Liquid-solid separation and washing, collecting the filtrate to obtain the extract, its components include xylooligosaccharides, xylose, arabinose, glucose, lignin, furfural, uronic acid and acetic acid, for absolute dry reed raw materials, The extraction rate of reed pentose sugar is 20-40%; (4) the reed residue of pre-extracting hemicellulose is put into cooking pot and cooks, and the butanediol amount that adopts is butanediol: water=40%～60% (volume percent), and liquid ratio is reed residue: liquid=1 : 4～10 (kg/l), cooking temperature 160～200 ℃, holding time 60～180min, reed is fully dissolved, and pulp is obtained; (5) After cooking, the reed pulp is washed, and the washing solution is 50% to 60% (volume ratio) of butanediol prepared according to the liquid ratio of 1:7 to 9. The washing temperature is 50°C-60°C. Glycol wash, and then rinse with water under normal temperature and pressure. 2. the reed organic solvent pulp pulping method of pre-extracting hemicellulose according to claim 1, is characterized in that: in step (3), adopt continuous pressing mode to carry out liquid-solid separation to the product of step (2), collect The extract was obtained from the filtrate, and the residue was collected for subsequent use. 3. The reed extract liquid product obtained by the method for preparing the reed organic solvent pulp of pre-extracted hemicellulose according to claim 1 or 2 is characterized in that: it is the reed obtained through steps (1) to (3) Extraction, for the raw material of dry reed, the extraction rate of reed pentose sugar is 20-40%, the pH value of the extract is 2.5-4.5, and the components include xylooligosaccharides, xylose, arabinose, glucose, lignin, furfural, uronic acid and acetic acid. 4. The application of the reed extract product according to claim 3, characterized in that: the reed extract is used for the preparation of xylose, xylooligosaccharides, xylitol, arabinose or ethanol. 5. adopt the reed coarse pulp product that the preparation method of reed organic solvent pulp described in claim 1～2 makes, it is characterized in that: be the reed coarse pulp that obtains through step (1) to (5), to starting Dry reed raw material, the yield of reed coarse pulp is 48-55%, and the kappa value of coarse pulp is 29-35. 6. The use of the reed coarse pulp product according to claim 5, characterized in that: the reed coarse pulp is used for the preparation of bleached chemical pulp.