JPS61160492A - Delignification of lignocellulose containing material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for delignifying raw materials containing raw cellulose, in which the raw materials are heat treated with chemicals containing furan derivatives and possibly also water.

, when using the term furan derivative, this meaning is taken to mean tetrahydrofuran compounds selected from the group consisting of alcohols, e.g. tetrahydrofurfuryl alcohol; esters, e.g. tetrahydrofurfuryl acetate; aldehydes, e.g. tetrahydrofurfural acid, e.g. tetrahydrofururancarboxylic acid. and a furan compound selected from the group consisting of an alcohol, such as furfuryl alcohol, a human, such as furfural, and/or an acid, such as 2-furanyl alcohol.

In the chemical delignification processes commonly used today, such as the sulfate and sulfite process, fibrous materials are separated from water by dissolving the lignin in a cooking solution consisting of inorganic chemicals dissolved in water. This process involves relatively high pressures, e.g. on the order of 6 to 1 Oate, and relatively high temperatures of 1
For example, the temperature is on the order of 160 to 180°C.

Notable drawbacks of these known methods are the unpleasant odors and the technically troublesome effect that the waste products have on the environment. The recovery and reuse of these chemical substances requires combustion of waste fluids and complex regeneration processes. Furthermore, when cellulose is cooked in the manner described above, only about half of the water is utilized for production purposes.

Recently, more attention has been paid to alternative delignification methods that avoid the above-mentioned drawbacks. The so-called organic solvent methods are of particular interest, as the aim of these methods is to dissolve lignin in organic solutions without damaging the cellulose fibers.

After separation and regeneration of the solution, the lignin and other soluble components can then be utilized.

Lignin solvents are described in "Lignins, Occurrences, Structure and Reactions".
rmation.

5structure and Reactions)J
Sarkanen, Ludwig
ig) ; Willie, Interscience (Wile
71terscience) N, Y., 1971.
Described in publications such as. However, lignin solvents as recognized in the above-mentioned published academic papers do not fulfill the requirements for a solvent suitable for technological processes.

In solvents that are suitable for technological processes.

It is required that lignin dissolution can also be carried out in the presence of water. This is because lignocellulose-containing raw materials always contain water to a greater or lesser extent. Thus, it is also necessary that the solvent be water-soluble. Furthermore, from the viewpoint of process acceptance, it is important that the solvent has low toxicity. Furthermore, the solvent must not react with lignin or other dissolved substances, since reaction would make regeneration more difficult or not possible at all.

Various alcohols have been shown to dissolve lignin to some extent at high temperatures. Low molecular weight alcohols such as methanol and ethanol appear to work best. However, the volatility of these substances makes solvent recovery and recycling difficult to achieve technically. Additionally, all alcohol-based cooking methods require relatively high temperatures of 160-220°C as well as the use of acid catalysts. The use of acid catalysts in combination with high temperatures reduces the quality of the fibrous material produced.

The process, which uses phenol as the lignin solvent and is carried out under normal pressure, was first published in Chemical & Engineering, News 6 Publication, Issue, March 31, 1981.
ng News publication 1ssue
)It is described in. This method expanded the range of objects used for organic solvent cooking. However, the toxicity of phenol may cause difficulties when large-scale production is carried out.

The delignification method is described in Rocha Patent Publication No. 672260 (Ru
ssian patent public on N
o, 872260). Here, tetrahydrofurfuryl alcohol is used as the lignin solvent.

This method assumes a cooking temperature of the order of 150 N 160° C. and the use of acid or alkaline catalysts. Additionally, the process is carried out under pressure, as is conventional for cellulose cooking processes. The experimental results obtained were not satisfactory in terms of yield or lignin content in the product.

The main object of the present invention is to eliminate the above-mentioned disadvantages.It is also an object of the present invention to delignify the lignocellulose-containing feedstock under mild conditions, i.e. at lower temperature and lower pressure. The key is to use new ways to do this. In particular, according to the present invention, the yield of the produced pulp is higher than that of the conventional method, and the lignin content, that is, the kappa number (Kappa nu
umber) is lower than before.

Furthermore, it is an object of the present invention to provide a new delignification process in which the lignin content and other dissolved components of the raw material are utilized after separation and/or regeneration.

Furthermore, it is an object of the present invention to provide a new delignification process which can also be delignified in the presence of water, ie suitable for delignifying damp, wet wood.

Furthermore, it is an object of the present invention to provide a new type of delignification process that does not produce unpleasant odors or other environmental/technical disadvantages of conventional processes.

A further object of the invention is a trowel to provide a process of the above type, in which the solvent used has low toxicity and does not react with the dissolved wood material.

Regarding the features of the invention, reference is made to the appended claims.

The invention is based on a new use of tetrahydrofurfuryl alcohol previously used for delignification. Surprisingly, according to the present invention, furan derivatives and/or mixtures thereof are prepared at relatively lower temperatures than previously, from 50 to 120 °C.

For example at 95-115°C, more preferably at about 104°C and at a lower pressure than before, 1-2 atm.

It has been found that the best steaming results are obtained when more preferably about 1 atm is used. In fact, the delignification effect of furan derivatives and/or their mixtures suggests that the hydrolysis of hemicellulose causes undesirable side reactions, which make the recovery of the solvent more difficult and reduce the product yield obtained from the raw material. It is more efficient at relatively low temperatures than at relatively high temperatures.

The method according to the invention carries out delignification at a low temperature of 100°C.
Even the following is possible. Therefore, the course of the reaction is well controlled and no disadvantageous side reactions occur. The cooking time is 1 to 6 hours, preferably 2 to 3 hours.

The delignification according to the present invention, which is carried out mainly at normal atmospheric pressure,
The production of major components of lignocellulose-containing materials using the 0-bottom method offers considerable technical and economic benefits, the most important of which is the simplification of process equipment and the greater sales yield from raw materials. : Can separate cellulose, hemicellulose and lignin, which is a useful end product.

Water droplets do not require drying or other costly pretreatments as are the case with many other organic solvent processes.

Due to the low cooking temperature, the energy consumption of the process is low.

The furan derivatives and/or their mixtures used as solvents in the water droplets can be used again after separation and regeneration, and are produced from bentosan dissolved in the cooking solution to compensate for technical losses.

Yet another advantage of the present invention is that the solvent is environmentally benign compared to compounds used in other organic solvent processes, such as phenol.

4. Preferred Embodiments The present invention will be disclosed in more detail by way of embodiments. Example 1 here describes some preferred embodiments of the water droplet, and the ¥ male side 2
discloses a prior art method.

Example 1 Approximately 20g of cellulose-containing raw material was added to 200g of THF.
A (tetrahydrofurfuryl alcohol) or TH
Mixed with FA aqueous solution. Catalyst was added to the solution and the mixture was kept at solution temperature for 1-6 hours. The pulp obtained after the process was crushed and washed. The kappa number of the obtained pulp was measured. The kappa number reveals the amount of lignin remaining in the pulp. The results are shown in Table 1 below.

1 Cover, sawdust 50 HCL 2 4 10
0 40 402 Cover, Chip 80 HC:L
l 4 104 49 033 Cover, chips
80) ICL O, 2541044θ 394
Pine, chip 80 HCL 1 4 104
45 295 Massage, chips 80 HCL +
4 104 45 156 Cover, chips 80
H2SO4-1410450387 Cover, sawdust 80
HC:L O,5410442+98 Hippo, Chip 40 H2SO斗549840408 Massage, Chip 80 HC:L I 13 50 50
391O cover, chip 100 HCL I
1 120 46 3511 Cover, chips 800
83COOHI 4 +03 55 5012
Straw 80 MCL I 4 104
38 2013 Bagasse 80 HCL
l 4 104 35 1 [i14 Kava chips 80 HCL O, 151045821 Example 2 50 g Kava chips, 240 g THFA, 34 g water and 9 g concentrated hydrochloric acid were heated in an autoclave to a temperature of 160°C and kept at this temperature for 2 hours. I kept it. The autoclay pressure was 6 bar. After cooling and reducing the pressure, the completely disintegrated pulp was removed from the autoclave.

The cellulose ttvtn structure of this pulp was disadvantageously destroyed.

In the disclosure and claims of this patent, concentrations are expressed as weight percent of the total amount of material or solution.

The invention is not limited to the embodiments shown here, but may vary within the scope of the appended claims. Then, in water-containing furan derivatives, the water comes from the raw material to be delignified, for example damp wood, or if desired, water can also be added together with the furan derivative.

Furthermore, as described in the Examples, the delignification can also be carried out with water-free furan derivatives. In other words, the water contained in the chemical comes from the raw material that is to be delignified.

Claims (10)

[Claims] (1) A method for delignifying a raw material containing lignocellulose, in which the raw material is heat-treated with a chemical substance containing furan and water, and the heat treatment is performed at a temperature of 50 to 120°C. (2) The method according to claim 1, wherein the heat treatment is performed at a temperature of 95 to 115°C. (3) The method according to claim 1, wherein the heat treatment is performed with a chemical substance containing 0 to 60 W/W% water. (4) The method according to claim 3, wherein the treatment is performed with a chemical substance containing 10 to 30 W/W% of water. (5) Claim 1, in which the processing time is 1 to 6 hours.
The method described in section. (6) The chemical substance is selected from mineral acids and organic acids.
2. The method of claim 1, comprising 1 to 5% W/W catalyst. (7) The method according to claim 6, wherein the chemical substance contains 0.1 to 2% W/W of catalyst. (8) The method according to claim 1, wherein the tetrahydrofurfuryl alcohol compound is separated from the solution after delignification and reused. (9) The method according to claim 1, wherein the process is carried out at a pressure of 1 to 2 atm. (10) The method according to claim 1, wherein the furan derivative is selected from the group consisting of tetrahydrofuran alcohols, esters, aldehydes, acids, and furan alcohols, aldehydes, and acids.