CS225851B1 - Method of treating wood and other ligno-cellulosic raw materials by prehydrolysing and fibrillating,or delignifying for further processing - Google Patents

Description

The invention relates to a process for treating wood and other lignocellulosic raw materials by pre-hydrolysis and pulping or delignification, respectively, for downstream processes.

Wood is a complex complex of vigorous organic macromolecular compounds with a complex anatomical structure, which also implies its unique mechanical, physical, chemical and biological properties. The chemical processing of wood into pulp uses mainly its polysaccharide components, especially cellulose. Hemicelluloses are used only partially and lignins use only their calorific value in the recovery of chemicals from leachate.

In the wet-fiber production of wood-fiber boards, part of the wood mass of up to 13 to 15% goes in the form of a water-soluble fraction containing 60% of carbohydrates and zero fibers to the waste water. Another possibility of chemical wood treatment is for example the production of 2-furaldehyde, where only about 25% of the wood mass is used.

From the literature are known and described the production of 2-furaldehyde and acetic acid according to MS. U.S. Patent No. 5,768,549; 120 136 and the production of D-xylose from deciduous trees according to Czech. U.S. Patent No. 5,768,549; 159 583.

Said processes improve the treatment of wood and other lignocellulosic raw materials by pre-hydrolysis and pulping, respectively delignification for downstream processes, which consists in that the wood chips or other lignocellulosic material is partially hydrolysed by dilute mineral acids such as 1.5 to 3% by weight sulfuric acid at boiling point or 0.75 to 1% by weight sulfuric acid at 120 to 35 ° C for 100 to 50 minutes. The prehydrolysate is separated and the prehydrolyzed chips are washed with hot water, neutralized with, for example, ammonia, and the silage is cold pulped or delignified by oxidation, chlorination or nitration for downstream processes.

The advantages of the proposed method of treating wood and other lignocellulosic raw materials by pre-hydrolysis and spinning or delignification, respectively, for downstream production are that they eliminate or reduce waste and that secondary wood sources and other plant lignocellulosic materials can also be processed.

Splitting and delignifying the chips is a simple process and the method of the invention will save the energy required for pulping using pressurized steam and alleviate the pulp working conditions, using the lignin portion as an organic fertilizer.

The prehydrolysate obtained is predominantly a mixture of carbohydrates in an amount of up to 20% calculated on the starting wood. The dry matter and the content of reducing substances before and after the inversion of beech wood hydrolysates are given in Table 1.

Table 1

Characteristic (%) h ₂ Sat ₄ (%) 1 (X) 2 (XX) 3 (XX) Dry matter 5.94 7.93 13.90 Reducing substances before inversion 1.85 2.95 4.82 Reducing substances after inversion 8.40 6.73 11.87 Content of pentoses on the dry matter of hydrolysates 56.42 62,12 6, 80

X 3-fold circulation XX 2-fold circulation

Spdsobu effects of the invention are also remeasured as loss of beech wood in pdsobení 1, 2 and 3% H ₂ S0 ₄ * ^{UTedené in} Table 2.

Concentration of H ₂ SO ₄ (%) 1 2 3 Wood weight loss (%) 7.37 14.32 17.53

The pre-hydrolyzate obtained can be used to produce crystalline D-xylose, feed white wines, 2-furaldehyde, respectively. is used as wood molasses for the feeding of cattle.

By partial hydrolysis, the complex of the macromolecular substances of the wood changes, the lignin-saccharide bonds are broken, the lignin goes into a plastic state, which results in a lower amount of energy compared to conventional processes. This is achieved by the method according to the invention, in that the partially hydrolysed chips a and are subjected to pulping without pressure steam, e.g. in a cold Bauer mill, thereby lignocellulosic fibers being compressed. These fibers can be further processed into fiberboard, as a carrier for feed granulation, or by delignification into pulp in an oxidative, chlorinated or nitrated manner.

The chips after partial hydrolysis can also be used for the production of particle board or by delignification to pulp.

The present invention is illustrated by way of example, without being limited thereto.

Example 1

Beech chips were partially hydrolyzed with 3% sulfuric acid at 120-1115 ° C for 120 minutes and after separation of the pre-hydrolyzate, 5.6% crystalline D-xylose, 7.7% syrup containing D-xylose, D-galactose were obtained , D-glucose, D-mannose, L-arabinose, and D-rhamnose, and 1.7% of the acid carbohydrates representing a mixture of alduronic acids, these data refer to the original wood.

The delignification of the hot water-washed pre-hydrolysed chips was carried out with diluted 2 to 5% nitric acid at boiling followed by addition of 2 to 4% ammonia to obtain pulp, which after bleaching is suitable for the preparation of pulp derivatives. The reaction also produced nitro-derivatives of lignin, which together with ammonium salts are suitable as humue-forming combined nitrogen fertilizer.

Claims (1)

Process for treating wood and other lignocellulosic raw materials by pre-hydrolysis and pulping or delignification for downstream processes, characterized in that wood chips or other lignocellulosic material are partially hydrolysed by dilute mineral acids such as 1.5 to 3% by weight sulfuric acid at boiling point or 0.75 to 1% by weight sulfuric acid at a temperature of 120 to 135 ° C, for 100 to 150 minutes, the prehydrolysate is separated and the prehydrolyzed chips are washed with hot water and neutralized with, for example, ammonia and cold disintegrated or delignified oxidation, chlorination or nitration of downstream production.