CS260302B1 - Method of polysaccharides stabilization of lignocellulose materials' alkaline-oxygenic delignification process - Google Patents

Abstract

The objective of the polysaccharide stabilization process in the process of alkali-oxygen delignification lignocellulosic materials is an improvement properties of pulp and increase is] extract. This purpose is achieved by: to an alkaline-oxygenated brewing solution delignification add molybdenum compounds in a catalytic amount. Stabilization method polysaccharides in the alkali-oxygen process delignification of lignocellulosic materials it is used in celutosopapieren industry.

Description

The invention relates to a process for stabilizing polysaccharides in the process of alkali-oxygen delignification of lignocellulosic materials.

Alkaline-oxygen delignification of lignocellulosic materials is a promising sulfur-free pulp technology. Pulp produced using oxygen has low strength properties compared to pulps prepared by other technological processes. Similarly, when bleaching chemical pulps with oxygen in an alkaline environment, carbohydrate degrades. In order to stabilize the polysaccharides in the alkaline-oxygen delignification, various catalysts have been tried to prevent degradation of the cellulosic material. Certain types of magnesium compounds [E. Sister, O. Valtia: Pepper and Traj 11, 695 (1972); S. Samuelson, L, Stolpe: Svensk Bapperstidn. 74, 545 (1971) J and manganese [E. Germer, J.G.Butko: Chimija drevesiny 3, 85 (1984)], the most common organic anthraquinone derivatives [B. G. Fiehn: Zellstoff und Papier 21, 3 (1972); Η. H. Holton: Pupl and Paper Can. 78, T128 (1977); have a protective effect on the oxidative degradation of lignocellulosic materials. So far, the protective effect of molybdate ions on polysaccharides in the process of pulp production and bleaching by alkali-oxygen delignification is not known.

The above-mentioned disadvantages are substantially eliminated by the method of stabilizing the polysaccharides in the process of alkaline-oxygen delignification of lignocellulosic materials, which comprises adding molybdenum compounds in the form of molybdenum ions containing molybdenum content of 0.02 to 0.5% by weight. %, based on the weight of the lignocellulosic material.

An advantage of the proposed method of stabilizing polysaccharides in the process of alkali-oxygen delignification is that the pulp yield is increased in the range of 1.7-4% at approximately the same lignin content. Molybdenum can be regenerated together with inorganic cooking chemicals, which is a difference compared to organic catalysts, for example anthraquinone. Molybdenum compounds are anticorrosive, non-toxic and do not pollute the environment.

Example 1 g of spruce abrasive wood is heated with 0.5 mol. and ^"1 hydrogénuhiličitanom sulfate containing 0.02 wt. % (by mass of wood) of molybdenum applied as sodium molybdate at 130 ° C for 2 hours in a 1:20 hydromodule autoclave in the presence of oxygen at a pressure of 1.0 MPa (at 20-25 ° C). The yield of pulp obtained is 88.4 wt. % with a lignin content of 25.9 wt. %.

Example 2

The procedure is as in Example 1 except that sodium molybdate is used in an amount of 0.05 wt. % molybdenum. The yield of pulp obtained was 89.2 wt. % with a lignin content of 25.9 wt. ° / o.

Example 3

The procedure is as in Example 1 except that sodium molybdate is used in an amount of 0.15 wt. % molybdenum. The yield of pulp obtained is 90.8 wt. % with a lignin content of 26.0 wt. %.

Example 4

The procedure is as in Example 1 except that spruce chips and 0.05% by weight ammonium molybdate catalyst are used. % molybdenum per mass of wood at an oxygen pressure of 20 psi (20-25 ° C) and the reaction mixture is heated at 150 ° C for 7 hours. The fiber yield was 76.0 wt. % with a lignin content of 20 wt. %.

To compare the stabilizing effect of molybdenum compounds with the alkali-oxygen delignification of lignocellulosic materials used hitherto, the following are examples:

Example 5

The procedure is as in Example 1 except that sodium molybdate is not added. The yield of pulp obtained is 86.7 wt. % with a lignin content of 25.9 wt. %.

Example 6

The procedure is as in Example 4 except that no ammonium molybdate is added. The yield of pulp obtained is 76.0 wt. With a lignin content of 23 wt. %.

The invention may find use in the manufacture of pulp.

Claims (1)

SUBJECT Process for stabilizing polysaccharides in the process of alkali-oxygen delignification of lignocellulosic materials, characterized in that molybdenum compounds in the form of molybdenum ions containing 0.02 to 0.15 wt. % molybdenum, based on the mass of the lignocellulosic material.