RU2237767C1 - Cellulose manufacture process - Google Patents

Abstract

FIELD: paper-and-pulp industry.

SUBSTANCE: process comprises pulping cellulose-containing raw material in aqueous alkali solution in presence of alcohols and catalyst, in particular complex compound containing manganese(II) and chelating ligand.

EFFECT: increased strength of cellulose.

6 cl, 1 tbl

Description

The invention relates to the field of wood processing, namely, the field of cellulose production, and can be used in the production of cellulose by removing non-cellulosic substances from cellulose-containing materials, mainly wood.

A known method of producing cellulose (US patent 4012280, 1977), including cooking wood materials in an alkaline cooking solution at elevated temperature and pressure in the presence of a redox catalyst (anthraquinone or its derivatives).

The disadvantage of this method should recognize the low mechanical characteristics of the resulting pulp.

A known method of producing cellulose (SU, copyright certificate 761647, 1972), including the cooking of cellulose-containing materials in a cooking solution containing organic acid and hydrogen peroxide in the presence of a sulfuric acid catalyst.

The disadvantage of this method should recognize the low mechanical characteristics of the resulting pulp.

A known method of producing cellulose (RU, patent 2119987, 1998), including the cooking of cellulose-containing material in sulfide cooking liquor, and sulfide cooking liquor contains a mixed magnesium-sodium base.

The disadvantage of this method should recognize the low mechanical characteristics of the resulting pulp.

The closest analogue of the proposed invention can be recognized as a method of cooking cellulose (RU, patent 2135665, 1999), including the cooking of cellulose-containing raw materials in an aqueous solution of alkali in the presence of alcohols and a redox catalyst (anthraquinone).

The disadvantage of this method should recognize the low mechanical characteristics of the resulting pulp.

The technical problem solved by the proposed invention is to develop a method for producing cellulose, characterized by high mechanical strength.

The technical result obtained by the implementation of the invention is to improve the environmental situation near the pulp manufacturing enterprises by eliminating sulfur compounds from the technological cycle, as well as increasing the percentage of cellulose yield having high mechanical characteristics.

To achieve the specified technical result, it is proposed to use a method for producing cellulose, including cooking cellulose-containing raw materials in an aqueous alkali solution in the presence of alcohols and a catalyst, moreover, a complex compound containing manganese (II) and a chelating ligand is used as a catalyst. Typically, acetylacetone or N-phenylanthranilic acid is used as the ligand at a ratio of manganese (II): ligand = 1: 1. Preferably, ethanol is used in the process, but methyl or isopropyl alcohols can also be used with their content of 20-30% of the volume of the cooking solution. Mostly the catalyst is used in an amount of 0.001-0.005% by weight of absolutely dry wood.

To obtain the catalyst used, it is necessary to mix in the appropriate molar ratio (preferably 1: 1) pre-prepared solutions of MnCl ₂ and ligand.

In the basic embodiment, the proposed method is implemented as follows.

Cellulose-containing material is poured with an alkaline-alcohol cooking solution. The cooking hydromodule is from 1: 3 to 1: 5, and the cooking temperature is 150-170 ° C. It is preferable to raise the process temperature to the final one within 1.5 - 2.5 hours with maintaining a constant temperature in the region of 110 - 130 ° C to improve the impregnation of wood with the cooking solution. Cooking time at the final temperature depends on the required degree of penetration of the pulp. The catalyst is introduced into the cooking solution immediately before serving. The rest of the method does not differ from the known method for producing cellulose using alkaline cooking solutions.

The specific conditions for the implementation of the method (temperature and composition of the cooking solution, time modes) are determined based on the composition and characteristics of the cellulose-containing raw materials.

In one embodiment of the method, spruce chips are poured with an alkaline (NaOH concentration of 60-65 g / l) cooking solution containing 25 volume% ethanol. Hydromodule cooking 1: 5. Cooking temperature of 160-165 ° C, raising the temperature to the final within 2 hours with a 30-minute stand at 120 ° C to improve the impregnation of wood with a cooking solution. Cooking time at a final temperature of 4-5 hours, depending on the required degree of cellulose penetration. The catalyst in an amount of 0.001-0.003% by weight of absolutely dry wood is set in the cooking solution immediately before the solution is fed to the cooking.

In another embodiment of the method, hardwood chips are poured with an alkaline (NaOH concentration of 55-60 g / l) cooking solution containing 20 volume% methanol. Hydromodule cooking 1: 4. Cooking temperature 165-170 ° C, raising the temperature to the final within 2 hours with a 30-minute parking at 130 ° C to improve the impregnation of wood with a cooking solution. Cooking time at a final temperature of 5-5.5 hours, depending on the required degree of cellulose penetration. The catalyst in an amount of 0.003-0.005% by weight of absolutely dry wood is set in the cooking solution immediately before being fed to the cooking.

In a third embodiment of the method, the pine chips are poured with an alkaline (NaOH concentration of 65-70 g / l) cooking solution containing 28 volume% ethanol. Hydromodule cooking 1: 3. The cooking temperature is 160-165 ° C, the temperature rises to the final within 2 hours with a 30-minute stand at 125 ° C to improve the impregnation of wood with the cooking solution. Cooking time at a final temperature of 4 - 4.5 hours, depending on the required degree of cellulose penetration. The catalyst in an amount of 0.002-0.004% by weight of absolutely dry wood is set in the cooking solution immediately before being fed to the cooking.

Comparative data for sodium boiling, alkaline water-ethanol cooking and alkaline water-ethanol cooking with the proposed catalyst are presented in the table.

For NSK-1 grade unbleached pulp, the breaking length (9000 m) and bursting strength (500 kPa) are normalized.

Natron cooking at 160 ° C does not allow to obtain cellulose, the wood does not boil and does not separate into fibers when washing with water, therefore, the indicators of mechanical strength are not determined.

A new environmentally friendly water-ethanol method for producing cellulose in an alkaline medium using a homogeneous catalyst has been developed, allowing

- increase the environmental safety of production by eliminating toxic mineral reagents (sulfur compounds) from the production cycle;

- increase the yield of cellulose by 3-4%;

- increase the mechanical strength of cellulose to values characteristic of sulfate cellulose.

Claims (6)

1. The method of producing cellulose, including cooking cellulose-containing raw materials in an aqueous alkali solution in the presence of alcohols and a catalyst, characterized in that the complex compound containing manganese (II) and a chelating ligand are used as a catalyst. 2. The method according to claim 1, characterized in that the acetylacetone or N-phenylanthranilic acid is used as the ligand. 3. The method according to claim 1, characterized in that the ratio of manganese (II): ligand = 1: 1 is used. 4. The method according to any one of claims 1 to 3, characterized in that ethanol is used. 5. The method according to claim 4, characterized in that ethanol is used in an amount of 20-30% of the volume of the cooking solution. 6. The method according to any one of claims 1 to 5, characterized in that the catalyst is used in an amount of 0.001-0.005% by weight of absolutely dry wood.