CS260305B1 - Method of lignin insulation - Google Patents

Abstract

The purpose of lignin isolation is to improve them chemical properties and improvement of the method lignin preparation. This purpose is achieved by the network by subjecting the extraction to 15 to 50 ° C lignocellulosic residue after removal pentose component by steaming lignocellulosic materials at 200 to 230 ° C and a pressure of 2.5 to 3 MPa. Method of lignin isolation has use in the chemical industry.

Description

The invention relates to a method for isolating lignin.

Lignin Pre Use In. the chemical industry can be obtained from waste liquors in the pulp and paper industry or from lignocellulosic materials such as wood, or from one-year lignified plants by alkaline degradation [Κ. V. Sarkanen, C. H. Ludwig: Lignins, Occurence, Formation, Structure and Reaction, Ed. Wiley Intersciemce, New York-London-Toronto (1972)]. The disadvantage of lignin isolated from waste in industrial delignifications is that it is poorly soluble, largely structurally altered, and contaminated with delignifying chemicals. Furthermore, lignin can be obtained as a residue in the hydrolysis of lignocellulosic materials by acids in the hydrolysis industry. A disadvantage of hydrolyzing lignin is its high degree of condensation with a difficult to modify polyaromatic structure. The disadvantages of the lignins extracted from the native lignocellulosic materials are the very low yields and the fact that their isolation is always accompanied by the dissolution of the hemicellulose component, which is present in the isolated lignins in an amount of 10 to 20 wt. % [F. E. Brauns, D. A. Brauns: The Chemistry of Lignin, Academic Press, New York-London, p. 62 (1980)].

The above-mentioned disadvantages are substantially eliminated by the method of lignin isolation consisting in subjecting the residue at 15 to 50 degrees Celsius to the residue after removal of the pentose component by steaming the lignocellulosic material at a temperature of 200 to 230 ° C and a pressure of 2.5 to 3 MPa.

The advantage of the proposed process is that the steaming of lignocellulosic materials in the production of furfural produces a waste material from which it is possible to isolate lignin with higher yields and with advantageous chemical properties, e.g. good solubility in some organic solvents, equipment-less process, chemicals, and reduced formation of undesirable liquid or gaseous wastes. Another advantage is that the organic solvents and ammonia used can be regenerated.

The lignocellulose residue used in Examples 2 to 7 is obtained after the conversion of straw pentoses to furfural:

Example 1

250 g of dry straw 92 wt. % is heated with 6 L of water in the reactor at 200 to 230 ° C for 5 to 20 s in a 13 L autoclave at a pressure of 2.5 to 3 MPa. The lignocellulose residue after removal of furfural and subsequent washing with 10 l of water was obtained in a yield of 180 g. Example 2

200 g of lignocellulose residue with a dry weight of 90% by weight. o / o washed with water is extracted with 4 L of acetone in the extractor for 8 hours at 25 ° C. Evaporation of the solvent gave 22 g of lignin containing 1.15 wt. % phenolic hydroxyl groups and 11.0 wt. % Of the methoxy groups.

Example 3

The procedure was as in Example 2 except that the lignocellulose residue was extracted with 4 L of methanol. The yield of lignin is 20 g. The content of phenolic hydroxyl groups is 1.22 wt. % and methoxy groups 10.1 wt. o / o.

Example 4

The procedure was as in Example 2 except that the lignocellulose residue was extracted with a 4 L 96 wt. % ethanol and water 1: 1 v / v at 15 ° C. The yield of lignin is 20.5 g. The content of phenolic hydroxyl groups is 1.25 wt. % and methoxy groups 9.8 wt. ° / o.

Example 5

200 g of lignocellulose residue with a dry weight of 90% by weight. % washed with water is extracted with 4 L of 96 wt. % ethanol and 1 wt. Aqueous 1% sodium hydroxide solution with stirring at 25 ° C for 24 h. The solid was then filtered off, the filtrate was evaporated to half volume and adjusted to pH 2 with 1 mole. 1 ^_1 acid. The precipitated lignin is filtered off and dried. 18 g of lignin containing 1.66 wt. % phenolic hydroxyl groups and 9.6 wt. % Of the methoxy groups.

Example 6

200 g of lignocellulose residue with a dry weight of 90% by weight. % is extracted with 5 L of 26 wt. % Aqueous ammonia solution at 15 degrees Celsius for 5 days. Evaporation of the ammonia gave 30 g of lignin containing 1.25 wt. % phenolic hydroxyl groups and 8.0 wt. % of methoxy groups. Example 7

The procedure was as in Example 6 except that the lignocellulose residue was extracted with a 96 wt. % ethanol and 26 wt. % aqueous ammonia solution (1: 1 v / v) at 25 ° C for 3 days. Evaporation of ammonia and ethanol gave 35 g of lignin containing 1.10 wt. % of phenolic hydroxyl groups and 9.0 wt. % of methoxy groups.

The invention can find use in the chemical industry in macromolecular chemistry as a raw material for the preparation of fertilizers, adsorbents, dispersants, adhesives, surfactants and the like.

Claims (1)

PŘEDMSΓ Process for isolating lignin soluble in organic solvents, by extraction with acetone, methanol, ethanol and / or a mixture thereof with water or an aqueous or aqueous-alcoholic solution of sodium or ammonium hydroxide or ammonium hydroxide, characterized in that it is subjected to extraction at 15 to 50 ° C the residue after removal of the pentose component by steaming the lignocellulosic materials at a temperature of 200 to 230 ° C at a pressure of 2.5 to 3 MPa.