A METHOD FOR THE DELIGNIFICATION OF FIBROUS MATERIAL AND USE OF A CATALYST

摘要

The invention refers to a method to delignify fibrous material comprising an aqueous suspension of fibers which has a consistency between 5 % - 40 %, with a peroxy compound that is used in amounts between 0.5 % - 10 % based on bone dry fibrous material, and with a metal complex of the general formula (1): [LnMnmXp]<z>Yq wherein Mn stands for manganese or iron, which can be present in oxidation state II, III, IV or V or in mixtures of these states; n and m are the integers 1-4; X is a coordinating ligand; p is an integer from 0 to 12; z is the charge of the complex and can be positive, neutral or negative; Y is a counter-ion or -molecule which depends on the charge of the complex; q is equal to z divided by the charge of Y; and L is a ligand and is represented by a macrocyclic organic molecule with general formula (2) wherein R<1>, R<2>, R<3> and R<4> can be either zero, H, alkyl, aryl or otherwise optionally substituted; D and D' are either N, NR, PR O, or S, wherein R can be substituted by H or alkyl or aryl or otherwise optionally substituted; t and t' are whole integers from 2 to 3, s is an integer between 2 and 4, u is an integer from 1 to 20, and v is 0 or 1; this metal complex is used at an amount of 0.0001 % - 0.1 % based on bone dry fibrous material, wherein the fibers are delignified at an initial pH-level between 7.5 and 13.5, at a reaction temperature between 20 DEG C and 130 DEG C, and with a reaction time between 15 and 360 minutes. Further, the invention relates to the use of a metal complex.