Decomposition of cellulose-contg materials - with lyes contg sodium hydroxide and sulphide and in addition an alkali polysul

摘要

Process comprising the stages of pre-steaming, impregnation of wood with an alkaline lye and main delignification in the vapour phase is improved in that the NaOH- and Na2S-contng. lye additionally contains an alkali polysulphide, whereby the dissolution of lignin is intensified and hemicellulose is protected against alkaline attack. As a result, yields are increased without impairing the quality of the product; the consumption of chemicals and energy is reduced. The method is esp. suitable for the prodn. of paper pulp from wood and annual plants.