Steam Explosion Pulping of Aspen Pretreated With Alcohol Mixed with a Non-Sulfur Chemical, 1992 Solvent Pulping Symposium Proceedings

A process based on alcohol to produce ultra-high-yield pulp as an alternative to the conventional processes has been studied in our laboratory at the University of Quebec in Trois-rivieres. In this work, aspen wood chips were impregnated with aqueous ethanol in presence of a second chemical as NaOH, Na2 C03 , NaHC03 or MgCl2 at various concentrations. Cooking was done with saturated vapor at high temperature (190°C) for short residence time mostly 2 and 4 min. The ratio of ethanol to aqueous solution used in this study was 50:50, 30:70, 15:85 and 0:l00. We have studied the influence of the nature of the chemicals, concentration of the chemicals and cooking time on pulp yield and properties. The presence of NaOH in impregnation solution consisting of aqueous alcohol or water remarkably improved the mechanical properties of the resulting pulp. The presence of alcohol seems to protect the pulp brightness. For similar yield range, pulp obtained with ethanol + NaOH shows superior pulp properties in comparison to the pulp obtained with ethanol + Na2 C03 or NaHC03 or MgC12. The pH of the impregnation liquor influences the pulp yield as well as pulp properties.