PROCESSES FOR PRETREATING AND PURIFYING A CELLULOSIC MATERIAL

摘要

A process for treating a cellulosic material comprising pretreating the cellulosic material and then extracting the cellulosic material with an extractant to selectively extract hemicellulose therefrom and separating the extracted hemicellulose to form a cellulosic product comprising less hemicellulose than the cellulosic material. The extractant comprises a cellulose solvent and a co-solvent. The cellulosic product advantageously retains its cellulosic fiber morphology. The processes involve separating and recovering the hemicellulose and separating and recycling various process streams employed in the process.