Chemical pretreatment of wood chips: A comparative study of mild steam explosion and hot water extraction

Paper in proceeding, 2015

Pretreatment of wood is a prerequisite for an efficient separation and utilization of its building blocks in future biorefinery concepts. Inherent recalcitrance of the cellulose-hemicellulose-lignin matrix of the cell wall poses huge challenges on separation of these components and implies usually a need for a broad set of methods targeting different components and providing as well chemical as morphological alterations. Mild steam explosion and hot water extraction are examples of typical pre-treatment methods enabling extraction of hemicelluloses and facilitating further processing of wood. Both are based on autohydrolysis of lignocellulosic material at high temperatures, but involve generally different conditions, the most prominent difference being a rapid disintegrating discharge employed in the steam explosion treatment, rendering morphological changes and altering structure accessibility compared to the physically less disruptive hot-water extraction. In this study we compare the key features of both of these methods and present that their effects on wood are somewhat non-uniform.