Abstract
Since wood pellet is a good medium for storage and transportation of woody biomass, it could be a promising raw material for biorefinery. However, wood pellet may change the chemical reactivity because wood suffer from physical pressure and heat during pelletization. In this study, delignification rate during soda cooking, a promising pretreatment method for softwood was compared between softwood whole wood pellet and the raw wood chip just before pelletization. The wood chips were further milled to smaller wood particles during pelletization to form wood pellets. Although wood pellet is easily disintegrated to the small wood particles in the beginning, delignification of wood pellet was slower than the raw chip. Longer cooking time and particle size reduction give very similar pulp yield between wood pellet and chip, indicating that the delignification rate was determined by the delayed diffusion of sodium hydroxide due to compression of the wood cell lumen by physical densification. Wood pellet could be digested in the same way as the raw wood only by longer impregnation in the reagent or particle size reduction, meaning that wood pellet could be used well enough as a raw material for saccharification.
