Introduction 

Most biorefineries define " the purpose of pretreatment is to destroy the structure of cellulosic biomass plant cell walls and make cellulose more accessible to the subsequent process "[1]. A variety of schemes have been developed, but none of them specifically targets the recovery of the hemicelluose (and the lignins) at that stage. In contrast, DalinYebo's sole interest is the conversion of the pentosans, i.e. the majority of the hemicelluloses, into value added chemicals, thus removing them from the biomass. The resulting residue is then available for upstream processing and can be