(374j) Towards Industrial Pretreatment of Lignocelluloses: Characterization of Dilute-Acid Pretreated Softwood and Identification of Scale Effects

Dilute-acid pretreatment is the most promising method for the conversion of natural softwood into easily degradable substrate. Due to the recalcitrance of natural biomass in combination with a need for high degree of conversion, pretreatment is regarded as the most critical step in the bioethanol process. Commercial dilute-acid pretreatment technologies are currently under development in several pilot projects worldwide. However, optimal pretreatment conditions obtained from lab-scale experiments seem not to be directly translatable to pilot scale and, so far, lab-scale experiments have consistently resulted in more degradable substrates. Thus, there is a need for understanding what features of the pretreated material, i.e. fiber surface properties, composition etc., represent a highly reactive substrate for subsequent enzymatic hydrolysis. This work presents results from a comprehensive characterization of pretreated softwood produced in lab-scale, accounting for effects of acid concentration, temperature and time in the pretreatment. The pretreatment is evaluated by enzymatic hydrolysis experiments and characterization is carried out by studying the adsorption capacity, accessible surface area, chemical composition and SEM examination of the fibers. In addition, samples produced in lab-scale and pilot scale are compared in order to identify the features responsible for the poorer performance in pilot scale.