ABSTRACT
Acid feedstock preprocessing includes a variety of unit operations that occur upstream of conversion that results in value-added feedstock intermediates with enhanced conversion performance and efficiency. Acid preprocessing improves feedstock quality and enzymatic digestibility by reducing non- structural components, such as ash, increasing catalyst penetration prior to pretreatment, and debranching xylan chains prior to downstream bioconversion. Sulfur dioxide has been used for pretreating woody feedstocks because it rapidly impregnates biomass tissue, providing uniform distribution of the catalyst. The processes include in situ biologically produced organic acids for feedstock ensiling, pre-impregnated biomass with an acid catalyst, and prehydrolysis of woody biomass for future forest biorefineries to provide both valuable co-products and reduced energy and processing inputs to the pulping process. The use of dicarboxylic acids to mimic the enzymatic hydrolysis of biomass has been used to reduce pretreatment requirements potentially reducing the need for acid-resistant materials for pretreatment.
