Fundamentals of Biomass Pretreatment at Low pH

Production of fuels and chemicals from lignocellulosic biomass typically requires an initial treatment to produce reactive intermediates. For ethanol production via biological conversion of sugars, this step is referred to as pretreatment and produces a more digestible form of biomass for subsequent enzymatic hydrolysis. Additionally, new developments in catalytic production of hydrocarbons for use as drop-in fuels or chemicals has generated interest in the conversion of biomass to reactive intermediates in addition to sugars such as furfural and levulinic acid that result from sugar dehydration. All of these intermediates can be generated through acid hydrolysis of biomass. In this chapter, changes in cellulose, hemicellulose, lignin, ash, and ultrastructure following acid hydrolysis of biomass are described. Furthermore, the evolution of acid treatment objectives is outlined along with common acidifying agents, reaction temperatures and times, and reactor configurations. Kinetic models of these reactions are also reviewed.