Hydrolysis pathways are appropriate for lignocellulose processing if higher selectivity is desired in biomass utilization, for example, in the production of chemical intermediates or targeted hydrocarbons for transportation fuel. Selective transformations require isolation of sugar monomers, a step which is complex and expensive for lignocellulosic feedstocks. Once sugar monomers are isolated, however, they can be processed efficiently at relatively mild conditions by a variety of catalytic technologies (Alonso et al., 2010).

The ability to recover and use the major components of lignocellulosic biomass (cellu­lose, hemicellulose, lignin) is critical in developing economically viable bioproducts and biorefineries. This project focuses on the biomass pretreatment step of hemicellulose acid hydrolysis to recover the hemicellulose sugars and prepare the biomass for subsequent enzymatic or acid cellulose conversion. The ultimate goal is to identify promising routes to reduce the sugar production cost by 30% compared with established methods. Researchers are investigating three hydrolysis systems: water-rich hydrolysis, water-restricted, and near neutral pH. Using different reactor configurations (e. g., batch tube, Parr, flow through) with varying solids and pH levels, researchers have developed comprehensive data on the destructuring, disaggregation, and depolymerization of hemicellulose to sugars. Flow rate has been found to enhance hemicellulose removal, which is inconsistent with models typi­cally applied to describe hemicelluloses hydrolysis. New models have been defined that reveal mass transfer could be important in explaining this anomaly. The flow through reactor experiments showed that lignin is modified as hemicellulose reacts, and the resulting disruption of lignin may play a significant role in enhancing cellulose digestion. In addition, researchers have shown that nonproductive adsorption on lignin can be reduced by prior treatment with low-cost proteins, thereby substantially cutting enzyme costs (Iranmahboob et al., 2002; Mosier et al., 2005; Patrick Lee et al., 1997; Wang et al., 2007; Yat et al., 2008).

The ideal process for cellulosic biomass conversion would be the production of liquid fuels from biomass in a single step at a short residence time. The liquid product produced in pyrolysis is called bio-oil, which is an acidic combustible liquid containing more than 300 compounds (Wang et al., 2008). Bio-oils are not compatible with existing liquid

transportation fuels including gasoline and diesel. To use bio-oil as a conventional liquid transportation fuel, it must be catalytically upgraded (Carlson et al., 2008). Zeolite catalysts added into the pyrolysis process can convert oxygenated compounds generated by pyrolysis of the biomass into gasoline-range aromatics.