(511a) Investigation of Reaction Pathways and Intermediates for the Production of High Purity Hydrogen Via Alkaline Thermal Treatment

A potential pathway for distributed energy from biomass is through alkaline thermal treatment. Alkaline thermal treatment converts biomass to hydrogen and alkali metal carbonate with minimal CO_x co-production at low temperature (i.e. less than 300 °C) and atmospheric pressure conditions by reacting the biomass with a strong basic hydroxide, such as NaOH, and steam. Due to these relatively mild conditions, the design of a simple, compact reactor becomes possible, and the produced hydrogen can be fed directly to a proton exchange membrane (PEM) fuel cell to produce electricity. Alkaline thermal treatment is a relatively new technology, with investigation having begun into model biomass compounds such as glucose and cellulose. However, the roles of the hydroxide and steam in directing the decomposition pathways of biomass toward the production of high-purity hydrogen at low temperature and atmospheric pressure conditions are not well understood. To elucidate the roles of the hydroxide and steam in alkaline thermal treatment, chemical and physical characterizations of the gaseous and solid products throughout the stages of the reaction are presented. Identified intermediate species were individually tested both in the presence and absence of hydroxide and steam in order to deduce steps along the reaction pathway that lead to the final observed gaseous and solid products of alkaline thermal treatment. Different hydroxides are evaluated in terms of hydrogen production.