(158b) A Chemical Perspective On the Conversion of Biomass to Fuels

From a chemical standpoint, the general [-CH₂O-]_n stoichiometry of cellulosic biomass implies the conversion of biomass to fuels - with general stoichiometry [-CH₂-]_n centers on the removal of oxygen. The stoichiometric hydrogen deficiency of biomass is accurately described by the effective hydrogen index (H-2(O))/C proposed by Chen et al., and all chemical processes for the conversion of biomass to fuels must remove the oxygen in biomass and concurrently increase the hydrogen content. Present direct and indirect processes for the conversion of biomass to hydrocarbon fuels use molecular hydrogen to increase the final H:C ratio of the fuel while rejecting oxygen as water. A potentially significant step in biomass-to-fuels conversion lies in the development of a single-step process that does not involve molecular hydrogen.

In this talk, I will briefly discuss our efforts to co-process hydrogen rich alkanes with biomass-derived oxygenates for the production of synthetic fuels. As raw materials for fuels, biomass and light alkanes lie at opposite ends of the chemical spectrum. Light alkanes are inert and their chemical conversion involves the removal of hydrogen and may involve oxygen addition while, biomass-feedstock contains oxygen, the removal of which limits biomass-to-fuels conversion and involves the addition of hydrogen. I will describe our results related to coupling biomass-deoxygenatation with alkane-dehydrogenation pathways over zeolite catalysts so that in essence, alkanes serve as a surrogate for molecular hydrogen for biomass deoxygenation while biomass serves as the oxygen carrier for hydrogen removal from alkanes.