The cost of transportation fuels produced from ligno-cellulosic biomass is currently not competitive with the cost of petroleum, due primarily to the high costs associated with the processing of biomass to produce the fuel. New processes for the conversion of biomass to liquid fuels must therefore be developed with a limited number of processing steps. In previous studies, we developed a process to produce liquid alkanes via integrated glycerol conversion to synthesis gas with Fischer-Tropsch synthesis. Recently, we have developed a novel catalytic approach which converts carbohydrates (sorbitol and glucose) derived from cellulose, to mono-functional chemical intermediates, which are currently derived exclusively from fossil fuels, and which can be converted to higher molecular weight alkanes (e.g., C5-C_(12) for gasoline, C9-C_(16) for jet fuel, and C_(10)-C_(20) for diesel applications). Figure 1 illustrates these approachs. While glycerol is converted primarily to H2/CO gas mixtures, sorbitol and glucose are converted to monofunctional hydrocarbon intermediates such as alcohols, ketones, carboxylic acids, and heterocyclic compounds with 4-6 carbon atoms on the same Pt-Re/C catalyst at similar reaction conditions (483-523 K, 18-27 bar). Subsequent aromatization, isomerization, aldol-condensation, and/or ketonization processes convert these functional molecules to alkanes suitable for use as fuel components.
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