Homogeneous catalysts stabilized in ionic liquids complement conventional heterogeneous catalysis and enzyme catalysis for the conversion of biomass and biomass-derived products into fuels and value-added products. Synthesis gas, a mixture of H2 + CO, is one of the top-ten platform chemicals produced from biomass and reacts with a variety of transition-metal oxides, including especially those of Fe, Co, Ru, Rh and Ir to form carbonyl anions and carbonyl-hydride anions that catalyze CO and hydrogen transfer reactions. With the appropriate homogeneous catalyst and ionic liquid, syngas is readily converted into methanol, which depending upon reaction conditions and catalyst, can be homologized into fuel ethanol or used to form dimethyl ether for diesel fuel or further converted into other fuel products. Homogeneous water-gas shift catalysis: H2O + CO = H2 + CO2, produces hydrogen for reaction and allows lower H2/CO molar ratios to be employed in the syngas that are more compatible with those formed by biomass gasifiers. Homogeneous water-gas shift allows fuel ethanol to be produced from water and CO alone, without the need to add any H2 gas, at a rate of 0.20 gethanol�gcatalyst-1�h-1. Moreover, at 220�C in high-pressure CO and with consumption of H2, water is efficiently removed to very low, near-equilibrium concentrations, drying by chemical reaction the ethanol product. Lignin residuum produced from corn stover and the cellulosic ethanol process is readily dissolved in ionic liquids. Homogeneous catalysts that are atomically dispersed as non-volatile anions or that are dispersed as small ionic cluster compounds (as identified by infrared spectroscopy) diffuse and are especially effective in breaking the ether bonds of lignin. The methoxy groups of lignin are catalytically reduced to methanol at rates superior to simple thermal decomposition. Co-produced from lignin are acetone, ethanol, 1-propanol and 2-propanol.  Acknowledgement:  U.S. Department of Energy, Office of Science (DE-SC0004376).

Homogeneous catalysts stabilized in ionic liquids for processing biomass and biomass-derived chemicals

248th National Meeting (2014)

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