Catalytic reduction of pyrolyzed biomass is required to remove oxygen and produce transportation fuels, but limited knowledge of how hydrodeoxygenation (HDO) catalysts work stymies the rational design of more efficient and stable catalysts, which in turn limits deployment of biofuels. This work reports results from a novel study utilizing both isotopically labeled phenol (which models the most recalcitrant components of biofuels) with D 2 O and DFT calculations to provide insight into the mechanism of the highly efficient HDO catalyst, Ru/TiO 2 . The data point to the importance of interface sites between Ru nanoparticles and the TiO 2 support and suggest that water acts as a cocatalyst favoring a direct deoxygenation pathway in which the phenolic OH is replaced directly with H to form benzene. Rather than its reducibility, we propose that the amphoteric nature of TiO 2 facilitates H 2 heterolysis to generate an active site water molecule that promotes the catalytic C−O bond scission of phenol. This work has clear implications for efforts to scale-up the hydrogen-efficient conversion of wood waste into transportation fuels and biochemicals.

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Molecular beam and bulb gas techniques were employed to study dissociative chemisorption of methane on Ir(111). The initial dissociative chemisorption probability (S0) was measured as a function of incident kinetic energy (Ei), surface temperature, and angle of incidence (θi). As the incident kinetic energy increases, the value of S0 first decreases and then increases with Ei indicating that a trapping-mediated chemisorption mechanism dominates methane dissociation at low kinetic energy, and a direct mechanism dominates at higher kinetic energies. The values of the reaction probability determined from molecular beam experiments of methane on Ir(111) are modeled as a function of Ei, θi, and surface temperature. These fits are then integrated over a Maxwell–Boltzmann energy distribution to calculate the initial chemisorption probability of thermalized methane as a function of gas and surface temperature. The calculations are in excellent agreement with results obtained from bulb experiments conducted with room-temperature methane gas over Ir(111) and indicate that a trapping-mediated pathway governs dissociation at low gas temperatures. At the high gas temperatures characteristic of catalytic conditions, however, these calculations indicate that a direct mechanism dominates methane dissociation over Ir(111). These dynamical results are qualitatively similar to the results of a previous study of methane dissociation on Ir(110), although the reactivity of thermalized methane is approximately an order of magnitude higher on the (110) surface of iridium.

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Pine (Pinus strobus) sawdust was pyrolyzed in a fluidized-bed reactor between the temperatures of 400 and 600 °C. The fixed-bed volume and residence time were optimized to maximize the liquid yield. We report the detailed physical and chemical properties of the bio-oil fraction collected during fast pyrolysis. The liquid yield was maximized at 500 °C, whereas increased gas formation occurred at 600 °C. 13C NMR of the bio-oil fractions indicated a decrease in the carbohydrate fraction and an increase in the aromatic fraction when pyrolysis temperatures were increased from 500 to 600 °C. Over the ranges of our investigation, the effects of the fixed-bed volume and residence time were negligible on the chemical composition of the bio-oil. Toluene and ethyl acetate bio-oil extracts were analyzed by gas chromatography/mass spectrometry following chemical derivatization. At increased reaction temperatures, the process favored conversion of guaiacols to catechols.