Bio-oil produced by fast pyrolysis of lignocellulosic biomass has attracted considerable attention as an intermediate liquid product towards the production of fuels. However its chemical instability, high viscosity, and corrosiveness limit their processability and storage. One of the greatest challenges in the upgrading of bio-oil is the accelerated degradation that occurs when the condensed liquid is subsequently heated for fractionation or other processing. Catalytic upgrading is an attractive strategy that can be used to optimize carbon efficiency and minimize hydrogen usage. Ketonization is an important path for the formation of C-C bonds from carboxylic acids. This reaction not only eliminates undesired acidity in the liquid but also generates ketones that can be easily hydrogenated to alcohols, which are subsequently used as alkylation agents. In this way, short carbon fragments (C1-C3) can be readily incorporated into the aromatic ring of phenolic compounds to produce components of the fuel pool.We found that Ru/TiO2 shows great promise as a ketonization catalyst both in the aqueous and vapor phases. We have also found that pre-reduction of the TiO2 is an effective method to optimize catalyst performance. The rate enhancement by reduction in H2 and the rate inhibition caused by the presence of O2 indicate that the active sites for this reaction include coordinatively unsaturated cations. The kinetics study gives evidence of a bimolecular pathway of adsorbed carboxylates that produce a �-ketoacid intermediate (see scheme). The negative reaction orders with respect to CO2, water, and acetone reflect the inhibition by competitive adsorption on the active sites. Analysis of the heats of adsorption, true activation energies, and activation entropies provide further evidence about the reaction mechanism and the nature of the transition state.  References: � �Improving carbon retention in biomass conversion by alkylation �� Appl. Catal. A 447, 14, 2012� �Aqueous Phase Ketonization of Acetic Acid over Ru/TiO2/Carbon Catalysts� J. Catal. 295, 169, 2012� �Ketonization of Carboxylic Acids: Mechanisms, Catalysts, and Implications for Biomass Conversion� ACS Catalysis (in press)

Kinetics and mechanism for the ketonization of carboxylic acids with different carbon chain lengths on Ru/TiO<sub>2</sub> catalysts

247th National Meeting (2014)

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Kinetics and mechanism for the ketonization of carboxylic acids with different carbon chain lengths on Ru/TiO2 catalysts

Kinetics and mechanism for the ketonization of carboxylic acids with different carbon chain lengths on Ru/TiO₂ catalysts