(513g) Kinetics of C-C Coupling Reactions with Carboxylic Acids and Oxygenates over Zeolites

Small carboxylic acids such as acetic acid are abundant and often problematic species resulting from the thermal decomposition of biomass. The conversion of these corrosive compounds by C-C coupling to produce more neutral ketones is very promising. These ketones can serve as stable platform molecules to undergo subsequent aldol condensation to ultimately yield fuel-range products. In this contribution, we discuss the surface intermediates involved in the conversion of carboxylic acids over zeolites. A detailed kinetic model is presented to describe the elementary steps of the process, which are supported by DFT calculations of various intermediates and transition states on H-ZSM-5. The critical role of surface acyl species is discussed. The role of confinement as well as the interaction with other adsorbed oxygenates and water is presented, with the identification of two distinct kinetic regimes where product selectivity can be tuned.