Ceramic solids – non-noble metal or semi-metal oxides, carbides, nitrides, sulfides, phosphides, etc. – can exhibit a wide range of surface chemical reactivity that is of interest to heterogeneous catalysis.  This surface reactivity is a strong function of ceramic composition and may be rationally tuned if understood fully. Our aim in this project is to develop a fundamental understanding of how the surface chemistry of a selection of transition metal ceramics are affected by the choice of metal and non-metal constituents.  Specifically, we focus on understanding how the oxophicility and carbon affinity of the ceramic can be tuned such that the recalcitrant oxygen removal and carbon-carbon bond formation can be promoted. Additionally, we aim to understand how to limit over hydrogenation of aromatic products by reducing van der Waals (vdW) interactions and unselective C=C activation. In this study, we have investigated the oxides, carbides, nitrides, sulfides, and phosphides of titanium (Ti), and nickel (Ni) in the deoxygenation of guaiacol – a model reaction. Through a combined quantum chemical modeling and experimental investigation, we found that 1) the production of benzene, toluene, and xylene (BTX) can promoted by enhancing the surface chemical reactivity towards oxygen to an appropriate degree such that phenolic oxygen removal is promoted; 2) the over hydrogenation of aromatic rings can be diminished by the reduction of vdW force on ceramics; and 3) transition metal electron count plays a direct and systematic role in dictating the surface oxophicility and carbon affinity of TM phosphides. Finally, methylation of the aromatic ring to produce the more valued products toluene and xylene can be promoted by providing variable sources of CH<sub>x</sub> groups, e.g., dimethyl carbonate, methanol, and methane.

Selecting and tuning non-noble metals to promote C-O bond cleavage and carbon-carbon coupling reactions

251st National Meeting (2016)

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