First dehydrogenation of ethanol catalyzed by a single atom of d-block metals

The initial dehydrogenation of ethanol is important in the development of sustainable and practical energy processes. Transition metals, especially the less expensive and more abundant 3d metals, are appealing as catalysts for ethanol dehydrogenation. As a single atom adsorbed to ethanol, these metals are likely to have enhanced selectivity and activity, in addition to maximized utilization efficiency. Density functional theory calculations were performed with Gaussian16 to investigate these ideas using both the B3PW91 and PBEPBE functional. The presented work explores the use of 18 different single metal atoms as catalysts in the first dehydrogenation of ethanol. All of the 3d metals, as well as eight 4d and 5d metals, were investigated as catalysts for this reaction. Three ethanol dehydrogenation pathways were studied for each metal catalyst: α-H, β-H, and o-H cleavage. Analysis of the energies of each reaction allowed for a determination of the dehydrogenation pathway most favored by each metal catalyst, and ultimately yielded a top catalyst for each dehydrogenation pathway. Based on the results of these calculations, the best predicted catalyst for o-H cleavage was scandium, for β-H and α-H cleavage was platinum. However, differences in the B3PW91 and PBEPBE results suggest that β-H cleavage could also be favored for Pt, and that another possible top catalyst for β-H cleavage could be Pd. This work will serve as a benchmark for heterogeneous catalysis of the ethanol dehydrogenation reaction.