Ceria is a key component in many heterogeneous catalysts. In typical applications ceria magnifies the performance of the active phase, but the stand-alone catalytic function of ceria is rare and usually related to oxidations. Interestingly, in a recent experimental study by some of us, we reported an unprecedented performance of pure ceria for the partial hydrogenation of alkynes to olefins with outstanding selectivity [1]. Experimental evidence shows that (111) facets are especially prone to hydrogenation and, therefore, here we combine in-depth characterization, catalytic tests, and density-functional theory (DFT) mechanistic studies to provide a molecular-level understanding of the hydrogenation of ethyne on the CeO2(111) surface. From this study we find that (i) hydrogen activation is the most probable ratelimiting step (BC in the figure) and (ii) a high-energy barrier of ca. 4 eV (FG in the figure) hinders the over-hydrogenation process, in line with the experimentally observed virtual absence of ethane at the reactor outlet. Our results open exciting perspectives for investigating the ability of pure ceria as a catalyst for the selective hydrogenation of alkynes and other functional groups.

Trabajo presentado en Chemistry and Molecular Sciences and Technologies COST Action CM1104, celebrado en Viena (Austria) del 18 al 19 de abril de 2013.

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