Interface Effects in Hydrogen Elimination Reaction from Isopropanol by Ni13 Cluster on θ-Al2O3(010) Surface

We present results of theoretical investigation on catalytic hydrogen elimination from isopropanol (C3H8O) by free and (theta-Al2O3(010)-supported Ni-13 cluster. The specific role played by the perimeter interface between the nickel cluster and alumina support is discussed. It is demonstrated that dehydrogenation of C3H8O on the free Ni-13 cluster is a two-step process with the first hydrogen elimination from the alcohol hydroxyl group, followed by C-H bond cleavage. Our calculations show that H elimination from OH group of C3H8O to Ni-13 cluster is the rate-determining step with the barrier of 0.95 eV, while the C-H bond cleavage requires overcoming the barrier of 0.41 eV. In the case of Ni-13 cluster supported on (theta-Al2O3(010) the isopropanol molecule adsorbs on top of the surface Al atom in the close vicinity of the nickel cluster, which results in considerable decrease in barrier for H elimination due to formation of the complementary adsorption sites at the metal/support interface. It is demonstrated that intermediate formation of the Ni-C bond considerably promotes C-H bond cleavage. The described mechanism provides fundamental understanding of the process of the oxidant-free catalytic hydrogen elimination from alcohols on supported nickel clusters and can serve as a tool for rational design of novel type of nanocatalysts based on abundant noble-metal-free materials.