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 θ-Al₂O₃(010)-supported Ni₁₃ 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 Ni₁₃ 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 Ni₁₃ 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 Ni₁₃ cluster supported on θ-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.