Enhanced Interfacial H2 Activation for Nitrostyrene Catalytic Hydrogenation over Rutile Titania-Supported Gold by Coadsorption: A First-Principles Microkinetic Simulation Study

Hydrogenation of aromatic nitro compounds is an efficient way to yield aniline, an extremely vital intermediate in many chemical industry fields. However, it is still a great challenge to prepare a catalyst with both high activity and selectivity for this important process when other reducible groups exist at nitroaromatics. Au/TiO2 catalysts could achieve good selectivity for the hydrogenation of nitroarenes with a reducible functional group. However, their activity is still not high. Their fundamental and systematic understandings are still lacking. In this work, the catalytic kinetics of the 4-nitrostyrene (4-NS) hydrogenation system at the binary Au/TiO2 interface is investigated by first-principles heterogeneous site microkinetics simulation. To solve the complex microkinetics model with heterogeneous multiple sites, an efficient hybrid iteration numerical method is proposed and utilized to overcome the stiff problem. Through realistic first-principles calculations and microkinetic analysis, the favorable adsorption configurations and possible catalytic mechanism are determined for 4-NS hydrogenation at the Au/TiO2 interface. It is found that the chemisorption of 4-nitrostyrene could significantly lower the energy barrier of H-2 dissociation at the interface, which could enhance the overall activity of the Au/TiO2 catalyst. It sheds light on a way to promote the activity of selective hydrogenation for metal oxide-supported gold catalysts through modulating the coordination of exposed surface cations.