The effects of MoOx decoration on the selective hydrogenation of crotonaldehyde over MoOx-promoted Ir/TUD-1 catalysts

Abstract

A series of MoOx-promoted Ir/TUD-1 catalysts were tested for liquid phase selective hydrogenation of crotonaldehyde. The promoted catalysts showed higher activity and selectivity than the unpromoted one, with the best performance being obtained on an Ir-0.1Mo/TUD-1 (with a crotyl alcohol yield of 86.7% and a turnover number of 325.7 h−1). The large pore sizes of the TUD-1 is beneficial to the diffusion of the reactant and thus the supported catalyst is more active than that supported on the commercial SiO2. The characterization results revealed decoration of Ir particles by MoOx, which altered the morphologies and electronic properties of the catalysts. Such decoration resulted in the generation of Ir-MoOx interfacial sites, which altered the adsorption and activation of crotonaldehyde molecule and brought up enhanced activity and selectivity. However, at high MoOx content, the Ir surface was fully covered by MoOx, which results in strong adsorption of crotonaldehyde and fewer surface Ir atoms for H2 dissociation and thus declined activity.