High-Density Formation of Ir/MoOx Interface through Hybrid Clustering for Chemoselective Nitrostyrene Hydrogenation.

Abstract

To form high-density metal/oxide interfacial active sites, we developed a catalyst preparation method based on hybrid clustering. An iridium-molybdenum (Ir-Mo) hybrid clustering catalyst was prepared by using the hybrid cluster [(IrCp*)4Mo4O16] (Cp* = η5-C5Me5) as the precursor. The Ir-Mo hybrid clustering catalyst selectively reduced the nitro group in the hydrogenation of 4-nitrostyrene, whereas the coimpregnated Ir-Mo catalyst reduced both the nitro and vinyl groups nonselectively. The hybrid clustering catalyst also exhibited high selectivity, even at a high Ir loading (5 wt %), in contrast to Ir/MoO3, which exhibited high selectivity only at low Ir loadings (<0.3 wt %). In situ X-ray absorption spectroscopy analysis revealed that oxygen vacancies were formed at the Ir/MoOx interface in the presence of H2. We concluded that a high-density Ir/MoOx interface contributes to the preferential adsorption of nitro groups on vacant sites, promoting the selective hydrogenation of nitro groups.