Molybdenum-Incorporated Mesoporous Silica: Surface Engineering toward Enhanced Metal-Support Interactions and Efficient Hydrogenation

In heterogeneous catalysis, strong metal-support interactions are highly desired to improve catalytic turnover on metal catalysts. Herein, molybdenum is uniformly incorporated into mesoporous silica (KIT-6) to accomplish strong interactions with iridium catalysts, and consequently, active and selective hydrogenation of carbonyl compounds. Mo-incorporated KIT-6 (Mo-KIT-6) affords electronic interactions to improve the proportion of metallic Ir-0 species, avoiding the easy surface oxidation of ultrafine metals in silica mesocavities. Owing to the effective H-2 activation and subsequent hydrogenation on metallic Ir-0 sites, optimal Ir/Mo-KIT-6 with a high Ir-0/Ir delta+ ratio delivers prominent performance in the hydrogenation of amides to amines and alpha,beta-unsaturated aldehydes to unsaturated alcohols. As for N-acetylmorpholine hydrogenation, the Ir/Mo-KIT-6 catalyst achieves efficient turnover toward N-ethylmorpholine with high selectivity (>99%) and exhibits activity that relies on the engineered chemical state of Ir sites. Such promotion is further proved to be universal in cinnamaldehyde hydrogenation. This work will provide new opportunities for catalyst design through surface/interface engineering.