Engineering electrophilic atomic Ir sites on CeO2 colloidal spheres for selectivity control in hydrogenation of α,β-unsaturated carbonyl compounds
Muhammad Mateen, Muhammad Nadeem Akhtar, Ling Gao, Weng‐Chon Cheong, Shanshan Lv, Yan Zhou, Zheng Chen
Abstract
Selective hydrogenation of the carbonyl bond in α,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects. Here, we demonstrate a facile emulsion-based molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO2 spheres (Ir1@CeO2). When applied to the hydrogenation of α,β-unsaturated aldehydes, Ir1@CeO2 catalyst remarkably exhibited ~ 100% selectivity towards unsaturated alcohols, whereas the formation of Ir nanoparticles on CeO2 drastically decreased the selectivity for unsaturated alcohols. Spectroscopic studies revealed that strong metal—support interactions triggered the charge transfer from Ir to CeO2, leading to the partial reduction of Ce4+ to Ce3+ along with the formation new Irδ+—O2−—Ce3+(OV) interfaces. The electrophilic atomic Ir species at the Irδ+—O2−—Ce3+ (OV) interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.