Improving the Activity and Selectivity of Ir/SiO<sub>2</sub> for the Selective Hydrogenation of Unsaturated Carbonyl Compounds by SnO<sub>2</sub> Promotion
Bin Chen, Jun Hu, Zhihao Yu, Lin Zhu, Chunzheng Wu, Hongbo Yu
Abstract
Improving catalytic hydrogenation by modifying noble metal catalysts with metal-oxide promoters is promising, but precisely controlling the metal–promoter interface to optimize performance is still challenging. In this study, we created Ir-SnO 2 /SiO 2 nanocatalysts with different Ir/Sn ratios using IrSn alloy precursors through careful calcination and reduction treatments. The SnO 2 -promoted catalysts showed much better conversion and selectivity than the original Ir/SiO 2 catalyst toward the hydrogenation of acetophenone to phenylethanol. The Ir-SnO 2 /SiO 2 catalyst with an Ir/Sn molar ratio of 5/1 (i.e., sample Ir 5 -(SnO 2 ) 1 /SiO 2 ) performed the best, achieving a 94% conversion rate and 99% selectivity. Our study found that SnO 2 promoters could reduce the surface electron density of the Ir nanoparticles (NPs), enhancing the adsorption of reactants; meanwhile, the new Ir-SnO 2 interface is more active for the dissociation of hydrogen compared to Ir alone. The optimal Ir 5 -(SnO 2 ) 1 /SiO 2 catalyst has demonstrated versatility by effectively catalyzing the hydrogenation of C═O bonds in a wide range of compounds, showing significant potential for various industrial applications in fine chemical synthesis and energy conversion.