Ultrathin Modified Silica “Skin” for the Transfer Hydrogenation Catalyst: Improving Selectivity by Adjusting Surface Wettability

Surface wettability of heterogeneous catalysts plays a crucial role in the catalytic activity and selectivity. In this work, an ultra-thin modified silica coating is firstly used as the “skin” to adjust the surface hydrophilicity of the catalyst, which promotes the catalytic activity and selectivity in the transfer hydrogenation of nitriles. The ultrathin-modified silica “skin” with 2–3 nm thickness is fabricated by the consecutive hydrolysis of (3-aminopropyl)triethoxysilane and n -propyltriethoxysilane, and the bimetallic catalyst Fe 3 O 4 @PtCu is encapsulated in the coating. The modified catalyst demonstrated significant catalytic efficiency for hydrogenation of benzonitrile to dibenzylamine. The reaction performs 93% conversion and 99% selectivity in “green” solvent H 2 O. Furthermore, the modified silica “skin” encapsulates the PtCu nanoparticles to prevent the leaching of active sites, thus brings excellent catalytic recyclability. More than Fe 3 O 4 @PtCu, the modified silica “skin” is applicable to a diverse range of catalysts, that is, PtCu/SiO 2 , PtCu/Al 2 O 3 , and PtCu/UiO-66, endowing them with additional catalytic activity and selectivity in the hydrogenation of nitriles.