Formation Combined with Intercalation of Ni and Its Alloy Nanoparticles within Mesoporous Silica for Robust Catalytic Reactions

Abstract

Intercalation of silica-supported nickel nanoparticles within mesoporous silica has been achieved through chemical reduction of nickel silicate with mesoporous silica ( mSiO2) coated on inner and outer surfaces. Formation of nickel nanoparticles was controlled at nickel silicate-silica interface and was well-confined by mSiO2 coating. Doping of other transition metals has been accomplished at the stage of nickel silicate formation, because of similarity in critical stability constants of respective metal salts. Doped nickel silicates were able to produce nickel-based bimetallic and trimetallic alloy nanoparticles within the final dual-shell configuration. This type of catalyst has been tested for both liquid- and gas-phase reactions, all showing good activity and selectivity. Ni nanoparticles could serve as the active catalyst or activity enhancer to other alloyed metals for different reactions. Especially for selective hydrogenation of trans-cinnamaldehyde, 100% selectivity toward hydrocinnamaldehyde at full conversion has been achieved without using noble metals. Spent catalysts in all cases showed no changes in terms of morphology and crystal structure, indicating this type of catalyst was robust under such reaction conditions, including gas-solid reaction systems.