Silica-modified Pt/TiO2 catalysts with tunable suppression of strong metal–support interaction for cinnamaldehyde hydrogenation

Abstract

Tuning Strong Metal-support Interactions (SMSI) is a key strategy to obtain highly active catalysts, but conventional methods usually enable TiOx encapsulation of noble metal components to minimize the exposure of noble metals. This study demonstrates a catalyst preparation method to modulate a weak encapsulation of Pt metal nanoparticles (NPs) with the supported TiO2, achieving the moderate suppression of SMSI effects. The introduction of silica inhibits this encapsulation, as reflected in the characterization results such as XPS and HRTEM, while the Ti4+ to Ti3+ conversion due to SMSI can still be found on the support surface. Furthermore, the hydrogenation of cinnamaldehyde (CAL) as a probe reaction revealed that once this encapsulation behavior was suppressed, the adsorption capacity of the catalyst for small molecules like H2 and CO was enhanced, which thereby improved the catalytic activity and facilitated the hydrogenation of CAL. Meanwhile, the introduction of SiO2 also changed the surface structure of the catalyst, which inhibited the occurrence of the acetal reaction and improved the conversion efficiency of C=O and C=C hydrogenation. Systematic manipulation of SMSI formation and its consequence on the performance in catalytic hydrogenation reactions are discussed.