Tailoring the Brønsted acidity of Ti−OH species by regulating Pt−TiO₂ interaction

Abstract

Bifunctional catalysts comprising metal and acid sites are commonly used for many reactions. Interfacial acid sites impact intermediate reactions more than other sites. However, controlling the type and amounts of interfacial acid sites by regulating metal-support interaction (MSI) via traditional methods is difficult. Thus, the influence of MSI on interfacial acid sites remains unclear. We prepared Pt-mTiO₂/α-Al₂O₃ (m represents the cycle number of TiO₂) catalysts via atomic layer deposition (ALD). New Brønsted acid sites were generated via Pt-TiO₂ interaction, and the acidity was precisely regulated by regulating Pt-TiO₂ interaction by changing the TiO₂ nanolayer thickness. We chose levulinic acid (LA) hydrogenation as a model reaction. The catalytic activity varied with the TiO₂ nanolayer thickness and was linearly correlated with the Ti-OH species (Brønsted acid) content. Pt-40TiO₂/α-Al₂O_3, with the highest acid site content of 0.486 mmol/g, exhibited the best catalytic activity. Hydrogen spillover and water dissociation at the Pt-TiO₂ interface promoted Ti-OH species generation.