Exploration of strong metal-support interaction in zirconia supported catalysts for toluene oxidation

Strong metal-support interaction (SMSI) can greatly affect the catalytic performance in various reactions. Herein, we demonstrated the formation of distinct SMSI in zirconia supported catalysts by changing the types of supported precious metals. Different from Pt/ZrO2 catalyst with interfacial SMSI (I-SMSI), Pd species in Pd/ZrO2 catalyst were more prone to generate the SMSI with Brønsted acid sites (B-SMSI) rather than interfacial structure. The formation of B-SMSI in Pd/ZrO2 catalyst was proven by the dramatic decrease in the Brønsted acid sites, which resulted in the high cationic Pd2+ content. Owing to the formation of B-SMSI, Pd/ZrO2 catalyst even possessed a comparable catalytic activity with Pt/ZrO2 catalysts for toluene oxidation. Moreover, Pd/ZrO2 catalyst with B-SMSI also exhibited excellent water and sulphur resistance together with high-temperature stability for toluene oxidation, which has great potential in practical application. In situ DRIFTS spectra revealed that the two types of SMSI could activate oxygen species, accelerate the toluene oxidation and improve the catalytic efficiency.