γ-Alumina-supported Pt17 cluster: controlled loading, geometrical structure, and size-specific catalytic activity for carbon monoxide and propylene oxidation

Abstract

Although Pt is extensively used as a catalyst to purify automotive exhaust gas, it is desirable to reduce Pt consumption through size reduction because Pt is a rare element and an expensive noble metal. In this study, we successfully loaded a Pt₁₇ cluster on γ-alumina (γ-Al₂O₃) (Pt₁₇/γ-Al₂O₃) using [Pt₁₇(CO)₁₂(PPh₃)₈]Cl_n (n = 1, 2) as a precursor. In addition, we demonstrated that Pt is not present in the form of an oxide in Pt₁₇/γ-Al₂O₃ but instead has a framework structure as a metal cluster. Moreover, we revealed that Pt₁₇/γ-Al₂O₃ exhibits higher catalytic activity for carbon monoxide and propylene oxidation than γ-Al₂O₃-supported larger Pt nanoparticles (Pt_NP/γ-Al₂O₃) prepared using the conventional impregnation method. Recently, our group discovered a simple method for synthesizing the precursor [Pt₁₇(CO)₁₂(PPh₃)₈]Cl_n. Furthermore, Pt₁₇ is a Pt cluster within the size range associated with high catalytic activity. By combining our established synthesis and loading methods, other groups can conduct further research on Pt₁₇/γ-Al₂O₃ to explore its catalytic activities in greater depth.