Understanding the crucial roles of catalyst properties in ethyl acetate and toluene oxidation over Pt catalysts

Abstract

Platinum catalysts supported on metal oxidesupports (CeO₂–ZrO₂, CeO₂, ZrO₂ and Al₂O₃) were prepared by a facile impregnation method. Significant differences in properties (medium strong acid density, Pt⁰ species content, Pt dispersion and oxygen density, etc.) were observed among these catalysts. The highest density of medium-strong acid sites, Pt dispersion, and content of metallic Pt⁰ species were observed in Pt/Al₂O₃ catalyst, and Pt/CeO₂–ZrO₂ catalyst gave the highest density of oxygen vacancy. Moreover, the activity orders of these Pt catalysts for ethyl acetate oxidation were very different from that of toluene. The T₉₉ of ethyl acetate oxidation over the Pt/CeO₂–ZrO₂, Pt/CeO₂, Pt/ZrO₂ and Pt/Al₂O₃ catalysts are at 190, 210, 230 and 250 °C, respectively. Ethyl acetate oxidation activity is in the order: Pt/CeO₂–ZrO₂ > Pt/CeO₂ > Pt/ZrO_{2 >} Pt/Al₂O₃. The T₉₉ of toluene oxidation over the Pt/CeO₂–ZrO₂, Pt/CeO₂, Pt/ZrO₂ and Pt/Al₂O₃ catalysts are 220, ₂60, 190 and 250 °C, respectively. Toluene oxidation activity is in order: Pt/ZrO₂> Pt/CeO₂–ZrO₂ > Pt/Al₂O₃ > Pt/CeO₂. The catalytic activities of these Pt catalysts for ethyl acetate mainly depend on the oxygen vacancy density, while the synergistic catalysis of Pt⁰ species and oxygen vacancies play an important role in toluene oxidation. This work could deepen our understanding to differentiate the dominant roles of catalyst properties on ethyl acetate and toluene oxidation over Pt catalysts.