Catalytic styrene combustion over Pt/ZSM-5 Catalysts: Elucidating the deactivation mechanism induced by surface acid sites

Abstract

Catalytic oxidation plays a pivotal role in styrene elimination, yet the development of highly active and robust catalysts remains a challenge. This work aims to elucidate the mechanisms underlying styrene oxidation and catalyst deactivation over the Pt@ZSM-5 catalyst. The Pt@ZSM-5 catalyst with low Si/Al ratio and high surface acidity leads to generation of small Pt particle, the initial activity of the catalyst varies in a volcanic curve with the size of Pt particles. Notably, the Pt@ZSM-5–40 catalyst with Pt particle size of 3.3 nm exhibits the highest reaction rate of 1.6 µmol gPt−1 s−1 at 100 °C. However, the Pt@ZSM-5 catalysts undergo significant deactivation at their T80 (the temperature styrene conversion of 80 %). Through comprehensive characterizations and detailed mechanistic studies, it has been observed that intermediates from styrene oxidation accumulate heavily on the catalyst, especially for the Pt@ZSM-5 catalyst with high acidity. Improving the reaction temperature could inhibit the deactivation which is dependent on the surface acidity of Pt@ZSM-5 catalyst. For instance, the Pt@ZSM-5–800 and Pt@ZSM-5–1200 catalysts remains high activity when reaction is operated at T99+30, whereas a substantially higher reaction temperature (T99+80) is required for both Pt@ZSM-5–18 and Pt@ZSM-5–40 catalysts to counteract deactivation. Our primary results provide insights to develop effective and robust catalyst for styrene oxidation.