Intermetallic compound PtMny-derived Pt?MnOx supported on mesoporous CeO2: Highly efficient catalysts for the combustion of toluene

Article abstract of DOI:10.1016/j.apcata.2020.117509

Intermetallic compounds are a kind of important materials in heterogeneous catalysis. In this work, we first synthesized the PtMn_y intermetallic nanocrystals using the polyvinyl pyrrolidone-assisted ethylene glycol reduction method, and then loaded them on the surface of mesoporous CeO₂ (meso-CeO₂) derived from a KIT-6-templating route, generating the mPt?nMnO_x/meso-CeO₂ (m = 0?0.39 wt%, n = 0?1.21 wt%) catalysts after calcination at 500 °C in air. It is found that the as-obtained catalysts displayed an ordered mesoporous architecture with surface areas of 95?108 m²/g. The 0.37Pt?0.16MnO_x/meso-CeO₂ sample exhibited the best catalytic performance for toluene combustion (T50 % =162 °C and T90 % =171 °C at space velocity = 40,000 mL/(g h)). Kinetic analysis reveals that the apparent activation energy (57 kJ/mol) obtained over the best-performing 0.37Pt?0.16MnO_x/meso-CeO₂ sample was lower than those (63?75 kJ/mol) obtained over the other samples. Furthermore, the 0.37Pt?0.16MnO_x/meso-CeO₂ sample possessed good thermal stability and water-resistant performance. Benzyl alcohol, benzoic acid, and maleic anhydride were proven to be the main intermediates of toluene combustion, hence, toluene combustion might take place through a sequence of toluene → benzyl alcohol and benzoic acid → maleic anhydride → carbon dioxide and water, which might obey the Eley?Rideal reaction mechanism. It is concluded that loading of Pt and MnO_x enhanced the adsorbed oxygen and Mn²⁺ species concentration and low-temperature reducibility, thus promoting toluene combustion over 0.37Pt?0.16MnO_x/meso-CeO₂.