Insight into the enhanced performance of TiO2 nanotube supported Pt catalyst for toluene oxidation

Featuring an assembly of identical pores, TiO2 nanotube array (TiNT) makes an ideal monolith-like support of noble metal catalysts for volatile organic compounds combustion. Herein, the deep oxidation of gaseous toluene over Pt/TiNT and anatase TiO2 (ATiO(2)) particles supported Pt catalysts are studied and compared. Pt/TiNT demonstrates remarkably enhanced performance over Pt/ATiO2 powder catalyst, and ranges among the best performances of the state of the art Pt based catalysts. A toluene conversion of (>) 95% at 185 degrees C and a multiple heating-cooling cyclic stable performance with a time of (>) 300 h are achieved over 0.4 wt% Pt/TiNT. In situ DRIFTS study indicates that toluene is sequentially oxidized to benzaldehyde, benzoate, aliphatic carboxylates species, CO and finally to CO2, and the decomposition of benzoate species is the key step. The unique performance of Pt/TiNT is attributed to its ordered monolith-like structure, well-dispersion and surface enrichment of Pt, and enhanced benzoate species decomposition rate.