Pt-support interaction and nanoparticle size effect in Pt/CeO₂-TiO₂ catalysts for low temperature VOCs removal

A series of Pt/CeO₂-TiO₂ catalysts (0.5 wt% Pt) with size-controllable Pt nanoparticles were prepared by a modified ethylene glycol reduction method and the Pt particle size effect of Pt/CeO₂-TiO₂ catalysts on benzene and 1,2-dichloroethane (DCE) degradation was investigated. It reveals that the metal-support interaction of PtO_x species and CeO₂-TiO₂ mixed oxides is enhanced by the reduced Pt particle sizes. The formation of more Pt²⁺ species and stronger redox properties at low-temperature resulted by the enhanced metal-support interaction of Pt/CeO₂-TiO₂ catalysts both greatly promotes the deep oxidation for benzene and C₂H₃Cl byproduct during DCE degradation at low temperature. Pt/CeTi-11 with the smallest average Pt particle size (1.53 nm) exhibits the highest activity among all the catalysts for benzene degradation, with T_90% of only 152 °C (1000 ppm, GHSV = 15,000 h^-1). However, more acidic sites (especially the strong acid) were formed on the Pt/CeO₂-TiO₂ catalysts with bigger Pt nanoparticle (>2.95 nm), contributing to activate and convert DCE to C₂H₃Cl. More importantly, Pt/CeO₂-TiO₂ catalysts are extremely stable in DCE degradation reaction, and have been scarcely influenced by the presence of benzene and water in the feed gases.