New insight into the design of highly dispersed Pt supported CeO2–TiO2 catalysts with superior activity for VOCs low-temperature removal

Abstract

A series of CeO2–TiO2 mixed oxides supports with various Ce/Ti molar ratio were synthesized by modified coprecipitation method. The corresponding Pt loaded (0.5 wt% Pt) catalysts were prepared by electronless deposition method and evaluated for the deep oxidation of n-hexane as a model VOCs. The results show that the CeO2 and TiOx nanoparticles can highly disperse into each other and form Ce2Ti2O7 solid solution with appropriate Ce/Ti molar ratio, which significantly improves their redox ability by enhancing the interaction between CeO2 and TiOx. The dispersibility of Pt species can also be adjusted by altering the Ce/Ti molar ratio, and Pt/CeTi-2/1 catalyst with Ce/Ti molar ratio of 2:1 exhibits the best Pt dispersibility that Pt species mainly exist as Pt single atoms. The high dispersion of Pt species in the Pt/CeO2–TiO2 catalysts would promote the catalytic activity of VOCs oxidation with low T90% values (1000 ppm, GHSV = 15,000 h−1), such as for n-hexane degradation with T90% of 139 °C. The characterizations reveal that the superior activity is mainly related to possessing the more Pt2+ species, adsorbed oxygen species and higher low-temperature reducibility owing to the strong interaction between highly dispersed Pt species and CeO2–TiO2 as well as the promoted migration of lattice oxygen by the formation of more Ce2Ti2O7 species. Furthermore, the Pt/CeTi-2/1 catalyst also exhibits excellent stability for chlorinated and other non-chlorinated VOCs oxidation, making it very promising for real application under various operating conditions.

Keywords

• Highly dispersed Pt species
• CeO2–TiO2 mixed oxides
• VOCs degradation
• Superior activity