Operando Spectroscopic Observation of CO Oxidation on a Pt/TiO₂ Catalyst in NO–CO Mixtures under Dark and UV Illumination

Abstract

The importance of catalytic CO oxidation for exhaust gas processing has inspired the development of efficient and durable catalysts that can be operated at low temperatures, as exemplified by supported noble metals. However, most of the related studies have neglected the potential effects of co-present exhaust gas components, such as NO. Herein, we compared the performances of platinized and bare TiO2 for the ambient-temperature (photo)­catalytic oxidation of CO by O2 in the co-presence of NO and used in situ Fourier transform infrared spectroscopy to elucidate the effects of platinization on the efficiency and mechanism of this oxidation. Catalytic CO oxidation was accompanied by competitive NO oxidation both in the dark and under ultraviolet (UV) illumination. In the dark, Pt/TiO2 achieved a higher CO removal efficiency than bare TiO2, which was ascribed to the enhanced adsorption of O2 and CO and the inhibition of NO overoxidation (mainly the oxidation of the monodentate nitrito form to the bidentate nitrate form). Under UV illumination, Pt/TiO2 efficiently promoted CO oxidation at photocatalytically active sites (Pt0–CO) by suppressing NO overoxidation and increasing the reduction of NO to N2O. Hence, the enhanced CO oxidation performance of Pt/TiO2 was due to its ability to control NO oxidation and reduction at ambient temperature, which presents a new strategy for the design of low-temperature CO oxidation catalysts.

Boosting the catalytic performance of Al2O3-supported Pd catalysts by introducing CeO2 promoters

“…2 However, the catalysts typically exhibit poor activities at low temperatures due to CO poisoning, while hightemperature environments often lead to the instability of noble metal species. 3 In view of the high cost of catalyst replacement and regeneration in industrial applications, the development of catalysts with excellent activity at low tempera-tures and remaining structurally stable at high temperatures is necessary and urgent. 4 Since the supports have a great influence on the catalytic activity of components according to the metal-support interactions, it is a very promising approach to improve the activity and stability of catalysts by designing and constructing specific supports.…”