Coupled Palladium-Tungsten Bimetallic Nanosheets/TiO_2 Hybrids with Enhanced Catalytic Activity and Stability for the Oxidative Removal of Benzene

摘要

Since the conventional Pd-based catalysts often suffer severe deactivation by water, development of a catalyst with good activity and moisture-resistance ability is of importance in effectively controlling emissions of volatile organic compounds (VOCs). Herein, we report the efficient synthesis of ultrathin palladium tungsten bimetallic nanosheets with exceptionally high dispersion of tungsten species. The supported catalyst (TiO2/PdW) shows good performance for benzene oxidation, and 90% conversion is achieved at a temperature of 200 degrees C and a space velocity of 40 000 mL g(-1). The TiO2/PdW catalyst also exhibits better water-tolerant ability than the traditional Pd/TiO2 catalyst. The high catalytic efficiency can be explained by the facile redox cycle of the active Pd2+/Pd-0 couple in the close-contact PdOx-WOx-TiO2 arrangement. We propose that the reason for good tolerance to water is that the lattice oxygen of the TiO2/PdW catalyst can effectively replenish the oxygen in active PdOx sites consumed by benzene oxidation. A four-step benzene transformation mechanism promoted by the catalyst is proposed. The present work provides a useful idea for the rational design of efficient bimetallic catalysts for the removal of VOCs under the high humidity conditions.