Atomically dispersed Pd sites on Ti-SBA-15 for efficient catalytic combustion of typical gaseous VOCs

Abstract

The development of atomically dispersed Pd site catalysts is attractive for maximizing metal utilization and reducing the dosage of Pd in the catalytic combustion of atmospheric volatile organic compounds (VOCs). Herein, we developed a scalable and economically feasible approach to prepare atomically dispersed palladium (Pd) sites on titanium substituted ordered mesoporous silica (Pd SSC/Ti-SBA-15) with an extremely low Pd loading (0.04 wt%). Characterization by AC-HAADF-STEM and in situ CO DRIFTS revealed the existence of isolated Pd sites in Pd SSC/Ti-SBA-15, and the Py-DRIFTS results demonstrated that the acidity of the catalyst was improved by doping with a small amount of Ti. The as-prepared Pd SSC/Ti-SBA-15 exhibited excellent catalytic activity (T₉₀ = 270 °C) for cyclohexane combustion, exceeding that of Pd nanoparticles supported on Ti-SBA-15 with a high Pd loading amount (0.5 wt%) (T₉₀ = 370 °C) and Pd SSC/SBA-15 without Ti substitution (T₉₀ = 420 °C). Furthermore, Pd SSC/Ti-SBA-15 displayed remarkable catalytic activity toward cyclohexane, n-hexane and styrene combustion and maintained 100% mineralizaion after 10 h. The excellent catalytic activity of the resultant Pd SSC/Ti-SBA-15 catalyst might be attributed to the considerable amount of acid sites derived from Ti substitution for promoting VOC adsorption and the maximized Pd utilization realized by atomic Pd sites supported on Ti-SBA-15. This work provides a new route for the development of low-cost and high-performance Pd-based catalysts for VOC abatement.