Photo-Thermo Catalytic Oxidation of C3H8 and C3H6 over the WO3-TiO2 Supported Pt Single-Atom Catalyst

Catalytic oxidation is a commonly employed technology in the industry for removing volatile organic compounds (VOCs) due to its exceptional efficiency under mild operating conditions. Although supported Pt-based nano-catalysts are recognized widely as one of the most promising and extensively used industrial catalysts for VOC abatement, their practical application, and development are restricted by their exorbitant cost. Single-atom catalyst (SAC) with maximized metal utilization and exclusive electronic character has been explored extensively in various catalytic reactions. However, Pt SAC is usually deemed to be inactive in hydrocarbon oxidation reactions in thermal catalysis, compared with its nanoparticle counterpart. Here, we demonstrate that the WO 3 -TiO 2 supported Pt SAC (Pt 1 /WO 3 -TiO 2 ) exhibits much higher activities than the corresponding nanoparticle catalyst (Pt NP /WO 3 -TiO 2 ) in photo-thermo catalytic oxidation of C 3 H 8 and C 3 H 6 , which represent different kinds of typical VOCs. A key finding is that the activities of Pt 1 /WO 3 -TiO 2 and Pt NP /WO 3 -TiO 2 can be accelerated in photo-thermo catalytic C 3 H 8 oxidation by overcoming oxygen poisoning. Upon the light irradiation, the apparent active energy ( E a ) of the Pt 1 /WO 3 -TiO 2 and Pt NP /WO 3 -TiO 2 decline from 116 to 60 kJ·mol −1 and from 103 to 30 kJ·mol −1 , respectively, substantiating their effectiveness in photo-thermo catalysis. Notably, a substantially higher reaction rate of 3792 μmol∙g Pt −1 ∙s −1 on the Pt 1 /WO 3 -TiO 2 is achieved, which should be a benchmark for C 3 H 8 oxidation. More intriguingly, photo-thermo catalytic C 3 H 6 oxidation on the Pt NP /WO 3 -TiO 2 is prohibited due to the strong adsorption-induced C 3 H 6 poisoning on the Pt nanoparticles, for which the E a of the Pt NP /WO 3 -TiO 2 catalyst for C 3 H 6 oxidation is maintained at approximately 55 kJ·mol −1 , regardless of the light irradiation. In comparison, the C 3 H 6 poisoning on the Pt 1 /WO 3 -TiO 2 can be mitigated by light illumination, where the E a of the Pt 1 /WO 3 -TiO 2 catalyst for C 3 H 6 oxidation dramatically reduced from 49 to 16 kJ·mol −1 , signifying that the high energy barrier of C 3 H 6 oxidation can be mediated by the light. Profiting from the apt affinity between C 3 H 6 and Pt single atoms, the photogenerated electrons accumulated on the Pt single atoms produce repulsive force towards the electron-rich C 3 H 6 molecules, which is conducive to the C 3 H 6 desorption from the Pt 1 /WO 3 -TiO 2 . Therefore, the Pt 1 /WO 3 -TiO 2 exhibits enhanced activity in photo-thermo catalytic C 3 H 6 oxidation. This study exemplifies that the advantages of SAC are not only saving the consumption of precious metals but also discovering new catalytic reactions on the account of the specific electronic characteristic. Download: Download high-res image (85KB) Download: Download full-size image