Three-dimensionally ordered mesoporous iron oxide-supported single-atom platinum: Highly active catalysts for benzene combustion

Single-atom catalysts are a kind of promising catalytic materials that can use the precious metal more efficiently. The KIT-6-templaing method was adopted to obtain three-dimensionally ordered mesoporous iron oxide (meso-Fe2O3). The meso-Fe2O3-supported single-atom Pt with a loading of x wt% (xPt1/meso-Fe2O3, x = 0.08, 0.15, and 0.25) catalysts were synthesized via a polyvinyl alcohol-protected reduction route. The 0.25 Pt1/meso-Fe2O3 sample showed much better catalytic activity than the meso-Fe2O3-supported Pt nanoparticle (0.25 PtNP/meso-Fe2O3) sample for benzene combustion, with the temperatures T10%, T50%, and T90% (corresponding to benzene conversions of 10, 50, and 90%) were 164, 186, and 198 °C at a space velocity of 20,000 mL/(g h), respectively. The TOFPt (2.69 s−1) obtained over 0.25 Pt1/meso-Fe2O3 at 160 °C was much higher than that (1.16 s−1) obtained over the 0.25 PtNP/meso-Fe2O3 sample at 160 °C. Furthermore, the 0.25 Pt1/meso-Fe2O3 and 0.15Pt1/meso-Fe2O3 samples exhibited better water-resistant ability than the 0.25 PtNP/meso-Fe2O3 sample, which was possibly due to formation of the active radicals and decomposition of carbonates in the presence of moisture. In situ DRIFTS results demonstrate that the phenolate and benzoquinone as well as cyclohexanone and maleate were the main intermediates in the oxidation of benzene. The good stability of the 0.15Pt1/meso-Fe2O3 and 0.25 Pt1/meso-Fe2O3 samples was associated with the strong interaction between Pt and meso-Fe2O3.