A series of catalysts composed of Pt–Fe nanoparticles supported on mesoporous silica SBA-15 (ca. 7 nm pore diameter) have been prepared by ultrasound-assisted coimpregnation of the metal precursors and evaluated in the nonoxidative dehydrogenation of isobutane. Prereduced catalytic systems were characterized by STEM-HAADF + EDS mapping and XAS to determine the chemical environment of the highly dispersed platinum active sites on the iron host matrix. While the monometallic platinum (nanoparticles) supported on SBA-15 material presented a rapid catalyst deactivation under reaction conditions, coordinatively unsaturated Pt–Fe (Pt ≪ Fe) sites located in the mesopores of SBA-15 showed a high steady-state activity (43% conversion) and selectivity (96% to isobutylene) in the dehydrogenation of isobutane at 550 °C for several hours. Temperature-programmed reduction profiles determined not only the substantially higher reducibility of FeOx species with doping amounts of platinum in the as-prepared (calcined) catalysts but also the detrimental structural changes undergone after consecutive reaction–regeneration cycles. Finally, reactivation under controlled conditions allows to minimize irreversible catalyst deactivation after successive cycles.
Bibliographical noteKAUST Repository Item: Exported on 2023-10-05
Acknowledgements: Funding for this work was provided by King Abdullah University of Science and Technology (KAUST). A.R.G. acknowledge support by his postdoctoral grant IJC2020-044050-I funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. XAS experiments were performed at NOTOS beamline (ALBA Synchrotron) with the collaboration of ALBA staff. We also thank Jullian Vittenet, Diego Mateo, and Alla Dikhtiarenko for technical support and Sandra Ramirez Cherbuy (InkScience) for artwork.