The triggering of catalysis via structural engineering at atomic level: Direct propane dehydrogenation on Fe-N3P-C

The on-purpose direct propane dehydrogenation (PDH) has received extensive attention to meet the ever-increasing demand of propylene. In this work, by means of density functional theory (DFT) calculations, we systematically studied the intrinsic coordinating effect of Fe single-atom catalysts in PDH. Interestingly, the N and P dual-coordinated single Fe (Fe-N 3 P-C) significantly outperform the Fe-N 4 -C site in catalysis and exhibit desired activity and selectivity at industrial PDH temperatures. The mechanistic origin of different performance on Fe-N 3 P-C and Fe-N 4 -C has been ascribed to the geometric effect. To be specific, the in-plane configuration of Fe-N 4 site exhibits low H affinity, which results in poor activity in C-H bond activations. By contrast, the out-of-plane structure of Fe-N 3 P-C site exhibits moderate H affinity, which not only promote the C-H bond scission but also offer a platform for obtaining appropriate H diffusion rate which ensures the high selectivity of propylene and the regeneration of catalysts. This work demonstrates promising applications of dual-coordinated single-atom catalysts for highly selective propane dehydrogenation. The polar configuration of the out-of-plane Fe-N 3 P-C can break conjugation-like electronic states near Fermi level and provide moderate H affinity which is not only important for C-H bond scissions, but also exhibit desired H diffusion rate that ensures high propylene selectivity.