Bimetallic PtZn nanoparticles anchored in high-silica SSZ-13 zeolite for efficient propane dehydrogenation

Abstract

Direct dehydrogenation of propane to propylene (PDH) is a promising route to meet the ever-growing global propylene demand, but the industrial Pt-based catalysts usually suffer from serious deactivation derived from coke deposition and sintering under harsh reaction conditions. In this work, PtZn bimetallic nanoparticles encapsulated into high-silica SSZ-13 zeolites (PtZn@SSZ-13) were synthesized via a facile ligand-protected interzeolite transformation strategy. In a PDH reaction, the synthesized 0.5Pt3Zn@SSZ-13 catalyst exhibits superior catalytic performance with a propane conversion of 23.7% and a propylene selectivity of 96.8%, which is significantly better than that of PtZn supported on high-silica SSZ-13 (0.5Pt3Zn/SSZ-13). Particularly, the high catalytic activity of this catalyst can be kept during three successive oxidation–reduction cycles. Detailed characterizations including HAADF-STEM, XPS, UV–Vis, H2-TPR reveal that the remarkable improvement of PDH performance is attributed to the PtZn synergistic effect as well as the confinement of SSZ-13 zeolites. The DFT calculations and microkinetic simulations also evidenced that the Pt particles anchored on the Zn-doped SSZ-13 zeolite pore framework possessed obviously higher propane dehydrogenation activity, whereas the anti-coking ability of 0.5Pt3Zn@SSZ-13 was also stronger than Pt (111) surface, demonstrating the superior performance of 0.5Pt3Zn@SSZ-13.