Finned Zn-MFI zeolite encapsulated noble metal nanoparticle catalysts for the oxidative dehydrogenation of propane with carbon dioxide

Abstract

Oxidative dehydrogenation of propane with carbon dioxide (CO2-ODP) characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO2 to valuable CO. However, the existing catalyst is limited due to the poor activity and stability, which hinders its industrialization. Herein, we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles (NPs) as bifunctional catalysts (NPs@Zn-MFI) for CO2-ODP. Characterization results reveal that the Zn2+ species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt, Rh, or RhPt are highly dispersed in the zeolite crystals. The isolated Zn2+ cations are very effective for activating the propane and the small NPs are favorable for activating the CO2, which synergistically promote the selective transformation of propane and CO2 to propylene and CO. As a result, the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield, satisfactory CO2 conversion, and long-term stability. Moreover, considering the tunable synergetic effects between the isolated cations and NPs, the developed approach offers a general guideline to design more efficient CO2-ODP catalysts, which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+ cations for Zn2+ cations in the MFI zeolite matrix.