(7d) Well-Defined Ptsn Alloyed Clusters for Highly Efficient Propane Dehydrogenation

Propane dehydrogenation (PDH) is an important process for on-purpose propylene production. Pt-Sn-based catalysts are currently employed in many commercialized processes.(1) However, many fundamental questions about the PtSn catalysts, including the optimal Pt-Sn ratio remains in debate. In this study, we prepared size and composition-controlled PtSn catalysts through the utilization of stannous platinum complexes. Our approach led to the preparation of PtSn clusters supported on Al2O3(2) and encapsulated within silicalite-1 zeolite(3), both demonstrating exceptional catalytic properties with propylene productivity above 1 mol propylene per gram catalyst per hour at 550^oC, at a high weighted hourly space velocity of 165. Notably, the silicalite-1 supported catalyst exhibited remarkable stability, with a deactivation rate of less than 0.002 per hour, and can be fully regenerated using air alone, showcasing its potential for industrial application.

Through comprehensive characterization, including aberration-corrected AC-STEM studies, alongside atomistic simulations via ab initio molecular dynamics (AIMD) and density functional theory (DFT), we unveiled that the alloyed clusters possess unique active sites that differ significantly from those offered by single metal atoms or bulk metal alloys. These findings suggest that the outstanding catalytic performance of the PtSn clusters may also stem from their dynamic structures under reaction conditions. Our work not only sheds light on the unseen potential of widely-known PtSn catalysts but also underscores the importance of controlled synthesis in developing highly efficient and stable catalysts for industrial processes.

1. Sattler, et al., Chem. Rev. 114, 10613–10653 (2014).
2. Xu, et al., Appl. Catal. B 341, 123285 (2024).
3. Lu, et al., Encapsulated Sub-nm Alloys for Highly Efficient Propane Dehydrogenation. submitted (2024)

Figure caption

Top panel: Representative STEM-HAADF images of the PtSn/Al2O3 and PtSn/Silicalite-1 catalysts prepared from stannous platinum complexes. Bottom panel: The space-time-yield of the PtSn/Silicalite-1 catalyst (star) and its deactivation rate, compared with the best ones reported in literature.