Silicon: A Surface Dopant for Stable Alumina-Supported PtGa Propane Dehydrogenation Catalysts by Favoring Redox and Carbon Dynamics

The exploitation of shale gas has stimulated the use of on-purpose propane dehydrogenation (PDH) technologies. These technologies rely on a continuous and rapid catalyst regeneration to maintain high propene production. For Pt-based catalysts, metal promotors and addi-tives, such as Ga and Si, have been shown to enhance catalyst productivity and stability. While most studies have focused on understanding the role of Ga as a promoter, the effect and role of Si on the catalytic properties are less explored and understood. Therefore, tailored mon-ometallic Pt and bimetallic Pt-Ga catalysts supported on alumina or Si-doped alumina are prepared via surface organometallic chemistry and evaluated under PDH conditions. The Pt catalyst containing both Ga and Si displays the highest propene productivity (1970 molC3= molPt-1 h-1 after 2 hours) and the lowest deactivation constant (0.31 h-1 after 2 hours), pointing out the critical role of both Ga and Si. While scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray absorption spectroscopy show that the catalyst structures of the as-reduced Pt-Ga catalysts are similar, post mortem analyses reveal that Si-doping of alumina-supported Pt-Ga PDH catalyst modifies redox and carbon dynamics. This modification maintains Pt active sites by yielding interfaces between Pt and GaOx domains along with a surface PtC structure that is correlated with increased structural dynamics and slower deactivation.