Enhanced Stability of Pt-Co Catalysts Supported on Zeolite Nanosponges for Propane Dehydrogenation

Abstract

Pt and Co supported on Al₂O₃, Na⁺-free SiO₂, mesoporous zeolite (MZ-Na⁺), and Na⁺-free MZ (MZ-OH) were prepared and investigated for propane dehydrogenation efficacy. These catalysts were characterized using XRD, STEM, CO-FTIR, H₂-TPR, and XPS. Of these catalysts, Pt−Co supported on MZ-Na⁺ and Al₂O₃ showed low activity and poor stability for propane dehydrogenation (PDH). On the other hand, Pt−Co supported on Na⁺-free SiO₂ or MZ-OH exhibited much greater activity and stability. This high catalytic performance was attributed to the formation of a high degree of alloying between Pt and Co, possibly facilitated by silanol groups. After optimizing cobalt content and catalyst reduction temperature, it was found that 1 wt% Pt-0.8 wt% Co supported on MZ-OH exhibited the best activity with a propane conversion of 64.4 % and propylene selectivity of 76.5 % that remained stable over 24 h on-stream. The correlation between catalyst characterization and PDH results showed that the existence of metallic cobalt on the catalyst surface facilitated coke deposition in the form of CoC_x and poor catalyst stability.