Influence of Oxygen Addition on the Reaction of Propane Catalytic Dehydrogenation to Propylene over Modified Pt-Based Catalysts

The influences of oxygen addition to catalytic dehydrogenation system on the structure and the dehydrogenation performance of Pt-based catalysts were investigated. The results showed that a small amount of oxygen addition into the reaction system could greatly improve the catalytic performance of Pt−Sn/Ce-γ-Al 2 O 3 catalyst although it evidently decreased the catalytic stability of Pt/γ-Al 2 O 3, Pt−Sn/γ-Al 2 O 3, and Pt/Ce-γ-Al 2 O 3 catalysts. The addition of a small amount of oxygen can decrease the pressure of hydrogen, eliminate coke, and provide partial heat for catalytic dehydrogenation reaction. Hydrogen chemisorption results indicated that steam could reduce the interactions between metal and support, thus promoting the sintering of platinum particles. That adverse effect of steam on the structure on Pt−Sn/Ce-γ-Al 2 O 3 was moderate, but it was serious on other Pt-based catalysts due to low-stability platinum particles. Both the promoting effect of Ce on the propane conversion and the inhibiting effect of Sn on the CO x formation could be simultaneously achieved during the reaction over Pt−Sn/ Ce-γ-Al 2 O 3 catalyst. At 546 °C, a 50% yield of propylene improvement was obtained due to the small oxygen addition.