Promotional effect of Na⁺ in the supported PtSnNa/SUZ-4 catalysts for propane dehydrogenation

The promotional effects of Na⁺ component in the supported PtSnNa/SUZ-4 catalysts for propane dehydrogenation have been studied by using X-ray diffraction (XRD), H₂ chemisorption, NH₃ temperature-programmed desorption (NH₃-TPD) and H₂ temperature-programmed reduction (H₂-TPR) combined with microreator tests. It has been shown that Na⁺ component in the supported PtSnNa/SUZ-4 catalysts can neutralize the strong acidic sites on the surface of SUZ-4 zeolite support, increasing the Pt dispersion and suppressing the cracking of olefin products and the formation of coke, leading to the increases of propene selectivity and catalytic stability. But, excessive Na⁺ ions in the catalyst decreases the interaction between Sn component and SUZ-4 zeolite support, resulting in the drastic decrease of catalytic activity for propane dehydrogenation.