Platinum-Modified ZnO/Al2O3 for Propane Dehydrogenation: Minimized Platinum Usage and Improved Catalytic Stability

Compared to metallic platinum and chromium oxide, zinc oxide (ZnO) is an inexpensive and low-toxic alternative for the direct dehydrogenation of propane (PDH). However, besides the limited activity, conventional zinc-based catalysts suffer from serious deactivation, because of ZnO reduction and/or carbon deposition. Considering the high cost of platinum, reducing the amount of platinum in the catalyst is always desirable. This paper describes a catalyst comprising ZnO modified by trace platinum supported on Al2O3, where the Zn2+ species serve as active sites and platinum acts as a promoter. This catalyst contains less platinum than traditional platinum-based catalysts and is much more stable than conventional ZnO catalyst or commercial chromium-based systems during PDH. It is proposed that ZnO was promoted to a stronger Lewis acid by platinum; thus, easier C-H activation and accelerated H-2 desorption were achieved.