Effect of potassium and platinum contents on catalytic performance of Pt/Al2O3 monometallic catalysts for propane dehydrogenation

Low-loaded Pt-based catalysts supported on γ-Al2O3 (bare or modified by K) were studied for propane dehydrogenation. The alumina support was modified by adding 0.5 and 4 wt.% of K using potassium acetate as precursor. 0.5 wt.% of K is sufficient for suppressing the acidity of the alumina. Ultradispersed Pt supported catalysts (0.1, 0.2 and 0.3 wt.%) were obtained by ion exchange on Al2O3 or Al2O3–0.5 K. During propane dehydrogenation reaction, 0.3 wt.%Pt/Al2O3 strongly deactivates, mainly due to coke deposition. For the same Pt loading, the presence of K strongly decreases this phenomenon without modifying the initial turnover frequencies (TOF). On the series supported on Al2O3–0.5 K, there is no effect of the Pt content on the TOF values showing that whatever the sample, ultradispersed Pt entities present the same activity. Finally, the selectivity towards propene formation strongly depends on propane conversion and seems to be not affected by the change in K and Pt contents.