Regeneration of a Pt-Sn/Al2O3 catalyst: Influence of heating rate, temperature and time of regeneration

We report in this work a study on the influence of heating rate (2-15 degrees C min(-1)), temperature (coke oxidation, 350-600 degrees C) and time (2-15 h) on the catalytic and structural properties of a regenerated Pt-Sn/Al2O3 catalyst (pretreated with H-2 at 350 degrees C). The catalyst was deactivated under industrial conditions (dehydrogenation of linear alkanes to mono-olefins). Compressed air was used as the oxidant agent. Samples were characterized by temperature-programmed reduction, textural properties, C and Cl contents and catalytic activity on n-heptane dehydrogenation. After treatment for 8 h under an oxidant atmosphere, the relevant properties of regenerated catalysts reached a final state. Slow heating rates have increased the catalytic activity of regenerated samples and the best regeneration temperature was 450 degrees C. At higher temperatures, Pt crystallites were observed. We suggest that the effect of Sn on Pt is of a geometrical nature.