Additive effect of Sn in Pt–Sn/ZnO–Cr2O3 catalyst for low-temperature dehydrogenation of isobutane Original Research Article

The performance of a Pt/ZnO–Cr2O3 catalyst, which has comparatively excellent performance for the low-temperature dehydrogenation of isobutane, improved upon addition of Sn. The additive effect of Sn was characterized by temperature-programmed reaction (TPR), TPD, chemisorption of CO or H2, and TG-DTA. As a result of these characterizations, details of the Sn addition to catalysts became clear. Sn 0.5–1.0 wt.% induced improved isobutene selectivity and stabilized catalytic activity over time. These effects are thought to occur because addition of optimal amounts of Sn suppressed coke deposition on the catalyst. However, due to excess Sn on the Pt surface (decreased Pt surface area), addition of Sn 3.0 wt.% resulted in a decline and ultimate deactivation of catalytic activity over time. Furthermore, results was suggested that addition of Sn facilitated the desorption of H2, isobutene, and 1,3-butadiene, thereby suppressing side reactions such as hydrocracking and isomerization.