Selective dehydrogenation of isobutane over supported Pt/Sn catalysts

Catalytic dehydrogenation of isobutane is important because of growing dema nd for isobutene asa precursor for the production of oxygenates required in reformulated gasoline. It was found that supporting tin and platinum in K- L-zeolite produces catalysts that exhibit high activity and selectivity for isobutane dehydrogenation. Furthermore, Pt/Sn/K-L-zeolite catalysts exhibi t high resistance to deactivation at conditions conducive to high dehydroge nation conversions. Fundamental investigations of silica-supported Pt/Sn ca talysts show that tin interacts with platinum to form Pt/Sn alloy particles , which reduces the size of surface Pt ensembles and inhibits the formation of highly dehydrogenated surface species required for the competing isomer ization, hydrogenolysis, and coking reactions. Similarly, the addition of p otassium to Pt/Sn/SiO2 increases the selectivity for isobutane dehydrogenat ion by further reducing the size of surface Pt ensembles. (C)2000 Elsevier Science B.V. All rights reserved.