Selective dehydrogenation of isobutane over supported Pt/Sn catalysts

Catalytic dehydrogenation of isobutane is important because of growing demand 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 exhibit high resistance to deactivation at conditions conducive to high dehydrogenation conversions. Fundamental investigations of silica-supported Pt/Sn catalysts 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 isomerization, hydrogenolysis, and coking reactions. Similarly, the addition of potassium to Pt/Sn/SiO2 increases the selectivity for isobutane dehydrogenation by further reducing the size of surface Pt ensembles. (C)2000 Elsevier Science B.V. All rights reserved.