Dehydrogenation and isomerization of n-butenes on mixed tin + antimony oxide catalysts

Abstract

The dehydrogenation and concurrent isomerization of the three n-butenes have been investigated at 474 K on a range of mixed tin + antimony oxide catalysts outgassed at 698 K. The initial approximately zero order reaction rates were used as a measure of catalytic activity to construct patterns of activity as a function of catalyst composition. Comparison of the patterns with those for the isomerization of 3,3-dimethylbut-1-ene and for the selective oxidation of propene on the same catalysts indicate that dehydrogenation of but-1-ene involves a π-allyl intermediate, while isomerization occurs through carbonium ion formation. For the cis- and trans-isomers, it is suggested that both reactions occur via a common allyl (but not π-allyl) type of intermediate.