Isomerization of butene over a chromia–alumina catalyst

Abstract

Psomerization runs were performed in a micro-reactor at 325 "C over a range of butene partial pressure of 84 t o 763 mm Hg and at a total pressure of approximately 1 atm. The isomerization rate of I-butene passed thro~igh a maximum ~i t h increasing I-butene partial pressure; the isornerization rate of cis-and trans-2-butcne increased asymptotically with increasing cis-and trans-2-butene partial pressures respectively. Stcreoselecti\ity was obserbed in the isomerization of each butene, and mas found to be independent of pressure. Catalyst deactivation resulted in loss in stereoselectivity. Results suggest that surface reactions control isornerization and proceed simultaneously on different active sites.Canadian Journal of Chemistry, 47, 323 (1969) Despite thecoinniercialimportance ofchromia-I11 particular, Hall and co-m orkers using isotope alumina catalyses for dehydrogenation-isomeri-and tracer techniques (9) provide considerable zation reactions, our understanding of the re-evidence for a carbonium ion intermediate on action mechailism on the catalyst and the trans-silica-alumina. Their studies (9) on activated port-kinetic rate-controlli~lg steps is incomplete. ;I-alumina lead them to suggest that more than This paper filrnishes new kinetic data on the one mecliai~ism is operative. Brouuer (5) attribisomerizatioil of buteiles over a commercial utes olefill isonierization on y-alumina to a carchromia-alumina catalvst taken with the illtent boniurn ion mechanism for cis-traus isomerizaof establishing rate-controlling steps and helping to elucidate the catalytic mecl~anism. This study extends earlier work (1) on butane dehydrogenation using the same catalyst, and suppleilieilts