Simultaneous dehydrogenation and isomerization of η‐butane to isobutene over ZSM‐22 and zinc‐modified ZSM‐5 zeolites

Abstract

Direct formation of isobutene from η‐butane was investigated over a zinc‐impregnated potassium‐ion‐exchanged ZSM‐5 dehydrogenation catalyst and an acidic shape‐selective ZSM‐22 skeletal isomerization catalyst. The experiments were performed in a fixed‐bed microreactor system operating at near‐atmospheric pressure. High selectivity to η‐butene was obtained over the zinc‐impregnated potassium‐ion‐exchanged ZSM‐5 dehydrogenation catalysts. The yield of isobutene increased after adding the acidic ZSM‐22 skeletal isomerization catalyst, although the selectivity to butene isomers slightly decreased because the skeletal isomerization of η‐butene was competing with other acid‐catalyzed reactions such as cracking and aromatization.