Monomolecular Skeletal Isomerization of 1-Butene over Selective Zeolite Catalysts

Abstract The mechanism of the 1-butene skeletal isomerization catalyzed by zeolites has remained elusive. We present direct evidence that even the initial isobutene formation over H-ferrierite, the best-known isomerization catalyst, is monomolecular in nature, whereas a bimolecular pathway is significant over the unselective H-ZSM-5. We also report that medium-pore high-silica H-HPM-1 outperforms H-ferrierite in selectively forming isobutene. This new catalyst displays a high activity and selectivity from the onset of the reaction, as well as an excellent resistance to deactivation, thanks to its anomalously weak acidity and low acid site density, together with an ability to effectively isolate reactant molecules from one another.