Research Articles : Selective Positional Isomerization of 2-Butene over Alumina and La-promoted Alumina Catalysts

Positional isomerization of 2-butene to 1-butene over alumina catalysts was investigated. The physical characteristics and acidity of activated alumina and η-alumina catalysts were analyzed by BET, XRD, ammo- nia-temperature programmed desorption, and infra-red spectroscopy of adsorbed pyridine. The effects of lantha- num addition on the acidity of catalysts and the isomerization were investigated. The yield of 1-butene over η -alumina catalyst was shown to be higher than that of activated alumina catalyst due to the larger BET surface area (287 m 2 /g) as well as the weak acidity of η-alumina. The catalytic activity does not correspond to the amount of Lewis acid sites, explaining the insignificant role of Lewis acid sites in the positional isomerization of 2-butene. It was proposed that the H site might be an active site for the positional isomerization of 2-butene to 1-butene.