A density-functional theory study on double-bond isomerization of 1-butene to cis-2-butene catalyzed by zeolites

Using density-functional theory, the double-bond isomerization of 1-butene to cis-2-butene over zeolites is investigated with a 3T cluster model simulating zeolite. At the B3LYP/6-31G(d, p) level, the complete geometry optimization and the activation energy calculation are performed. It is found that the OH group of acidic site of zeolite protonates the side C atom of double-bond of 1-butene and simultaneously, the neighboring O atom of the cluster abstracts a hydrogen atom from the butene, restoring the zeolite active site and yielding adsorbed cis-2-butene. The reaction shows a concerted mechanism. The calculated activation barrier is close to the experimental data.