Using density functional theory, the rearrangement of butene double bond catalyzed by a 3T cluster model of zeolite was investigated. At the B3LYP/6-31G(d,p) level, the complete geometry optimization and the activation energy calculation were performed. It was found that the OH group of acidic site of zeolite adsorbed the double bond of 1-butene with formation of a π-complex, then the side C atom of the double bond of butene drew this proton simultaneously, and the neighboring O atom of the cluster abstracted a hydrogen atom from the butene to yield adsorbed cis-2-butene, lastly restoring the zeolite active site. The whole reaction process showed a concerted mechanism. The calculated apparent activation barrier was 55.9 kJ/mol in agreement with experimental data.

Key words: zeolite, butene, double bond isomerization, density functional theory