Abstract: Using density functional theory(DFT), the double-bond isomerization of 1-butene to trans-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 with a EZP correction. It is found that the process include three steps, physical adsorption→chemical reaction→physical desorption. Firstly, the OH group of the acidic site of zeolite adsorbs the double-bond of 1-butene and forms a π-complex. Secondly, the double-bond isomerization reaction shows a concerted mechanism and yields the adsorbed trans-2-butene. Lastly, trans-2-butene is produced by desorption and the zeolite active site is restored. The calculated apparent activation energy is 57.1 kJ•mol^-1, which is in agreement with the experimental data.

Key words: Zeolite, Butene, Double-bond isomerization, Density functional theory, Transition state