QUANTUM CHEMICAL STUDIES OF ETHYLENE INTERACTION WITH ZEOLITE OH-GROUPS

An ab initio quantum chemical study of the mechanism of formation of surface ethoxy groups from ethylene on high silica H-zeolites was carried out using a Gaussian 80 program with the 3-21 G basis set. The obtained results show that the reaction coordinate during ethoxylation of the zeolite surface is rather complicated and that in the transition state the charge distribution and geometry of the ethyl fragment closely resemble those of the classical form of the free ethyl carbenium cation. The mechanism of some acidically catalyzed transformations of olefins over H-zeolites is discussed on the basis of these results.