A QUANTUM-CHEMICAL STUDY OF THE INTERACTION OF MOLECULAR-HYDROGEN WITH BRIDGING HYDROXYL-GROUPS IN ZEOLITES AND THE REACTION OF H-D EXCHANGE BETWEEN THESE SPECIES

The mechanism of the interaction between bridging OH groups in zeolite s and molecular hydrogen is studied by the SCF nonempirical method usi ng the 3-21 G basis set supplemented by polarization functions for the oxygen and hydrogen atoms. Analysis of the surface of the potential e nergy for the reaction of H-D exchange of molecular deuterium with the bridging hydroxyl groups shows that this reaction occurs through a cy clic six-membered transition state with a relatively low activation ba rrier. Distinctions between the mechanisms of the interaction of molec ular hydrogen with bridging and terminal hydroxyl groups are revealed.