Ab initio study on isotope exchange reactions of H2 with surface hydroxyl groups in lithium silicates

Effects of Al atoms on the hydrogen exchange reactions of hydrogen molecules with surface hydroxyls in silicates are investigated by ab initio calculations at the HF/6-31G ∗∗ and MP2/6-31G ∗∗ levels with the model clusters H3SiOH and H3Si(OH)Al(H)2OSiH3. The direct interaction of Al atoms with surface hydroxyl is found to bring about the lowering in the potential energy barrier of exchange reactions between H2 and H3SiOH. The lowering is explained by the changes of the reaction mechanism and the weakening of the O–H bond in surface hydroxyl by the interaction of Al atoms.