DFT calculations show that the interaction between hydrogen atoms and the surface of MgO and SiO2 is weak or even repulsive and that the migration of H atoms from a metal particle to a non-reducible support is strongly endothermic. Transition-state theory therefore estimates that the surface migration of hydrogen atoms from a metal particle to a non-reducible support is much too slow to explain the observed hydrogenation of molecules adsorbed on the support by spillover of H atoms. On the other hand, H atoms bind strongly to the surface of WO3, because the H atoms transform into electrons, which reduce the W6+ cations, and protons, which bind strongly to the oxygen anions. Hydrogen spillover to defect-free surfaces of non-reducible metal oxides cannot take place, but spillover to defects is possible, as well as spillover from a metal particle to an oxygen-containing group on a carbon surface.

Hydrogen spillover to defect-free non-reducible supports is not possible

243rd National Meeting (2012)

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