Probing the nature of acetylene bound to the active site of a NiNa-zeoliteY catalyst by in situ neutron scattering

An investigation of the interaction between a catalytic system and its subs trate (reactant) using neutron diffraction with isotopic substitution (NDIS ) is reported. Specifically, the interaction between acetylene and nickel i on exchanged sodium zeolite Y has been investigated using NDIS in situ, rev ealing the radial distribution of distances at the disordered nickel sites. This is the first time that NDIS has been used for an in situ study, as we ll as the first time that a catalytic system has been structurally interrog ated using this method. The experimental findings are supported and amplifi ed by density functional calculations. Both experiment and theory reveal a Ni-II-(eta(2)-C2H2) complex with small but significant deviation of the geo metry exhibited by acetylene in its free state.