Determination using Sandals of the surface structure of hydrogen adsorbed on Raney nickel, a commonly used hydrogenation catalyst. The arrows highlight the Ni–H distance of 1.68 Å and the H•••••H distance of 2.54 Å in both the experimental data (purple) and an ab initio calculation (red).
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Heterogeneous catalysis (catalysis where the catalyst is in a different phase from the reactants – e.g. a solid catalyst and gaseous reactants) is a key economic driver in advanced nations.
It is integral to processes that range from crude oil refining to fine chemical and pharmaceutical production. Knowledge of the adsorbed species on the surface of a heterogeneous catalyst is an essential component in understanding and optimising a catalyst’s performance. Real catalysts are generally nanocrystalline and there are no experimental methods available for structure determination of hydrogenous adsorbed species on such materials. We have used neutron diffraction to show that it is possible to obtain structural information for adsorbed hydrogenous species on real catalysts as opposed to idealised systems under ultra-high vacuum. Bond distances are directly obtainable from the experimental data and the method works at room temperature in the presence of 1 bar of reactive gas. The method is completely general: it is applicable to any heterogeneous catalyst whether amorphous or nanocrystalline, a metal or an oxide.
P Albers (AQura, Germany), SF Parker, DT Bowron, S Imberti, AK Soper, K Refson (ISIS)
Contact: Dr SF Parker, firstname.lastname@example.org
Further reading: SF Parker et al, Angew Chemie, submitted.
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