A. Cimino et al., High and low surface area NiO-MgO and CoO-MgO solid solutions: a study of XPS surface composition and CO oxidation activity, TOP CATAL, 8(3-4), 1999, pp. 171-178
Oxide solid solutions NiO-MgO of high surface area were studied by XPS. The
surface Ni2+ concentration was found to be equal, within experimental erro
rs, to the bulk concentration. The result is analogous to that found previo
usly for the low surface area NiO-MgO system and for both the high and low
surface area systems of CoO-MgO. The catalytic oxidation of CO by O-2, on h
igh and low surface area NiO-MgO and CoO-MgO materials, was investigated wi
th the aim of relating the catalytic activity with transition metal ion nat
ure and concentration. Turnover frequency data (CO2 molecules produced per
second per surface atom) show that the activity is due primarily to the tra
nsition metal ions and is not subject to the ions being in special configur
ations (dimers or trimers) or in special positions (edges, corners). The ac
tivity of CoO-MgO is higher than that of NiO-MgO solid solution.