Structure and catalytic activity of iron oxide and magnesium oxide solid solutions. Part 3.—E.s.r. characterization

Abstract

Magnesium oxide + iron oxide, fired both in air and in a reducing atmosphere, and magnesium oxide + iron oxide + lithium oxide (up to 1 % atomic Fe) were investigated by e.s.r. spectroscopy.

The effects of outgassing at various temperatures and of N₂O decomposition on the e.s.r. spectra are discussed in terms of surface redox processes. The incipient formation of the spinel phase, MgeFe₂O₄, and its precipitation, at the highest outgassing temperatures adopted, were readily studied by the e.s.r. technique.

The hypotheses previously proposed on the modification of the catalyst solid state, occurring during N₂O decomposition and/or in the vacuum treatment, are confirmed by the present study. Further details are also given.