Studying Hydrotalcite-Like Compounds Isomorphically Substituted with Iron and Cobalt via Inverse Temperature-Programmed Reduction

Abstract

The reducibility of multicomponent layered double hydrotalcite-like hydroxides containing Mg2+, Co2+, Al3+, and Fe3+ at different ratios of these metal cations and products of their thermal destruction in a hydrogen flow is studied via inverse temperature-programmed reduction (bTPD). It is shown that the temperature-programmed reduction profiles for layered double hydroxides (LDHs) contain signals corresponding not only to the reduction of iron and cobalt cations incorporated into the structure of brucite-like layers, but also ones corresponding to the reduction of cobalt and iron from the mixed oxides or spinel-like phases that appear due to the thermal destruction of LDHs occurring simultaneously with a reduction in iTPR measurements. Signals presumably corresponding to the reduction of residual nitrate anions are also revealed in iTPR profiles.