Investigation on the kinetic mechanism of the reduction of Fe2O3/CoO-decorated carbon xerogels: A non-isothermal study

摘要

The reduction of Fe2O3 and CoO oxides supported on carbon xerogels was studied to elucidate the effect of the nanoconfinement of the catalyst in carbon matrices. Resorcinol formaldehyde xerogels were synthesized, impregnated with iron and cobalt nitrates, and subsequently heated to obtain the oxides. The mechanism of oxide reduction to a metal with hydrogen was investigated by in-situ synchrotron X-ray diffraction in dynamic, non isothermal conditions. Kinetic profiles of the reactions are obtained by plotting the diffraction intensities of selected Bragg peaks vs. temperature. The extracted Temperature-Programmed-Reduction (TPR) diagrams were best fitted by the Avrami-Erofeev and the n-order kinetic models for the iron and the cobalt oxide reduction reactions, respectively. The activation energies for the two-step reduction of Fe2O3 to FeO and then to Fe are 80 and 15.1 kJ mol(-1). Such results may contribute to developing efficient and inexpensive catalysts based on non noble metals like Fe, Co, via deposition of metal complexes on mesoporous supports.