RESIDUAL OIL CRACKING WITH GENERATION OF HYDROGEN - DEACTIVATION OF IRON-OXIDE CATALYST IN THE STEAM IRON REACTION

The deactivation of iron oxide catalyst in residual oil cracking with generation of hydrogen was studied. This new process consists of two main stages: the cracking of residual oil and hydrogen generation resulting from the steam-iron reaction, and the reduction of the iron oxide catalyst. We found that the hydrogen-producing activity of the iron oxide catalyst declined during consecutive reduction and oxidation cycles. The aging rate was dependent on the reaction conditions. When the rate of oxidation was not fast enough to convert prereduced wustite (FeO) to magnetite (Fe3O4), the wustite accumulated and the activity declined. The accumulation of wustite is considered to induce the sintering of the catalyst. This hinders the free access of the reaction gases and reduces the rate of the iron oxide-gas phase reaction. We concluded that it is essential to balance the stoichiometry of the reduction and oxidation to prevent the deactivation of the catalyst.