INFLUENCE OF VARIOUS METAL-OXIDES IN THE BISTABILITY OBSERVED IN THE OXIDATIVE DEHYDROGENATION OF 2 - PROPANOL OVER COPPER-CATALYSTS

This article presents new results concerning a bistability phenomenon observed recently in the oxidative dehydrogenation of 2- propanol over copper catalysts. In this system, an activity hysteresis loop is obse rved when the partial oxygen pressure is varied. This bistability has been explained by the oxidation of metallic copper when the partial ox ygen pres sure increases and copper oxide reduction when the partial o xygen pressure decreases. In the experiments reported here, an externa l second phase (alpha-Sb2O4, SnO2, Cr2O3, CeO2, Co3O4, MoO3, PbO2, NiO , Bi2O3 and MnO2) has been mixed with the copper catalysts. This modif ies the hysteresis loop. The possible role played by the oxygen spillo ver at low temperature (150 degrees C) on this modification is discuss ed.