RESUMO
In this work, the synthesis of catalyst with perovskite structure and chemical formula La1-XCeXMnO3 at x = 0 - 0.5 were successfully obtained by an ultrasonic-assisted hydrothermal method. Results show that the addition of Ce in La1-XCeXMnO3 have not substantial effect in textural and morphological properties; however, the formation of a new crystalline phase with final composition CeOX-La1-XCeXMnO3 was detected at values x > 0.3. All synthesized catalysts were tested in the soot oxidation under both, loose and tight contact in 20% O2/N2 or 5% O2/N2 atmospheres. CeOX-La1-XCeXMnO3 at x = 0.3 resulted in the best catalytic activity with activation energy values of 57.9 kJ.mol-1. The interaction between Ce3+ and Mn4+ species in this catalyst can transfer electrons generating Mn3+ and Ce4+. This reduction from Mn4+ to Mn3+ is accompanied by migration of vacancies to the surface promoting the adsorbed oxygen from the gas phase, need for balancing the chemical states. By increasing the temperature above 300 °C, the bulk oxygen migration to the surface is enhanced being the responsible for the oxygen availability. The formation of CeOX-La1-XCeXMnO3 promotes a stable redox cycle allowing the reusability of this catalyst even at low oxygen pressures after three different reaction cycles.
