Synthesis of oxide supported LaMnO3 perovskites to enhance yields in toluene combustion

a b s t r a c t Perovskite-type oxides of LaMnO3 were synthesized by citrate sol-gel method in the presence of an oxide support. The physicochemical properties of the LaMnO3 supported materials were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), thermogravimetric and differ- ential thermal analysis (TGA/DTA), N2 adsorption-desorption, X-ray diffraction (XRD), high transmission electron microscopy (HRTEM-EDX) and oxygen isotopic exchange analysis. Their catalytic performances, especially those related to the catalyst stability, were evaluated for the total oxidation of toluene. To this aim, three consecutive catalytic cycles were performed for each catalyst. The LaMnO3 perovskite phase appeared to interact with TiO2 and Y2O3-ZrO2 (YSZ) supports in a manner that affected both oxygen mobility and catalytic activity in total toluene oxidation. The isotopic exchange results matched well the catalytic tests. Indeed, the supported materials showed a remarkable oxygen exchange activity and higher catalytic performances than that of pure perovskite. For YSZ, this could be attributed to the influ- ence of oxygen vacancies and oxygen ions on the support. Regarding TiO2, this improvement could be attributed to the reducibility properties of titania (TiIV/TiIII). Strong metal-support interactions (SMSI) between the perovskite and the support were observed.