Catalytic oxidation of trichloroethylene from gas streams by perovskite-type catalysts.

Three perovskite-type catalysts including LaMnO3, La0.8Ce0.2MnO3, and La0.8Ce0.2 Mn0.8Ni0.2O3 are prepared using citric acid sol-gel method and evaluated as catalyst for the oxidation of trichloroethylene (TCE) in air with temperature ranging from 100 to 600 °C. The physicochemical properties of three perovskite-type catalysts were characterized by SEM, EDS, XRD, BET, and XPS to investigate the relationship with catalytic activities. The results show that the removal efficiency of TCE achieved with La0.8Ce0.2Mn0.8Ni0.2O3 (the best one) reaches 100% at 400 °C and the mineralization efficiency reaches 100% at 600 °C. The enhanced activity can be attributed to the addition of Ce and Ni which increases the surface areas, active oxygen species, and the redox ability of the Mn4+/Mn3+ ratio on the catalyst surface. As La0.8Ce0.2Mn0.8Ni0.2O3 is applied for TCE oxidation, the main intermediate chlorinated byproduct detected is tetrachloroethylene (C2Cl4) which is generated by the reaction of TCE and chlorine (Cl2). The activation energy for the TCE oxidation with La0.8Ce0.2Mn0.8Ni0.2O3 catalyst is 51 kJ/mol using kinetic models of power-law type.