LaMn1-xCoxO3 perovskite-like doped and impregnated with Cu for the enhancement of toluene total oxidation

Abstract

Perovskite-like materials have gained great interest and importance due to their wide range of applications, especially in the context of the world of sustainability. In this study, the effect of copper on the catalytic performance of LaMn1-xCoxO3 perovskite-like oxides towards toluene oxidation was investigated. Preliminary activity results indicated that perovskites with higher Mn content or x = 0.0 and 0.25, (LM = LaMnO3 and LMC = LaMn0.75Co0.25O3), could be selected as base catalysts to evaluate the copper addition either by structural doping or surface impregnation. It was found that Cu-impregnated catalysts (Cu[x]/LM and Cu[x]/LMC) exhibited better catalytic activity towards toluene oxidation compared to Cu-doped catalysts (LM-Cu[x] and LMC-Cu[x]), achieving total oxidation temperatures below 300 °C. It was found that copper appeared in the impregnated perovskite catalysts in the form of CuO, which is also an active species for toluene oxidation. While, in the Cu-doped catalysts, the CuO segregation was not seen, which could partly explain the low catalytic efficiency of these solids. From the evaluated perovskites, the most active ones against toluene oxidation were Cu[0.3]/LM and Cu[0.4]/LMC, which curiously showed two different oxidation mechanisms for toluene oxidation, the first followed a suprafacial (surface oxygen) mechanism, while the second followed an intrafacial (network oxygen) mechanism.