Study of catalytic oxidation of toluene using Cu-Mn, Co-Mn and Ni-Mn mixed oxides catalysts

Abstract

The successful synthesis of AMn2O4 (A = Co, Cu, and Ni) spinels via solution combustion was achieved in less time than other methods. All catalysts with the same fuel/nitrate ratio were used to oxidize toluene, and the relationship between their properties and activities was investigated. Among all, nickel manganite exhibited the most promising activity, and by changing the fuel/nitrate ratio, it was sought to obtain the most appropriate structure for the reaction studied. Physico-chemical analysis was used to define the characteristics of the synthesized catalysts. The results showed the successful synthesis of spinels and indicated that other materials peaks (single oxide phases) exist in the catalyst structure. BET-BJH analyses reveal the mesoporous structures and, given the limitations of the equipment, were all classified as less than 10 m2/g. The SEM images evidence the influence of the urea content used. The particle size increases at higher fuel/nitrate ratios. Samples of NiMn1.67 and NiMn2.08 showed larger and denser, sparsely dispersed clusters. Simultaneously considering reactor analysis and test results, it was found that the synthesized catalyst with a fuel/nitrate ratio of 0.5 has the best performance on toluene oxidation.