Catalytic oxidation of toluene: comparative study over powder and monolithic manganese-nickel mixed oxide catalysts (original) (raw)

Catalytic oxidation of toluene: comparative study over powder and monolithic manganese-nickel mixed oxide catalysts This paper is focused on development of the metal monolithic structure for total oxidation of toluene at low temperature. The well adhered catalyst, based on the mixed oxides of manganese and nickel, is washcoated on the Al/Al 2 O 3 plates as metallic support. The influence of different reaction variables on the catalytic performance in the toluene oxidation is investigated. For the comparison purposes results observed for the manganese-nickel mixed oxide supported on the metallic monolith are compared with those obtained using powder type of the same catalyst. Prepared manganese-nickel mixed oxides in both configurations show remarkable low-temperature activity for the toluene oxidation. The reaction temperature T 50 corresponding to 50% of the toluene conversion is observed at temperatures of ca. 400-430K for the powder catalyst and at ca. 450-490K for the monolith configuration. The appropriate mathematical models, such as onedimensional (1D) pseudo-homogeneous model of the fixed bed reactor and the one-dimensional (1D) heterogeneous model of the metal monolith reactor are applied to describe and compare catalytic performances of both reactors. Validation of the applied models is performed by comparing experimental data with theoretical predictions. The reaction rate constants, activation energies and frequency factors are estimated. The obtained results confirmed that the reaction over the monolithic structure is kinetically controlled, while in the case of the powder catalyst the reaction rate is influenced by the intraphase diffusion.