Catalysts containing 2-10 wt% MnO2 supported on TiO2 were examined for H2O2 decomposition. Catalysts were prepared by impregnation of high TiO2 surface area. XRD, SEM and surface area measurements gave evidence of a uniform distribution of the active phase on the support surface and of the absence of segregated manganese oxides phases. Temperature programmed reduction measurements showed the presence, besides MnO2, of different Mn oxides species formed by interaction between the active phase and the support surface. The MnO2 reducibility increased whilst the mean oxidation state of manganese decreased with increasing manganese content. Catalytic tests were performed in a batch reactor with 50 or 70% concentration H2O2 solutions. Catalytic activity was very high at beginning of the tests and decreased with time, reaching a final constant value that was increasing with manganese content. Kinetic constants, evaluated assuming a first order reaction rate, were comparable or higher than those of similar manganese based catalysts. An optimal MnO2 content was found corresponding to the quite complete surface monolayer coverage. A reaction mechanism involving Mn4+ - Mn3+ redox couple has been proposed

Decomposition of hydrogen peroxide on MnO2/TiO2 catalysts

RUSSO, ANNAMARIA;TURCO, MARIA;BAGNASCO, GIOVANNI
2004

Abstract

Catalysts containing 2-10 wt% MnO2 supported on TiO2 were examined for H2O2 decomposition. Catalysts were prepared by impregnation of high TiO2 surface area. XRD, SEM and surface area measurements gave evidence of a uniform distribution of the active phase on the support surface and of the absence of segregated manganese oxides phases. Temperature programmed reduction measurements showed the presence, besides MnO2, of different Mn oxides species formed by interaction between the active phase and the support surface. The MnO2 reducibility increased whilst the mean oxidation state of manganese decreased with increasing manganese content. Catalytic tests were performed in a batch reactor with 50 or 70% concentration H2O2 solutions. Catalytic activity was very high at beginning of the tests and decreased with time, reaching a final constant value that was increasing with manganese content. Kinetic constants, evaluated assuming a first order reaction rate, were comparable or higher than those of similar manganese based catalysts. An optimal MnO2 content was found corresponding to the quite complete surface monolayer coverage. A reaction mechanism involving Mn4+ - Mn3+ redox couple has been proposed
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/303936
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