The improved reactivity of manganese catalysts by Ag in catalytic oxidation of toluene

Authors: Zhenping Qu, Yibin Bu, Yuan Qin, Yi Wang, Qiang Fu

Abstract:
The effects of Ag on Mn/SBA-15 catalysts have been investigated in the toluene catalytic oxidation. The reactivity of catalysts is related closely to the Ag/Mn molar ratio, and the sample with 1:3 of Ag/Mn molar ratio exhibits the highest reactivity for toluene oxidation, with a complete conversion at 260 ^◦C. Based on the characterization results, it is found that Ag enters into MnO₂ phase, and the Ag_1.8Mn₈O₁₆ mixed phase forms. Meanwhile Ag leads to parts of MnO₂ being transformed into Mn₂O3. The Ag/Mn molar ratio has a strong influence on the molar ratio of the surface Mn4+ to Mn3+ and surface adsorbed oxygen (Oads) to lattice oxygen (Olatt)through the interaction between silver and MnO_x. The coexistence of MnO₂, Mn₂O₃, Ag_1.8Mn₈O₁₆, and the strong interactions between Ag and Mn species exhibit a good synergetic interaction, which promotes the reducibility of catalysts and the formation of abundant active lattice oxygen, thus increasing the catalytic activity of toluene oxidation. And the formation of intermediate benzaldehyde should be closely link with the lattice oxygen of the Mn based catalyst.

Keywords:
Toluene oxidation
Ag-Mn/SBA-15
Redox properties
Lattice oxygen
Interaction

Published in: Applied Catalysis B: Environmental (Volumes 132–133, Pages 1-552, 27 March 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

The improved reactivity of manganese catalysts by Ag in catalytic oxidation of toluene

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