Oxidation of p-chlorotoluene to p-chlorobenzaldehyde over manganese-based octahedral molecular sieves of different morphologies

• MnO2 (OMS-2) of rod-, fibrous-, dendritic-, and nest-like morphologies were synthesized.
• Nest-like OMS-2 is highly active for liquid-phase partial oxidation of p-chlorotoluene.
• Catalytic activity is related to high concentration and mobility of oxygen species.

Manganese-based octahedral molecular sieves (OMS-2) of rod-like, fibrous-like, dendritic-like, and nest-like morphologies were synthesized by solid-state reaction, reflux, and hydrothermal methods, respectively. The materials were characterized and tested for liquid-phase oxidation of p-chlorotoluene to p-chlorobenzaldehyde. Over nest-like OMS-2, p-chlorotoluene conversion was significantly higher than that of the others. The differences in catalytic performance are attributed to the effects of composition and structure. The high activity of nest-like is due to the high concentration of oxygen adspecies and good mobility of oxygen species, whereas the poor performance of dendritic-like is due to the presence of chromium.

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