Chemical-physical properties of spinel CoMn₂O₄ nano-powders and catalytic activity in the 2-propanol and toluene combustion: Effect of the preparation method

Abstract

Spinel-type CoMn₂O₄nano-powders are prepared using sol-gel auto combustion (SGC) and co-precipitation (CP) methods and their catalytic activities are evaluated in combustion of 2-propanol and toluene. The chemical-physical properties of the oxides are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N₂-adsorption-desorption, temperature programmed reduction (TPR) and scanning electron microscopy (SEM). After calcination at 700°C, CoMn₂O₄-SGC shows higher amounts of the normal-type spinel phase and is more crystalline than CoMn₂O₄-CP. Higher calcination temperatures (850°C) do not affect very much the weight percentage of the normal-type spinel phase; although the crystal size slightly increased. The TPR analysis evidences a large number of Mn³⁺ cations in CoMn₂O₄-SGC compared to CoMn₂O₄-CP. This difference, together with the higher surface area, could justify the higher activity of CoMn₂O₄-SGC in both the investigated reactions.

Keywords:

• Spinel oxides
• CoMn₂O₄
• catalytic oxidation
• 2-propanol
• toluene

Acknowledgements

The authors are thankful to those who contributed to enhancing this project, especially Iranian Nanotechnology Initiative Council for financial support and the Institute for the Study of Nanostructured Materials (ISMN) of the National Research Council (CNR) of Italy for the collaboration in this work.