Abstract:

A series of NiO/Mn₃O₄ monolithic catalysts with different NiO contents was prepared by ball-milling of Ni(NO₃)₂·6H₂O, Mn₃O₄ and pseudo boehmite precusors via subsequent impregnation with cordierite, followed by calcination. These catalysts were tested for ozone decomposition. It was found that the 30NiO/Mn₃O₄(mass fraction of NiO in total mass is 30%) catalyst has the highest activity at a space velocity of 20000 h^-1, and leads to 98% conversion of ozone, while the catalyst remains stable. When the space velocity is increased to 40000 h^-1, the 50NiO/Mn₃O₄(mass fraction of NiO in total mass is 50%) catalyst gives the highest activity, with a ozone conversion at about 90%. But the catalyst suffers deactivation. Characterizations by X-ray diffraction(XRD), TPR, XPS and BET reveal that the presence of Mn₃O₄ in the NiO increases the specific surface area of the catalyst, and electronic interaction between Mn₃O₄ and NiO. Meanwhile, the co-presence of Mn₃O₄ and NiO in the catalyst results in facile reduction of these oxides. This synergy is believed to be responsible for the enhanced catalytic performance.

Key words: Mn₃O₄, NiO, catalyst, Ozone decomposition, active site