BACKGROUND: Benzene (C6H6) is a typical kind of volatile organic compound (VOC) which can exert great harm to both human health and the environment, and, thus, which needs to be eliminated before its emission. In this work, porous manganese–nickel (Mn-Ni) composite oxide catalysts were synthesized through the oxalate route and applied to thermal catalytic oxidation of C6H6. By means of activity tests and relative physico-chemical characterizations, the factors affecting the activity of those Mn-Ni composite oxides were explored. RESULTS: Nitrogen (N2)-adsorption/desorption and X-ray photoelectron spectroscopy (XPS) measurements indicated that the Brunauer–Elmett–Teller (BET) surface area and the content of surface-adsorbed oxygen species were increased due to the addition of Ni into Mn oxide (MnOx). Meanwhile, the oxygen mobility and reducibility also were improved in the Mn-Ni composite oxides. Accordingly, compared with MnOx, the Mn-Ni catalysts showed higher activity for thermal catalytic oxidation of C6H6. Moreover, porous Mn-Ni composite oxides with a Mn:Ni molar ratio of 4:1 (Mn4Ni1) displayed the best catalytic activity. Further investigation indicated that the excellent catalytic performance of Mn4Ni1 composite oxides could be ascribed mainly to the larger BET surface area and the richer content of surface-adsorbed oxygen species, as well as stronger oxygen mobility and better reducibility compared with other Mn-Ni catalysts. CONCLUSIONS: The Mn4Ni1 composite oxides showed a lowest T90 value of 172 °C (C6H6 concentration 200 ppm, WHSV 60 000 mL g−1 h−1) among all of the obtained Mn-Ni composite oxides. Moreover, it also exhibited favourable catalytic stability at 210 °C in the presence or absence of moisture.
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