| Summary: | In this work, soot oxidation was conducted over a series of Mn-X/γ-Al<sub>2</sub>O<sub>3</sub> (M = Ce, Co and Cu) binary catalysts in a dielectric barrier discharge reactor. The soot conversion in the plasma–catalytic system was in the order of Mn/γ-Al<sub>2</sub>O<sub>3</sub> (57.7%) > Mn-Co/γ-Al<sub>2</sub>O<sub>3</sub> (53.9%) > Mn-Ce/γ-Al<sub>2</sub>O<sub>3</sub> (51.6%) > Mn-Cu/γ-Al<sub>2</sub>O<sub>3</sub> (47.7%) during the 30 min soot oxidation process at 14 W and 150 °C. Meanwhile, the doping of Ce, Co and Cu slightly improved the CO<sub>2</sub> selectivity of the process by 4.7% to 10.3% compared to soot oxidation over Mn/γ-Al<sub>2</sub>O<sub>3</sub>.It is worth to note that the order of CO<sub>2</sub> selectivity was in the opposite order with soot oxidation rate. The effects of discharge power, oxygen content in the carrier gas and reaction temperature on plasma–catalytic soot oxidation was systematically analyzed. The catalyst characterizations, including N<sub>2</sub> adsorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction by H<sub>2</sub> and temperature-programmed desorption of O<sub>2,</sub> were conducted to illustrate the reaction mechanisms of plasma–catalytic soot oxidation and reaction pathways.
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