Efficient simultaneous removal of diesel particulate matter and hydrocarbons from diesel exhaust gas at low temperatures over Cu–CeO₂/Al₂O₃ coupling with dielectric barrier discharge plasma

Diesel particulate matter (DPM) and hydrocarbons (HCs) emitted from diesel engines have a negative affect on air quality and human health. Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem. In this study, Cu-doped CeO₂ loaded on Al₂O₃ coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs. Removals of DPM and HCs at 200 °C using the catalyst were as high as 90% with plasma but below 30% without plasma. Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process. It was found that Cu–CeO₂ can promote the formation of adsorbed oxygen (\mathrmM^+ –\mathrmO^-_2 ) and terminal oxygen (M=O), which can react with DPM to form carbonates that are easily converted to gaseous CO₂. Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.