Non-thermal plasma injection-CeO2-WO3/TiO2 catalytic method for high-efficiency oxidation of elemental mercury in coal-fired flue gas

•A non-thermal plasma and catalysis system based on CeO2-WO3/TiO2 was developed to oxidize Hg0 in the flue gas.•Approximately 86.6% of the Hg0 was oxidized and 32.9 μg kJ−1 of energy yield was obtained at 110 °C and 2.6 J L−1.•The NTPIC system widened the temperature windows of the catalyst (80-300 °C).•The NTPIC system overcame the inhibitory effect of NO in the plasma alone system.

The combined method of non-thermal plasma injection and 3%CeO2-WO3/TiO2 catalysis system was proposed to enhance Hg0 oxidation in flue gas. Compared with the plasma system, the combined system had excellent oxidation performance. Approximately 86.6% of Hg0 was oxidized and energy yield reached 32.9 µg kJ−1 at 2.6 J L−1 and 110 °C . The combined system widened the temperature windows of CeO2-WO3/TiO2 catalyst (80-300 °C), showed good resistance to H2O and SO2, and also overcame the inhibitory effect of NO on Hg0 oxidation in the plasma system·NH3 inhibited the Hg0 oxidation; however, the coexistence of NO with NH3 significantly mitigated the inhibition. In the combined system, the CeO2-WO3/TiO2 catalyst could catalytically decompose the ozone generated by gas discharge, and increased the production of high adsorbed active oxygen, which was favorable for Hg0 oxidation process. The Hg0 oxidation process followed the homogeneous reaction mechanism and the Mars-Maessen mechanism in NTP injection system and CeO2-WO3/TiO2 system, respectively.

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