Microwave assisted catalytic removal of elemental mercury from flue gas using Mn/zeolite catalyst

The integrated microwave with Mn/zeolite and ozone (MCO) and combined microwave with Mn/zeolite (MC) was employed to oxidize elemental mercury (Hg0) in simulated flue gas. The results show that mercury removal efficiency attained 35.3% in the MC, over 92% of Hg0 removal efficiency could be obtained in the MCO. The optimal microwave power and empty bed residence time (EBRT) in the microwave plasma catalytic oxidation were 264 W and 0.41 s, respectively. The effect of Hg0 oxidation in the MCO was much higher than that in the MC. Microwave accentuated catalytic oxidation of mercury, and increased mercury removal efficiency. The additional use of ozone to the microwave–catalysis over Mn/zeolite led to the enhancement of mercury oxidation. Mn/zeolite catalyst was characterized by X–ray diffraction (XRD), X–ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FT–IR), scanning electron microscopy (SEM) and the Brunauer Emmett Teller (BET) method. Microwave catalytic mercury over Mn/zeolite was dominated by a free radical oxidation route. Ozone molecules in air could enhance free radical formation. The coupling role between ozone and radicals on mercury oxidation in the MCO was formed. The MCO appears to be a promising method for emission control of elemental mercury.