Remove elemental mercury from simulated flue gas by CeO₂-modified MnO_x/HZSM-5 adsorbent

In this study, we synthesized a Ce-modified Mn/HZSM-5 adsorbent via the ultrasound-assisted impregnation for Hg-0 capture. Given the addition of 15% CeO2, similar to 100% Hg-0 efficiency was reached at 200 degrees C, suggesting its promotional effect on Hg-0 removal. The doped Ce introduced additional chemisorbed oxygen species onto the adsorbent surfaces, which facilitated the oxidation of Hg-0 to HgO. Even though adding CeO2 led to a weakened adsorbent acidity, yet it appeared that this negative affect could be completely overcome by the enhanced oxidative ability, which finally endowed Ce-modified Mn/HZSM-5 with a satisfactory Hg-0 removal performance within the whole investigated temperature range. During the Hg-0 capture process, chemisorption was predominant with Mn(4+)operating as the main active site for oxidizing Hg-0 to Hg2+. Finally, the 15Ce-Mn/HZSM-5 adsorbent exhibited good recyclability and stability. However, its tolerance to H2O and SO2 appeared relatively weak, suggesting that some modification should be conducted to improve its practicality.