ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
FeCl3-modified Co–Ce oxides catalysts for mercury removal from coal-fired flue gas
Honghu Li, Shengkai Wang, Xu Wang, Yuan Wang, Nian Tang, Siwei Pan, and Jiangjun Hu
Wuhan University, Wuhan, People’s Republic of China
Abstract: FeCl3-modified Co–Ce oxides catalysts were prepared by a glycine–nitrate combustion method followed by FeCl3 impregnation, and Hg0 removal efficiencies of the obtained samples were investigated in a laboratory-scale fixed-bed system. Effect of factors (including FeCl3 loading value, reaction temperature and flue gas compositions) on mercury removal over FeCl3-modified Co–Ce oxides catalyst and its co-benefit of NO conversion were examined. Results showed that the FeCl3-modified Co–Ce oxides catalysts presented high mercury removal activities below 300 °C in the absence of HCl. The 8% FeCl3–CC could remove >90% Hg0 at optimum temperature (150 °C) in N2 and achieve a Hg0 removal efficiency of about 86% and a simultaneous NO conversion efficiency of about 48.5% at 250 °C in the N2 + O2 atmosphere. NO would slightly suppress the mercury removal but significantly improve it when NO was added together with O2. SO2 exhibited an obvious negative effect on the removal of mercury, but H2O slightly inhibited it. This inhibition could be attributed to the competitive adsorption. The characterization results (BET, XRD, SEM, XPS and TG) demonstrated that FeCl3 was successfully introduced to the Co–Ce oxides and manifested the formation of Co3O4–CeO2 composites. XPS and Hg-TPD results indicated that both active Cl species and oxygen species contributed to the oxidation removal of elemental mercury over FeCl3-modified Co–Ce oxides, which followed the Mars–Maessen mechanism.
Keywords: FeCl3 modification; Co–Ce oxides; Mercury removal; Flue gas
Full paper is available at www.springerlink.com.
Chemical Papers 71 (12) 2545–2555 (2017)