ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

E-mail: jjhu1963@outlook.com

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.

DOI: 10.1007/s11696-017-0250-4

Chemical Papers 71 (12) 2545–2555 (2017)