Enhanced activity and SO₂ resistance of Co‐modified CeO₂‐TiO₂ catalyst prepared by facile co‐precipitation for elemental mercury removal in flue gas

Abstract

The Co‐modified CeO 2 ‐TiO 2 catalyst prepared by facile co‐precipitation was used for efficient elemental mercury oxidation in flue gas. Results indicated that Co doping greatly enhanced the activity and SO 2 resistance of the CeO 2 ‐TiO 2 catalyst. In the presence of 5% O 2 , 500 ppm NO, 800 ppm SO 2 and 3% H 2 O at 200 °C, the Hg 0 removal efficiency of CeCo 3 /Ti could maintain at about 87% for a relatively long time. Characterizations of catalysts (BET, XRD, Raman spectroscopy, TEM, H 2 ‐TPR, O 2 ‐TPD, XPS, TG‐MS and SO 2 ‐DRIFTS) were carried out to reveal the mechanism of Co modification on the redox ability, SO 2 resistance and resultant mercury oxidation removal performance of catalyst. It was found that an interaction of Ce with Co promoted the dispersion of CeO 2 , increased chemisorbed oxygen concentration, and improved the oxygen storage capacity and the reducibility of catalyst, which was beneficial to the improvement of Hg 0 oxidation removal. Hg 0 would adsorb onto the catalyst and react with surface active oxygen species replenished by gas‐phase O 2 to be oxidized via Mars‐Maessen mechanism. SO 2 consumed the surface active oxygen species and resulted in the reduction of Ce 4+ to Ce 3+ , which induced the deactivation of catalyst. The introduced Co in CeO 2 ‐TiO 2 catalyst exerted the function of protecting Ce 4+ from being poisoned by SO 2 and thus promoted the sulfur resistance and Hg 0 removal performance of the catalyst in the presence of SO 2 .