Enhanced activity and SO<sub>2</sub> resistance of Co‐modified CeO<sub>2</sub>‐TiO<sub>2</sub> catalyst prepared by facile co‐precipitation for elemental mercury removal in flue gas
Honghu Li, Jingdong Zhang, Yanxiao Cao, Fei Li, Chaoyang Liu, Yongwei Song, Jiangjun Hu, Yuan Wang
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 .