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

Comparative study of Co/TiO₂, Co–Mn/TiO₂ and Co–Mn/Ti–Ce catalysts for oxidation of elemental mercury in flue gas

Honghu Li, Shengkai Wang, Xu Wang, Nian Tang, Siwei Pan, and Jiangjun Hu

School of Resource and Environmental Sciences, Wuhan University, Wuhan, People’s Republic of China

E-mail: jjhu1963@outlook.com

Abstract: The Co–Mn/Ti–Ce catalyst prepared by sol–gel and impregnation method was evaluated for catalytic oxidation of Hg⁰ in the simulated flue gas compared with Co/TiO₂ and Co–Mn/TiO₂. The results showed that Co–Mn/Ti–Ce catalyst exhibited higher catalytic activity (around 93% Hg⁰ removal efficiency in the temperature of 150 °C with 6% O₂, 400 ppm NO, 200 ppm SO₂ and 3% H₂O) than Co/TiO₂ and Co–Mn/TiO₂. Based on the characterization results of N₂ adsorption–desorption, XRD, UV–Vis, XPS, H₂-TPR and Hg-TPD, it could be concluded that the lower band gap, better reducibility and mercury adsorption capability and the presence of Co³⁺/Co²⁺, Mn⁴⁺/Mn³⁺ and Ce⁴⁺/Ce³⁺ redox couples as well as surface oxygen species contributed to the excellent Hg⁰ oxidation removal performance. In addition, well dispersion of active components and a synergetic effect among Co, Mn and Ce species might improve the activity further. A Mars–Maessen mechanism is thought to be involved in the Hg⁰ oxidation. The lattice oxygen derived from MnO_x or CoO_x would react with adsorbed Hg⁰ to form HgO and the consumption of lattice oxygen could be replenished by O₂. For Co–Mn/Ti–Ce, MnO_x−1 could be alternatively reoxidized by the lattice oxygen derived from adjacent CoO_x and CeO_x which is beneficial to the Hg⁰ oxidation.

Keywords: Co–Mn/Ti–Ce catalyst; Elemental mercury; Catalytic oxidation; Characterization

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0152-5

Chemical Papers 71 (9) 1569–1578 (2017)