Promotional effect of SO2 on CeO2-TiO2 material for elemental mercury removal at low temperature

The influence of SO2 on Hg-0 removal behavior over CeO(2)eTiO(2) (CeTi) adsorbent prepared by a sol-gel method was investigated at low temperature. The fresh, sulfated, and used materials were well characterized by means of N-2 physisorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, hydrogen gas temperature-programmed reduction (H-2-TPR), thermal gravimetric and differential scanning calorimetry (TG-DSC), and X-ray photoelectron spectroscopy (XPS) techniques to illustrate the promotional mechanism of SO2 on Hg-0 removal. The results indicated that in the initial reaction period, the Hg-0 removal efficiency significantly increased with the presence of SO2 because of the reaction between CeTi and SO2. With the sulfation time increasing, the promotional effect of SO2 on Hg-0 removal over CeTi adsorbent gradually decreased due to the presence of large amount of cerium sulfate species. The Hg-0 removal efficiency over CeTi first increased with the reaction temperature increasing, and then decreased with further temperature rising above 150 degrees C. The reducibility of CeTi significantly decreased after sulfation, while the sulfation led to an enhancement of the Ce3+ content formed on the adsorbent surface. In the process of Hg-0 removal with SO2 presence, the redox couple of [CeO2 (Ce4+) <-> Ce2O3 ( Ce3+)] played a significant role in Hg-0 removal to proceed, and SO2 made an important contribution to this redox process. Copyright (c) 2016 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.