Promotional effect of SO2 on CeO2eTiO2 material for elemental mercury removal at low temperature

Özet

The influence of SO2 on Hg0 removal behavior over CeO2eTiO2 (CeTi) adsorbent prepared by a solegelmethod was investigated at low temperature. The fresh, sulfated, and used materials were well characterizedby means of N2 physisorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR), Raman, hydrogen gas temperatureeprogrammed reduction (H2eTPR), thermal gravimetric anddifferential scanning calorimetry (TGeDSC), and X-ray photoelectron spectroscopy (XPS) techniques toillustrate the promotional mechanism of SO2 on Hg0 removal. The results indicated that in the initialreaction period, the Hg0 removal efficiency significantly increased with the presence of SO2 because ofthe reaction between CeTi and SO2. With the sulfation time increasing, the promotional effect of SO2 onHg0 removal over CeTi adsorbent gradually decreased due to the presence of large amount of ceriumsulfate species. The Hg0 removal efficiency over CeTi first increased with the reaction temperatureincreasing, and then decreased with further temperature rising above 150 C. The reducibility of CeTisignificantly decreased after sulfation, while the sulfation led to an enhancement of the Ce3þ contentformed on the adsorbent surface. In the process of Hg0 removal with SO2 presence, the redox couple of[CeO2 (Ce4þ) 4 Ce2O3 (Ce3þ)] played a significant role in Hg0 removal to proceed, and SO2 made animportant contribution to this redox process.