A novel low temperature catalyst regenerated from deactivated SCR catalyst for Hg0 oxidation

In order to address the problems of treatment of deactivated SCR catalysts and explore the potential of the MnOx-based low temperature catalysts, a procedure was proposed in the present work. In the procedure, the deactivated SCR catalyst served as the catalyst support and MnOx was loaded on it. The supported catalyst was used for He oxidation in the coal-fired flue gas. Characterization of X-ray fluorescence, N-2 adsorption-desorption, X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and thermogravimetry were conducted to study the properties of the fresh and spent samples and explore the Hg-0 oxidation mechanism. The synthesized catalysts showed good performance on Hg-0 oxidation in a broad temperature range (150 degrees C-350 degrees C) and exhibited superior Hg-0 oxidation activity at 250 degrees C. The results indicated that the unpoisoned V2O5 and MnOx were active for Hg-0 oxidation in the presence of HCI and O-2, but they played different roles at different temperature. At 150 degrees C and 250 degrees C, the MnOx was the active species for the oxidation reaction while the unpoisoned V2O5 inhibited the Hg-0 oxidation process indirectly. However, at 350 degrees C, the V2O5 was mainly involved in Hg-0 oxidation. The results also indicated that both Hg-0 and HCI were adsorbed by the catalysts at different temperatures, and the adsorbed species reacted to form oxidized mercury. Therefore, the regenerated SCR catalyst might be a promising catalyst for the control of Hg-0 emission from the coal-fired flue gas at low temperature. (C) 2016 Elsevier B.V. All rights reserved.