Chemical Engineering Journal, Vol.316, 1103-1113, 2017
Activity of CuCl2-modified cobalt catalyst supported on Ti-Ce composite for simultaneous catalytic oxidation of Hg-0 and NO in a simulated pre-sco process
To achieve the high Hg oxidation efficiency in the atmospheres with low concentration of HCI or in temporary absence of HCI and facilitate the following SCR process, CuCl2-CoOx/Ti-Ce catalyst for simultaneous catalytic oxidation of Hg and NO in a pre-sco process (300-420 degrees C) was developed. N-2 adsorption-desorption, XRD, TG and XPS techniques were used to characterize the catalyst and its catalytic performance was evaluated in a laboratory-scale fixed-bed system. Results indicated that the oxidation process occurred at CuCl2 sites and CoOx sites separately for Hg and NO over the catalist. With an increasing CuCl2 loading, more active CuCl2 species would form and both amorphous and crystalline phase of CuCl2 contribute to the excellent mercury oxidation capacity, however, resulting in the decrease of NO conversion efficiency. CuCl2 might hinder the interaction between NO species and CoOx sites. Thus, well dispersion of CuCl2 and CoOx species over catalyst surface could relieve the suppression. In the presence of 5 ppm HCl and 6%O-2, a sustainable Hg oxidation capability (nearly 100% at 360 degrees C) could be achieved over 7%CuCl2-CfC catalyst. Elemental mercury at gaseous state collided with the CuCl2 sites of catalyst and reacted with the active CI to form HgCl2. The consumption of active CI species could be compensated by the gas phase HCI with the aid of O-2. SO2 did not show a significant negative effect on Hg oxidation but suppressed NO oxidation. SO2 with high concentration would speed up the formation of sulphates, resulting in the loss of activity. (C) 2017 Elsevier B.V. All rights reserved.