Revealing insights into the correlations between structure and performance of CrOx monometallic oxide for Hg0 capture

Abstract

This study explored the impacts of the synthesis methods on the Hg0 elimination ability of CrOx adsorbents. In the sample series, the adsorbent prepared using the sol-gel method (labeled as Cr(S)) presented the best Hg0 capture performance; its Hg0 removal efficiency stayed above 88% at 150 and 200 °C and even rose to ∼97% at 250 °C in the entire 5-h Hg0 capture process. The presence of bountiful surface acid sites aided the sufficient adsorption of Hg0 and an enhancement in the oxidizability primarily accelerated the subsequent Hg0 oxidation step, which constituted the central reason for the satisfactory Hg0 capture capability of Cr(S). The Mars-Maessen mechanism assisted in understanding the Hg0 capture process over Cr(S), in which chemisorption was dominant with Cr6+ and Oα serving as the active sites and HgO formed as the final oxidation product.