A-site doped mullite-type oxides A0.5Sm0.5Mn2O5 (A = Y, Pr) with boosted Hg0 removal performance under high GHSV

• A-site doped mullite-type oxides were successfully synthesized by a sol–gel method. • Y 0.5 Sm 0.5 Mn 2 O 5 shows an 82.22 % Hg 0 conversion rate at 150℃ under a high GHSV (1000000 h −1 ). • The chemical and physical properties of raw SmMn 2 O 5 can be well regulated through Y doping. Mn-based mullite-type oxides have been considered one of the most promising catalysts, and the modification of mullite-type oxides significantly affects the catalytic performance. Here, A-site doped mullite-type oxides are successfully synthesized by the typical sol–gel method and used for Hg 0 catalytic oxidation. Y 0.5 Sm 0.5 Mn 2 O 5 shows the highest Hg 0 conversion rate (82.22 % at 150℃) compared with Pr 0.5 Sm 0.5 Mn 2 O 5 (74.16 % at 150℃) and SmMn 2 O 5 (73.94 % at 150℃) under a high GHSV (1000000 h −1 ), and the Hg 0 conversion rate could reach 100 % under a relatively lower GHSV (500000 h −1 ). Miscellaneous techniques including HRTEM, XPS, EPR, H 2 -TPR, O 2 -TPD, NH 3 -TPR, and Hg-TPD have been utilized to deeply investigate the critical factors influencing the catalytic performance. The results demonstrate that the highest Mn 4+ content, richest active oxygen species, and highest reducibility contribute to the superior catalytic performance of Y 0.5 Sm 0.5 Mn 2 O 5 ·NH 3 -TPD and Hg-TPD results reveal that Hg 0 can be more preferentially adsorbed and oxidized on Y 0.5 Sm 0.5 Mn 2 O 5 . The modified mullite-type oxide Y 0.5 Sm 0.5 Mn 2 O 5 shows superior Hg 0 catalytic oxidation performance under a high GHSV and exhibits great potential in Hg 0 removal from flue gas in coal-fired power plants.