Boosting SO2‑tolerant oxidation of Hg0 and chlorobenzene over MnCo2O4@TiO2 catalyst via constructing shielding effects.

[Display omitted] • MnCo 2 O 4 @TiO 2 was successfully synthesized and showed high SO 2 -tolerant performance. • The interaction between MnCo 2 O 4 and TiO 2 promoted more Co3+, moderate acidic sites and weaken sulfate deposition. • Purification mechanism for Hg0 and chlorobenzene in the presence of SO 2 was proposed. Currently, it was still challenging to improve the SO 2 -tolerant catalytic oxidation of Hg0 and chlorobenzene in flue gas. Herein, we developed a MnCo 2 O 4 @TiO 2 core–shell material that employed a self-shielding mechanism to prevent sulfate deposition. The optimal MnCo 2 O 4 @TiO 2 -2 catalyst achieved 100 % Hg0 removal efficiency at 250 °C under 150–600 ppm SO 2 , and also showed enhanced SO 2 resistance during chlorobenzene conversion at 275 °C. The strong interaction between MnCo 2 O 4 and TiO 2 facilitated the electronic transfer from MnCo 2 O 4 to TiO 2 , thereby producing more Co3+ and maintaining the high reactivity. Further, the mesoporous TiO 2 layer facilitated the generation of moderate acid sites, improved the distribution of surface oxygen species, and weakened SO 2 adsorption on catalyst. Under the protection of mesoporous TiO 2 layer, the generation of Mn/Co sulfates could be inhibited effectively. In particular, the suitable TiO 2 shell balanced the chemical adsorption and oxidation processes of Hg0 on the catalyst. This enhancement led to improved single Hg0 removal efficiency and SO 2 -tolerant Hg0 removal performance. During chlorobenzene degradation in presence of SO 2 , the oxidation path of chlorobenzene on MnCo 2 O 4 @TiO 2 occurred via chlorobenzene → phenolates → maleates → formates/acetates → CO 2 and H 2 O. Although sulfate formation would cover the active surface and inhibit the reaction path, the TiO 2 shell could attenuate this negative effect. This study provided a new approach for the development of SO 2 -tolerant transition metal oxide with superior performance, holding significant academic and practical value. [ABSTRACT FROM AUTHOR]

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