Recent advances in MnO2-based adsorbents for mercury removal from coal-fired flue gas

Mercury emissions from power stations have threatened the natural environment and human health. Adsorption is one of the most effective technologies for the abatement of mercury. As the key component, the performance of the adsorbents directly decides the mercury removal efficiency of the whole system. Extensive research has been conducted on the removal of mercury using manganese-based adsorbents and to some extent, a satisfactory result is obtained. In this review, the progress on the applications of MnO2-based materials for mercury removal was discussed. Firstly, the fundamentals of MnO2, including its crystalline information and synthesis methods, were summarized. Secondly, physicochemical properties and mercury removal performance of various adsorbents, including raw MnO2, MnO2-supported and MnO2 mixed oxide adsorbents, were introduced. Considering that SO2, HCl, H2O and NO constituted the most common components in coal-fired flue gas, the effects of these gas species on adsorbent mercury capture capacity were evaluated and the results indicated that whether or not these components promoted mercury removal closely depended on the mirco-structure and formula of the adsorbents. As well, the possible mercury adsorption mechanisms of the adsorbents under different conditions were discussed and the key intermediate together with the rate-determining step was also uncovered. After summarizing the recyclability and regeneration methods of the reported adsorbents, we concluded with suggestion that attention should be focused on the development of new MnO2-based adsorbents suitable for the long-term operation under real flue gas conditions in future research.

Automated summary

This review discusses the progress in the application of MnO2-based materials for mercury removal, summarizing the fundamentals of MnO2, the properties of various adsorbents, and the effects of gas species on mercury capture capacity. The possible mercury adsorption mechanisms and regeneration methods are also explored, with a suggestion for the development of new MnO2-based adsorbents for future research.