Mercury Removal by Carbon Materials with Emphasis on the SO2–Porosity Relationship

The effect of textural properties on the Hg/SO₂ relationship is key to developing cost-effective technologies for mercury removal in energy production processes. Furthermore, the developed model material, with a hierarchically controlled pore structure, provides new insights that can be applied to other carbon-based adsorbents/catalysts in different applications.

Mercury is a pollutant of great global concern. Although numerous studies have been carried out for its removal from energy production processes, there are still some gaps in this field that must be filled to improve the development of adsorbents/catalysts capable of retaining it. In this study, a model material with controlled pore structure is developed to evaluate the effect of pore structure on SO₂ tolerance during Hg⁰ adsorption. The carbon material is loaded with different active species of iron. The results show that hematite is the reactive iron species for Hg capture. In contrast to the general assumption, a well-developed microporosity is not the only textural parameter that should be considered to improve flue gas Hg retention. In fact, highly microporous materials are prone to SO₂ poisoning. Therefore, the role of porosity in mercury capture in the presence of SO₂ must be evaluated from a new perspective, taking into account the textural characteristics as a whole. The developed model demonstrates that a carbonized material can be as effective for mercury removal as a more expensive activated carbon material, responding to the growing demand for cost-effective technologies.

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