Removal of Elemental Mercury by MnOx Catalysts Supported on TiO2 or Al2O3

The performance of two Mn-based catalysts/sorbents developed for simultaneous low-temperature selective catalytic reduction (SCR) of NO x with NH 3 and Hg capture was studied in the temperature range 50–250 °C. In particular, the effect of the type of support (TiO 2 vs Al 2 O 3 ) on both NO x conversion and Hg capture efficiency was investigated. The two catalysts displayed significant and quite similar NH 3 -SCR activity at low temperatures, showing an optimal performance in the range 80–140 °C. On the contrary, the Mn-based sorbent over TiO 2 showed a much better Hg capture performance than that supported over Al 2 O 3 . The most likely reason was the higher proportion of Mn 4+ sites, as revealed by H 2 -temperature-programmed reduction and X-ray diffraction analysis. The presence of NO in the simulated flue gas slightly decreased the Hg capture performance of the sorbents, while NH 3 had a limited impact. Overall, MnO x -based catalysts appear to be well suited for the simultaneous SCR and Hg capture, with the TiO 2 -supported one showing the most promising results.