Manganese Oxide/Titania Materials for Removal of NO _x and Elemental Mercury from Flue Gas

Abstract

A novel catalyst for low temperature selective catalytic reduction (SCR) using CO as reductant, MnO x supported on titania, has been shown to be effective for both elemental mercury capture and low temperature SCR. In low temperature (200 °C) SCR trials using an industrially relevant space velocity (50 000 h−1) and oxygen concentration (2 vol %), nearly quantitative reduction of NO x was obtained using CO as the reductant. Fresh catalyst used as an adsorbent for elemental mercury from an inert atmosphere showed remarkable mercury capture capacity, as high as 17.4 mg/g at 200 °C. The catalyst effectively captured elemental mercury after use in NO x reduction. Mercury capture efficiency was not affected by the presence of water vapor. Mercury capacity was reduced in the presence of SO2. Manganese loading and bed temperature, which influence surface oxide composition, were found to be important factors for mercury capture. X-ray photoelectron spectroscopy (XPS) results reveal that the mercury is present in its oxidized form (HgO) in spent catalyst, indicating the participation of lattice oxygen of the catalyst in the reaction. These results suggest that a single-step process integrating low temperature SCR and mercury capture from flue gas might be feasible.

Elemental mercury capture and oxidation by a regenerable manganese-based sorbent: The effect of gas composition

“…Manganese oxides have been reported to have a good mercury capture potential [1,[5][6][7][8]. Moreover MnO x based catalysts are widely studied for their high activity and selectivity for NO x reduction in flue gases via the low temperature (<200°C) NH 3 -SCR reaction, which is a typical redox process [9].…”

Nanosized Cation-Deficient Fe−Ti Spinel: A Novel Magnetic Sorbent for Elemental Mercury Capture from Flue Gas

“…11 Because elemental mercury is not soluble in water, it is difficult to remove with currently available removal devices. 12 Therefore, elemental mercury can be a major species in the exhaust gas of coal-fired utilities. 13 In China, the total mercury concentrations in the flue gas from coal-fired boilers are in the range of 1.92-27.2 μg m -3 , and elemental mercury accounts for 66-94% of the total mercury.…”

Simultaneous Control of Elemental Mercury/Sulfur Dioxide/Nitrogen Monoxide from Coal-Fired Flue Gases with Metal Oxide-Impregnated Activated Carbon

“…For MnO x /CAC, deconvolution resulted in two fitting peaks corresponding to 641.0 and 642.3 eV, which can be assigned to the oxidation state of Mn 3+ and Mn 4+ , respectively. The data are encouraging because an increasing ratio of Mn 4+ /Mn 3+ could promote the Hg 0 oxidation (Ji et al, 2008;Li et al, 2010;Tian et al, 2011;Li et al, 2012). For the XPS result of CuO x /CAC, two peaks corresponding to 931.8 and 934.1 eV can be deconvoluted and assigned to the oxidation state of Cu + and Cu…”