Heterogeneous oxidation of elemental mercury vapor over RuO2/rutile TiO2 catalyst for mercury emissions control

Abstract

The catalytic oxidation of elemental mercury (Hg(0)) vapor is an effective way to enhance mercury removal from coal-fired power plants. RuO 2 catalyst was found to be an excellent Hg(0) oxidation catalyst. When rutile TiO 2 was used as the catalyst support, RuO 2 formed well dispersed nano-layers due to the very similar crystal structures of RuO 2 and rutile TiO 2 , giving higher Hg(0) oxidation activity over anatase TiO 2 support. The RuO 2 /rutile TiO 2 catalyst can be used at the tail end section of the selective catalytic reduction (SCR) unit for Hg(0) oxidation. It showed good Hg(0) oxidation performance under sub-bituminous and lignite coal simulated flue gas conditions with low concentration of HCl or HBr gas. The RuO 2 /rutile TiO 2 catalyst also showed excellent resistance to SO 2 under bituminous coal simulated flue gas, maintaining higher than 90% Hg(0) oxidation with up to 2,000 ppmv SO 2 present. The oxidized mercury in a form of HgCl 2 has a high solubility in water and can be easily captured by other air pollution control systems such as wet scrubbers in coal-fired power plants.

Co3O4 Nanosheets Preferentially Growing (220) Facet with a Large Amount of Surface Chemisorbed Oxygen for Efficient Oxidation of Elemental Mercury from Flue Gas

“…Mercury, as a major contaminant in coal-fired flue gas, is receiving worldwide attention due to its extreme toxicity, high volatility, persistence, and bioaccumulation in the environment. − Mercury in coal-fired flue gas exists in three different forms: particle-bound mercury (Hg p ), oxidized mercury (Hg 2+ ), and zero-valent mercury (Hg 0 ). − Among these forms, Hg 0 is the most difficult to remove by conventional environmental protection equipment because of its high volatility and insolubility. , It has been shown that converting Hg 0 to an easily removable form of Hg 2+ is a viable method to control Hg 0 emission from coal-fired flue gas. , …”

“…4−6 Among these forms, Hg 0 is the most difficult to remove by conventional environmental protection equipment because of its high volatility and insolubility. 7,8 It has been shown that converting Hg 0 to an easily removable form of Hg 2+ is a viable method to control Hg 0 emission from coal-fired flue gas. 9,10 Transition-metal oxide materials such as Co, Mn, Cu, and Ce are usually used in the Hg 0 oxidation process.…”

Mechanism of ethylene oxychlorination over ruthenium oxide

“…RuO 2 is an active catalytic material in a variety of processes, including catalytic CO [1][2][3], NH 3 [4], alcohol [5], and Hg oxidation [6], as well as in electrochemical phenolic wastewater oxidation [7], or as an anode in water splitting cells [8]. In addition to its electrochemical applications [9,10], one of the most significant industrial uses of RuO 2 is in HCl oxidation (Deacon process), where it is the best performing catalyst to produce molecular chlorine at low temperature [11][12][13][14].…”

Enhanced activity and SO2 resistance of Co‐modified CeO2‐TiO2 catalyst prepared by facile co‐precipitation for elemental mercury removal in flue gas

“…Up to present, several methods have been proposed for the mercury abatement from flue gas, such as sorbent injection, photochemical oxidation, electro‐catalytic oxidation and catalytic oxidation . Modified active carbons (sulfur/halogen/metal oxides modified) can effectively remove elemental mercury from flue gas, but the high operation cost and complex separation progress from ultrafine fly ash hinders its application.…”