Influence of SO3 on mercury removal with activated carbon: Full-scale results

Sjostrom, Sharon; Dillon, Martin; Donnelly, Brian; Jean, Bustard,; Filippelli, Greg; Glesmann, Rob; Orscheln, Tom; Wahlert, Steve; Chang, Ramsay; O'Palko, Andrew

doi:10.1016/j.fuproc.2009.08.019

Cited by 35 publications

(27 citation statements)

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“…mercury oxidation [15,28,38,39]. To explain the decrease in mercury retention in activated carbons in the oxy-combustion atmosphere different competitive reactions need to be taken into consideration: (i) the high proportion of CO 2 present in the gas composition might be occupying a part of activated carbon microporous structure competing for the same adsorption sites as mercury [22], (ii) the H 2 O molecules in the flue gas (in oxy-combustion they may be present in concentrations of up to 30%) might be adsorbed into the micropore structure of the activated carbon reducing the number of active sites for mercury adsorption [12,24,[43][44][45], (iii) a higher proportion of oxidation of SO 2 to SO 3 that could occur during oxy-combustion [33,46] will inhibit mercury adsorption because SO 3 will be competing with mercury for the same binding sites [19,25,30,47]. The role of SO 3 is not clear.…”

Section: Resultsmentioning

confidence: 99%

Influence of a CO2-enriched flue gas on mercury capture by activated carbons

López-Antón

Rumayor

Dı́az-Somoano

et al. 2015

Chemical Engineering Journal

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Section: Resultsmentioning

confidence: 99%

Influence of a CO2-enriched flue gas on mercury capture by activated carbons

López-Antón

Rumayor

Dı́az-Somoano

et al. 2015

Chemical Engineering Journal

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“…Fly ash is rich in silica (SiO 2 ), lime (CaO), and unburnt carbon, all of which may participate in catalyzing the oxidation of mercury. The alkaline minerals that are present may also help to neutralize acid gases such as SO 2 , which reduces oxidized mercury, and SO 3 , which may combine with H 2 O to form H 2 SO 4 on the ash surface and physically hinder further oxidation (25,26). HCl (without Cl 2 ) was not observed to have any significant impact on Hg 0 oxidation, with and without fly ash.…”

Section: Heterogeneous Oxidation Of Mercurymentioning

confidence: 92%

“…There is also considerable evidence to suggest that sulfur in SO 2 is oxidized to S(VI) on carbon surfaces (22)(23)(24), which may result in additional gaseous SO 3 when activated carbon is injected for mercury control. In addition, many coal-fired power plants intentionally add SO 3 to condition the flue gas for more effective removal of fly ash using electrostatic precipitators (25,26).…”

Section: Importance Of So 2 and So 3 For Mercury Capture In Coal-firementioning

confidence: 99%

Understanding the effects of sulfur on mercury capture from coal-fired utility flue gases

Morris

Morita

Jia

2010

Journal of Sulfur Chemistry

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Coal combustion continues to be a major source of energy throughout the world and is the leading contributor to anthropogenic mercury emissions. Effective control of these emissions requires a good understanding of how other flue gas constituents such as sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ) may interfere in the removal process. Most of the current literature suggests that SO 2 hinders elemental mercury (Hg 0 ) oxidation by scavenging oxidizing species such as chlorine (Cl 2 ) and reduces the overall efficiency of mercury capture, while there is evidence to suggest that SO 2 with oxygen (O 2 ) enhances Hg 0 oxidation by promoting Cl 2 formation below 100 • C. However, studies in which SO 2 was shown to have a positive correlation with Hg 0 oxidation in full-scale utilities indicate that these interactions may be heavily dependent on operating conditions, particularly chlorine content of the coal and temperature. While bench-scale studies explicitly targeting SO 3 are scarce, the general consensus among full-scale coal-fired utilities is that its presence in flue gas has a strong negative correlation with mercury capture efficiency. The exact reason behind this observed correlation is not completely clear, however. While SO 3 is an inevitable product of SO 2 oxidation by O 2 , a reaction that hinders Hg 0 oxidation, it readily reacts with water vapor, forms sulfuric acid (H 2 SO 4 ) at the surface of carbon, and physically blocks active sites of carbon. On the other hand, H 2 SO 4 on carbon surfaces may increase mercury capacity either through the creation of oxidation sites on the carbon surface or through a direct reaction of mercury with the acid. However, neither of these beneficial impacts is expected to be of practical significance for an activated carbon injection system in a real coal-fired utility flue gas.

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“…Activated carbon injection is considered to be one of the most cost effective options for mercury control at coal-fired power plants but the presence of SO 3 can decrease mercury capture on the carbon surface dramatically by competing for the same binding sites on the carbon surface (Sjostrom et al, 2009;. suggested a need for further investigations to explain the interaction between mercury and sulphur.…”

Section: Emission Of Mercurymentioning

confidence: 99%