Impacts of acid gases on mercury oxidation across SCR catalyst

Zhuang, Ye; Laumb, Jason D.; Liggett, Richard; Holmes, Mike; Pavlish, John H.

doi:10.1016/j.fuproc.2007.03.010

Cited by 105 publications

(49 citation statements)

References 4 publications

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“…Enhancement of Hg el oxidation activity was observed as HCl concentrations increased from 1 to 50 ppm [72]. An increase in Hg oxidation with increasing HCl concentrations was also mentioned by Kamata et al [21].…”

Section: Influence Of Flue Gas Constituentssupporting

confidence: 71%

“…Modifications of SCR catalysts for achieving high Hg el oxidation performance are of interest as well. In order to determine their efficiency in oxidizing Hg el from flue gases, the SCR catalysts were tested at in the laboratory and in pilot [71][72][73][74] and full scale conditions(e.g., [75]). Some of these Hg el oxidation results are presented in Table 3.…”

Section: Mercury Oxidation On Scr Catalystsmentioning

confidence: 99%

“…Hg adsorption on catalyst surfaces has been mentioned in a number of studies [25,72,73]. Hg el adsorption on the SCR catalyst surface was only observed in the absence of HCl [76,77].…”

Section: Mercury Adsorption On Scr-catalystsmentioning

confidence: 99%

“…Hong et al [78] observed that increasing the NH 3 /NO ratio led to a decrease in Hg el oxidation activity of SCR catalysts at 350 °C. Eswaran and Stenger [76] [72] indicated that SO 2 and SO 3 had a mitigating effect on Hg el oxidation by SCR catalysts in the presence of HCl. This behavior was attributed to the competitive adsorption of SO 2 , SO 3 and HCl on the SCR catalyst surface active sites [72].…”

Section: Influence Of Flue Gas Constituentsmentioning

confidence: 99%

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Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

2012

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Abstract:The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a great deal of interest. Selective catalytic reduction (SCR), noble metal and transition metal oxide based catalysts have been investigated at both the laboratory and plant scale with this objective. A review article published in 2006 covers the progress in the elemental mercury (Hg el ) catalytic oxidation area. This paper brings the review in this area up to date. To this end, 110 papers including several reports and patents are reviewed. For each type of catalyst the possible mechanisms as well as the effect of flue gas components on activity and stability are examined. Advantages and main problems are analyzed. The possible future directions of catalyst development in this environmental research area are outlined.

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Section: Influence Of Flue Gas Constituentssupporting

confidence: 71%

Section: Mercury Oxidation On Scr Catalystsmentioning

confidence: 99%

“…Hg adsorption on catalyst surfaces has been mentioned in a number of studies [25,72,73]. Hg el adsorption on the SCR catalyst surface was only observed in the absence of HCl [76,77].…”

Section: Mercury Adsorption On Scr-catalystsmentioning

confidence: 99%

Section: Influence Of Flue Gas Constituentsmentioning

confidence: 99%

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Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

2012

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“…The kinetics of these reactions depends on the rate of suppression of excited states and the stoichiometry , Agarwal and Stenger 2007, Cauch et al 2008. Despite the very short lifetime of a chlorine atom, kinetic data show that the reaction between Cl and Hg atoms represents the dominating homogeneous reaction of oxidation, kinetically restricted by the presence of other fl ue gas components, mainly CO, H 2 O, NO, and SO 2 (Laudal et al 2000, Niksa et al 2002, Zhuang et al 2007a, Zhuang et al 2007b). …”

Section: Mercury Speciation In Fl Ue Gasesmentioning

confidence: 99%

Transformations of mercury in processes of solid fuel combustion – review

Czaplicka¹,

Pyta²

2017

Archives of Environmental Protection

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Abstract:The paper presents current reports on kinetics and mechanisms of reactions with mercury which take place in the exhaust gases, discharged from the processes of combustion of solid fuels (coals). The three main stages were considered. The fi rst one, when thermal decomposition of Hg components takes place together with formation of elemental mercury (Hg 0 ). The second one with homogeneous oxidation of Hg 0 to Hg 2+ by other active components of exhaust gases (e.g. HCl). The third one with heterogeneous reactions of gaseous mercury (the both -elemental and oxidised Hg) and solid particles of fl y ash, leading to generation of particulate-bound mercury (Hg p ). Infl uence of exhaust components and their concentrations, temperature and retention time on the effi ciency of mercury oxidation was determined. The issues concerning physical (gas-solid) and chemical speciation of mercury (fractionation Hg 0 -Hg 2+ ) as well as factors which have infl uence on the mercury speciation in exhaust gases are discussed in detail.

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Investigation on elemental mercury removal and antideactivation performance of modified SCR catalysts

Cai

Wang

et al. 2018

Asia-Pacific J Chem Eng

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The ever-growing concern of mercury exhausted from coal-fired boiler is driving the requirement for using novel catalysts with stable Hg 0 removal efficiency. However, the influences of flue gas components on Hg 0 removal performance of modified and deactivated catalysts have been seldom investigated previously. The antideactivation ability of modified catalysts is still unclear. In this study, cerium (Ce) and zirconium (Zr) were utilized to modify the honeycomb V 2 O 5 -WO 3 /TiO 2 catalysts. Sodium (Na) was doped on the rudimentary and modified catalysts by impregnation method to obtain deactivated catalysts. Elemental mercury removal efficiency of the catalysts was measured using a lab-scale experimental system under various working conditions. Characterization of the catalysts was conducted to further analyze the mechanism of Hg 0 removal process. Physical adsorption plays an important role in Hg 0 removal over catalysts in the atmosphere of N 2 and O 2 . The introduction of SO 2 has an adverse effect on Hg 0 removal because of the competitive adsorption. NO and HCl motivate the Hg 0 removal through different mechanisms whereas NH 3 has little effect on the removal efficiency. Mars-Maessen mode could be responsible for the excellent Hg 0 removal performance and the splendid antideactivation ability of Ce-modified catalysts. The efficiency of Zr-modified catalysts is lower due to the decline of vanadium content.

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Impacts of acid gases on mercury oxidation across SCR catalyst

Cited by 105 publications

References 4 publications

Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

Transformations of mercury in processes of solid fuel combustion – review

Investigation on elemental mercury removal and antideactivation performance of modified SCR catalysts

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