Adsorption and oxidation of mercury in tail-end SCR-DeNOx plants—Bench scale investigations and speciation experiments

Straube, Sandra; Hahn, Thomas; Koeser, Heinz

doi:10.1016/j.apcatb.2007.10.031

Cited by 75 publications

(44 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, simultaneous SO 2 oxidation was incorporated; second, a conventional Thiele analysis now resolves internal pore diffusion across the catalyst wall thickness from the intrinsic reactivity of adsorbed species on the catalyst surface, to directly relate catalyst morphology and composition to the multipollutant performance of the SCR reactor; and, third, the analysis now accounts for simultaneous Hg 0 oxidation by both Br and Cl species, to handle applications in which bromide salts are sprayed on coal or otherwise injected into a gas cleaning system. In the analysis, a simple premise connects NO and SO 2 conversion to the Hg 0 oxidation behavior on SCRs: that halogens compete for surface sites with NH 3 , and that Hg 0 contacts these halogenated sites either from the gas phase or as a weakly adsorbed species, which is consistent with the virtual elimination of Hg 0 adsorption on V 2 O 5 by the DeNO X process (Staube et al, 2008). Since the extension to Br species was not included in the first publication on the distributed analysis for Hg 0 oxidation, it is presented in the appendix.…”

Section: Scr Unit Simulationsmentioning

confidence: 63%

Analytical management of SCR catalyst lifetimes and multipollutant performance

Niksa¹,

Krishnakumar²,

Ghoreishi

2016

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

Selective catalytic reduction (SCR) catalysts are deactivated by several mineral and metallic trace elements at highly variable rates determined by fuel quality and furnace firing conditions. With a loss in activity, NO is reduced over a longer inlet length of the SCR monolith, which leaves a shorter trailing section to sustain the most favorable conditions to oxidize Hg 0 and SO 2 . Since virtually no operating SCR was designed for Hg oxidation and since different monoliths are routinely combined as layers in particular units, the Hg oxidation performance of any SCR fleet is largely unmanaged. The analysis in this paper directly relates a measurement or manufacturer's forecast on the deterioration in NO reduction with age to corresponding estimates for oxidation of Hg 0 . It accommodates any number of catalyst layers with grossly different properties, including materials from different manufacturers and different ages. In this paper, the analysis is applied to 16 full-scale SCRs in the Southern Company fleet to demonstrate that catalyst deactivation disrupts even the most prominent connections among the Hg 0 oxidation performance of commercial SCRs and the behavior of fresh catalysts at lab, pilot, and even full scale.Implications: Catalyst deactivation confounds even the most prominent connections among the Hg 0 oxidation performance of commercial SCRs and the behavior of fresh catalyst at lab, pilot, and even full scale. The halogen dependence has been emphasized throughout the literature on catalytic Hg 0 oxidation, based on a large database on fresh catalysts. But for deactivated catalysts in commercial SCRs, the number of layers is much more indicative of the Hg 0 oxidation performance, in that SCRs with four layers perform better than those with three layers, and so on. The new qualified conclusion is that Hg 0 oxidation is greater for progressively greater HCl concentrations only among SCRs with the same number of layers, even for an assortment of catalyst design specifications and operating conditions. PAPER HISTORY

show abstract

Section: Scr Unit Simulationsmentioning

confidence: 63%

Analytical management of SCR catalyst lifetimes and multipollutant performance

Niksa¹,

Krishnakumar²,

Ghoreishi

2016

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

show abstract

“…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%

“…Eswaran and Stenger [76] also reported strong Hg adsorption in the presence of H 2 SO 4 . Hg el adsorption slightly increased when SO 2 was present [73]. Straube et al [73] investigated the effect of different parameters on Hg adsorption on SCR catalysts under tail-end conditions (low HCl and SO 2 concentration).…”

Section: Mercury Adsorption On Scr-catalystsmentioning

confidence: 99%

“…Hg el adsorption slightly increased when SO 2 was present [73]. Straube et al [73] investigated the effect of different parameters on Hg adsorption on SCR catalysts under tail-end conditions (low HCl and SO 2 concentration). They suggested that mercury adsorption involved chemisorption and the formation of Hg-O bonding on the SCR catalyst surface.…”

Section: Mercury Adsorption On Scr-catalystsmentioning

confidence: 99%

“…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%

See 2 more Smart Citations

Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

2012

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Research on the effect of additives on mercury speciation in coal‐fired derived flue gas

Gao

Sun

et al. 2016

Env Prog and Sustain Energy

View full text Add to dashboard Cite

In order to study the effect of additives on mercury speciation in coal‐fired derived flue gases, the additives experiment was conducted in one 110MW coal‐fired power plant, the additives including calcium bromide and iron oxide. Taking advantage of the Ontario Water Act (OHM) and sorbent tube method, mercury at the denitration (SCR) entrance and export and desulfurization (WFGD) entrance was sampled and the variation of mercury before and during adding the additives was analyzed. The results show that the additives of calcium bromide can oxidize elemental mercury and contribute to increasing the proportion of divalent mercury, and in denitration device, the ratio of divalent mercury in flue gas shows an increasing trend along with the increasing of calcium bromide. However, there is no such trend appearing at desulfurization entrance. In addition, the additives of iron oxide have no obvious effect on the oxidation of elemental mercury in flue gas. Adding a small amount of iron oxide has little effect on the form of mercury, and may even reduce the proportion of divalent mercury. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1566–1574, 2016

show abstract

Adsorption and oxidation of mercury in tail-end SCR-DeNOx plants—Bench scale investigations and speciation experiments

Cited by 75 publications

References 10 publications

Analytical management of SCR catalyst lifetimes and multipollutant performance

Analytical management of SCR catalyst lifetimes and multipollutant performance

Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

Research on the effect of additives on mercury speciation in coal‐fired derived flue gas

Contact Info

Product

Resources

About