SCR Catalyst Regeneration - 10 years of R&D Development 

and Commercial Application 

Mega Symposium 

Power Plant Air Pollution Control Symposium 

Sponsored by EPA, NETL, EPRI, AWMA 

Baltimore, Maryland 

August 25 – 28, 2008

Paper Number 104 

Mark Ehrnschwender April Freeman Sibley 

Plant Services Director Research Engineer 

Evonik Energy Services Southern Company Generation 

P.O. Box 1727 P.O. Box 2641 

304 Linwood Road Suite 102 600 North 18th Street 

Kings Mountain, NC 28086 Birmingham, AL 35291-8195 

Phone: 704 – 734 – 0688 Phone: 205 – 257 – 6114 

Fax: 704 – 734 – 1088 Fax: 205-257-5367 

Mark.Ehrnschwender@evonik-energyservices.us Apfreema@southernco.com 

1 

10.3155/2008CP175.104
 

ABSTRACT 

With year round SCR operation a widespread use of catalyst regeneration will minimize catalyst 

replacement costs. Evonik has more than ten (10) years of R&D and full scale catalyst 

regeneration experience. The paper explains developments over the last ten (10) years in catalyst 

regeneration to the current most advanced state-of-the-art regeneration process. Full scale 

regeneration results for all types of commercially available catalyst including: 

• Full activity recovery for an application burning high sulfur Southern Illinois Basin coal. 

• Opportunities to increase activity above the original value for an application burning 

world market compliance coal. 

• SO2/SO3 conversion rate reduction for an application burning high sulfur Southern 

Illinois Basin coal. 

• Mercury oxidation for an application burning mid-sulfur Southern Appalachian coal. 

• Catalyst longevity (number of regeneration cycles) covering catalyst that was regenerated 

for the fourth time after about 100,000 SCR operating hours. 

• Maintaining mechanical catalyst strength and structural integrity. 

INTRODUCTION 

Southern Company and Evonik Energy Services have a variety of programs underway to better 

understand the influencing factors and interactions of pollutants to the Selective Catalytic 

Reduction (SCR) and the SCR catalyst. This is primarily being driven by environmental 

legislation to reduce the emissions from coal fired units in the United States and around the 

world. 

Early emissions legislation focused on sulfur dioxide (SO2) and nitrous oxide (NOX) reductions 

in the 1980’s and 1990’s. These pollutants were the primary contributors to acid rain and were 

the focal point of the EPA and legislature. 

In the late 1990’s and throughout 2000, the EPA focus has been on the acid mist, greenhouse 

gases and mercury emissions from coal fired power plants. The SCR is of particular interest as 

the catalyst will release oxygen and provide co-benefit to the oxidation of other pollutants which 

can be removed in an oxidized form where not easily removed in the elemental, such as mercury. 

Unfortunately, it can also oxidize pollutants, like sulfur dioxide to sulfur trioxide, which were in 

a form to be captured, however, converted to a form much more difficult to remove. 

2 

With the pending and established environmental regulations, the need for co-benefit applications 

within the SCR has become almost a necessity. As wet flue gas desulfurization (wFGD) systems 

come on-line and the units switch to a higher sulfur coal, the SCR is looked upon to provide cobenefit, particularly to help with mercury removal. It is well established that along with NOX
 

reduction, SCR technology has potential for oxidizing mercury thereby providing enhanced 

removal in downstream wFGD systems. 

Southern Company has conducted testing at it slip stream reactor located at one of its generating 

stations which is a 150 MW, T-Fired unit of the 1950’s vintage. This unit is located at a 

generating plant in the southeastern portion of the United States. The coal that is fired is a highBtu eastern bituminous coal, with a sulfur content of roughly 1.5%. Coal mercury levels were 

relatively consistent, ranging from approximately 150 to 200ppb. 

The pilot equipment consisted of three identical parallel reactors. Each reactor was equipped 

with a dummy layer (flow straightening grid), and two layers of catalysts. The internal reactor 

dimensions were approximately 13” square. Catalyst “baskets” were constructed, each 

consisting of four (4) standard honeycomb elements, for a total of eight (8) elements per reactor 

(two baskets/layer x 4 elements each). The height of the catalyst was consistent with full-scale 

applications at slightly over 1 meter. 

The facility was designed for a nominal reactor operating temperature of 700 o

F, with 

temperature being controlled with in-line electric heaters. Depending on inlet gas temperature 

and flow rate requirements for a test condition, other temperatures may be obtained. Each 

reactor had a nominal design flow of 400 scfm (68 oF, 1 atm). To induce flow though the 

reactors, a tail-end fan and primary inlet dampers are installed to control the flow. 

Evonik Industries, Energy Group currently operates over 10,000 MW’s of coal fired capacity in 

four different countries and is faced with similar environmental issues. The SCR’s in the fleet 

include seventeen (17) high-dust, six (6) low-dust and one (1) tailing end with operating 

experience of over 20 years on a 12 month x 24 hour operation per year. 

Being an independent power producer, cost effective solutions are required to maintain a 

competitive posture. Through its engineering support group an extensive amount of analysis has 

been done to develop the low cost solutions. 

This paper combines the understandings of both organizations in regards to operation of the SCR 

and its capabilities to assist and enhance the capture of the various pollutants. 

BODY 

In the Midwest, there has been a significant amount of activity in the installation of wet flue gas 

desulphurization (wFGD) systems for the capture of sulfur dioxide (SO2). This is in an effort to 

meet the Clean Air Interstate Regulations (CAIR) which for geographic purposes is limited to 

states east of the Mississippi River. Prior to these installations (with the vast majority 

operational by 2010), the units were firing a higher cost, lower sulfur, environmental compliance 

or near compliance coal. With the wFGD systems, the units have the ability to utilize lower cost, 

higher sulfur fuels and still meet the environmental requirements. 

In addition to the wFGD systems, SCRs were also installed as part of the Clean Air Act of 1990 

and the CAIR requirements. With the conversion back to the higher sulfur fuels, the sulfur 

dioxide (SO2) to sulfur trioxide (SO3) conversion rate of the catalyst can become critical. The 

3 
 

SO3, a particle size less than 2 microns (acid mist), is not captured in a wFGD system. With an 

emission rate of greater than 8 ppm, a visible “blue” plume from the stack is produced. Efficient 

operation of the SCR and more particular, the optimized SCR catalyst management becomes 

more critical. 

Midwestern Fuel 

Many of the units that are installing wFGD systems will be converting from a lower sulfur 

compliance coal to a Midwestern higher sulfur fuel (Illinois or western Kentucky fuel). The 

Midwestern fuels tend to have much higher levels of arsenic and sulfur. Many of the units are 

firing a blend consisting of Western PRB fuels with lower sulfur Eastern fuels to meet the 

environmental mandates. The higher levels of arsenic in the eastern fuels are partially mitigated 

by the higher levels of calcium in the PRB fuels. This has the benefit of extending the life of the 

SCR catalyst. 

In 2010, the emissions levels of CAIR affected plants will have to be further reduced which will 

require the installation of wFGD systems on the larger size units. 

Fuel Influences 

Catalyst performance and flue gas effects on the SCR catalyst are influenced by a variety of 

constituents in the fuel and their level of content within the fuel. The primary constituents that 

have a significant impact are: arsenic, calcium, iron, nitrogen, potassium, sulfur, and sodium. 

The catalyst is comprised mainly of titanium oxide, molybdenum (plate type catalyst) or tungsten 

(honeycomb type catalyst), and vanadium pentoxide (V2O5). The vanadium pentoxide (V2O5) 

will release oxygen to the ammonia converting the nitrous oxide to nitrogen and water. 

NOX + NH3 + O2 → N2 + H2O 

There are two different ways the effectiveness of oxygen release of the SCR catalyst can be 

minimized. The first is called catalyst poisoning; a substance attaches or combines with the 

vanadium pentoxide (V2O5) to form another compound which eliminates the potential for the 

release of the oxygen. The second is blinding or the plugging of the pores of the catalyst which 

prevents the ammonia from reacting with the vanadium pentoxide (V2O5). Poisoning or blinding 

both serve the same function of reducing the potential or “life” of the catalyst. 

The common constituents in the fuel that cause poising are arsenic and phosphate. These 

constituents will combine with the vanadium to tie up the oxygen to prevent the oxygen release 

for the NOX or other constituents. 

The blinding constituents consist of calcium, sodium, and potassium and in essence plug the 

pores of the catalyst to prevent ammonia / nitrous oxide from coming into contact with the 

vanadium pentoxide (V2O5) catalyst material. 

The sulfur in the fuel converts primarily to sulfur dioxide with a small amount to other species 

including sulfur trioxide (SO3). Typically, the amount of SO3 is approximately 0% - 0.2% of the 

total SOX from the combustion process. 

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The SO3 combining with water will form sulfuric acid, hence acid gas. With an SO3 content 

above 10 to 20 ppm a “blue plumb” will be noticed from the stack. The blue plumb is dependent 

upon the stack diameter, and ambient air conditions. 

As an example, a Midwestern medium sulfur fuel would be about 2000 ppm of SO2. This would 

equate to about 0 - 4 ppm of SO3 emitted which would not cause a blue plumb. 

SCR Design 

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Figure 1: SCR Arrangement 

The most common SCR designs that were 

deployed in the United States over the 

 last ten (10) years are area a 3 or 4 layer design 

(see Figure 1). It was customary to install catalyst 

with one layer of the reactor spare. As there 

is a decay in the potential of the catalyst 

(ability to convert the nitrous oxide), the 

additional layer is installed. With this 

additional layer, the SO3 will likewise 

increase. 

Referring to the ‘blue plume” SO3 example 

without an SCR, the SO3 was approx. 4 ppm. 

With the addition of a 2 x 1 SCR arrangement 

with a 0.5% conversion rate catalyst, each layer 

will contribute an additional 10 ppm of SO3. 

The two layer arrangement will increase the 

SO3 from 4 ppm to roughly 24 ppm. Thus, adding 

another layer of catalyst would require additional reagent to mitigate the “blue plume” stack 

effect which in turn would require some type of SO3 mitigation system to eliminate the visible 

plume. 

Catalyst Layer

Catalyst Layer

Spare Catalyst 

2 (installed) X 1 (spare) Arrangement 

Gas Flow 

What we have seen is that customers are looking at a strategy to minimize the layers installed in 

the SCR to minimize the SO3 emissions or the size of the SO3 mitigation system. In addition, 

they are looking for ways to reduce the SO2 to SO3 conversion rate of the catalyst or purchasing 

lower conversion rate catalyst. 

NOX / SO3 Catalyst Reaction 

Understanding how the various reactions occur provides thoughts and concepts for minimizing 

the SO3 conversion rate. 

The catalyst is produced by the original catalyst manufacturer (OCM) by mixing a somewhat 

homogeneous compound of ceramic, the titanium dioxide, vanadium and either molybdenum 

and/or tungsten. The ceramic material is either pressed onto a substrate layer of stainless steel 

mesh (plate type catalyst), extruded (honeycomb type catalyst) or manufactured similar to 

cardboard (corrugated type catalyst). 
 

The catalyst surface is constructed with a series of pores to provide a greater surface area. This 

minimizes the total volume of the catalyst required in the reactor to meet the removal 

requirements. 

0.15 to 0.20 mm 

6 

Flue 

gas 

flow 

The SO2 to SO3 conversion rate is dependent upon a number of variables including available 

surface area in the catalyst pores, reactor temperature, and catalyst wall thickness. The NOX

reaction has precedence over the SO2 to SO3

conversion and will react with the oxygen released 

from the vanadium pentoxide (V2O5) more readily. 

Both the SO2 to SO3 conversion as well as the NOX

reaction occur at greater temperatures. However, 

these two reactions are directly opposite one 

another for the SCR requirements. NOx 

conversion 

zone 

SO2

conversion 

zone 

In Figure 2, the NOX / Ammonia (NH3) / vanadium 

pentoxide (V2O5) reaction occurs near the outer 

surface within ~0.150 to 0.200 mm; below 

0.200 mm, the SO3 reaction occurs due to the 

slower reaction time. 

Figure 2: Conversion Zones 

To reduce the depth of the pores, OCM’s have decreased the wall thickness of the catalyst from 

original wall thickness of 0.8 to 1.2mm down to 0.6 or less. This has reduced the conversion rate 

of the catalyst. Early catalyst had a SO2 to SO3 conversion rate of between 0.5 to 1%. Today, 

these have been reduced to 0.2 to 0.3%. There are a lot of variables that effect this rate. 

Mercury Oxidation of catalyst 

Mercury (Hg) is primarily in the elemental metallic phase (Hgo) as it is introduced into the 

boiler. As the flue gas travels through the process, the elemental mercury transitions into 

oxidized mercury (Hg2+), the bulk of this taking place in the SCR. In its elemental form, 

mercury (Hgo

) is not easily captured and can be released into the environment as a hazardous 

substance. 

In the SCR, the mercury oxidizes in the vapor phase in the presence of chlorine, yielding a 

higher potential for mercury oxidation. The oxidized mercury (typically in the form of mercuric 

chloride- HgCl2 from the reaction with chlorine inherent in the fuel) is water soluble and can be 

removed in the FGD. This phenomenon shows a proportional relationship between mercury 

oxidation and chlorine content. 

In the reaction process, ammonia (NH3) adsorption takes precedence over site chlorination, 

therefore the NOX reaction is highly favored over the oxidation of mercury. 

Several factors can influence mercury oxidation in the SCR. These can include coal type, 

halogen content in the coal, SCR temperature, catalyst age and type, and space velocity. 
 

In addition, ammonia adsorption minimizes the coverage of chlorinated sites, thus NOx 

reduction inhibits Hg oxidation, with both reactions taking place on the surface. In several 

experiments conducted, it has been observed that at DeNOx rates up to 90%, mercury oxidation 

greatly occurs. However, beyond 90% DeNOx, oxidation is greatly reduced. Adversely, 

chlorine content has no effect on DeNOx performance. In ranges from 0-50 ppm, chlorine 

appears to have the greatest affect on mercury oxidation. Higher temperature ranges enhanced 

DeNOx potential and reduced mercury oxidation potential while lower temperatures enhance 

mercury oxidation and lowered DeNOx activity. 

In addition to mercury oxidation, SCR catalysts also oxidize sulfur dioxide (SO2) to sulfur 

trioxide (SO3), the precursor to sulfuric acid (H2SO4). The correlation between mercury 

oxidation and SO2/ SO3 conversion is close and the reaction mechanisms are as follows: 

 2Hg + 4HCl + O2 Æ 2HgCl2 + 2H2O 

 2SO2 + O2 Æ 2SO3

The reaction of mercury with the HCl and oxygen is considered to be a diffusion-controlled 

reaction that takes place in the gas phase. The rate of reaction of mercury oxidation is faster than 

the diffusion velocity of the mercury through the SCR catalyst due to its molecular weight 

whereas the reaction rate of SO2 to SO3 conversion is slower than the diffusion velocity of SO2

through the catalyst. By altering the catalyst based upon the reaction mechanism, allowing the 

more active sites to oxidize mercury instead of convert SO2 to SO3, higher oxidation rates 

(>90%) can be achieved while maintaining low conversion rates (< 0.5%). 

Catalyst Regeneration 

Catalyst rejuvenation / regeneration process has evolved over the last ten (10) years. Evonik was 

one of the initial organizations involved in the development and commercialization of catalyst 

rejuvenation / regeneration. The initial years of catalyst rejuvenation / regeneration were focused 

on the removal of the catalyst poisons and blinding materials from the catalyst and the 

impregnation of vanadium trioxide (V2O3) onto the catalyst. 

From 2000 forward, the focus has been on process improvements to increase the longevity of the 

catalyst and a more thorough understanding of the various reactions to improve the performance 

of the catalyst. This was required by Evonik to satisfy the demands of Evonik’s operating fleet 

of coal fired units which have over 10,000 m3 of catalyst. 

As stated earlier, the OCM used a “homogeneous” material combining all the materials into the 

catalyst ceramic material including the vanadium. The materials are either applied to the metal 

substrate and pressed onto the metal substrate (“plate type catalyst”), extruded (“honeycomb type 

catalyst”), or similar to cardboard manufacture (“corrugated type catalyst”). 

Evonik’s regeneration process utilizes a combination of Evonik held patents, patent pending and 

licensed technology to rejuvenate and regenerate (impregnation of both vanadium and 

molybdenum / tungsten) in a single dip process. The vanadium metal is soluble in an acidic (low 

pH) solution whereas the molybdenum and tungsten are soluble in a basic (high pH) solution. 

7 
 

The original – single dip process for impregnation of the vanadium is to dip the catalyst into a 

solution and then dry the catalyst. 

Utilizing a double dip process has a major disadvantage when working with different pH 

solutions. The second dip will have the tendency to remove or extract materials from the initial 

dip, since these materials will want to draw the metals impregnated in the first dip back into the 

solution. The effectiveness of the material impregnated in the significantly diminished. 

In addition to the development activities of Evonik on a single dip process, Evonik has expended 

significant R&D into the selective impregnation of the various metals (vanadium, molybdenum 

and/or tungsten) where they provide the optimum performance in the catalyst. The Evonik 

patent pending process impregnates the vanadium on the surface of the catalyst and to a 

controlled shallow depth into the catalyst. The molybdenum and/or the tungsten are impregnated 

into the deeper areas of the pores. (See ) Figure 2

The combination of these two Evonik developments provide the advantage of a reduction of the 

SO2 to SO3 conversion rate from 30% to 50% of the original conversion rate of the catalyst while 

maintaining the same catalyst activity (KO). 

Catalyst Longevity 

The catalyst longevity is another consideration for the regeneration process. 

The impregnation of the molybdenum / tungsten into the deep pore areas of the 

catalyst material is very critical to maintain the structural integrity of the 

catalyst. 

There are two types of tests for the structural 

integrity of the catalyst; compressive and 

bonding (refer to Figure 3). The 

compressive test is the amount of force 

applied in the direction of flow. 

The bonding test is in 90 degrees to the 

direction of flow. 

Figure 3: Catalyst Strength Test 

There is a separate test for plate type catalyst there is a “drop” test to determine the amount of 

ceramic material that dislodges from the catalyst metal substrate. 

Catalytic material can not only be damaged during the regeneration phase but during removal 

from the SCR and re-installation, as well as during the transportation from the power plant to the 

regeneration facility and back. The transportation methodology for “honeycomb” is to transport 

them in a 90 degree angle to the regular flow direction. Plate and corrugated type catalysts are 

transported in flow direction. Honeycomb plate will have the greatest stress in the transport at 

the center of the module as shown in Figure 4. Any type of damage to the honeycomb logs will 

not be immediately visible, because the bouncing of the “plate” type modules during transport 

8 
 

will force the catalyst material to dislodge from the substructure. The evidence is clearly visible 

by the small diamonds of catalyst material on the truck bed. 

Moisture has a detrimental effect on the catalyst strength. This includes both the surface 

moisture as well as the inherent or crystalline moisture. During the regeneration process, the 

strength is reduced by some 50% due to the moisture in the catalyst. 

Width of Truck

Gas Flow Gas Flow

Plate / Corrugated Catalyst

Height of 

catalyst

Most Stressed area

logs

Gas Flow Gas Flow

Width of Truck

Honeycomb Catalyst

Height of catalyst

Figure 4: Catalyst Transportation 

Re-calcination 

Evonik introduced re-calcination to the regeneration market to help improve the longevity of the 

catalyst and to provide a product which exceeds the original performance of the catalyst. This 

includes the complete activity replenishment; regain the greatest amount of strength back into the 

catalyst by removing the water and replenishing the strength materials that are lost during 

regeneration process. Even the catalyst manufacturer uses calcination in order to (1) strengthen 

the catalyst by curing/drying the ceramic material by removing both the surface and inherent 

moisture, (2) bond the strength metals of the catalyst (tungsten / molybdenum) into the catalyst 

material and (3) reestablish the full activity of the catalyst. It should be noted that the inherent / 

crystalline water can only be removed at temperatures exceeding 760 o

F. Also, the vanadium 

trioxide (V2O3) material needs to be heated above 400 o

F to transform the vanadium to a 

vanadium pentoxide material (V2O5). 

Similar to calcination of the original catalyst, re-calcination was introduced in the regeneration 

process by Evonik to perform similar functions as the OCM’s. Our research has shown that after 

regeneration without re-calcination 20 to 50% of the bonding strength is lost. The loss is caused 

by the reduction of molybdenum and / or tungsten lost in the rejuvenation of the catalyst. Figure 

5 shows an actual example of a catalyst that was regenerated without the replenishment of the 

strength metals. Results after the regeneration showed a loss of 27% of the tungsten material 

(9% down to 6.5%). There was about an 8% loss in the compressive strength and a 45% loss in 

the bonding strength. This is honeycomb type of catalyst and the catalyst is not likely to stand 

another regeneration or transportation cycle. 

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Figure 5: Mechanical Strength Loss 

Furthermore, a second set of tests were performed after the 2nd outage season. This test further 

showed that there was not an increase in strength after operating cycles. 

Re-calcination and proper metal impregnation has demonstrated that over 95% of the strength is 

regained in both directions. 

Evonik just finished the 4th regeneration of a layer at Evonik’s Bexbach station. This layer had 

over 100,000 hours of operation prior to this regeneration validating that proper regeneration can 

provide significant longevity to catalyst. The fourth regeneration was completed and the catalyst 

was re-installed back into the unit. 

The economics of catalyst regeneration are shown in Figure 6. The assumptions are an 18 month 

outage cycle with a layer replaced during each cycle. The savings are 46% over a new purchase 

scenario. 

NPV Estimated Cost

New Catalyst Life Cycle Cost $37.6 M $57.2 M

Regenerated Life Cycle Cost $18.2 M $30.5 M

NPV Benefit $19.4 M $26.7 M

Figure 6: Regeneration Benefit 

Conclusions 

Catalyst regeneration is a viable process and has been in commercial operation for ten (10) years 

and is continually improving to provide a product that is the same as a new product with 

improved SO2 to SO3 conversion rate. 

10 
 

It is expected that an SCR will provide a co-benefit by reducing NOx and oxidizing mercury 

while minimizing the SO2 to SO3 conversion. With faster rates of reaction, simultaneous NOx 

reduction and mercury oxidation can occur, provided there is the presence of ammonia. This 

would tend to equate that the mercury oxidation would occur in the lower elevations of the 

reactor and the NOX removal in the upper layers. The reactions for both of these constituents 

will occur on the outer wall or just in the pores of the catalyst. 

The SO2 to SO3 conversion occurs in the deeper part of the pores of the catalyst. By minimizing 

the amount of vanadium pentoxide V2O5 at these locations, Evonik has observed that this 

reaction can be inhibited through actually operating and testing experience. Mercury oxidation 

within the SCR continues to be studied to quantify the amount of oxidation and identify the exact 

location where this oxidation occurs. There is a significant amount of R&D and testing being 

conducted by companies like Southern Company and Evonik as well as the OCM’s. 

SUMMARY 

With annual operation of SCR beginning in 2009 in most of the mid western states and wFGD in 

2010, mercury mandates from the various states, and a pending final decision on the outcome of 

the CAIR and CAMR rulings, the SCR will become a more critical device for multi-emission 

control. 

To minimize the annual operating cost of the SCR with the year round operation, minimizing the 

catalyst replacement cost will be of a major concern. Regeneration has proven itself as a viable 

technology and significant cost reduction mechanism. Many utilities are analyzing their fleet 

SCR requirements including regeneration within their catalyst management strategy. 

REFERENCES 

1. Senior, Constance; Oxidation of Mercury Across Selective Catalytic Reduction Catalysts 

in Coal-Fired Plants; J. Air & Waste Management Association, Vol. 56, p. 23-31 

2. Niksa, Stephen; Fujiwara, Naoki; A Predictive Mechanism for Mercury Oxidation on 

Selective Catalytic Reduction Catalysts under Coal Derived Flue Gas; J. Air & Waste 

Management Association, Vol. 55, p. 1866-1875 

3. Kai, Keiichiro; Kikkawa, Hirofumi; Kato, Yasuyoshi; Nagai, Yoshinori; Gretta, William; 

SCR Catalyst with High Mercury Oxidation and Low SO2 to SO3 Conversion; Combined 

Power Plant Air Pollutant Control Mega Symposium, Baltimore. MD., August 28-31, 

2006 

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4. Niksa, Stephen; Fujiwara, Naoki; Predicting Complete Mercury Speciation Along Coal 

Fired Utility Exhaust Systems; Combined Power Plant Air Pollutant Control Mega 

Symposium, Washington, D.C., August 30-September 2, 2004 

5. Niksa, Stephen; Fujiwara, Naoki; Predicting Mercury Speciation In Coal- Derived Flue 

Gases; Combined Power Plant Air Pollutant Control Mega Symposium, Washington, 

D.C., May 19-22, 2003 

6. Gale, Thomas; Blankenship, George; Hinton, W. Scott; Cannon, Jared; Lani, Bruce; Hg 

Oxidation compared for Three Different Commercial SCR Catalysts; Combined Power 

Plant Air Pollutant Control Mega Symposium, Baltimore. MD., August 28-31, 2006 

7. Laudal, Dennis; Thompson, Jeffery; Pavlish, John; Brickett, Lynn; Chu, Paul; Srivastava, 

Ravi; Lee, C.W.; Kilgroe, James; Evaluation of Mercury Speciation at Power plants 

Using SCR and SNCR NOx Control Technologies