The Design of Flow-Through Diesel Oxidation Catalysts

Wyatt, Mark F.; Manning, Wendy; Roth, Stan; D'Aniello, M. J.; Andersson, Emil; Fredholm, S.

doi:10.4271/930130

Cited by 32 publications

(6 citation statements)

References 17 publications

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“…It is known that the functions of some exhaust gas catalysts, such as NO x storage and reduction (NSR) catalysts and diesel oxidation catalysts (DOC), are affected by SO 2 formed from sulfur in fuel during engine combustion processes. , The introduction of low-sulfur fuels (<10 ppm) in Europe helped to mitigate this problem, but for a concentration of 10 ppm sulfur in fuel, about 0.5 vppm SO 2 still have to be expected in the exhaust gas, which is high enough to cause long-term deactivation of sensitive catalysts. , …”

Section: Introductionmentioning

confidence: 99%

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts

Kröcher¹,

Widmer²,

Elsener³

et al. 2009

Ind. Eng. Chem. Res.

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The deactivation of NO oxidation by SO 2 was studied with the use of commercial diesel oxidation catalysts (DOC) and Pt/Al 2 O 3 as reference material, coated on cordierite monolith. Despite their slightly different elemental compositions, the NO conversion rates of the fresh commercial catalysts were very similar. The maximum NO conversion was 38% at 350 °C, and above this temperature conversion started to be limited by the thermodynamics of the reaction. The rates of NO conversion strongly decreased with the start of SO 2 dosing. For analysis of SO 2 conversion and uptake, SO 2 and SO 3 /H 2 SO 4 were determined separately in the gas phase by absorption and titration. Under typical exhaust gas conditions (1 ppm SO 2 , 250 °C), the catalysts functioned as sulfur traps and stored a large part of the emitted SO 2 . The SO x storage was divided into two phases: a fast saturation of the catalyst surface with sulfuric acid, which hampered NO conversion, and a slow, long-lasting sulfation of the washcoat. The storage capacities of the oxidation catalysts reached their maxima at 250 °C due to the temperature dependency of sulfur adsorption and desorption. Adsorbed sulfuric acid desorbed between 350 and 400 °C, whereas more stable compounds, such as aluminum sulfate, were decomposed at higher temperatures. Deactivated catalysts could be completely regenerated within a few minutes at temperatures above 350 °C. However, repeated or lengthier thermal treatments resulted in a reduced sulfur storage capacity and irreversible activity losses for NO oxidation due to a reduction of the active surface by sintering.

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Section: Introductionmentioning

confidence: 99%

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts

Kröcher¹,

Widmer²,

Elsener³

et al. 2009

Ind. Eng. Chem. Res.

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“…In one catalyst it was found that the addition of VzO5 suppressed the activity of the Pt for the 'SOz conversion reaction without diminishing the rate of SOF oxidation reaction [3][4][5]. It has also been shown that Rh additions to a Pt catalyst will suppress sulfate formation [6].…”

Section: So2+o2mentioning

confidence: 99%

New applications of monolithic supported catalysts

Farrauto¹

1997

React Kinet Catal Lett

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Monolithic materials have been widely used for over 20 years as catalyst supports in the abatement of emissions fTom mobile and stationary sources. They have been most successfully used for applications where high volmnetric flow rates and potential for thermal shock are required. Their use is expected to further increase as new applications are found. o This paper describes three new catalytic technologies which require a monolithic support; 1) the diesel oxidation catalyst commercialized in 1994 and 2) NOn abatement with hydrocarbons in lean environments and 3) catalytically supported thermal combustion both of which are currently under development.

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“…There have been several studies on the use of diesel oxidation catalysts for the control of the exhaust emissions. These studies have generally focused on the use of platinum group oxidation catalysts for control of HC, CO, and SOF (Wyatt et al 1993).…”

Section: Diesel Oxidation Catalystsmentioning

confidence: 99%

“…29 shows the comparisons of the CO emissions with the aging hours and the fuel sulfur. All CO emissions were reduced from the full flow engine-out to DOC-out evaluations.…”

mentioning

confidence: 99%

Influence of fuel sulfur content on emissions from diesel engines equipped with oxidation catalysts

Evans¹

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Diesel oxidation catalysts (DOCs) are a viable exhaust aftertreatment alternative for alleviating regulated exhaust emissions of hydrocarbon (HC), carbon monoxide (CO), and particulate matter (PM) from diesel-fueled heavy-duty engines. This study was a part of the Diesel Emissions Control-Sulfur Effects (DECSE) program that was aimed at determining the impact of diesel fuel sulfur levels on diesel oxidation catalysts that were designed to lower brake-specific PM, HC, and CO emissions from on-highway trucks and buses in the 2002-2004 model years. The research focused on high-temperature DOCs installed on a Cummins ISM370 ESP engine, and low-temperature DOCs installed on a Navistar T444E engine to determine how the DOCs affect the various emissions, how fuel sulfur affects emissions, and how fuel sulfur poisons the catalysts over time. The DOCs were found to affect the brake-specific PM, HC, and CO emissions. The PM emissions were not significantly affected by the DOCs when lower sulfur fuels (3 ppm and 30 ppm) were used. Brake-specific PM emissions were dramatically increased with the higher sulfur fuel (350 ppm) due to the formation of sulfates and the associated sulfate bound water. Hence, fuel sulfur affected the brake-specific PM, HC, and CO emissions from DOC equipped heavy-duty diesel engines. Brake-specific HC emissions were eliminated by nearly 100% by the use of the DOCs. The DOCs had various reduction efficiencies ranging from 90% to 100% for CO emissions from the Navistar engine and 24% to 79% for the Cummins engine. The DOCs were only evaluated for only 250 aging hours, which is a relatively short duration. Over this short amount of time, there was no significant evidence of the fuel sulfur poisoning the diesel oxidation catalysts. iii ACKNOWLEGDEMENTS After six years of college education, a part of my life has finally ended. However, there is another part about to begin. Through the past two years of graduate school I have encountered some rough times, but it seemed that the better always won. As I look back on these past two years, I know I could not have accomplished everything on my own. I would like to take this time to express my thanks to the ones that helped see me through this challenging and rewarding time. The first and foremost who needs to be recognized is God. I would never be here if were not for Him. Even though He is unseen, I know His presence is always with me. He needs to be recognized due to the fact that too often He does go unacknowledged. Now to my parents, where I believe there is not enough time and words to show my appreciation and gratitude. Mom and Dad, without your love, encouragement, understanding, and support, I know none of this could have been possible. You have been there for me all the way, and I know you will always be there for me in the future. I can't express how much I love the two of you for this. You need to be recognized for one huge accomplishment, financially supporting three boys through engineering school. Dad, I know it was a lot of hard work for you, a...

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The Design of Flow-Through Diesel Oxidation Catalysts

Cited by 32 publications

References 17 publications

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts

New applications of monolithic supported catalysts

Influence of fuel sulfur content on emissions from diesel engines equipped with oxidation catalysts

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The Design of Flow-Through Diesel Oxidation Catalysts

Cited by 32 publications

References 17 publications

Adsorption and Desorption of SOxon Diesel Oxidation Catalysts

Adsorption and Desorption of SOxon Diesel Oxidation Catalysts

New applications of monolithic supported catalysts

Influence of fuel sulfur content on emissions from diesel engines equipped with oxidation catalysts

Contact Info

Product

Resources

About

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts

Adsorption and Desorption of SO_xon Diesel Oxidation Catalysts