Durability Evaluation of Urea SCR Catalysts for Heavy Duty Diesel Engines
Kmt Kmhkarian, Eric Ligng, Joe Cibulka Chterpi 1 lar, inc.
2000 DEER C’cmference
slm Dliyp, CA
&~TERPILlAR’
OUTLINE
* Introduction
*Ruf ionuk
*Lab.Evaluation v5iperimenlul Desi,yn
*Engine Evaluation ‘E”Tper+nfd lik&gn
* ~ummary/Conclusions
Project Objective
+Aasess the potential long-term durability of various SCH catalyst formulations for mobile heavy duty diesel application.
* Identify and evaluate deactivation mechanism l I) Thermui u#~g
l 2) Poisoning (c: okingj
*Develop simple aging tests to “stress” the catalysts
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*Use tests to evajuate commercial SCR catalyst formulations l hpplier parrici]Jation
WTERPIUAR --
Thermal Deactivation Evaluation
*6 SCR catalyst formulations (A - F) -3 aging temperatures (470”, 520’, 4% 570” C) *S aging durations (fresh, 930, 1000 hours) -Samples aged in titmosphere tube furnace
+Reactor Bench Test Conditions: I Gas Conccn tratbn : ---. ..-...--.--.- 1 co, 8 ‘%
Wimulnted dicscl exhaust cc? SOU ppm
-4 temperstures cvnluatcd (250”, 32S, 400”, S20” C) so *Space velocity = 50,000 hr-’
*Chemiluminescence ,VOx analyzer, FTIR
MTERPILLAR”
r
Catalyst Aging Test -‘ -
To Exhaust
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NH
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CU Compwition
q= 10%
H,O= IO%
SO, - 30 ppm
NO * 200 ppm
NH, - 200 ppm
N3 = balance -... . . .
lj@cal AQ~Q Cond(~~p~~
Total flow * 5 litarlmin
Temperawe - 479,520,570 t
NOx Conversion Performance Thermal Aging = 470” C
GATERPILIAR
NOx Conversion Perft-wmance Thermal.Aging = 520” C
.* ma Nmln
Trmperrbm = 400 C Tampwdurw - 520 C . ..* * . . . . . . .
NOx Conversion Performance Thermal Aging = 570” C
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+Aging Conditions:
*6 SCR, catalyst formulations (A - F) * 14.6 titer HOD cngCnss (MY98) *Co king cycle *Exhaust splY through “3 pack” *3 aging durations (fresh, 500, 1000 hours)
-- --
Engine Aging (Coking Cycle) Evaluation
+Performance Testing Conditions: * 14.6. liter cngincs
*5 temperatures evaluated f-250*, 340”, 420’; 470”, 52s C) *Space:V&city = 15,000 - 35,000 hr-1 *MHJNOx = 0.8 (0.6 at 250” C) *Chemilum~incscenqe NOx analyzer, FTlR
tWTERPlUAR*
Engine Aging Test Setup
EnginIe Aging Results
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7-19
Summary + 6 SCR catalysts wcrc subjertcd to laboratory (furnace) and engine
tests for durations up to MM haurs.
4 Tests were used as a durability screwing tool to evaluate the
catalyst’s resistance to thermal and coking deactivation.
* Fresh NOx conversion prerformsnce differences wcrc noted in bench testing (at low and high temps) but not in engine &sting.
* The sampfcs exhibited significantly different thermal deactivation resistance.
r)zSamples A Br I3 showed superior durability.
* Through 1 DOD hours of aging, no clear trends were observed for coking desctivationldurability among the samples.
WIl’ERPIUAR*
Conclusions \
* ILkactivation tests arc an cffcctivc tool for evaluating the long-term durability of SCR catalyst formulaPions from suppliers.
*Thermal deactivation appears to be more of an issue than coking deactivation for SCR catalysts.
*More significant at higher aging temperatures ml500 hour aging data will be examined
*Perform physical analysis on tested samples to correlate material changes with performance results.
* Inves,tigate development of a more cffcct.ive coking test for future screening work.
