Hydrocarbon Poisoning of Cu-Zeolite SCR Catalysts

Luo, Jinyong; Yezerets, Aleksey; Henry, Cary; Hess, Howard; Kamasamudram, Krishna; Chen, Hai-Ying; Epling, William S.

doi:10.4271/2012-01-1096

Cited by 31 publications

(52 citation statements)

References 13 publications

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“…The recent discovery of small-pore transitional metalexchanged zeolite catalysts, which are commonly believed to be immune to the accumulation of long-chain HCs and consequently to poisoning by them, opened an avenue to minimize such catalyst deactivation [1,2,3,4]. However our results, discussed in this paper, indicated that measurable amounts of long-chain HC can store even on small-pore Cu-zeolite catalysts under certain conditions, having a limited detrimental impact on catalyst performance.…”

Section: Introductioncontrasting

confidence: 63%

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Hydrocarbon Storage on Small-Pore Cu-Zeolite SCR Catalyst

Kumar

Kamasamudram

Yezerets

2013

SAE Int. J. Engines

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In this study we investigated the interaction of short-and long-chain hydrocarbons (HCs), represented by propene (C 3 H 6 ) and n-dodecane (n-C 12 H 26 ), respectively, with a state-of-the-art small-pore Cu-Zeolite SCR catalyst. By varying HC adsorption conditions, we determined that physisorption was the primary mechanism for some minor HC storage at low temperatures (< 200°C), while chemical transformation was involved in more substantial HC storage at higher temperatures (200-400°C). The latter was evidenced by the oxygen-dependent and thermally-activated nature of the storage process, and further confirmed by the carbon-rich composition of the deposits.The nature of HC-derived deposits of different origins and amounts was further probed using the standard SCR reaction at kinetically challenging conditions (at 200°C), as well by ammonia adsorption/desorption experiments. The resulting observations indicate that the carbonaceous deposits originating from long-chain HCs accumulate solely on the outer surface of the zeolite crystallites, while short-chain HCs can access both the external surface and the pores.The stored HCs can be readily removed in the form of CO, CO 2 , and H 2 O by an oxygen-rich mixture at elevated temperatures or by using NO 2 as an oxidant at lower temperatures.

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Section: Introductioncontrasting

confidence: 63%

“…It is well known that zeolites can store hydrocarbons (HCs) [1,2,3,4]. Several exhaust gas conditions could potentially lead to the exposure of the SCR catalyst to HCs, for example relatively low exhaust temperatures during extended vehicle idling, cold start conditions, and even DPF regeneration events.…”

Section: Introductionmentioning

confidence: 99%

Hydrocarbon Storage on Small-Pore Cu-Zeolite SCR Catalyst

Kumar

Kamasamudram

Yezerets

2013

SAE Int. J. Engines

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“…Cuzeolites offer a higher activity compared to Fe-zeolites at low temperatures and a sub-optimal NO 2 /NO x ratio [11]. Unfortunately, these catalysts possess drawbacks such as a susceptibility towards hydrothermal conditions [12][13][14][15] besides hydrocarbon and chemical poisoning [16][17][18][19].…”

Section: Introductionmentioning

confidence: 97%

“…This feature can results in detrimental effects, such as when the light-off temperature is reached and the stored hydrocarbon is suddenly oxidized, it may lead to a rising temperature that may destroy the zeolite. Again, the small-pore zeolites hinder this deactivation mechanism due to their limited diffusion of hydrocarbons [16,17,21].…”

Section: Introductionmentioning

confidence: 99%

“…Since the dealumination product, an aluminum hydroxide moiety, (Al(OH) 3 ) has a larger diameter compared to that of the CHA structure, it is possible that the aluminum cannot escape from the pores or might be attached back to the framework maintaining the zeolite structures [20]. Another superiority of this class of catalysts is their durability towards hydrocarbon poisoning [16]. The large and medium pore zeolites adsorb significant amounts of hydrocarbons, particularly during cold-start conditions.…”

Section: Introductionmentioning

confidence: 99%

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