The Uses and Challenges of Zeolites in Automotive Applications

Modén, Björn; Donohue, James M.; Cormier, W.E.; Li, Hongxin

doi:10.1007/s11244-010-9595-4

Cited by 34 publications

(35 citation statements)

References 51 publications

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“…As it has been previously reported [27], there is a significant effect of copper loading on the reducibility of the different copper species. From our data, it can be confirmed that an increase of the copper loading shifts the reduction peaks to lower temperature [15], due to the formation of dimeric copper species as the copper loading increases [28].…”

Section: Catalyst Characterizationsupporting

confidence: 66%

Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

et al. 2015

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The viability of hybrid systems conformed by a combination of Pt-Ba/Al 2 O 3 NSR and Cu-ZSM-5 SCR catalysts is studied with both catalysts over monolithic structures in order to maximize the removal of NO x from lean-burn engines exhaust gases. To optimize performance of these coupled NSR-SCR systems, the NSR catalyst has to work under operational conditions completely different from those optimal when the NSR-only catalyst works, as in the coupled system the intermediate production of ammonia needs to be apparently increased, and then adsorbed in the SCR catalyst (Cu-ZSM-5) which is placed downstream in order to complete elimination of remaining NO x (NO?NO 2 ) selectively to N 2 with minimal amounts of other nitrogen derivates, i.e. N 2 O and NH 3 . The suitable control of operational conditions, specifically H 2 concentration and duration of the rich period, allows establishing the optimal working conditions of the NSR-SCR double system in the practical application, which resulted in temperature around 200°C and H 2 concentration in excess (3-4 %).

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Section: Catalyst Characterizationsupporting

confidence: 66%

Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

et al. 2015

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“…In particular, controlling NO x emission from a diesel-engine automobile, which is expected to show high combustion efficiency toward CO 2 reduction, 1 is critical because of stringent regulations like EURO 6 and US 10. 2 As a result of the lean-burning conditions in diesel engines, it is difficult to remove NO x using the conventional three-way catalyst installed on gasoline engines. A selective catalytic reduction (SCR) system using urea, which is served as a source of ammonia (NH 3 ) as a reductant, has been widely applied to remove NO x under oxidizing conditions.…”

mentioning

confidence: 99%

Two-step Catalytic System Using Pulsatile Heating to Achieve NO Decomposition in the Presence of Water Vapor

Harada¹,

Ohnishi²,

Ogura³

2016

Chem. Lett.

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Direct decomposition of nitric oxide (NO) into nitrogen and oxygen was catalyzed on a copper-loaded zeolite catalyst with high conversion (>80%) by a newly proposed microwave pulsatile heating system, even in the presence of water vapor, while no reaction took place in a conventional reactor using an electric furnace under the same reaction conditions. Removal of nitrogen oxides (NO x ) from combustion exhaust is an important problem that needs to be addressed for protecting humans and the environment. In particular, controlling NO x emission from a diesel-engine automobile, which is expected to show high combustion efficiency toward CO 2 reduction, 1 is critical because of stringent regulations like EURO 6 and US 10.2 As a result of the lean-burning conditions in diesel engines, it is difficult to remove NO x using the conventional three-way catalyst installed on gasoline engines. A selective catalytic reduction (SCR) system using urea, which is served as a source of ammonia (NH 3 ) as a reductant, has been widely applied to remove NO x under oxidizing conditions. Although NH 3 can selectively reduce NO x in a wider temperature window, even in the presence of excess oxygen, this system is too large to install on-board the light vehicles currently preferred in Japan. 3 In addition, thanks to the improvement in the thermal efficiency of engines, the exhaust temperature becomes lower than 200°C during an urban drive, 4 making the chemical reactions for removal of NO x quite complicated and difficult to achieve.As an inherently ideal method, catalytic decomposition of nitrogen monoxide (NO) into N 2 and O 2 has been researched. However, it has not been commercialized so far, mainly because of the activity and stability of the catalysts tested for the reaction. Among these, copper-loaded zeolites, which were first reported by Iwamoto et al., 5 show high catalytic activity for the decomposition of NO into N 2 and O 2 . Out of a large number of Cu-zeolites, Cu-ZSM-5 (Cu-MFI) showed the highest catalytic performance. There are numerous reports on Cu-zeolites involving the active Cu species, a suitable zeolite topology, and the reaction mechanism, 69 including a remarkable review published by Iwamoto et al. 10 The major problems of decomposition using Cu-zeolites are high reaction temperatures (>400°C), low hydrothermal stability of the catalyst, and very low efficiency of NO removal in the presence of water vapor. If NO decomposition is applied to a commercial use, the after-treatment step for NO x and a total system for purification would possibly become smaller and lighter than the current catalyst technology.To overcome the two major problems raised above for NO decomposition, we have proposed a two-step reaction system using Cu-or Fe-zeolite catalysts.3 At a lower temperature, NO is adsorbed in the cavity of the metal-loaded zeolite; the adsorbed NO is then decomposed at a higher temperature. In this communication, we report a prototype reaction system that enables us to realize the two-step, repeatable decompositi...

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“…This is particularly challenging for copper exchanged zeolites that typically loose more catalytic NH 3 -SCR activity than their iron equivalents under hydrothermal conditions. [68]. As shown in Chapter 2 and recently reported by Fickel et al small-pore zeolites show superior hydrothermal stability compared to other zeolites.…”

Section: Introductionmentioning

confidence: 69%

“…For the abatement of NO x using copper zeolites, by far most literature data is available for Cu-MFI, Cu-BEA, Cu-FAU, Cu-MOR and Cu-FER. [16][17][18][19][20][21][22][23][24][25][26][27] Over the years less common topologies, which are not commercially available, have also been studied as potential candidates for the SCR reaction, [28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

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Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

Vennestrøm¹

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The Uses and Challenges of Zeolites in Automotive Applications

Cited by 34 publications

References 51 publications

Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

Two-step Catalytic System Using Pulsatile Heating to Achieve NO Decomposition in the Presence of Water Vapor

Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

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