Enhancement of decane-SCR-NO over Ag/alumina by hydrogen. Reaction kinetics and in situ FTIR and UV–vis study

Sazama, Petr; Čapek, Libor; Drobná, Helena; Sobalı́k, Zdenĕk; Dědeček, Jiřı́; Arve, Kalle; Wichterlová, Blanka

doi:10.1016/j.jcat.2005.03.013

Cited by 196 publications

(205 citation statements)

References 27 publications

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“…loading was between 5 and 7 wt % in contrast to literature, 2,8,15,17,20,21,33,34,42,43 where 2 wt % is typically reported as the standard catalyst. It is believed that these high loadings of silver can be obtained by using boehmite as the precursor for γ-alumina, as this ensures a high surface area for the final catalyst (see Table 1) and has been reported 35 to maintain a strong interaction between silver and alumina, preventing silver from sintering during calcination.…”

Section: Resultsmentioning

confidence: 83%

“…This finding is in agreement with previous findings that the presence of NO strongly influences the activation of the hydrocarbon. 8,13,15 The hydrogen effect will be discussed in more detail based on the combined in situ EXAFS and DRIFTS measurements.…”

Section: Resultsmentioning

confidence: 99%

“…8,13,17,18 Formates were observed to form immediately after switching to the reaction mixture at 100°C from bands at 1590 (ν as (OCO)), 1390 (δ(CH)), and 1376 (ν s (OCO)) cm -1 . These bands were observed up to approximately 250°C.…”

Section: Resultsmentioning

confidence: 99%

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New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

et al. 2010

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The performance of silver alumina catalysts and silver aluminate was studied in the selective catalytic reduction (SCR) of NO by propene. The use of boehmite during the impregnation step ensured a strong interaction between the silver species and the alumina surface in the final calcined catalyst. Thus, higher silver loadings (5-7 wt % silver) could be used without significant loss in selectivity to N 2 during SCR. The nature of the silver species and the formation of adsorbed surface species during SCR and hydrogen-assisted SCR (H 2 -SCR) was studied by activity measurements and by combined in situ IR and X-absorption spectroscopic measurements. The combination of these techniques in the same reaction cell allowed simultaneous monitoring of the state of silver and the formation of surface species under realistic reaction conditions. The active silver species on alumina support were concluded to be 2-dimensional oxidic Ag n δ+ species. Silver aluminate was ruled out as a possibility for an active phase for the SCR reaction. The oxidic Ag n δ+ species were present under both SCR and H 2 -SCR reaction conditions and even on a prereduced catalyst under the SCR reaction conditions. Hydrogen is proposed to enhance the formation of adsorbed surface species, especially nitrites, but not to change the nature of the active silver sites.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

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New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

et al. 2010

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“…13,159,160 In the presence SO 2 , the deteriorated Recently, it was found that the presence of H 2 significantly enhanced the low temperature activity of Ag-based catalysts for NO x reduction by hydrocarbons. 17,40,[209][210][211] Up to now, however, the interpretation of the H 2 promotional effect on HC-SCR has been under debate. To increase the rate of NO x conversion, basically, the hydrogen must accelerate the rate(s) of the slow step(s) in the reaction of HC-SCR, while the slow step(s) are likely to vary depending on the reaction temperature and feed conditions.…”

Section: Reactivity Of Intermediates Originating From Partial Oxidatimentioning

confidence: 99%

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

2014

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Selective catalytic reduction of NO x using NH 3 or hydrocarbons (NH 3 -SCR or HC-SCR) in oxygen-rich exhaust from diesel engines remains a major challenge in environmental catalysis. The development of highly efficient, stable and environmentally-benign catalysts for SCR processes is very important for practical use. In this feature article, the structure-activity relationship of vanadium-free catalysts in the NH 3 -SCR reaction is discussed in detail, including Fe-, Ce-based oxide catalysts and Fe-, Cu-based zeolite catalysts, which is beneficial for catalyst redesign and activity improvement. Based on our research, a comprehensive mechanism contributing to the performance of Ag/Al 2 O 3 in HC-SCR is provided, giving a clue to the design of a catalytic system with high efficiency.

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“…623 K using a series of lower alkanes (alkenes) as reductants. Using in situ FTIR spectroscopy, it was discovered that the formation of some intermediates, such as acetate, nitrite, nitrate species, and isocyanate (ANCO), was promoted by the addition of H 2 over Ag/ Al 2 O 3 surface in the SCR of NO x with several hydrocarbons [7][8][9][10]. However, the SCR of NO x by oxygenates in the presence of H 2 has not been reported.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen promotes the selective catalytic reduction of NO by ethanol over Ag/Al2O3

Zhang

2007

Catalysis Communications

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Enhancement of decane-SCR-NO over Ag/alumina by hydrogen. Reaction kinetics and in situ FTIR and UV–vis study

Cited by 196 publications

References 27 publications

New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Hydrogen promotes the selective catalytic reduction of NO by ethanol over Ag/Al2O3

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Enhancement of decane-SCR-NO over Ag/alumina by hydrogen. Reaction kinetics and in situ FTIR and UV–vis study

Cited by 196 publications

References 27 publications

New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

New Insights into the Active Surface Species of Silver Alumina Catalysts in the Selective Catalytic Reduction of NO

Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Hydrogen promotes the selective catalytic reduction of NO by ethanol over Ag/Al2O3

Contact Info

Product

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Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects