Selective catalytic reduction of nitrogen monoxide by methane on zeolite catalysts in an oxygen-rich atmosphere

Kikuchi, Eiichi; Yogo, Katsunori

doi:10.1016/0920-5861(94)80093-6

Cited by 216 publications

(80 citation statements)

References 6 publications

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“…Actually, the catalytic activity and selectivity are dependent on the priority of NO x to O 2 for the reaction with hydrocarbon. In the oxidizing atmosphere, CH 4 selectively reacts with NO x instead of being completely combusted with O 2 over H-ZSM-5 containing Co, Mn, Ga, In, and Pd catalysts [1][2][3][4][5][6][7][8][9][10]. NO 2 formation on the catalyst surfaces is thought to be a necessary step in the SCR, and the presence of O 2 is needed to form this active NO x species [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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On the selectively catalytic reduction of NOx with methane over Ag-ZSM-5 catalysts

Shi

Cheng

et al. 2002

Applied Catalysis B: Environmental

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Section: Introductionmentioning

confidence: 99%

“…Unlike the SCR of NO x with other hydrocarbons, only zeolites modified with limited metals, such as Co 2+ , Mn 2+ , Ni 2+ , Ga 3+ , In 3+ , and Pd 2+ are good catalysts for the SCR of NO with methane [1][2][3][4][5][6][7][8][9][10]. Whereas some other zeolite catalysts, e.g.…”

Section: Introductionmentioning

confidence: 99%

On the selectively catalytic reduction of NOx with methane over Ag-ZSM-5 catalysts

Shi

Cheng

et al. 2002

Applied Catalysis B: Environmental

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“…In another study, it was found that Ga-ZSM-5 and In-ZSM-5 catalysts were highly active and selective for NO reduction by CH 4 . It was shown that Ga-ZSM-5 was strongly inhibited by moisture, while In-ZSM-5 was fairly active even in the presence of 10% moisture [25]. In fact, most of the catalysts reported for this purpose so far are appreciably deactivated by moisture.…”

Section: Catalytic Conversion Of Pollutants In Automobile Emissions Umentioning

confidence: 94%

Gold, an alternative to platinum group metals in automobile catalytic converters

et al. 2011

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Catalytic convertors based on the use of platinum, palladium and rhodium play a major role in the cleaning of automobile emissions. Gold, when dispersed as nano-sized particles, has demonstrated significant activity in the conversion of toxic components, including carbon monoxide, unburnt hydrocarbons and nitrogen oxides, in engine emissions and some advantages over the platinum group metals. Some research outcomes on the application of nano-sized gold for the conversion of these components are reviewed. Several key issues in relation to its performance and applicability in catalytic convertors such as low-temperature activity and thermal stability and the possibilities of substituting platinum group metals for automobile emission control with gold are discussed.

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“…It has been reported that Ga 2 O 3 Al 2 O 3 catalyst systems show high NO x -SCR activity. 6 Ga ion-exchanged H-MFI is also a widely-known catalyst for NO x -SCR with methane, as reported by Kikuchi et al 7 and Inui et al 8 Ga species on H-MFI show high and selective activity for NO x -SCR, but Ga modification brings about low acidity of H-MFI support because of coverage of non-framework Ga ions on the strong acid sites. 9 The NO x -SCR reactivity is likely to relate to the formation rate of NO 2 , and thus the acidity of Gamodified H-MFI is important to oxidize NO to NO 2 .…”

mentioning

confidence: 86%

Gallosilicate-Based Catalysts for NOx-SCR with CH4

Nagashima¹,

Nakamura²,

Okada³

et al. 2009

Bulletin of the Chemical Society of Japan

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Ga-incorporated H-MFI (GaMFI) metallosilicate catalysts show robust activity for selective catalytic reduction of NO x (NO x -SCR) with CH 4 , although the reactivity of NO CH 4 is very low in the absence of O 2 . Over these catalysts, NO x CH 4 reaction proceeds selectively in the presence of O 2 . In contrast, FeMFI shows high activity for NO CH 4 reaction without O 2 , although no reactivity is shown in the presence of O 2 . In addition, transition-metal ion modification on FeMFI does not enhance NO x -SCR activity. From the results of XRD and XAFS characterization at Ga and Si K-edges, active Ga species are incorporated in H-MFI frameworks with T d symmetry. Local structure around Ga is very stable but distorted Si O 4 local structure can be formed after NO x -SCR reaction with CH 4 .Zeolites are well known as microporous materials, and have been applied widely to several engineering processes because of surface activity resulting from acidity. Zeolites are open framework aluminosilicates consisting of SiO 4 and AlO 4 , interconnected via oxygen atoms, and both Si and Al are present with T d symmetry in the framework. Distortion of T d sites (SiO 4 and AlO 4 ) is often brought about by application of several thermal processes or reactions. MFI zeolites are typical catalysts with unique activity for several useful reactions. In particular, Cu 2+ ion-exchanged H-MFI shows high deNO x activity with hydrocarbons. 1,2 For ion-exchanged zeolite catalysts, significant problems due to hydrothermal stability cannot be avoided in the case of modified MFI. On the other hand, metallosilicates are an appropriate material because active transition-metal ions are incorporated onto the framework. 3 For example, Fe 3+ -substituted MOR zeolites show high NO-SCR activity for methane. 4 But deactivation during the reaction is a major issue. We synthesized Fe-and Ga-MFI with various metal ratios by hydrothermal synthesis. Fe 3+ -and Ga 3+ -cosubstituted MFI (FeGaMFI) can be obtained. These materials show unique reactivity for NO x -SCR. 5 FeMFI with high Fe ratio shows high NO CH 4 reactivity, while no activity for NO x -SCR in the presence of O 2 . In contrast, GaO x is an appropriate component for NO x -SCR. It has been reported that Ga 2 O 3 Al 2 O 3 catalyst systems show high NO x -SCR activity. 6 Ga ion-exchanged H-MFI is also a widely-known catalyst for NO x -SCR with methane, as reported by Kikuchi et al. 7 and Inui et al. 8 Ga species on H-MFI show high and selective activity for NO x -SCR, but Ga modification brings about low acidity of H-MFI support because of coverage of non-framework Ga ions on the strong acid sites. 9 The NO x -SCR reactivity is likely to relate to the formation rate of NO 2 , and thus the acidity of Gamodified H-MFI is important to oxidize NO to NO 2 . In order to design useful and robust NO x -SCR catalysts, Ga-incorporated MFI metallosilicates (gallosilicates: GaMFI) are attractive because of stronger acidity than Ga ion-exchanged MFI. 9,10 Therefore, both the strong acidity and structural stabil...

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Selective catalytic reduction of nitrogen monoxide by methane on zeolite catalysts in an oxygen-rich atmosphere

Cited by 216 publications

References 6 publications

On the selectively catalytic reduction of NOx with methane over Ag-ZSM-5 catalysts

On the selectively catalytic reduction of NOx with methane over Ag-ZSM-5 catalysts

Gold, an alternative to platinum group metals in automobile catalytic converters

Gallosilicate-Based Catalysts for NOx-SCR with CH4

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