Catalytic reduction of NH4NO3 by NO: Effects of solid acids and implications for low temperature DeNOx processes

Savara, Aditya; Li, Mei Jun; Sachtler, Wolfgang M.H.; Weitz, Eric

doi:10.1016/j.apcatb.2007.12.008

Cited by 95 publications

(90 citation statements)

References 48 publications

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“…108 Yet, in another aspect, a promotion effect by Brønsted acidity on the NH 3 -SCR reaction could still be observed if the catalysts contained the most favorable Fe species, and Schwidder et al 108 concluded that this was probably due to the obvious promotion of an acidcatalyzed intermediate step in the NH 3 -SCR reaction (e.g. the decomposition of NH 4 NO 2 ) similar to the results reported by Li et al 109 and Savara et al, 110 which might be the rate-determining step at low temperatures. In addition, Brandenberger et al 111 concluded that the Brønsted acid sites might not be required directly in the SCR process for adsorbing or activating NH 3 , but they were necessary to bind and disperse the reactive Fe 3+ ions in the preparation process for Fe-based zeolite catalysts, similar to the results reported by Iwasaki et al 104 Furthermore, the zeolite support with Brønsted acidity could also play a role as an NH 3 reservoir, regardless of the form in which the NH 3 was stored, and in the NH 3 -SCR reaction the stored NH 3 could migrate to the active sites so as to undergo a reaction with NO.…”

Section: Nh 3 -Scr Of No X Over Zeolite Catalystssupporting

confidence: 57%

“…Mou et al 65 creatively synthesized novel a-Fe 2 O 3 nanorods and g-Fe 2 O 3 nanorods by aqueous precipitation and calcination/refluxing methods, showing the same morphology but totally different exposed crystal facets. They clearly concluded that the g-Fe 2 O 3 nanorods enclosed by reactive (110) and (100) facets, simultaneously exposing Fe 3+ and O 2À sites, were highly active for the activation of NH 3 and NO, and thus highly active for the NH 3 -SCR reaction. In contrast, the a-Fe 2 O 3 nanorods enclosed by (210) and (001) facets only exposed Fe 3+ sites and showed relatively poor SCR activity, due to the lack of neighboring oxygen anions for the activation of NH 3 and NO.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Nh 3 -Scr Of No X Over Zeolite Catalystssupporting

confidence: 57%

Section: Introductionmentioning

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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“…At maximum the ammonium nitrate conversions were 88, 59.1 and 19% at HNO3:NH4NO3 = 12, 7 and 4, respectively. Based on the literature review [11] and experimental data, it is reasonable to suggest that the decomposition of ammonium nitrate in water is associated with the oxidation by Nitrous acid (HNO2):…”

Section: Resultsmentioning

confidence: 99%

Studies of Catalytic Properties of Inorganic Rock Matrices in Redox Reactions

Dobrynkin¹,

Batygina²,

Носков³

2017

J. sustain. dev. energy water environ. syst.

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Intrinsic catalytic properties of mineral matrices of various kinds (basalts, clays, sandstones) were studied, which are of interest for in-situ heavy oil upgrading (i.e., underground) to create advanced technologies for enhanced oil recovery. The elemental, surface and phase composition and matrix particle morphology, surface and acidic properties were studied using elemental analysis, X-ray diffraction, adsorption and desorption of nitrogen and ammonia. The data on the catalytic activity of inorganic matrices in ammonium nitrate decomposition (reaction with a large gassing), oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltenes into maltenes (the conversion of heavy hydrocarbons into more valuable light hydrocarbons) were discussed. In order to check their applicability for the asphaltenes hydrocracking catalytic systems development, basalt and clay matrices were used as supports for iron/basalt, nickel/basalt and iron/clay catalysts. The catalytic activity of the matrices in the reactions of the decomposition of ammonium nitrate, oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltens was observed for the first time.

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“…As well known in the literature [17][18][19], at F-SCR conditions, i.e., when feeding equimolar amounts of NO and NO 2 , NO 2 is adsorbed on the SCR catalyst in the form of nitrate and nitrite surface species. As schematically displayed in Fig.…”

Section: Implications For the F-scr Mechanismmentioning

confidence: 99%

Enhancing the Low-T NH3-SCR Activity of a Commercial Fe-Zeolite Catalyst by NH4NO3 Dosing: an Experimental and Modeling Study

Marchitti

Hemings

Nova

et al. 2015

Emiss. Control Sci. Technol.

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The potential improvement of DeNOx efficiency enabled by injecting calibrated amounts of NH 4 NO 3 (AN) aqueous solution into lean engine exhausts prior to NH 3 -SCR converters (Enhanced-SCR) has been investigated by dynamic and steady-state catalytic activity runs over a commercial Fe-zeolite monolith catalyst. The study was performed varying GHSV (35,000-100,000 h −1 ), temperature (150-550°C), as well as AN and NO 2 feed concentrations. The results demonstrate that already at low temperature (180°C) the DeNOx activity of the investigated catalyst at Standard-SCR conditions is greatly boosted by the addition of AN: for example, the injection of 250 ppm of NH 4 NO 3 incremented the NO conversion from ∼15 to ∼85 % at GHSV = 50,000 h −1 , with feed NO = NH 3 = 500 ppm. Furthermore, the dosed NH 4 NO 3 was completely converted, with no undesired release of N 2 O. We show also that the Enhanced-SCR pathway proceeds through a first step wherein AN rapidly oxidizes NO to NO 2 , which then goes on to react with NH 3 according to the Fast-SCR reaction. Based on this sequential reaction scheme, a simple kinetic model has been developed and successfully fitted to all the collected data.

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Catalytic reduction of NH4NO3 by NO: Effects of solid acids and implications for low temperature DeNOx processes

Cited by 95 publications

References 48 publications

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

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

Studies of Catalytic Properties of Inorganic Rock Matrices in Redox Reactions

Enhancing the Low-T NH3-SCR Activity of a Commercial Fe-Zeolite Catalyst by NH4NO3 Dosing: an Experimental and Modeling Study

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Catalytic reduction of NH4NO3 by NO: Effects of solid acids and implications for low temperature DeNOx processes

Cited by 95 publications

References 48 publications

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

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

Studies of Catalytic Properties of Inorganic Rock Matrices in Redox Reactions

Enhancing the Low-T NH3-SCR Activity of a Commercial Fe-Zeolite Catalyst by NH4NO3 Dosing: an Experimental and Modeling Study

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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

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