Selective catalytic oxidation (SCO) of ammonia to nitrogen over Fe-exchanged zeolites prepared by sublimation of FeCl3

Qi, Gongshin; Gatt, Joseph E.; Yang, Ralph T.

doi:10.1016/j.jcat.2004.05.023

Cited by 115 publications

(63 citation statements)

References 27 publications

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“…This mechanism was mainly supported by the results obtained on Pt or transition metal oxide catalysts [1][2][3][4][5]. Two other insights into the reaction mechanism of NH 3 oxidation have been proposed in recent years [6][7][8][9][10][11][12][13]. One is the SCO by a direct route involving a hydrazinium-type intermediate [7,8].…”

Section: Introductionmentioning

confidence: 75%

“…Three major reaction pathways have been proposed for the SCO of NH 3 to N 2 over different catalysts [1][2][3][4][5][6][7][8][9][10][11][12][13]. Zawadzki [1] proposed an imide (NH) mechanism in which the first step yields NH, and then the NH reacts with atomic oxygen (O) to form nitroxyl (HNO) and further conversion to N 2 or nitrous oxide (N 2 O), or NH could even react with molecular O 2 to produce nitric oxide (NO).…”

Section: Introductionmentioning

confidence: 99%

“…The other is a two-step mechanism called in situ or ''internal" selective catalytic reduction (iSCR), which involves the oxidation of a significant percentage of NH 3 into NO x species, and the NO x species subsequently react with NH 3 to form N 2 [9][10][11]. Many noble metal catalysts, such as Ag (powder), Pt, Pt/Al 2 O 3 , Rh/Al 2 O 3 , Pd/Al 2 O 3 , Pt-ZSM-5, Pd-ZSM-5, and Rh-ZSM-5, have been suggested to follow this iSCR route [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of selective catalytic oxidation of ammonia to nitrogen over Ag/Al2O3

Zhang

2009

Journal of Catalysis

203

127

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Mechanism O 2 uptake In situ DRIFTS a b s t r a c tThe mechanism of selective catalytic oxidation (SCO) of NH 3 over Ag/Al 2 O 3 was studied by NH 3 temperature-programed oxidation, O 2 -pulse adsorption, and in situ DRIFTS of NH 3 adsorption and oxidation. The essence which affects the low temperature activity of Ag/Al 2 O 3 has been elucidated through the mechanism study. Different Ag species on Ag/Al 2 O 3 significantly influence O 2 uptake by catalysts; while different oxygen species affect the activity of NH 3 oxidation at low temperature. The activated -NH could react with the atomic oxygen (O) at low temperatures (<140°C); however, the -NH could also interact with the O 2 at temperatures above 140°C. At low temperatures (<140°C), NH 3 oxidation follows the -NH mechanism. However, at temperatures above 140°C, NH 3 oxidation follows an in situ selective catalytic reduction (iSCR) mechanism (two-step formation of N 2 via the reduction of an in situ-produced NO x species by a NH x species).

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Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanism of selective catalytic oxidation of ammonia to nitrogen over Ag/Al2O3

Zhang

2009

Journal of Catalysis

203

127

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“…The third mechanism, also called ''internal'' selective catalytic reduction (iSCR) (e.g., [13,33,34]) consists of two main steps. In the first step ammonia is oxidised to NO:…”

Section: Resultsmentioning

confidence: 99%

Selective Catalytic Oxidation (SCO) of Ammonia to Nitrogen over Hydrotalcite Originated Mg–Cu–Fe Mixed Metal Oxides

et al. 2011

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Mg-Cu-Fe oxide systems, obtained from hydrotalcite-like precursors, were tested as catalysts for the selective catalytic oxidation (SCO) of ammonia. Copper containing catalysts were active in low-temperature SCO processes; however, their selectivity to nitrogen significantly decreased at higher temperatures. The optimum composition of the catalyst to guarantee high activity and selectivity to N 2 was proposed. Temperature-programmed experiments, SCO catalytic tests performed with various contact times and additional tests on the samples in the selective catalytic reduction of NO with ammonia showed that the SCO process over the studied calcined hydrotalcites proceeds according to the internal SCR mechanism and oxidation of ammonia to NO is a rate-determining step in the low-temperature range.

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“…Previous studies showed that noble metals such as Pt, Ir and Au were active for the reaction of SCO of NH 3 at low temperature, however, the selectivity of N 2 was not satisfied for the reason that the main by-product at low temperature was N 2 O [4][5][6][7][8] [9][10][11][12][13][14][15][16][17], and many ion-exchanged zeolite catalysts [18][19][20][21][22], have also been investigated for the SCO of NH 3 , but NH 3 conversion levels of these catalysts at low temperature were not high enough to be of practical use.…”

Section: Introductionmentioning

confidence: 99%