Effect of NO upon N<sub>2</sub>O Decomposition over Fe/ZSM-5 with Low Iron Loading

Sang, Chimin; Kim, Bryan H.; Lund, C.R.F.

doi:10.1021/jp048884m

Cited by 51 publications

(42 citation statements)

References 29 publications

(87 reference statements)

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“…Regarding kinetics and mechanism, either N 2 O dissociation or O 2 desorption have been suggested as the rate determining step in the overall process. [8][9][10][11][12][13][14][15][16][17] From DFT modeling of the…”

Section: Introductionmentioning

confidence: 99%

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Guesmi

Berthomieu

Bromley

et al. 2010

Phys. Chem. Chem. Phys.

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The characterization of Fe/ZSM5 zeolite materials, the nature of Fe-sites active in N 2 O direct decomposition, as well as the rate limiting step are still a matter of debate. This theoretical result was compared to the experimentally observed steady state kinetics of the N 2 O decomposition and temperature-programmed desorption (TPD) experiments. A switch of the reaction order with respect to N 2 O pressure from zero to one occurs at around 800 K suggesting a change of the rate determining step from the a-oxygen recombination to a-oxygen formation. The TPD results on the molecular oxygen desorption confirmed the mechanism proposed.

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Section: Introductionmentioning

confidence: 99%

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Guesmi

Berthomieu

Bromley

et al. 2010

Phys. Chem. Chem. Phys.

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“…Although extensive experimental and theoretical studies have been devoted to the understanding of the mechanism of the N 2 O decomposition, the nature, the nuclearity, and valence of the active iron sites [3][4][5][6][7]11,12 as well as the rate-limiting step [13][14][15][16][17] are still debated. However, it is generally admitted that whatever the preparation methods, several types of iron are present in Fe-ZSM-5.…”

Section: Introductionmentioning

confidence: 99%

Nitrous Oxide Decomposition on the Binuclear [Fe^II(μ-O)(μ-OH)Fe^II] Center in Fe-ZSM-5 Zeolite

2008

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The reaction mechanism for nitrous oxide (N 2 O) direct decomposition into molecular nitrogen and oxygen was studied on binuclear iron sites in Fe-ZSM-5 zeolite using the density functional theory (DFT + complex for the N 2 O decomposition. The first step of the catalytic reaction corresponds to a spontaneous adsorption of N 2 O over Fe II sites, followed by the surface atomic oxygen loading and the release of molecular nitrogen. The formation of molecular O 2 occurs through the migration of the atomic oxygen from one iron site to another one followed by the recombination of two oxygen atoms and the desorption of molecular oxygen. The computed reactivity over the binuclear iron core complex [Fe+ is consistent with experimental data reported in the literature. Although the dissociation steps of the N 2 O molecules, calculated with respect to adsorbed N 2 O intermediates, are highly energetic, the energy barrier associated with the atomic oxygen migration is the highest one. Up to 700 K, the oxygen migration step has the highest free energy barrier, suggesting that it is the rate-limiting step of the overall kinetics. This result explains the absence of O 2 formation in experimental study of N 2 O decomposition at temperatures below 623 K.

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“…The catalyst activity is known to be sensitive to the presence of other gases in the stream like H 2 O, CO, NO, hydrocarbons, etc. Different research groups have observed that NO accelerates N 2 O decomposition [23][24][25][26][27][28][29]. The activated catalysts lose their activity for the low temperature N 2 O decomposition in the presence of water vapours.…”

Section: Introductionmentioning

confidence: 99%

Low temperature decomposition of nitrous oxide over Fe/ZSM-5: Modelling of the dynamic behaviour

2005

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The kinetics of N 2 O decomposition to gaseous nitrogen and oxygen over HZSM-5 catalysts with low content of iron (<400 ppm) under transient and steady-state conditions was investigated in the temperature range of 250-380 8C. The catalysts were prepared from the HZSM-5 with Fe in the framework upon steaming at 550 8C followed by thermal activation in He at 1050 8C. The N 2 O decomposition began at 280 8C. The reaction kinetics was first order towards N 2 O during the transient period, and of zero order under steady-state conditions. The increase of the reaction rate with time (autocatalytic behaviour) was observed up to the steady state. This increase was assigned to the catalysis by adsorbed NO formed slowly on the zeolite surface from N 2 O. The formation of NO was confirmed by temperature-programmed desorption at temperatures >360 8C. The amount of surface NO during the transient increases with the reaction temperature, the reaction time, and the N 2 O concentration in the gas phase up to a maximum value. The maximum amount of surface NO was found to be independent on the temperature and N 2 O concentration in the gas phase. This leads to a first-order N 2 O decomposition during the transient period, and to a zero-order under steady state. A kinetic model is proposed for the autocatalytic reaction. The simulated concentration-time profiles were consistent with the experimental data under transient as well as under steady-state conditions giving a proof for the kinetic model suggested in this study. #

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Effect of NO upon N₂O Decomposition over Fe/ZSM-5 with Low Iron Loading

Cited by 51 publications

References 29 publications

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Nitrous Oxide Decomposition on the Binuclear [Fe^II(μ-O)(μ-OH)Fe^II] Center in Fe-ZSM-5 Zeolite

Low temperature decomposition of nitrous oxide over Fe/ZSM-5: Modelling of the dynamic behaviour

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Effect of NO upon N2O Decomposition over Fe/ZSM-5 with Low Iron Loading

Cited by 51 publications

References 29 publications

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

Nitrous Oxide Decomposition on the Binuclear [FeII(μ-O)(μ-OH)FeII] Center in Fe-ZSM-5 Zeolite

Low temperature decomposition of nitrous oxide over Fe/ZSM-5: Modelling of the dynamic behaviour

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Effect of NO upon N₂O Decomposition over Fe/ZSM-5 with Low Iron Loading

Nitrous Oxide Decomposition on the Binuclear [Fe^II(μ-O)(μ-OH)Fe^II] Center in Fe-ZSM-5 Zeolite