Density functional theory study of nitrous oxide decomposition over Fe- and Co-ZSM-5
Iron- and cobalt-exchanged ZSM-5 are active catalysts for the dissociation of nitrous oxide. In this study, density functional theory was used to assess a possible reaction pathway for the catalytic dissociation of N2O. The active center was taken to be mononuclear [FeO]+ or [CoO]+, and the surrounding portion of the zeolite was represented by a 24-atom cluster. The first step of N2O decomposition involves the formation of [FeO2]+ or [CoO2]+ and the release of N2. The metal-oxo species produced in this step then reacts with N2O again, to release N2 and O2. The apparent activation energies for N2O dissociation in Fe-ZSM-5 and Co-ZSM-5 are 39.4 and 34.6 kcal/mol, respectively. The preexponential factor for the apparent first-order rate coefficient is estimated to be of the order 107 s-1 Pa-1. While the calculated activation energy for Fe-ZSM-5 is in good agreement with that measured experimentally, the value of the preexponential factor is an order of magnitude smaller than that observed . The calculated activation energy for Co-ZSM-5 is higher than that reported experimentally. However, consistent with experiment, the rate of N2O decomposition on Co-ZSM-5 is predicted to be significantly higher than that on Fe-ZSM-5.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Studies. Chemical Sciences, Geosciences, and Biosciences Division (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 799571
- Report Number(s):
- LBNL-49413; R&D Project: 402001; B& R KC0302010; TRN: US200218%%272
- Journal Information:
- Journal of Physical Chemistry B, Vol. 106, Issue 28; Other Information: Journal Publication Date: Jul. 18, 2002; PBD: 19 Dec 2001
- Country of Publication:
- United States
- Language:
- English
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