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Study of 2-H-heptafluoropropane and its thermal decomposition using UV Photoelectron spectroscopy and ab initio molecular orbital calculations

Study of 2-H-heptafluoropropane and its thermal decomposition using UV Photoelectron spectroscopy and ab initio molecular orbital calculations
Study of 2-H-heptafluoropropane and its thermal decomposition using UV Photoelectron spectroscopy and ab initio molecular orbital calculations
The thermal decomposition of 2-H heptafluoropropane CF3CHFCF3 at low pressure, heavily diluted in argon, has been studied over the temperature range 600-2000 C using photoelectron spectroscopy. Comparison of the results obtained has been made with results of recent electronic structure calculations of possible decomposition pathways and results of a shock tube study. The most favoured reaction thermodynamically, to produce CF3CF=CF2 + HF, is found to be the main decomposition reaction at lower temperatures, 600-900 ?C. At higher temperatures, 900-1200 C, the decomposition reaction to give C2F4 + CF3H was found to become important. No evidence for CF3CHFCF3 ? CF3CHF + CF3, a reaction expected to be important from a shock tube study, performed at much higher pressures, or for CF3CHFCF3 ? CF3CF + CF3H was obtained, although for the latter reaction it is likely that CF3CF converts into C2F4 under the conditions used before photoionization, in the ionization region of the photoelectron spectrometer. At higher temperatures C3F6 decomposes to C2F4 + CF2, and C2F4 decomposes to CF2. Ab initio calculations have been performed of the adiabatic and vertical ionization energies of possible primary pyrolysis products to assist assignment of the photoelectron spectra recorded for heated flowing gas samples. A comparison is made between the threshold photoelectron (TPE) spectrum and the photoelectron spectrum (PE) of CF3CF=CF2
1520-5215
3540-3550
Copeland, Grant
1adc6e1f-c40d-4a4d-93e1-91b1900eeb60
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Dyke, John
46393b45-6694-46f3-af20-d7369d26199f
Chow, Wankai
7782cbe2-f996-45d2-8883-af349dbd35fb
Mok, Daniel K.W.
49a4e516-0e71-4f59-a3ec-bd607b47ef33
Chau, Foo-Tim
e15ec394-d11b-4cbe-91f3-cdac037d9d0e
Copeland, Grant
1adc6e1f-c40d-4a4d-93e1-91b1900eeb60
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Dyke, John
46393b45-6694-46f3-af20-d7369d26199f
Chow, Wankai
7782cbe2-f996-45d2-8883-af349dbd35fb
Mok, Daniel K.W.
49a4e516-0e71-4f59-a3ec-bd607b47ef33
Chau, Foo-Tim
e15ec394-d11b-4cbe-91f3-cdac037d9d0e

Copeland, Grant, Lee, Edmond P.F., Dyke, John, Chow, Wankai, Mok, Daniel K.W. and Chau, Foo-Tim (2010) Study of 2-H-heptafluoropropane and its thermal decomposition using UV Photoelectron spectroscopy and ab initio molecular orbital calculations. Journal of Physical Chemistry A, 114 (10), 3540-3550. (doi:10.1021/jp1000607).

Record type: Article

Abstract

The thermal decomposition of 2-H heptafluoropropane CF3CHFCF3 at low pressure, heavily diluted in argon, has been studied over the temperature range 600-2000 C using photoelectron spectroscopy. Comparison of the results obtained has been made with results of recent electronic structure calculations of possible decomposition pathways and results of a shock tube study. The most favoured reaction thermodynamically, to produce CF3CF=CF2 + HF, is found to be the main decomposition reaction at lower temperatures, 600-900 ?C. At higher temperatures, 900-1200 C, the decomposition reaction to give C2F4 + CF3H was found to become important. No evidence for CF3CHFCF3 ? CF3CHF + CF3, a reaction expected to be important from a shock tube study, performed at much higher pressures, or for CF3CHFCF3 ? CF3CF + CF3H was obtained, although for the latter reaction it is likely that CF3CF converts into C2F4 under the conditions used before photoionization, in the ionization region of the photoelectron spectrometer. At higher temperatures C3F6 decomposes to C2F4 + CF2, and C2F4 decomposes to CF2. Ab initio calculations have been performed of the adiabatic and vertical ionization energies of possible primary pyrolysis products to assist assignment of the photoelectron spectra recorded for heated flowing gas samples. A comparison is made between the threshold photoelectron (TPE) spectrum and the photoelectron spectrum (PE) of CF3CF=CF2

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Published date: 11 February 2010

Identifiers

Local EPrints ID: 147141
URI: http://eprints.soton.ac.uk/id/eprint/147141
ISSN: 1520-5215
PURE UUID: 1b03778e-e28f-4473-b724-472b352b978f
ORCID for John Dyke: ORCID iD orcid.org/0000-0002-9808-303X

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Date deposited: 23 Apr 2010 10:08
Last modified: 17 Dec 2019 02:04

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