The study of thermal decomposition of 2-bromo-3,3, 3-trifluoropropene and its fire-extinguishing mechanism

Article abstract of DOI:10.1016/j.jfluchem.2013.05.008

As a new kind of Halon replacement, 2-bromo-3,3,3-trifluoropropene (BTP) is highly effective at fire suppression with an extinguishment concentration lower than that of Halon 1301. Although the physical properties and extinguishing characteristics of BTP have been widely reported, there are relatively few studies on its thermal pyrolysis and extinguishing mechanisms. In this study, the thermal decomposition of BTP was studied over a temperature range of 25-800 8C and the decomposition products were analyzed by GC and GC-MS. Experimental results showed that the decomposition products were mainly trifluoropropyne (CF3CCH) and/or bromotrifluoromethane (CF3Br). The calculated apparent activation energies for the thermal pyrolysis of BTP by first order reaction approximation were in excellent agreement with the theoretical calculation results by Gaussian 03. Furthermore, by analyzing decomposition products and their chemical inhibition effect, thermal decomposition mechanism of BTP and its chemical extinguishing mechanism at high temperature were then proposed.

Full text of DOI:10.1016/j.jfluchem.2013.05.008

Journal of Fluorine Chemistry 153 (2013) 101–106
Contents lists available at SciVerse ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
The study of thermal decomposition of 2-bromo-3,3,
3-trifluoropropene and its fire-extinguishing mechanism
a
b
c
Xiaomeng Zhou a, , Weiwang Chen , Mingyong Chao , Guangxuan Liao
*
a The College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
b Department of Chemistry and Chemical Engineering, Heze University, Heze, Shandong 274015, PR China
c State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, PR China
A R T I C L E I N F O
A B S T R A C T
Article history:
As a new kind of Halon replacement, 2-bromo-3,3,3-trifluoropropene (BTP) is highly effective at fire
suppression with an extinguishment concentration lower than that of Halon 1301. Although the physical
properties and extinguishing characteristics of BTP have been widely reported, there are relatively few
studies on its thermal pyrolysis and extinguishing mechanisms. In this study, the thermal decomposition
of BTP was studied over a temperature range of 25–800 8C and the decomposition products were
analyzed by GC and GC–MS. Experimental results showed that the decomposition products were mainly
trifluoropropyne (CF3CCH) and/or bromotrifluoromethane (CF3Br). The calculated apparent activation
energies for the thermal pyrolysis of BTP by first order reaction approximation were in excellent
agreement with the theoretical calculation results by Gaussian 03. Furthermore, by analyzing
decomposition products and their chemical inhibition effect, thermal decomposition mechanism of BTP
and its chemical extinguishing mechanism at high temperature were then proposed.
Received 18 April 2013
Accepted 8 May 2013
Available online 16 May 2013
Keywords:
Halon replacement
Thermal decomposition
Fire-extinguishing
Kinetics
Radicals
ß 2013 Elsevier B.V. All rights reserved.
1. Introduction
degradation, which should result in a short atmospheric lifetime.
The average cup burner extinguishment concentration of BTP (2.6%
The Montreal Protocol (1987), along with its subsequent
amendments, has mandated ban on the production and
by volume) is considerably lower than that of Halon 1301 [13].
According to K.O. Patten, BTP is among the shortest-lived of
bromocarbons evaluated thus far, with a lifetime of 4.3–7.0 days.
As a result, the potential effects of BTP on ozone and climate are
only 0.0028–0.0052 and 0.0028–0.0050 for ODP and GWP (100-
year time horizon) respectively [14]. Furthermore, due to its
relatively low boiling point (34–35 8C at atmospheric pressure)
and high vapor pressure (0.74 bar at 25 8C), BTP can be readily
gasified to reach its extinguishment concentration in a confined
space. BTP is also a substance of low toxicity with the NOAEL and
LOAEL values of 0.5% and 1.0% (vol.%) respectively, as low as the
toxicity testing data of Halon 1211 [11]. Thereby, BTP would be an
excellent Halon replacement agent from the point view of its
acceptable environmental, physical and toxicological properties.
The physical properties and extinguishing characteristics of BTP
have been widely reported in recent years, however, very few
researches have been conducted on the thermal pyrolysis of BTP and
itsfire-extinguishingmechanism.Forexample, Orkin[14,15]studied
a possible degradation mechanism of bromoalkenes in atmosphere
using the flash photolysis resonance fluorescence technique. In
addition, HF production mechanism of BTP in fire extinguishing
process was calculated previously at B3LYP/6-311++G(d,p) theory
level by our research group[16]. Zhang and Lin [17] investigated the
decomposition of 1-bromo-3,3,3-trifluoropropene by Gaussian 98
a
application of Halons and chlorofluorocarbons (CFCs) due to their
considerable destruction to stratosphere ozone via BrOx and ClOx
catalytic cycles [1–5]. For this, tremendous efforts have been made
to search for suitable Halons and CFCs replacements over the
recent years. Hydrofluorocarbons (HFCs) and hydrochlorofluor-
ocarbons (HCFCs), such as HFC-227ea and HFC-236fa, have been
reported to be clean agents and are being used as substitutes for
Halons [6–8]. However, HFCs and HCFCs will eventually be phased
out of application in the foreseeable future due to their
unacceptably long atmospheric lifetime (ALT) and high global
warming potential (GWP) [9]. Thus, it is still an arduous task to find
more advanced Halon replacement agents that have superior fire
suppression performance and acceptable environmental, physical
and toxicological properties [10–12].
2-Bromo-3,3,3-trifluoropropene (CF3CBr = CH2, BTP) has been
selected as one kind of Halon replacements as the molecule
contains both bromine atom for chemical fire-suppression activity
and a carbon–carbon double bond to promote tropospheric
* Corresponding author. Tel.: +86 22 23504894; fax: +86 22 23507765.
E-mail address: zhouxm@nankai.edu.cn (X. Zhou).
0022-1139/$ – see front matter ß 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jfluchem.2013.05.008

102
X. Zhou et al. / Journal of Fluorine Chemistry 153 (2013) 101–106
and pointed out three possible decomposition pathways for 2-
bromo-3,3,3-trifluoropropene. By evaluating the suppressing per-
formance of water mist with bromofluoropropene on gasoline pool
fires, Ni and Chow [18] also approached the physical and chemical
inhibition effect of BTP briefly. However, most of these reported
researches focused mainly on the theoretical level, lacking experi-
mental validation. Therefore, further experimental researches are
necessary to illustrate the pyrolysis of BTP and its fire-extinguishing
mechanism.
In this study, BTP was pyrolyzed with a flow of nitrogen carrier
gas in a tubular pyrolysis reactor over the temperature range of
25–800 8C. Its decomposition products were analyzed by gas
chromatography (GC) and gas chromatography–mass spectrome-
try (GC–MS). Then, the apparent activation energy for the thermal
pyrolysis of BTP was calculated by first order reaction approxima-
tion based on experimental data, and the bond dissociation
energies (BDEs) and energy barriers were calculated by Gaussian
03 at the B3LYP/6-311++G(d,p) theory level. Finally, combined
with theoretical calculation results, decomposition and extin-
guishing mechanisms of BTP were emphatically studied by
analyzing decomposition products and their chemical inhibition
effect. This research may provide guidance to the optimal design of
BTP-based fire suppression system and facilitate the industrial
application of BTP.
Fig. 2. The decomposition ratios of BTP at various temperatures with three different
residence time of 3 s, 5 s, 10 s.
Fig. 2 shows the decomposition ratios of BTP in a carrier gas of
nitrogen with three different residence time of 3 s, 5 s and 10 s at
various temperatures. From the curves in the figure we can see that
the decomposition ratio of BTP is a monotonically increasing
function of temperature and higher temperature corresponds to
higher decomposition ratio of BTP. Besides, a longer residence time
in the reactor also results in a higher decomposition ratio. Fig. 3
shows the decomposition ratios of BTP in a carrier gas of nitrogen
with three different initial mole fractions (10%, 20% and 50%). From
the figure we can see that the decomposition ratio of BTP increases
rapidly with the increase of pyrolysis temperature, while no
obvious influence by the initial mole fraction of BTP was observed.
2. Results and discussion
2.1. Experimental results
Pyrolysis of BTP was studied in a tubular pyrolysis reactor at a
constant heating rate of 3 8C minꢀ1 from 25 8C to 800 8C. Fig.
1
shows the decomposition ratios of BTP at various temperatures in
carrier gas of nitrogen with a fixed mole fraction of BTP (20%) and a
constant nitrogen flow rate of 5.5 mL sꢀ1. From the figure we can see
that BTP exhibits great stability and extremely low decomposition
ratios when the temperature is below 600 8C, which indicates that at
a temperature lower than 600 8C, it is the BTP molecules rather than
decomposition products react with reactive radicals within the
flame to stop the combustion reaction [19]. When the temperature
rises above 600 8C, there is a rapid increase in the decomposition
ratio of BTP. Besides, during the course of the experiment, obvious
carbonization of BTP was observed above 760 8C.
2.2. Chemical kinetics analysis
From the perspective of chemical kinetics, if the reaction rate of
the thermal decomposition is assumed to be proportional to the
first order of BTP concentration, the following equation can be
used:
ꢀ
ꢁ
AðBTPÞ
ln
¼ lnð1 ꢀ
a
Þ ¼ ꢀkðBTPÞt
(1)
A0ðBTPÞ
Based on the decomposition curve of BTP as illustrated in Fig. 1,
pyrolytic behavior of BTP was further studied in a carrier gas of
nitrogen at various temperatures in a range from 600 8C to 800 8C.
where
a
(%) = 1 ꢀ A(BTP)/A0(BTP) is the decomposition ratio of BTP,
t (s) is the reaction time, and k(BTP) is the first-order rate
Fig. 1. The decomposition ratios of BTP at various temperatures with a flow of
Fig. 3. The decomposition ratios of BTP at various temperatures with three different
nitrogen carrier gas.
initial mole fraction of 10%, 20% and 50%.

X. Zhou et al. / Journal of Fluorine Chemistry 153 (2013) 101–106
103
Table 1
coefficient for the BTP pyrolysis, expressed by the Arrhenius
equation as follows:
The fitted equations and thermodynamic data calculated in Fig.5.
Mole
Fitted equation
R2
Apparent
Ea (kJ molꢀ1
)
ꢂ
ꢃ
Ea
fraction
k ¼ A exp
(2)
RT
10%
20%
50%
ln ln[1/(1 ꢀ
ln ln[1/(1 ꢀ
ln ln[1/(1 ꢀ
a
a
a
)] = 36.87–37.37 ꢂ 103/T
)] = 39.36–39.50 ꢂ 103/T
)] = 37.52–37.79 ꢂ 103/T
0.9551
0.9850
0.9908
310.7
328.4
314.2
where Ea (kJ molꢀ1) is the activation energy, R = 8.3145 J molꢀ1 Kꢀ1
is the ideal gas constant, A is the pre-exponential factor and T (K) is
the absolute temperature.
Eq. (3) was obtained by introducing Eq. (2) into Eq. (1). Note
that, for first order chemical reaction, the thermal decomposition
ratio is irrelevant to the initial concentration of the reactant. And in
a narrow temperature range, there must be a linear correlation
Fig. 5. The same goes for the possible transition states. Beyond that,
the bond distances and bond dissociation energies (BDEs) for BTP
molecular associated with energy barriers for three feasible
decomposition pathways, which were listed in Table 2, were also
investigated at the same basis set and theory level. All BDEs and
energy barriers involved in the dissociation and decomposition
reactions of BTP are expressed by thermal enthalpies that
corrected by zero point energy, based upon frequency calculation
(freq = temperature = 873.15) by Gaussian 03.
between ln ln[1/(1 ꢀ
a
)] and 1/T with a fixed residence time (see
Eq. (4)).
ꢂ
ꢃ
ꢀEa
lnð1 ꢀ
a
Þ ¼ ꢀA exp
t
(3)
(4)
RT
ꢀ
ꢁ
1
Ea
From the theoretical calculation results we can see that the
dissociation energy of C-Br bond (308.2 kJ molꢀ1) is the lowest
among all the bonds in the BTP molecule. The long bond distance
and low dissociation energy mean that the bond is loosely attached
and easy to break, and Brꢁ radical can be easily formed at a
relatively lower energy. Besides, bond dissociation energy of C–C
bond (386.3 kJ molꢀ1) is much lower than BDE values of C–F, C–H
and C55C bonds except for C–Br bond. The conclusion draw from
ln ln
¼ ꢀ
þ constant
1 ꢀ
a
RT
Based on the experimental data of the three different initial
mole fraction experiments with a fixed residence time of 5 s, the
calculation results of Eq. (4) are plotted in Fig. 4. From the plot it
can be observed that the relationship between ln ln[1/(1 ꢀ
a)] and
1000/T is linear, and fitted well. So, it is reasonable to assume the
thermal degradation of BTP to be the first order reaction from
above calculation and Fig. 3. The apparent activation energies
calculated are 314.2 kJ molꢀ1, 328.4 kJ molꢀ1, 310.7 kJ molꢀ1 with
the relative error within 6% and the results are categorized in
Table 1.
above is that BTP molecule may provide CF3 and Brꢁ radicals at
ꢁ
high temperature, which are very effective in extinguishing a fire.
In addition, the energy barriers of three possible decomposition
pathways were also calculated using TS method, among which the
pathway 1, CF3CBrCH2–TS1–CF3CCH + HBr, was calculated to have
the lowest energy barrier of 300.1 kJ molꢀ1. Another pathway that
leads to product channel, CF2 + FBrCH2, has an energy barrier of
437.1 kJ molꢀ1. The calculation results indicate that the most
probable dissociation products should be (CF3CCH + HBr) for the
lowest energy barrier. Likewise, (CF3Br + CCH2) with energy barrier
of 502.0 kJ molꢀ1 should be the most difficult products to produce.
8
2.3. Theoretical analysis by Gaussian 03
In order to reveal the thermal decomposition of BTP and its fire
extinguishing mechanisms, theoretical analysis by Gaussian 03
was performed. Density function theory (DFT) method accompa-
nied with 6-311++G(d,p) basis set was employed to do this. During
the calculation, geometrical optimization and frequency analysis
for BTP, including feasible decomposition products or fragments,
and transition states, were probed theoretically with Gaussian 03
at the B3LYP/6-311++G(d,p) theory level. Besides, connections
between reactants, transition structures and products were
confirmed by intrinsic reaction coordinate (IRC) calculation. Part
of the calculation results, such as molecular structure of BTP and
corresponding optimized geometrical parameters, are depicted in
>
>
>
300:1 kJ molꢀ1
ꢀ!
CF3CCH þ HBr
CH2CFBr þ CF2
CF3Br þ CCH2
>
>
TS1
>
>
<
437:1 kJ molꢀ1
CF3CBr¼CH2
ꢀ!
>
>
TS2
>
>
>
502:0 kJ molꢀ1
>
>
:
ꢀ!
TS3
To verify the above theoretical calculation results and investi-
gate the decomposition products of BTP, the gaseous products
were also detected by GC–MS. Analysis of the obtained mass
spectrum reveals two major decomposition products. One with the
characteristic fragments at m/z = 69, 75 and 94 (molecular ion
Table 2
BDEs and energy barriers calculated by Gaussian 03.
Bonds/
Bond
Reaction equations
BDEs/energy
barriers
(kJ molꢀ1
)
pathways
distance
˚
(A)
C–Br
1.906
1.511
1.325
1.350
1.348
1.083
1.081
—
CF3CBrCH2–CF3(Cꢁ)CH2 + Brꢃ
308.2a
386.3a
727.9a
447.7a
479.8a
464.9a
471.5a
300.1b
437.1b
502.0b
C–C
CF3CBrCH2–CF3ꢁ + CH2(Cꢁ)Br
ꢁ
CF3CBrCH2–CF3(Cꢁ)Br + CH2
C5C
(C–F)1
CF3CBrCH2–CH2CBrCF2ꢁ + Fꢁ
CF3CBrCH2–CH2CBrCF2ꢁ + Fꢁ
CF3CBrCH2–CF3CBrCHꢁ + Hꢁ
CF3CBrCH2–CF3CBrCHꢁ + Hꢁ
CF3CBrCH2–TS1–CF3CCH + HBr
CF3CBrCH2–TS2–CF2ꢁ + CFBrCH2
CF3CBrCH2–TS3–CF3Br + CCH2
(C–F)2
(C–H)1
(C–H)2
Pathway 1
Pathway 2
Pathway 3
—
—
a
Bond dissociation energy (BDE) values of different bonds.
b
Fig. 4. Relationship between ln ln[1/(1 ꢀ
a)] and 1000/T.
Reaction energy barriers of three feasible decomposition pathways for BTP.

104
X. Zhou et al. / Journal of Fluorine Chemistry 153 (2013) 101–106
Fig. 5. Geometrical optimization of BTP and three possible transition states.
peak) is proved to be CF3CCH, and the other with molecular ion
peak at m/z = 148 is CF3Br. Nonetheless, the principal product
varies with the pyrolysis temperature. In a temperature range of
600–700 8C, CF3CCH is detected to be the principal product; while
when the temperature rises above 700 8C, the major product
turned out to be CF3Br. That is, for BTPs thermal decomposition, the
formation of CF3Br requires more energy than the formation of
CF3CCH. It is worthwhile to note that, however, no clear evidence in
mass spectrum can prove the formation of CFBrCH2 during our
whole experiment. This is probably because that the CF3Br is
mainly formed by CF3ꢁ and Brꢁ radicals dissociated from different
BTP molecules rather than formed by monomolecular cracking
reaction. In this case, CF3Br can be generated with much less
energy. Besides, the apparent activation energies calculated above
by first order reaction approximation fall among the energy barrier
of reaction path 1 and BDE values of C–Br and C–C bonds, which
shows that experimental results and theoretical analysis receive
excellent agreement. The high apparent activation energy can also
explain the good stability of BTP which requires a pyrolysis
temperature of 600 8C.
extinguishment. In earlier reports on flame inhibition, Rosser and
Wise [20] suggested the basic mechanism of flame inhibition by
halogen compounds and pointed out that Brꢁ radical makes a great
contribution to the extinguishment of a fire by removing the
propagating radicals in a flame. The inhibition mechanism has
been further justified and refined by Butlin and Simmons [21],
Westbrook [22,23] etc., and was widely cited in recent years.
Takahashi et al. [24] and Hamins [25] suggested that hydrogen
atoms and hydroxyl radicals are the main active species in
combustion and are converted to relatively unreactive H2 or H2O
molecules through the following catalytic cycle:
HBr þ Hꢁ ! H2 þ Br
HBr þ OHꢁ ! H2O þ Br
Besides, Westbrook [22] pointed out that the bromine catalytic
cycle reactions are the important pathway in regeneration of HBr,
though the direct reaction Hꢁ + Brꢁ + M ! HBr + M has rather
slower kinetics.
Hꢁ þ Brꢁ þ M ! HBr þ M
Brꢁ þ Brꢁ þ M ! Br2 þ M
2.4. Thermal decomposition and extinguish mechanisms
Based on above experimental results and theoretical analysis,
the thermal decomposition mechanism of BTP can be summarized
as follows. When the temperature reaches to 600 8C, the lowest
energy barrier (300.1 kJ molꢀ1) is overcome and the decomposi-
tion of BTP begins, leading to the formation of (CF3CCH + HBr). As
the temperature rises, CF3ꢁ and Brꢁ radicals will be dissociated from
different BTP molecules for a little higher energy required, and
contribute to the generation of CF3Br. Almost all decomposition
products and radicals, such as CF3ꢁ, Brꢁ, CF3Br, make significant
contribution to extinguishing a fire.
Hꢁ þ Br2 ! HBr þ Brꢁ
In addition to the above reports, chemical suppression and
thermal decomposition of CF3 and related radicals have been
ꢁ
deeply studied previously by other researchers [26–34]. The
extinguishing mechanism reactions that promote the consump-
tion of propagating raꢁdicals in a flame are summarized in Table 3,
which contribute CF3 to be an efficient fire extinguishing group.
In consideration of the experimental results and the BDEs and
energy barriers calculated by Gaussian 03, the reaction fluxes for
the decomposition of BTP are summarized in Fig. 6, together with
the chemical extinguishing mechanism at high temperature which
Like Halons, BTP is a chemically acting fire extinguishant. The
contribution of chemical mechanism to the extinguishment of fires
predominates over the physical mechanism. It is necessary to
probe into the chemical effect of these products and radicals on fire
mostly depending on Brꢁ, CF3 and related radicals.
ꢁ

X. Zhou et al. / Journal of Fluorine Chemistry 153 (2013) 101–106
105
Table 3
Summary of mechanism reactions that CF3 extinguish a fire.
ꢁ
No.
Mechanism reactions
References
1
2
CF3Br ! CF3 + Br
[34]
CF3 + H ! CF3H
[26,27,29,32]
[32]
3
CF3H ! CF2 + HF
4
CF3H + H ! CF3 + H2
CF3H + OH ! CF3 + H2O
CF3H ! CF2 + HF
[26,28,29,31]
[26,28,29–31]
[29,33]
[28,29,33,34]
[30,32,33]
[26,30,32,33]
[30,34]
[30]
5
6
7
CF3 + OH ! CF2O + HF
CF3 + H ! CF2 + HF
CF3 + O ! CF2O + F
CF3 + F ! CF4
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
CF4 + H ! CF3 + HF
CF2 + O ! CO + 2F
CF2 + OH ! CF2O + F
CF2 + H ! CF + HF
CF2 + O ! CFO + F
CF2O + H ! CFO + HF
CF2O + O ! CO2 + 2F
CF + O2 ! CFO + O
CF + OH ! CO + HF
CFO + CF3 ! CF4 + CO
CFO + H ! CO + HF
CFO + OH ! CO2 + HF
CFO + O ! CO2 + F
CO + OH ! CO2 + H
CO + O + M! CO2
[30,32]
[28,32]
[27,32,33]
[30]
[30,34]
[30]
[33,34]
[32]
[34]
[30,34]
[30,34]
[30,34]
[32]
[30]
3. Conclusions
Fig. 6. Reaction fluxes for BTP decomposition and extinguishing mechanism at high
temperature.
Thermal decomposition of BTP was investigated experimen-
tally and theoretically in this study. Experimental results
show that BTP is a relative stable extinguishing agent with a
decomposition temperature around 600 8C, which were in
agreement with the high apparent activation energies obtained
by experimental and theoretical calculation. In a temperature
range from 600 8C to 800 8C, the decomposition ratio of BTP
increases with the rise in temperature, and raises noticeably by
extending residence time. But, little influence was exerted by
altering the initial mole fraction of BTP. The major decomposi-
tion products in a carrier gas of nitrogen were verified to be
CF3CCH and/or CF3Br. Beyond thaꢁt, we attribute its good fire
extinguishing effect to Brꢁ and CF3 and related radicals at high
temperature by removing active species from the combustion
zone catalytically. The good properties and fire extinguishing
effect of BTP contribute it to be an excellent Halon replacement
agent.
4. Experimental
4.1. Materials
2-Bromo-3,3,3-trifluoropropene (purity ꢄ99.75% after rectifi-
cation) used in this study was obtained from the reaction of
CF3CHCH2 (g) with Br2 (liquid) at a low temperature, followed by
dehydrobromination by aqueous solution of potassium hydroxide
Fig. 7. Schematic diagram of the thermal degradation experiment system.

106
X. Zhou et al. / Journal of Fluorine Chemistry 153 (2013) 101–106
Table 4
of BTP. The operating conditions of GC and GC–MS are shown in
Table 4. The decomposition ratios of BTP were calculated using the
following formula: (%) is the
decomposition ratio of BTP, A(BTP) and A0(BTP) are the chro-
matographic peak areas of BTP with a constant injection sample
size before and after pyrolysis severally.
GC and GC–MS operation conditions.
a
= 1 ꢀ A(BTP)/A0(BTP), where
a
Parameters
Instrument
GC
GC–MS
Beifen-Ruili SP-3420A
Shimadzu
GC-MS-QP2010 ultra
Rtx-5ms, 30.0 m,
Column
DB-5, 30.0 m,
0.25 mm, 0.25um
6 mL minꢀ1
35 8C
0.25 mm,0.25
2 mL minꢀ1
180 8C
mm
Carrier gas flow rate
Column temperature
Injection
Acknowledgements
40
m
L gas injection,
40 mL gas injection,
split mode
1:50
split mode
1:50
This work was supported by the National Natural Science
Foundation of China (Grant no. 51176078) and Jiangsu Province-
supporting Science and Technology Program (BE2010677).
Split ratio
Injection temperature
Detector (FID) temperature
Ion source temperature
Ionization method
Ionizing energy
250.00 8C
40 8C
250.00 8C
200.00 8C
Electron impact
70 eV
References
[1] M.J. Molina, F.S. Rowland, Nature 249 (1974) 810–812.
[2] R.J. Salawitch, S.C. Wofsy, M.B. McElroy, Planet. Space Sci. 36 (1988) 213–224.
[3] S.C. Wofsy, M.B. McElroyp, N.D. Sze, Science 187 (1975) 535–536.
[4] H. Yu, E.M. Kennedy, A. Uddin, S.P. Sullivan, B.Z. Dlugogorski, Int. J. Chem. Kinet. 37
(2005) 134–146.
[5] Y. Hu, Y. Xu, T. Wang, C. Wang, S. Li, J. Anal. Appl. Pyrolysis 90 (2011) 27–32.
[6] M.C. Su, S.S. Kumaran, K.P. Lim, J.V. Michael, A.F. Wagner, D.A. Dixon, J.H. Kiefer, J.
DiFelice, J. Phys. Chem. 100 (1996) 15827–15833.
[7] A. McCulloch, J. Fluorine Chem. 100 (1999) 163–173.
[8] R.L. Powell, J. Fluorine Chem. 114 (2002) 237–250.
[9] T.J. Wallington, W.F. Schneider, D.R. Worsnop, O.J. Nielsen, J. Sehested, W.J.
Debruyn, J.A. Shorter, Environ. Sci. Technol. 28 (1994) 320A–326A.
[10] R.E. Tapscott, R.S. Sheinson, V.I. Babushok, M.R. Nyden, R.G. Gann, NIST Technical
Note 1443, 2001.
Scan range
m/z 35.0–500.00
[35,36]. Common purity nitrogen with a purity of not less than
99.5% was used as the carrier gas.
CF3CH¼CH2 þ Br2illumꢀi!nationCF3CHBrCH2Brꢀ!CF3CBr¼CH2
KOH
0ꢅ5 ꢆ
C
60 ꢆ
C
4.2. Experimental equipments and procedures
[11] J. Grigg, A. Chattaway, 12th Halon Options Technical Working Conference
(HOTWC), Albuquerque, NM, (2002), pp. 1–10.
[12] R.G. Gann, 13th Halon Options Technical Working Conference (HOTWC), Albu-
querque, NM, (2003), pp. 1–13.
[13] J.D. Mather, R.E. Tapscott, 10th Halon Options Technical Working Conference
(HOTWC), Albuquerque, NM, (2000), pp. 154–163.
[14] K.O. Patten, V.G. Khamaganov, V.L. Orkin, S.L. Baughcum, D.J. Wuebbles, J.
Geophys. Res. Atmos. 116 (2011) D24307.
The schematic diagram of the thermal degradation device is
shown in Fig. 7. This system mainly consists of a tubular pyrolysis
reactor (40.0 cm long and 1.0 cm in internal diameter) that made of
nickel–copper alloy, a programmable temperature control device,
and a products analysis and exhaust gas treatment system. All
experiments were carried out at atmospheric pressure. The
temperature of the reactor was measured and controlled by the
temperature control device with three K-type sheathed thermo-
couples evenly distributed throughout the surface of the reactor,
showing that the temperature deviation was controlled within
ꢅ5 8C. The temperatures used to process experiment data were
provided by thermocouple d inside the reactor. During the execution
of experiments, the mixture of BTP (g) and carrier gas was preheated
prior to entering the tubular reactor, and the initial mole fraction of
BTP and the residence time in the reactor were regulated by adjusting
the flow rate of BTP and carrier gas.
Prior to the experiment, the tubular pyrolysis reactor was
immersed in acetone for 2 h to get rid of impurities firstly. After
drying at 110 8C in oven, the reactor was installed in the heater and
was heated to 500 8C for 1 h with N2 flow to remove contaminants.
After cooling to room temperature, BTP was then injected into the
reactor and the reactor was heated to 800 8C at a constant heating
rate of 3 8C minꢀ1. After removal of particulates and acid gases by
passing through a filter and a warm water scrubber (see Fig. 7), the
gaseous degradation products were collected and then analyzed
by gas chromatography (GC) and gas chromatography–mass
spectrometry (GC–MS).
[15] V.L. Orkin, F. Louis, R.E. Huie, M.J. Kurylo, J. Phys. Chem. A 106 (2002) 10195–
10199.
[16] B. Zhou, X. Zhou, X. Jin, T. Chen, Acta Chim. Sinica 68 (2010) 1829–1836.
[17] M. Zhang, Z. Lin, J. Mol. Struct. Theochem. 899 (2009) 98–110.
[18] X. Ni, W.K. Chow, Appl. Therm. Eng. 31 (2011) 3864–3870.
[19] R.E. Tapscott, J.D. Mather, J. Fluorine Chem. 101 (2000) 209–213.
[20] W.A. Rosser, H. Wise, Symp. Int. Combust. Proc. 7 (1958) 175–182.
[21] R.N. Butlin, R.F. Simmons, Combust. Flame 12 (1968) 447–456.
[22] C.K. Westbrook, Combust. Sci. Technol. 23 (1980) 191–202.
[23] C.K. Westbrook, Combust. Sci. Technol. 34 (1983) 201–225.
[24] K. Takahashi, Y. Sekiuji, Y. Yamamori, T. Inomata, K. Yokoyama, J. Phys. Chem. A
102 (1998) 8339–8348.
[25] T. Noto, V. Babushok, A. Hamins, W. Tsang, Combust. Flame 112 (1998) 147–160.
[26] G.D. Brabson, E.A. Waiters, J. Schiro, C. Spencer, R.E. Tapscott, R.A. Patterson, 6th
Halon Options Technical Working Conference (HOTWC), Albuquerque, NM,
(1996), pp. 611–613.
[27] K. Takahashi, Y. Yamamori, T. Inomata, J. Phys. Chem. A 101 (1997) 9105–9110.
[28] N.K. Srinivasan, M.C. Su, J.V. Michael, S.J. Klippenstein, L.B. Harding, J. Phys. Chem.
A 111 (2007) 6822–6831.
[29] H. Fukaya, T. Ono, T. Abe, J. Chem. Soc.-Chem. Commun. (1995) 1207–1208.
[30] A.B. Murphy, A.J.D. Farmer, E.C. Horrigan, T. McAllister, Plasma Chem. Plasma
Process. 22 (2002) 371–385.
[31] P.J. Van Tiggelen, M. Lefebvre, F. Evariste, 5th Halon Options Technical Working
Conference (HOTWC), Albuquerque, NM, (1995), pp. 667–679.
[32] V. Babushok, T. Noto, D.R.F. Burgess, A. Hamins, W. Tsang, Combust. Flame 107
(1996) 351–367.
[33] N.K. Srinivasan, M.C. Su, J.V. Michael, A.W. Jasper, S.J. Klippenstein, L.B. Harding, J.
Phys. Chem. A 112 (2008) 31–37.
[34] G.S. Fallon, H.K. Chelliah, G.T. Linteris, Symp. (Int.) Combust. 26 (1996)
1395–1403.
[35] F.G. Drakesmith, O.J. Stewart, P. Tarrant, J. Org. Chem. 33 (1967) 280–285.
[36] W. Xu, New Chem. Mater. 33 (2005) 27–31.
4.3. Products analysis
In this study, GC and GC–MS were used to identify the
decomposition products, and to quantify the decomposition ratios