Thermal decomposition of gaseous ammonium nitrate at low pressure: Kinetic modeling of product formation and heterogeneous decomposition of nitric acid

Article abstract of DOI:10.1021/jp9058005

The thermal decomposition of ammonium nitrate, NH₄NO₃ (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation o

Full text of DOI:10.1021/jp9058005

1
3556
J. Phys. Chem. A 2009, 113, 13556–13561
Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling
of Product Formation and Heterogeneous Decomposition of Nitric Acid
J. Park* and M. C. Lin*
Department of Chemistry, Emory UniVersity, Atlanta, Georgia 30322
ReceiVed: June 19, 2009; ReVised Manuscript ReceiVed: September 29, 2009
The thermal decomposition of ammonium nitrate, NH
K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric
acid. The sublimation of NH NO at 423 K was proposed to produce equal amounts of NH and HNO
followed by the decomposition reaction of HNO , HNO + M f OH + NO + M (where M ) third-body
and reactor surface). The absolute yields of N , N O, H O, and NH , which can be unambiguously measured
and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the
detailed [H,N,O]-mechanism established earlier for the simulation of NH -NO (Park, J.; Lin, M. C.
4 3
NO (AN), in the gas phase has been studied at 423-56
4
3
3
3
,
3
3
2
2
2
2
3
3
2
Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN
decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357).
Since the homogeneous decomposition reaction of HNO
3
itself was found to be too slow to account for the
consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition
of HNO
OH + NO
concentrations of NH
3
in our kinetic modeling. The heterogeneous decomposition rate of HNO
3
, HNO
3
+ (B
2
O
3
/SiO
2
) f
2
+ (B
2
O
3
/SiO
2
), was determined by varying its rate to match the modeled result to the measured
7
-1
3
and H
2
O; the rate could be represented by k2b ) 7.91 × 10 exp(-12 600/T) s ,
which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.;
Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO decomposition on glass
3
reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily
predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.
Introduction
NH + NO f H NO + NO
2
2
2
4 3
Ammonium nitrate (AN, NH NO ) is a convenient source of
f N O + H O
N
2
O for laboratory experiments. The mechanism for N
2
O
2
2
formation in the melt of AN is believed to involve primarily
1
the reaction of ammonium with nitrate ions.
NH + NO f N H + OH
2
2
+
4
-
3
NH NO (l) f NH + NO
4
3
f N + H O
2
2
+
4
-
3
+
-
2
NH + NO f NH OH + NO
3
+
-
2
NH OH + NO f 2HNO + H O f N O + 2H O
The mechanism for gas-phase chain reactions is more complex,
involving H and OH as key chain carriers with NH and NO (x )
-3) as major participants in the redox process. Although kinetic
3
2
2
2
x
x
f H N O +H O f N O + 2H O
2
2
2
2
2
2
1
1,2,4,5
studies of AN have been performed by several authors,
Under higher temperature and particularly low-pressure
important mechanistic questions remain unanswered. In an effort
to establish and validate a detailed mechanism for reactions of
[H,N,O]-containing systems at high temperatures in conjunction
conditions, contributions from gas-phase reactions become
2
significant. In the gas phase the decomposition of NH
4
NO
3
is
6
clearly dominated by the simple dissociation into the acid and
base components, most likely similar to the decomposition of
the ADN (ammonium dinitramide) system at low pressure:3
with the NH -deNOx process as well as the combustion of AN
3
and ADN, we have recently carried out a low-pressure study on
the thermal decomposition of AN in a manner similar to that
3
employed in our ADN decomposition study using a quartz flow
reactor employed with a molecular beam sampling/mass spec-
7
NH NO (s) f NH (g) + HNO (g)
trometer based on the approach of Saalfeld and co-workers. The
4
3
3
3
rates of formation of the products, which can be unambiguously
HNO f OH + NO
3
2
measured and quantitatively calibrated (for example, N
and NH ) covering 450-956 K under a constant pressure at 5-6.2
torr, He are kinetically modeled using the detailed mechanism
2 2 2
, N O, H O,
3
OH + NH f NH +H O
3
2
2
8
established earlier for the simulation of NH
3
-NO
2
and ADN
*
To whom correspondence should be addressed. Phone: (404) 727-6841.
Fax: (404) 727-6586. E-mail: jpark05@emory.edu (J.P.); chemmcl@emory.edu
M.C.L.).
3
decomposition reactions. Both experimental and kinetically mod-
eled results are reported herein.
(
1
0.1021/jp9058005 CCC: $40.75  2009 American Chemical Society
Published on Web 10/21/2009

Thermal Decomposition of Gaseous NH
4
NO
3
J. Phys. Chem. A, Vol. 113, No. 48, 2009 13557
Figure 1. Schematic diagram of the experimental apparatus.
Figure 2. Mass spectra of the AN decomposition products at different
reaction temperatures as indicated.
Experimental Procedure
The study of the thermal decomposition reaction of sublimed
AN was carried out by using a pyrolysis/mass spectrometric
technique in the temperature range 450-956 K. The schematic
diagram of the apparatus for the sublimation process and the
supersonic mass spectrometric sampling technique is shown in
Figure 1.
distillation. He and N (99.9995%, UHP, Specialty Gases) were
used without further purification. After an AN sample was
introduced into the reaction system, it was typically evacuated
under high vacuum at room temperature for several days to
minimize water contamination.
2
The sublimation of AN took place in a thermostatted sample
holder. In order to achieve homogeneous heating of the sample,
we employed continuously circulated hot ethylene glycol-water
solution using a NESLAB RTC-110 temperature controller
which has an accuracy and reproducibility of 0.3 K. The
pyrolysis of the sublimed AN sample entrained with 5-6.2 torr
He carrier gas was performed under slow-flow conditions in a
Results and Discussion
Kinetic Modeling of the AN Decomposition Reaction.
Thermal decomposition of AN was studied in the temperature
range 450-956 K at total flow rate (F in units of standard cubic
centimeter per minute, sccm) of 23 sccm with total pressure of
5 torr or total flow rate of 45 sccm with total pressure of 6.2
torr using He as a carrier gas. The initial reactants were obtained
from the sublimation of AN at the constant temperature of 423
K and carried into the preheated Saalfeld reactor at 450 K. The
typical mass spectra covering m/z ) 10-50 obtained at different
reactor temperatures are presented in Figure 2. No noticeable
peaks beyond m/z ) 50 were observed within our detectivity.
As the reaction does not take place below 450 K in our time
7
Saalfeld-type quartz tubular reactor tube, which has an inner
diameter of 10 mm and a length of 140 mm with a conical
sampling hole at the center. The reactor was mounted perpen-
dicularly to the detection axis of a quadrupole mass spectrometer
(
QMS, Extrel model C50), and the reaction tube was wrapped
with a 15 mm thick, 15 mm wide Nichrome ribbon and insulated
with ceramic wool. The reactor temperature could be varied
from 300 to 1000 K by adjusting the current through the heater.
In order to minimize heterogeneous surface effects, the inner
wall of the reactor was pretreated with boric acid, followed by
an extensive bake-out at 1000 K under high vacuum.
The detection chamber housing the mass spectrometer was
separated from the supersonic expansion chamber by a metal
plate with a 1.0 mm orifice skimmer (Beam Dynamics model
scale (t e 40 ms), the concentration of NH
equal to that of HNO ) and the small traceable amounts of N
and N (Figure 2, vide infra) were employed as the initial
3
(assumed to be
3
2
O
2
concentrations of the reactants present for the kinetic modeling
of higher temperature results.
1
) mounted at the center of the plate. The supersonically
The residence (or reaction) time was calculated with the
measured flow rate (F in sccm) based on the ideal gas law, t(s)
expanded molecular beam was introduced through the skimmer
into the ionization region of the spectrometer. The products from
the pyrolyzed reaction were supersonically sampled and ionized
by electron-impact ionization at 30 eV followed by QMS mass
selection. During the experiment, the pressures in the reaction
)
(273 × 60/760) (PV/FT), where V is the volume of the reactor
3
in cm , P is the total reaction pressure in torr, and T is the reactor
temperature in K.
-5
and detection chambers were maintained at (5-10) × 10 and
As indicated above, our kinetic modeling was performed
with the assumption that [NH ] ) [HNO ] , and the reaction
was initiated by the decomposition of HNO followed by the
-
6
(
5-10) × 10 torr, respectively.
3
0
3 0
The absolute concentrations of NH
3 2 2 2
, N , N O, and H O were
3
calibrated with carefully prepared standard mixtures. The
concentration of each individual molecule was obtained by the
chain reactions involving H and OH with NH and NO (x )
x
x
1
-3):
1
6
following formula: [R] ) 9.66 × 10 (%) PF
R T
/TF molecules/
cm , where % is the percentage of each molecule in its gas
3
NH NO (s) f NH (g) + HNO (g)
(1)
(2a)
(2b)
(3)
4
3
3
3
mixture, P is the total reaction pressure in torr, T is the reaction
temperature, F
the total flow rate of all gases. The initial concentration of HNO
generated by the sublimation of AN at 423 K, was assumed to
be the same as that of NH measured with the reactor
R
is the flow rate of each gas mixture, and F
T
is
HNO + M f OH + NO + M
3 2
3
,
HNO + (B O /SiO ) f OH + NO + (B O /SiO )
3
2
3
2
2
2
3
2
3
OH + NH f NH + H O
3
2
2
temperature set at 450 K, at which no reaction was found to
occur.
NH + NO f H NO + NO
(4a)
(4b)
2
2
2
AN (ammonium nitrate g99%, Aldrich), NH
3 2
, H O (deion-
f N O + H O
2
2
ized water), and N O were purified by standard trap-to-trap
2

1
3558 J. Phys. Chem. A, Vol. 113, No. 48, 2009
NH + NO f N H + OH
Park and Lin
(5a)
(5b)
2
2
f N + H O
2
2
For kinetic modeling, we employed 115 reactions which have
been utilized in our previous studies of the NH + NO (x ) 2,
and ADN decomposition reactions.
x
y
8
-11
3
3
; y ) 1, 2) reactions
The detailed reaction mechanism is provided in the Supporting
Information, and only key reactions employed in the modeling
are presented in Table 1. Because the homogeneous initiation
reactions, including HNO
NH f H NNO + H
were insufficient to account for the consumption of NH
the formation of H O, we have to take into consideration the
heterogeneous decomposition of HNO (2b) in our kinetic
modeling. The initial heterogeneous decomposition of HNO
was guided by the decomposition rate of HNO on glass reactors
by Johnston and co-workers. Further discussion on the
heterogeneous decomposition kinetics and its rate determination
will be given in greater detail later with a literature review.
Figure 3 shows our two sets of experimental data with kinetic
modeling results. The results of the modeling based on the
homogeneous initiation reaction 2a and the heterogeneous
initiation reaction 2b are presented by the dashed and solid
curves, respectively. The modeled concentrations with the
heterogeneous initiation reaction 2b agree reasonably well for
3
+ M f OH + NO
2
2
+ M (2a), HNO
O, and other potential processes,
and
3
1
2
+
3
2
2
3
2
3
Figure 4. Heterogeneous decomposition reaction rate of nitric acid
on the following: O, 10 mm id and 70 mm length (this work, boric
acid coated quartz reactor); 0, 6 mm id and 140 mm length (ref 13,
glass reactor); +, 25 mm id and 140 mm length (ref 13, glass reactor).
3
3
1
3
NO and NO
fragmentation peaks of HNO
noticeable peaks beyond m/z ) 50 were observed within our
detectivity under the experimental conditions, the parent peak
2
peaks at m/z ) 30 and 46, respectively, from the
3
at m/z ) 30, 46. Since no
of HNO at m/z ) 63 could not be utilized for kinetic
3
measurements.
the conversion of NH
3
and the growth of H
2
O. The other major
Key Elementary Reactions. The gas-phase dissociation
2
products were NO and NO , but we were not able to differentiate
reaction of HNO
3 2
into the NO and OH radicals (2a) and its
reverse reaction have been extensively investigated both
experimentally1
we employed our previous work on the HNO
rate which was done by high-level ab initio molecular orbital
4,15
and theoretically.
16-19
In kinetic modeling
decomposition
3
16
and statistical theory calculations. The potential energy surfaces
have been computed with a modified Gaussian 2 (G2M)
method.20 The rate constant had been calculated by means of
the canonical variational RRKM approach. This theoretically
predicted rate constant showed reasonably good agreement with
the available experimental results, and its rate is represented
3
2.7
3
16
by k2a ) 4.30 × 10 T exp(1250/T) cm /(mol s).
Another influential process, which generates the NH
and H O, OH + NH f NH + H O (3), has been well
established experimentally and theoretically over a broad
2
radical
2
3
2
2
2
1
temperature range. k
000 K. The existence of the curvature is consistent with our
theoretically predicted result for the reverse process, NH
3
exhibits a strong upward curvature above
1
2
+
3
3
2.94
H
2
O f OH + NH
mol s), computed with the transition state theory (TST) with
tunneling corrections using the TS parameters obtained by a
G2M/B3LYP/6-311G(d,p) calculation.22 The expression for k
given in the mechanism was computed with the equilibrium
3
, k-3 ) 2.33 × 10 T exp(-5566/T) cm /
(
3
-
2
0.53
constant K-3 ) 2.68 × 10
T
exp(5846/T); it was used
without adjustment.
The total rate constant and product branching ratios in reaction
a used for this work were determined in this laboratory by
4
laser-photolysis mass spectrometry (PLP/MS) over the temper-
1
0
ature range of 300-990 K. The rate constant is given by k
4
Figure 3. Comparison of experimental data and kinetic modeling
results for the sublimed AN decomposition process. Symbols represent
experimental data obtained from two different batches of AN samples.
Curves are kinetic modeling results with (solid curves) or without
16
-1.44
3
) 8.10 × 10
T
exp(-135/T) cm /(mol s) as a result from
O production, ꢀ4b ) k4b
4a + k4b), ꢀ4b was found to be independent of temperature,
.19 ( 0.02, in the range investigated. This result agreed well
this study. The branching ratio for N
2
/
(
k
(
dashed curves) the heterogeneous decomposition of HNO
concentrations are (a) NH ) HNO ) 2.30 mtorr, N ) 0.05 mtorr,
residence (reaction) time ) 25.75/T s (T in kelvin) and P ) 5.0 torr
with He as carrier gas, (b) NH ) HNO ) 1.70 mtorr, N ) 0.07
mtorr, N O ) 0.10 mtorr, residence (reaction) time ) 15.16/T s (T in
kelvin) and P ) 6.2 torr with He as carrier gas.
3
. Initial
0
3
3
2
2
3
with those reported by Hershberger et al., 0.14 ( 0.03 and
24
0
.24 ( 0.03, at room temperature and with that reached by
kinetic modeling of the NH + NO reaction in the temperature
range of 850-1350 K by Glarborg et al. However, our result
3
3
2
2
3
2
25

Thermal Decomposition of Gaseous NH
4
NO
3
J. Phys. Chem. A, Vol. 113, No. 48, 2009 13559
a
TABLE 1: Key Reactions and Rate Constants for the Kinetic Modeling of the Sublimed AN System
reactions
A
n
Ea
ref
1
2
NH NO ) NH + HNO
3
sublimation
4
3
3
0
0
0
1
1
0
1
0
0
0
3
7
6
6
6
7
7
8
0
7
a
HNO + M ) OH + NO + M
4.30 × 10
2.7
0.0
-2486
25120
566
16
3
2
2
3
4
4
5
5
6
7
8
b
HNO + (B O /SiO ) ) OH + NO + (B O /SiO ) 7.91 × 10
this workb
3
2
3
2
2
2
3
2
NH + OH ) NH + H O
2.00 × 10
6.56 × 10
1.54 × 10
1.43 × 10
1.20 × 10
2.11 × 10
8.73 × 10
2.00 × 10
2.1
22
10
10
9
3
2
2
a
b
a
b
NH + NO ) H NO + NO
-1.5
-1.5
1.4
268
2
2
2
NH + NO ) N O + H O
268
2
2
2
2
NH + NO ) N H + OH
-1776
298
2
2
NH + NO ) N +H O
1.6
9
2
2
2
OH + OH ) H O + O
1.4
-397
-1667
1000
15
38
10
2
OH + HNO ) H O + NO
3
3.5
3
2
OH + H NO ) HNO + H O
2.0
2
2
a
n
3
is in units of cal/mol. b First-order rate
Rate constants, defined by k ) AT exp(-E
coefficient.
a
/RT), are given in units of cm , mol, and s; E
a
was inconsistent with the large value of ꢀ4b ) 0.59 ( 0.03 at
Petit in a static reactor at 303 K,30 and they reported the
decomposition of HNO yields NO and NO as products.
Rogaski et. al also reported that HNO reacted heterogeneously
on Degussa FW2 (an amorphous carbon black comprising
medium oxides) leading to the formation of NO, NO , and H O.
Recently Choi and Leu studied extensively the decomposition
of HNO on Degussa FW2, graphite, hexane soot, and kerosene
2
6
room temperature reported by Meunier et al.
3
2
31
We have also carried out a series of experiments for the
determination of total rate constant and the branching ratios of
the pivotal reactions 5a and 5b employing the PLP/MS technique
3
2
2
9
32
covering a broad range of temperatures, 300-1200 K. We
determined the total rate constants for the reactions and their
3
7
1.40
product branching ratios as k5a ) 1.43 × 10 T exp(894/T)
soot and reported that its decomposition rates strongly depend
on the experimental conditions and the type of solid surface
1
7
-1.61
3
and k5b ) 1.20 × 10
T
exp(-150/T) cm /(mol s). The
+ NO,
kinetic data for product branching in reaction 5b, NH
2
used. Significant HNO
and NO, NO , H O, and other unidentified volatile products were
produced. Similar HNO decomposition behavior on graphite
3
decomposition was observed on FW2
-3
-4
can be represented as R5a ) 9.69 × 10 - 1.31 × 10 T +
2
2
-7
2
-11
3
3
.96 × 10 T - 9.72 × 10 T by a least-squares analysis
3
27
of R5a based on three different sets of our data (300-1200 K),
was also observed, although the extent of the decomposition
was much smaller than that on FW2. However, very little
28
those of Glarborg and co-workers (1200 - 1370 K), and those
2
9
of Votsmeier et al. (1330-1670 K).
Heterogeneous Decomposition of HNO
reactivity of HNO
surfaces. A fast heterogeneous decomposition of HNO
to NO , NO, H O, and O was also observed by Rossi and his
co-workers33 in their study on the thermal decomposition of
NH NO using mass spectrometric detection of vapor-phase
3
was shown on hexane and kerosene soot
3
. Nitric acid is the
3
leading
prototype of a sticky molecule having a significant residence
time on all surfaces, and its values strongly depend on the
experimental conditions and the type of technique employed.
2
2
2
4
3
1
3
In 1951 Johnston and his co-workers first studied the kinetics
of the thermal decomposition of HNO vapor in two glass cells
species and FTIR detection of condensable products. Theoreti-
cally, Parrinello and co-workers34 studied the detailed hetero-
geneous interaction processes between gas-phase nitric acid and
a graphite surface which led to the dissociation of the nitric
3
of considerably different surface-to-volume ratios and an inner
diameter of 6 or 25 mm with a length of 140 mm. All
experiments were performed with about 5-25 torr of HNO
3
at
2
acid and the production of NO and OH radicals in the gas phase
a total pressure of 1 atm using nitrogen, oxygen, or carbon
dioxide as a carrier gas in the temperature range of 373-738
K. The rate constants derived from their heterogeneous decom-
position reactions are summarized in Figure 4 for comparison
with our modeled values presented below. As shown in Figure
by ab initio molecular dynamics study at several different levels
of density functional theory (DFT).35
Furthermore, different types of heterogeneous reactions of
HNO
3
were studied by Rossi et al. They measured the reaction
on decane
(C10H22) soot surface and a series of salt powers (NaCl, NaBr,
probability and surface residence time of HNO
3
36
4
, the decomposition rate was significantly dependent on the
surface-to-volume ratio and insensitively on temperature below
73 K. However, there was a rapid change in the rate constant
37
KCl, and KBr) in a low-pressure flow reactor (Knudsen cell)
using modulated molecular beam mass spectrometry for the
quantification of reactant uptake and product release onto the
5
with temperature showing a first-order reaction above 700 K
without any dependence on carriers gases used in their
experimental conditions.
3
gas phase. The heterogeneous reaction of HNO with soot from
a rich decane flame was proposed to be reduced to HONO as
the main product, dependence on carrier gases formation of NO
The heterogeneous decomposition reaction of HNO
3
on an
amorphous carbon surface has been investigated by Thlibi and
2
and NO ; the latter also reacted on black soot to produce

1
3560 J. Phys. Chem. A, Vol. 113, No. 48, 2009
Park and Lin
heterogeneous decomposition of HNO
3
(2b) and another im-
portant secondary reaction, OH + NH
3
f H
2
2
O + NH (3),
which has been described earlier in detail.
Summary
3 2 2 2
The absolute yields of NH , H O, N O, and N measured in
the thermal decomposition of AN, sublimed at 423 K below
melting point, were kinetically modeled with a mechanism
consisting of 115 reactions, assuming that the initial concentra-
tion of NH
mechanism employed was established through our earlier studies
of the NH (x ) 2, 3) + NO (y ) 1, 2) systems, with the
addition of the HNO decomposition reaction whose rate
3 3
is approximately equal to that of HNO . The
x
y
3
constants were computed theoretically by means of ab initio
MO/statistical theory calculations. In order to account for the
fast overall decomposition reaction, the heterogeneous decom-
position of HNO
constant determined by varying its rate constant to match the
modeled result with the measured concentrations of NH and
3
has to be assumed in the mechanism; its rate
3
7
H
2
O could be reasonably represented by k2b ) 7.91 × 10
-1
exp(-12 600/T) s . The kinetically modeled results with the
heterogeneous initiation rate can satisfactorily account for the
overall experimental product formation over the temperature
range studied.
As mentioned in the Introduction, we had previously studied
Figure 5. Sensitivity analysis at 952 K with NH
3
) HNO
3
) 1.70
the kinetics of the thermal decomposition of ADN using the
mtorr, N
2
) 0.07 mtorr, N
2
O ) 0.10 mtorr, and P ) 6.2 torr with He
3
as carrier gas.
same apparatus; the measured yields of NH
3
, H
2
O, N
2
O, and
N
2
could be reasonably accounted for with the homogeneous
additional NO.36 HNO
also showed stronger absorption on salt
(g) + NaCl(s) f
2 2
[H,N,O]-mechanism using our theoretically predicted HN(NO )
3
decomposition rate constant without invoking the heterogeneous
initiation process as in the present AN case. The major difference
between the two systems lies primarily in the higher stability
of HNO
HN(NO
surfaces producing hydrogen halide as HNO
HCl(g) + NaNO
(s).37
As alluded to above, the homogeneous decomposition reaction
of HNO (2a) was far too slow and insufficient to initiate further
chain reactions as observed experimentally. As shown in Figure
with dashed curves, no noticeable reactant decay or product
formations were found. In order to account for the consumption
of NH and the formation of H O in our kinetic modeling (Figure
), we take into consideration the heterogeneous decomposition
of HNO (2b) (see Table 1). The heterogeneous decomposition
rate was determined by varying its rate to match the modeled
yields of NH and H O to experimentally measured concentra-
3
3
1
6
3
[D(HO - NO
2
) ) 50 kcal/mol] than that of
3
3
2
)
2
[D(HN(NO ) - NO ) 38 kcal/mol].
2
2
3
Acknowledgment. This work was supported by the Office
of Naval Research under grant no. N00014-02-1-0133. M.C.L.
gratefully acknowledges the support from Taiwan’s National
Science Council for a distinguished visiting professorship at the
Center for Interdisciplinary Molecular Science, National Chiao
Tung University, Hsinchu, Taiwan.
3
2
3
3
3
2
tions. The values of k2b are presented in Figure 4 together with
Johnston’s result13 for comparison. Our results may be repre-
Supporting Information Available: The reactions and rate
constants for the kinetic modeling of the sublimed AN system.
This information is available free of charge via the Internet at
http://pubs.acs.org.
7
-1
sented by k2b ) 7.91 × 10 exp(-12 600/T) s . In this work
all experiments were performed with 1.7 and 2.3 mtorr of HNO
derived from AN decomposition at total pressures of 6.2 and
.0 torr, respectively, using He as a carrier gas in the boric acid
3
5
coated quartz tubular reactor tube with an inner diameter of 10
mm and a length of 70 mm as aforementioned. As shown in
Figure 4, the heterogeneous decomposition rate of HNO on
3
References and Notes
(
1) Rosser, W. A.; Inami, S. H.; Wise, H. J. Phys. Chem. 1963, 67
(9), 1753.
(
2) Brower, K. R.; Oxley, J. C.; Tewari, M. J. Phys. Chem. 1989, 93,
the coated quartz surface was slightly faster than that on the
4
029.
glass surface at all temperatures studied (373-738 K) by
(
3) Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998,
1
3
Johnston and co-workers. Interestingly, the extrapolation of
Johnston’s result agrees with our result in the high temperature
range (>850 K).
2
7, 2351–2357.
(4) Friedman, L.; Bigeleisen, J. J. Chem. Phys. 1950, 18 (10), 1325.
(
5) Rossi, M. J.; Bottaro, J. C.; McMillen, D. F. Int J. Chem. Kinet.
1
993, 25, 549.
6) Lyon, R. K. Int. J. Chem. Kinet. 1976, 8, 318; United States Patent
Figure 5 presents the results of sensitivity analysis for the
(
three major species measured, NH
3
, H
2
O, and N
2
O at 952 K.
3,900,554.
(
7) Wyatt, J. R.; De Corpo, J. J.; McDowell, M. V.; Saalfeld, F. E.
Only reactions which are sufficiently influential (g5% that of
the most influential key process) are included in the figure. The
ReV. Sci. Instrum. 1974, 45, 916. J. Mass Spectrom. Ion Phys. 1975, 16,
3
3.
sensitivity coefficient is defined as Sij(t) ) ∂C
where C (t) is the concentration of species i at t and k
rate constant of the jth reaction. The results of the sensitivity
analysis show that the consumption of NH and the formation
of H O and N O products are strongly affected by the
i
(t)/∂k
j
·k
j
j
/C
is the
i
(t),
(8) Park, J.; Lin, M. C. Technologies and Combustion for a Clean
Environment. Proc. 4th Int. Conf. 1997, 34-1, 1–5.
9) (a) Park, J.; Lin, M. C. J. Phys. Chem. 1996, 100, 3317–19. (b)
Park, J.; Lin, M. C. J. Phys. Chem. A 1997, 101, 5–13.
10) (a) Park, J.; Lin, M. C. Int. J. Chem. Kinet. 1996, 28, 879–883. (b)
Park, J.; Lin, M. C. J. Phys. Chem. A 1997, 101, 2643–2647.
i
(
3
(
2
2

Thermal Decomposition of Gaseous NH
4
NO
3
J. Phys. Chem. A, Vol. 113, No. 48, 2009 13561
(
11) Thaxton, A. G.; Hsu, C.-C.; Lin, M. C. Int. J. Chem. Kinet. 1997,
(23) Quandt, R.; Hershberger, J. J. Phys. Chem. 1996, 100, 9407.
(24) Lindholm, R.; Hershberger, J. J. Phys. Chem. A 1996, 27,
2
9, 245–251.
(
(
12) Musin, R. N.; Lin, M. C. J. Phys. Chem. A 1998, 102, 1808.
13) Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am.
4991.
(25) Glarborg, P.; Dam-Johansen, K.; Miller, J. A. Int. J. Chem. Kinet.
Chem. Soc. 1951, 73, 2319–21.
14) (a) Donahue, N. M.; Dubey, M. K.; Morhschladt, R.; Demerjian,
K. L.; Anderson, J. G. J. Geophys. Res. 1997, 102, 6159. (b) Gershenzon,
Yu. M.; Dement’ev, A. P.; Nalbandyan, A. B. Kinet. Catal. 1979, 20, 565.
1995, 27, 1207.
(
(26) Meunier, H.; Pagsberg, P.; Sillesen, A. Chem. Phys. Lett. 1996,
261, 277–282.
(27) Park, J.; Lin, M. C. J. Phys. Chem. A 1993, 103, 8906–07.
(28) Glarborg, P.; Kristensen, P. G.; Dam-Johansen, K.; Miller, J. A. J.
Phys. Chem. A 1997, 101, 3741.
(29) Votsmeier, M.; Song, S.; Hanson, R. K.; Bowman, C. T. J. Phys.
Chem. A 1999, 103 (11), 1566.
(30) Thlibi, J.; Petit, J. C. In Impact of Emissions from Aircraft and
Spacecraft upon the Atmosphere; Schumann, U., Wurzel, D., Eds.; Koln:
Germany, 1994.
(
(
c) Smith, G. P.; Golden, D. M. Int. J. Chem. Kinet. 1978, 10, 489–501.
d) Glaenzer, K.; Troe, J. Ber. Bunsen-Ges. Phys. Chem. 1974, 78, 71. (e)
Godfrey, T. S.; Hughes, E. D.; Ingold, C. J. Chem. Soc. 1965,(f) Harrison,
H.; Johnston, H. S.; Hardwick, E. R. J. Am. Chem. Soc. 1962, 84, 2478–
2
482.
(
(
15) Tsang, W.; Herron, J. T. J. Phys. Chem. Ref. Data 1991, 20, 609.
16) (a) Chakraborty, D.; Park, J.; Lin, M. C. Chem. Phys. 1998, 231,
3
1
9. (b) Zhu, R. S.; Lin, M. C. J. Chem. Phys. 2003, 119 (20), 10667–
(31) Rogaski, C. A.; Golden, D. M.; Williams, L. R. Geophys. Res. Lett.
0677.
1997, 24, 381.
(
(
17) Doclo, K.; Roethlisberger, U. Chem. Phys. Lett. 1998, 297, 205.
18) Houk, K. N.; Condroski, K. R.; Pryor, W. J. Am. Chem. Soc. 1996,
(32) Choi, W.; Leu, M.-T. J. Phys. Chem. A 1998, 102, 7618.
(
33) Rossi, M. J.; Bottaro, Jeffrey C.; McMillen, D. F. Int. J. Chem.
1
1
18, 13002.
Kinet. 1993, 25 (7), 549–70.
34) (a) Rodriguez-Fortea, A.; Iannuzzi, M.; Parrinello, M. J. Phys.
(
(
19) Sumathi, R.; Peyerhimhoff, S. D. J. Chem. Phys. 1997, 107, 1872.
20) Mebel, A. M.; Morokuma, K.; Lin, M. C. J. Chem. Phys. 1995,
(
Chem. C 2007, 111 (5), 2251–2258. (b) Rodriguez-Fortea, A.; Iannuzzi,
M.; Parrinello, M. J. Phys. Chem. B 2006, 110 (8), 3477–3484.
03, 7414.
21) (a) Atkinson, R.; Baulch, D. L.; Cox, R. A.; Hampson, R. F., Jr.;
Kerr, J. A.; Rossi, M. J.; Troe, J. J. Phys. Chem. Ref. Data 1997, 26, 1329–
499. (b) Corchado, J. C.; Espinosa-Garcia, J.; Hu, W.-P.; Rossi, I.; Truhlar,
(
(
35) (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648. (b) Becke, A. D.
J. Chem. Phys. 1992, 96, 2155.
36) Munoz, M. S. S.; Rossi, M. J. Phys. Chem. Chem. Phys. 2002, 4
20), 5110–5118.
37) (a) Koch, T. G.; Van den Bergh, H.; Rossi, M. J. Phys. Chem.
1
(
D. G. J. Phys. Chem. 1995, 99, 687–694. (c) Cohen, N.; Westberg, K. R.
J. Phys. Chem. Ref. Data 1991, 20, 1211–1311. (d) Jeffries, J. B.; Smith,
G. P. J. Phys. Chem. 1986, 90, 487. (e) Zabielski, M. F.; Seery, D. J. Int.
J. Chem. Kinet 1985, 17, 1191. (f) Salimian, S.; Hanson, R. K.; Kruger,
C. H. Int. J. Chem. Kinet. 1984, 16, 725.
(
(
Chem. Phys. 1999, 1 (11), 2687–2694. (b) Fenter, F. F.; Caloz, F.; Rossi,
M. J. J. Phys. Chem. 1996, 100 (3), 1008–1019.
(
38) Xia, W. S.; Lin, M. C. J. Chem. Phys. 2001, 114, 4522–4532.
(
22) Mebel, A. M.; Moskaleva, L. V.; Lin, M. C. THEOCHEM 1999,
2
23, 461–462.
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