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A thermoanalytical study of the catalytic oxidation of carbonaceous residues of nitrocellulose decomposition
305
Thennochinzica Acta. 29 0
(1979) 305-308 Els,evier Scientific Publishing Company, Amsttxdam - Printed in the Netherlands
A THERMOANALYTICAL
STUDY OF THE CATALYTIC
OF NITROCELLULOSE
N. Eisenreich
OXIDATION
OF CARBONACEOUS
RESIDUES
DECOMPOSITION
and A. Pfeil
Fraunhofer-Gesellschaft, 7507 Pfinztal
Institut
fiir Chemie
der Treib-
und Explosivstoffe,
1 (G-F-R.)
ABSTRACT Carbonaceous
residues
of nitrocellulose
ted from TA and combustion tive
experiments
and doublebase and analyzed
propellants were collec-
in air by TG and quantita-
DTA.
The residues react like charcoal. lates have
strong influence
a
Burning
catalysts
on the reaction
like lead and copper
interval
and kinetic
salicy-
parameters_
INTRODUCTION Under
certain
under
formation
ved during DB in
conditions
pure NC* and NC contained
of a carbonaceous
slow heating
residue.
of NC or DB in a TA experiment
decompose
for example,
or during
is obser-
combustion
of
a bomb.
The oxidation
process
of this material
is an important
DB (refs. l-2). In this paper, the oxidation rial
in DB thermally
This residue,
in air and the
influence
of burning
reaction
catalysts
step.in
the combustion
of the carbonaceous
of
mate-
is studied.
METHODS The following zer, sample
samples
weight
Thermoanalyzer,
were .analyzed by simultaneous
5 mg, heating
rate
1 K/min)
TG/DTA
(Mettler
and quantitative
Thermoanaly-
DTA (DuPont
990
sample weight 0.5 - 1.0 mg, heating rate 10 K/min) in air (purge
rate 10 l/h): I) Carbonaceous
residues
The DB samples cylate)
of DB combustion
were El (catalyst-free),
and E4 (4% Cu salicylate)
2) Carbonaceous
residues
in a Crawford
type
E2 (4% Pb304),
(details
strand burner.
E3 (4% Pb sali-
see ref. 3).
of El, E2, E3 and E4 obtained
after heating
at a rate of 1 K/min in air. *
Abbreviations
used:
DB = doublebase
propellant,
NC = nitrocellulose
to 523 K
306 3) Carbonaceous
residues
a rate of 0.5 K/min
of NC (13.3% N) obtained in air and mixtures
after heating
of the residue
to 523 K at
with 4% Cu salicy-
late or 4% Pb salicylate4) Charcoal
and activated
and beech
(Dynamit
salicylate Assuming
z were
tative
reaction
and their
kinetics,
calculated
DTA curves
ting curve
Nobel AG)
(Merck),
charcoal
mixtures
of black peat,
white peat
with 4% CuO, Pb304,
Cu
or Pb salicylate.
simple
factors
charcoal
using
activation
from a direct
energies
least squares
E and z as fit parameters
E and pre-exponential fit of the TG and quanti-
(ref. 4). The following
fit-
was used:
-i Y(T)
=
exp
(y denotes
I-z/aJexp
the sample
the universal
of
weight,
(I)
T the temperature,a
the
linear heating
rate
and R
gas constant).
The quantitative
rivative
(-E/RT) dTJ
DTA curves
(1) _
normalized
on the
area were fitted
by the first
de-
_
RESULTS Fig. 1 shows typical
a strong
exothermic
thermal
diagrams
peak at temperatures
in ref. 3. In the presence
cribed shifted
drastically
Similar
observations
An analysis IR spectra
samples
were made
above 600 K, in addition
of burning
catalysts
display
to those
the reaction
des-
interval .is
in the thermal
the residues
diagrams
of the slow thermal
of the combustion decomposition
residu-
of NC and
(e.g. Figs. 3-4):
of the carbonaceous in Fig. 3 show
residues
yielded
a carbon
that the characteristic
and the C-O band of pre-heated
NC (II)
are absent
content
of
C-H and N-O bands in the residues
>95%.
The
of NC (I)
of NC (III)
(IV).
and DB combustion TABLE
The DTA curves
to lower temperatures_
es of the 06 samles, the carbon
of the DB samples.
1
Kinetic
parameters
sample
of the oxidation E
log2
reaction %
sample
kcal/mole combust.res.El
decomp.res.
ES E4 El E2 E3 E4
27.0 5.99 23.0 5.33 not evaluated 22-O 5-67 27.5 4.89 86.0 .24.85 60.5 15.85 24.2 5.20
E
z
4:
5.92
0.8
log
kcal/mole 2.5 2.6
2-g 0.9 1.3
002
NC pure + Cu sal + Pb sal
charcoal + Cu sal -I-cue f f Pb sal Pb,O,
29.8 21.1
45.6 28-4 28.9 26.2
30.2 34.0
‘3.51 11.54 5.59 6.00 4.99 7-99 6.78
0.8 1.3 0.7 1.3 1.0 O-8 0.8
Fiq. 1. TG / DTA of DB samples heating rate of 2 KImin.
In Figs.
3-4
experimental
Fig. 2. IR spectra of NC (I), thermally pretreated NC (II, III) and E2 combustion residue (IV).
at a
quantitative
DTA and TG
of points are compared to the corresponding suming simple first The quality in most
cases.
significantly
order kinetics_
thermal decomposition 38.6,
as-
which is C I
of the second order fit
curves were
in all cases.
The parameters of charcoal ted charcoal
curves which were calculated
by the mean standard deviation
The mean standard deviation higher
by a series
The parameters are summarized in Table 1.
is expressed
of the fit
fit
curves represented
were closest
residues
and the charcoals
41.1 and 45.6 kcal,
the parameters of. all
to those obtained
for the combustion and
of DB and NC. The activation of white peat,
respectively.
for
activa-
black peat and beech were 46.8,
A linear
samples in a plot
energies
relationship
was found between
of log z against E.
DISCUSSION In view of the small standard deviation describe that,
the experiment al results . The kinetic
under the conditions
charcoal charcoal.
we used simple first
type material.
stated,
process
to
parameters in Table 1 suggest
NC or NC in DB thermally
The oxidation
order kinetics
decompose into a
of this material
is like that of
a)
Fig. 3. DTA of combustion residues El (o), E2 (+) and E4 (A) at a heating rate of 10 K/min (a) and TG of decomposition residues El (0), E2 (A), E3 (+) and E4 (x) at
Fig. 4. NC (0)) sal (A) (a) and sal (A)
TG of decomposition residues NC + Cu sal (+) and NC + Pb at a heating rate of 1 K/min TG of charcoal (0) with Cu and Pb sal (+) at a heating
a heating
rate
1 K/min
(b).
formation
of
The
rate
of
IR spectra
1 K/min
reflect
(b).
characteristic
steps
of
in the
the
charcoal
type material during the thermal decomposition of NC by the change or disappearance of C-H, C-O or N-O bands. The activation
tion
of charcoal
agree The
well burning
samples
and the
catalyst-free
with those reported in the catalysts
have
a drastic
energies
literature influence
are comparable
reacand
(ref_5). on the
In DB compounds the burning cata lysts
studied.
of the oxidation
NC and DE residues
oxidation
act
process of all
in two ways:
they
catalyse the decompos!tion of NC (ref. 3) and are still active during the oxidation
of
the
charcoal
type
residue
formed
during
decomposition
_
ACKNOWLEDGEMENT We are indebted to Texdata Vertriebs-GmbH, Ettlingen for writing our draft on their VYDEC word processing system. REFERENCES 1 D-J Hewkin and P_D_ Stone, 2 N_ Eisenreich, Propellants 3.N. Eisenreich, and A. Pfeil, 4 N_ Eisenreich, Dissertation 5 N. Patai, E. Hoffmann and
ICT Jahrestagung 1974, Karlsruhe, Explos., 3(1978)141. Thermochim. Acta, in press. TU Miinchen (1978).
L. Rajbenbach,
J_appl.Chem.,
p-35.
2(1952)306.
Thennochinzica Acta. 29 0
(1979) 305-308 Els,evier Scientific Publishing Company, Amsttxdam - Printed in the Netherlands
A THERMOANALYTICAL
STUDY OF THE CATALYTIC
OF NITROCELLULOSE
N. Eisenreich
OXIDATION
OF CARBONACEOUS
RESIDUES
DECOMPOSITION
and A. Pfeil
Fraunhofer-Gesellschaft, 7507 Pfinztal
Institut
fiir Chemie
der Treib-
und Explosivstoffe,
1 (G-F-R.)
ABSTRACT Carbonaceous
residues
of nitrocellulose
ted from TA and combustion tive
experiments
and doublebase and analyzed
propellants were collec-
in air by TG and quantita-
DTA.
The residues react like charcoal. lates have
strong influence
a
Burning
catalysts
on the reaction
like lead and copper
interval
and kinetic
salicy-
parameters_
INTRODUCTION Under
certain
under
formation
ved during DB in
conditions
pure NC* and NC contained
of a carbonaceous
slow heating
residue.
of NC or DB in a TA experiment
decompose
for example,
or during
is obser-
combustion
of
a bomb.
The oxidation
process
of this material
is an important
DB (refs. l-2). In this paper, the oxidation rial
in DB thermally
This residue,
in air and the
influence
of burning
reaction
catalysts
step.in
the combustion
of the carbonaceous
of
mate-
is studied.
METHODS The following zer, sample
samples
weight
Thermoanalyzer,
were .analyzed by simultaneous
5 mg, heating
rate
1 K/min)
TG/DTA
(Mettler
and quantitative
Thermoanaly-
DTA (DuPont
990
sample weight 0.5 - 1.0 mg, heating rate 10 K/min) in air (purge
rate 10 l/h): I) Carbonaceous
residues
The DB samples cylate)
of DB combustion
were El (catalyst-free),
and E4 (4% Cu salicylate)
2) Carbonaceous
residues
in a Crawford
type
E2 (4% Pb304),
(details
strand burner.
E3 (4% Pb sali-
see ref. 3).
of El, E2, E3 and E4 obtained
after heating
at a rate of 1 K/min in air. *
Abbreviations
used:
DB = doublebase
propellant,
NC = nitrocellulose
to 523 K
306 3) Carbonaceous
residues
a rate of 0.5 K/min
of NC (13.3% N) obtained in air and mixtures
after heating
of the residue
to 523 K at
with 4% Cu salicy-
late or 4% Pb salicylate4) Charcoal
and activated
and beech
(Dynamit
salicylate Assuming
z were
tative
reaction
and their
kinetics,
calculated
DTA curves
ting curve
Nobel AG)
(Merck),
charcoal
mixtures
of black peat,
white peat
with 4% CuO, Pb304,
Cu
or Pb salicylate.
simple
factors
charcoal
using
activation
from a direct
energies
least squares
E and z as fit parameters
E and pre-exponential fit of the TG and quanti-
(ref. 4). The following
fit-
was used:
-i Y(T)
=
exp
(y denotes
I-z/aJexp
the sample
the universal
of
weight,
(I)
T the temperature,a
the
linear heating
rate
and R
gas constant).
The quantitative
rivative
(-E/RT) dTJ
DTA curves
(1) _
normalized
on the
area were fitted
by the first
de-
_
RESULTS Fig. 1 shows typical
a strong
exothermic
thermal
diagrams
peak at temperatures
in ref. 3. In the presence
cribed shifted
drastically
Similar
observations
An analysis IR spectra
samples
were made
above 600 K, in addition
of burning
catalysts
display
to those
the reaction
des-
interval .is
in the thermal
the residues
diagrams
of the slow thermal
of the combustion decomposition
residu-
of NC and
(e.g. Figs. 3-4):
of the carbonaceous in Fig. 3 show
residues
yielded
a carbon
that the characteristic
and the C-O band of pre-heated
NC (II)
are absent
content
of
C-H and N-O bands in the residues
>95%.
The
of NC (I)
of NC (III)
(IV).
and DB combustion TABLE
The DTA curves
to lower temperatures_
es of the 06 samles, the carbon
of the DB samples.
1
Kinetic
parameters
sample
of the oxidation E
log2
reaction %
sample
kcal/mole combust.res.El
decomp.res.
ES E4 El E2 E3 E4
27.0 5.99 23.0 5.33 not evaluated 22-O 5-67 27.5 4.89 86.0 .24.85 60.5 15.85 24.2 5.20
E
z
4:
5.92
0.8
log
kcal/mole 2.5 2.6
2-g 0.9 1.3
002
NC pure + Cu sal + Pb sal
charcoal + Cu sal -I-cue f f Pb sal Pb,O,
29.8 21.1
45.6 28-4 28.9 26.2
30.2 34.0
‘3.51 11.54 5.59 6.00 4.99 7-99 6.78
0.8 1.3 0.7 1.3 1.0 O-8 0.8
Fiq. 1. TG / DTA of DB samples heating rate of 2 KImin.
In Figs.
3-4
experimental
Fig. 2. IR spectra of NC (I), thermally pretreated NC (II, III) and E2 combustion residue (IV).
at a
quantitative
DTA and TG
of points are compared to the corresponding suming simple first The quality in most
cases.
significantly
order kinetics_
thermal decomposition 38.6,
as-
which is C I
of the second order fit
curves were
in all cases.
The parameters of charcoal ted charcoal
curves which were calculated
by the mean standard deviation
The mean standard deviation higher
by a series
The parameters are summarized in Table 1.
is expressed
of the fit
fit
curves represented
were closest
residues
and the charcoals
41.1 and 45.6 kcal,
the parameters of. all
to those obtained
for the combustion and
of DB and NC. The activation of white peat,
respectively.
for
activa-
black peat and beech were 46.8,
A linear
samples in a plot
energies
relationship
was found between
of log z against E.
DISCUSSION In view of the small standard deviation describe that,
the experiment al results . The kinetic
under the conditions
charcoal charcoal.
we used simple first
type material.
stated,
process
to
parameters in Table 1 suggest
NC or NC in DB thermally
The oxidation
order kinetics
decompose into a
of this material
is like that of
a)
Fig. 3. DTA of combustion residues El (o), E2 (+) and E4 (A) at a heating rate of 10 K/min (a) and TG of decomposition residues El (0), E2 (A), E3 (+) and E4 (x) at
Fig. 4. NC (0)) sal (A) (a) and sal (A)
TG of decomposition residues NC + Cu sal (+) and NC + Pb at a heating rate of 1 K/min TG of charcoal (0) with Cu and Pb sal (+) at a heating
a heating
rate
1 K/min
(b).
formation
of
The
rate
of
IR spectra
1 K/min
reflect
(b).
characteristic
steps
of
in the
the
charcoal
type material during the thermal decomposition of NC by the change or disappearance of C-H, C-O or N-O bands. The activation
tion
of charcoal
agree The
well burning
samples
and the
catalyst-free
with those reported in the catalysts
have
a drastic
energies
literature influence
are comparable
reacand
(ref_5). on the
In DB compounds the burning cata lysts
studied.
of the oxidation
NC and DE residues
oxidation
act
process of all
in two ways:
they
catalyse the decompos!tion of NC (ref. 3) and are still active during the oxidation
of
the
charcoal
type
residue
formed
during
decomposition
_
ACKNOWLEDGEMENT We are indebted to Texdata Vertriebs-GmbH, Ettlingen for writing our draft on their VYDEC word processing system. REFERENCES 1 D-J Hewkin and P_D_ Stone, 2 N_ Eisenreich, Propellants 3.N. Eisenreich, and A. Pfeil, 4 N_ Eisenreich, Dissertation 5 N. Patai, E. Hoffmann and
ICT Jahrestagung 1974, Karlsruhe, Explos., 3(1978)141. Thermochim. Acta, in press. TU Miinchen (1978).
L. Rajbenbach,
J_appl.Chem.,
p-35.
2(1952)306.