Chemistry Reference
In-Depth Information
Fig. 8.10
Plots of the non-
isothermal rate of AP decom-
position (DTA with thermal
dilution) against the conver-
sion degree at ω = 10
.
0(
1
),
7.4 (
2
), 5.0 (
3
), 1.5 (
4
), 1.05
(
5
) deg min
−
1
min
-1
0.16
0.12
0.08
0.04
0.2
0.4
0.6
0.8
1.0
0.2
0.4
0.6
0.8
1.0
The nonisothermal reaction rates obtained by DTA and TGA are in a very good
agreement within the experimental accuracy (Fig. 8.13).
The results of the analysis of the experimental nonisothermal data and the ˙
)
dependencies (Fig. 8.14) recalculated for isothermal conditions (see Sect. 4.3)
clearly indicate the existence of two stages in AP high-temperature decomposi-
tion. The first stage (“fast”) is characterized by relatively low conversion degrees
(
η
(
η
<
0
.
1-0.15), while the second one (“slow”) takes place at higher conversion
degrees (
η
>
0.15-0.18). The “fast” decomposition can be described by a kinetic
equation for a first-order reaction with activation energy
E
1
= 133
η
4kJmol
−
1
.The
data on
k
1
(Fig. 8.15) obtained are in a satisfactory agreement with the literature data
[10, 9] obtained by different (isothermal) methods based on weight decrease and the
evolution of gas.
The expression for
k
1
remains constant at temperatures from 200 to 450
◦
C, which
implies that the mechanism for the “fast” AP decomposition does not change in this
temperature range, although the contribution from each stage changes.
The reaction order of the “slow” stage is 0.5 (Table 8.2 and Fig. 8.16), and its
activation energy is
E
2
= 133
±
4kJmol
−
1
(Fig. 8.17).
±
