Environmental Engineering Reference
In-Depth Information
Fig. 5.18
Relationship
between combustion velocity
of nitroglycerine and pressure
30
25
20
15
10
5
0
0
200
400
600
800
1000
P
(mmHg)
5.4.1.3 The Preparation of Nitroglycerine
The early preparation method of nitroglycerine included direct esteri
cation by
glycerinum and nitric acid.
CH
2
OH
CH
2
ONO
2
+
3HNO
3
CHOH
CHONO
2
+
3H
2
O
CH
2
OH
CH
2
ONO
2
It was later discovered that the reaction designed had low reaction rate but also that
the glycerinum and intermediate products of the reaction have some side effects in the
oxidation environment for a long time, resulting in unsafety of the production process.
The preparation process of nitroglycerine with nitro-sulfuric acid as nitrating agent
and sulfuric acid as dehydrating agent is used in the modern method of nitri
cation.
It is well known that glycerinum dinitrate can be produced by nitration of
glycerinum in a mixed acid of nitric acid and sulfuric acid. The typical composition
of the mixed acid is 1.0 % H
2
O, 47
50 % HNO
3
, and 49
52 % H
2
SO
4
. The
-
-
appropriate reaction temperature is 5
15
°
C. The nitration coef
cient is in the range
-
of 5
11. The conversion of glycerinum is up to 95
97.6 %. It is an exothermal
-
-
reaction with
ʔ
H of 439.5 J/mol glycerinum.
In industry, because of the accumulation of nitration heat, the reaction heat
usually exceeds the value obtained at laboratory scale. The main reaction mechanism
of nitration of glycerinum can be expressed as:
H
2
SO
4
C
3
H
5
(ONO
2
)
3
+ 3H
2
O +439.5 mol
C
3
H
5
(OH)
3
+ 3HNO
3
Actually, the nitrate heat of the nitration reaction of glycerinum in industry is
two times higher than that at small scale. The reaction rate is as fast as only 1
