3
76
PRASAD AND VASHISHT
CONCLUSIONS
A one-step process for production of caprolactam and
polycaprolactam by liquid phase ammoximation of cyclo-
hexanone by nitric oxide and ammonia over a Al2O3–
SiO2 catalyst is demonstrated. Although ammoximation of
cyclohexanone by hydrogen peroxide and ammonia results
in high selectivity and yield of cyclohexanone oxime, the
present process is better in the sense that it produces poly-
caprolactam directly. A maximum conversion of 46.67%
with a maximum yield of 37.78% and selectivity of 80.95%
for caprolactam, at a cyclohexanone : NO : NH3 molar ratio
of 1 : 2.9 : 1.7 and a temperature of 348 K, is achieved.
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4
(
SCHEME II. Mechanism of ammoximation of cyclohexanone by nitric
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3
4
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Our study, however, was in the liquid phase and we did not
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(
7
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�
�
�
8
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(
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The resulting caprolactam reacts with ammonia to pro- 18. Sato, S., Hasebe, S., Sakurai, H., Urabe, K., and Izumi, Y., Appl. Catal.
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duce polyamide via anionic polymerization (3). The degree
of polymerization of the reaction mixture increased with
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1
(
2
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133 (1978).
2
a
2
2
2
relation [�] = KM , where K and a are constants and [�] is
the intrinsic viscosity. The values of K and a were taken to
�
3
be 3.2 � 10 and 0.62, respectively (22). Molecular weights
were determined for random runs and were always found
to be in the range 500–5000.