The synthesis of hydrazine from ammonia in a glow discharge

Abstract

The glow discharge is one of the most economic methods of producing electrons as reaction promoters in gas phase chemical reactions. The reaction considered here is that between electrons and ammonia to produce hydrazine with nitrogen and hydrogen as by products. A parallel flow cylindrical reactor with porous electrodes was operated at a pressure of 10 torr over a range of power levels from 1 to 10 watts input/cc of reactor volume. Continuous direct current and pulsed direct current power was supplied to the reactor. Previous work has shown that high energy yields of hydrazine are obtained by using low discharge power levels and low residence times. This work compares the fast flow continuous d. c. system with the pulsed d. c. system of equivalent residence time. The results show that the pulsed discharge gives higher energy yields and conversions to hydrazine than the continuous d. c. discharge energy yields of over 40 gms/kwh being recorded. The reason for the improved results in the pulsed discharge system is thought to be due to the lower overall hydrogen atom concentration present. The lower concentration reduces the degradation of hydrazine by hydrogen atoms. The discharge pulse also gives higher energy electrons and hence a higher rate of primary reaction between the electrons and ammonia. The relative effects of the different discharge zones, the addition of helium gas to the ammonia and the effects of wall reactions on the energy yield and conversions to hydrazine were determined for the continuous d. c. system. The current voltage characteristics of the continuous d. c. discharge were also measured. A tentative kinetic model of the reacting system is proposed and recommendations are made for future studies in this field.