The thermal decomposition of solid urea hydrogen peroxide

Abstract

The thermal decomposition of solid urea hydrogen peroxide has been studied at temperatures between 333 and 358 K in flowing nitrogen atmospheres. The decomposition of freshly-prepared material follows Avrami-Erofeyev kinetics, −ln(1 − α) = kt n , where n = 2 at low temperatures and low conversions, and apparently increases with degree of conversion and temperature up to 17 at 358 K. The high values of n are associated with complex melting of the adduct with liberation of oxygen. An activation energy of 113 kJ mol −1 for the low- n decomposition has been calculated; the frequency factor is 10 13 s −1. Aged material decomposes by a phase boundary process with an activation energy of 66 kJ mol −1 and a frequency factor of 10 6 s −1. Micrographs are presented which clarify the bulk kinetics.