Thermal decomposition of ammonia borane at 357 K

Abstract

The heat effect of ammonia borane decomposition at 357 K under atmospheric pressure in glass and copper cells has been determined by calorimetry. The enthalpy of BH3NH3 heat-induced decomposition in glass ampoules is of–24.8±2.3 kJ/mol; this value includes the structural reorganization into diammoniate of diborane of–4.0±2.8 kJ/mol and the thermal effect of decomposition into polyamidoborane of–20.8±1.6 kJ/mol. In the case of experiments in copper cells a much higher (–47.6±8.3 kJ/mol) heat evolution is observed. The solidstate 15N and 11B NMR analysis of samples after the calorimetric experiment has shown that partial oxidation of the sample into boric acid occurs in copper cells.