Carbon Dioxide-Facilitated Low-Temperature Hydrogen Desorption from Polyaminoborane

Abstract

Gaseous CO2 environments dramatically enhance the thermolytic dehydrogenation of polyaminoborane (PAB) at 85 - 90 degrees C. By exposing PAB to 2.07 MPa CO2, 5.48 wt % hydrogen based on the mass of ammonia borane (AB) desorbs in less than 1 h, while 4 h is required to generate 5.04 wt % hydrogen by maintaining PAB at 120 degrees C without using CO2. The total hydrogen desorbed from the initial AB is 11.38 wt % under the CO2 atmosphere at 85 degrees C, including the hydrogen release during the transition from AB to PAD. The main contributing factors to the facile hydrogen release are the promoting effect of newly formed formic acid and the exothermic effect of the reaction between PAB and CO2. Spectroscopic and elemental analyses of the solid spent PAB confirm the degree of dehydrogenation and indicate that the decomposed residue has an empirical formula of BN0.86H2.34(CO2)(0.17).