Development of a reaction mechanism for liquid-phase decomposition of ammonia borane

Publication date: Available online 12 October 2019Source: Thermochimica ActaAuthor(s): Tanusree Chatterjee, Stefan T. ThynellAbstractUsing quantum mechanics (QM) calculations, a detailed reaction mechanism for liquid-phase decomposition of ammonia borane (AB) is developed. The primary objective of this study is to provide comprehensive understanding regarding the chemical kinetics involved in H2 release process during AB dehydrogenation, to explore the pathways of oligomerization leading to ring formation during the second phase of AB decomposition and to explain the experimental observations using the proposed mechanism. Along with QM studies, we have also performed TGA/DSC studies coupled with Fourier transform infrared (FTIR) spectroscopy. In previous experimental studies, there is no consensus regarding release of NH3 in gaseous phase during thermal decomposition of AB. Experiments performed in this study using FTIR spectroscopy confirm the presence of NH3 in gaseous phase during both steps of AB decomposition. Furthermore, we have also studied the effect of different heating rates on the trend of NH3 evolution during AB decomposition, which has not been done previously. To identify reaction pathways based on QM studies, transition state theory (TST) is used in this study. Using G4(MP2) compound method, thermodynamic properties are calculated for both equilibrium species and transition states using the Gaussian 09 program package. For these condensed-phase calculations, S...

Source: Thermochimica Acta - October 13, 2019 Category: Chemistry Source Type: research