TY - JOUR
T1 - Confined rapid thermolysis studies of ammonia borane
AU - Weismiller, M. R.
AU - Wang, S. Q.
AU - Chowdhury, A.
AU - Thynell, S. T.
AU - Yetter, R. A.
N1 - Funding Information:
The authors would like to gratefully acknowledge and thank the Air Force Office of Scientific Research (AFOSR) and NASA for their sponsorship of this program under contract no. FA9550-11-1-0002.
PY - 2013/1/10
Y1 - 2013/1/10
N2 - Thermochemical calculations of ammonia borane (AB, H3NBH 3), which has a hydrogen content of 19.6% by weight, indicate that it has the potential to boost specific impulse in chemical propulsion applications due to its high hydrogen content and the moderate exothermicity of decomposition. Research to date on AB decomposition has focused on relatively slow heating rates. These studies have shown that the mass lost due to decomposition increases with increasing heating rate. This trend has been confirmed in this work, as mass loss continues to increase up to 50 K/min, the limit of most TGA/DSC instruments. In this research effort, confined rapid thermolysis was used to examine the decomposition of AB under isothermal conditions. Fourier transform infrared (FTIR) spectroscopy and time-of-flight mass spectrometry (ToF-MS) were employed to identify the gaseous products, which include H2, NH3, H2NBH2, and c-N3B3H6. The decomposition resulted in significant condensed-phase products as well, which were pressed into a KBr pellet and examined with FTIR spectroscopy. FTIR transmission spectra of the condensed-phase products with several heating durations show the disappearance of absorption bands of AB and appearance of bands attributed to polymeric species. Condensable gas-phase products were also collected from the stream of decomposition products, and FTIR spectroscopy showed they have absorption bands similar to the polymeric species, indicating that the H2NBH 2 will readily condense out of the gas-phase products and polymerize at low temperatures.
AB - Thermochemical calculations of ammonia borane (AB, H3NBH 3), which has a hydrogen content of 19.6% by weight, indicate that it has the potential to boost specific impulse in chemical propulsion applications due to its high hydrogen content and the moderate exothermicity of decomposition. Research to date on AB decomposition has focused on relatively slow heating rates. These studies have shown that the mass lost due to decomposition increases with increasing heating rate. This trend has been confirmed in this work, as mass loss continues to increase up to 50 K/min, the limit of most TGA/DSC instruments. In this research effort, confined rapid thermolysis was used to examine the decomposition of AB under isothermal conditions. Fourier transform infrared (FTIR) spectroscopy and time-of-flight mass spectrometry (ToF-MS) were employed to identify the gaseous products, which include H2, NH3, H2NBH2, and c-N3B3H6. The decomposition resulted in significant condensed-phase products as well, which were pressed into a KBr pellet and examined with FTIR spectroscopy. FTIR transmission spectra of the condensed-phase products with several heating durations show the disappearance of absorption bands of AB and appearance of bands attributed to polymeric species. Condensable gas-phase products were also collected from the stream of decomposition products, and FTIR spectroscopy showed they have absorption bands similar to the polymeric species, indicating that the H2NBH 2 will readily condense out of the gas-phase products and polymerize at low temperatures.
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U2 - 10.1016/j.tca.2012.10.008
DO - 10.1016/j.tca.2012.10.008
M3 - Article
AN - SCOPUS:84870334059
SN - 0040-6031
VL - 551
SP - 110
EP - 117
JO - Thermochimica Acta
JF - Thermochimica Acta
ER -