Confined rapid thermolysis/FTIR spectroscopy of hydroxylammonium nitrate

Measurements have been made to investigate the isothermal decomposition characteristics of hydroxylammonium nitrate (HAN) in the condensed phase over the temperature range from 120 to 180 C. Experiments were conducted at atmospheric pressure in a nitrogen environment using confined rapid thermolysis (CRT)TFTIR spectroscopy. Results show that the major IR-active decomposition species of HAN-water mixtures are H₂O, N₂O, NO, NO₂, and HNO₃. For solid HAN, N₂O is the dominant species formed, and HNO₃ concentration is somewhat higher than that in solution state at the same temperature. It is conjectured that the evolution of species from the HAN-water mixture can be split into three general separate regions: 1) proton transfer is initiated and subsequent reactions form a pool of the highly reactive species HONO and HNO, 2) these species are involved in many subsequent reactions causing the evolution of gas-phase species and depletion of HAN, and 3) reactions in the condensed phase occur among products from HAN decomposition. Foils exposed to rapid thermolysis of HAN experienced essentially no pitting or fracturing over the range of temperatures studied.