Thermal decomposition behavior, thermal stability and thermal explosion risk evaluation of a novel green hydroxylamine ionic liquid salt

Abstract

Hydroxylamine salts are important chemical raw materials to a wide range of applications ranging from the synthesis of caprolactam, to pesticides and medicine. However, challenging setbacks associated with environmental pollution, equipment corrosion and explosive safety hazards are inevitably encountered with traditional hydroxylamine salts due to the release of strong acids and their poor thermal stability. In order to address those mentioned above environmental and safety challenges, an acidic ionic liquid, instead of inorganic acids, was introduced to stabilize hydroxylamine. Hence, a novel green chemical-hydroxylamine 1-sulfobutyl-3-methyl imidazole hydrosulfate salt ((NH2OH)2·[HSO3-b-mim]·HSO4) was created. It is essential to systematically study thermal decomposition behavior, thermal stability and safety of the novel hydroxylamine ionic liquid salt. This study used the thermogravimetric method to investigate the thermal decomposition process of (NH2OH)2·[HSO3-b-mim]·HSO4. The mechanism of thermal decomposition function and kinetic model were obtained by the Coats-Redfern method. The thermal explosion risk of (NH2OH)2·[HSO3-b-mim]·HSO4 under adiabatic conditions was evaluated using a differential scanning calorimeter (DSC) and an accelerated adiabatic calorimeter (ARC). The results indicate that (NH2OH)2·[HSO3-b-mim]·HSO4 exhibits good thermal stability and safety, providing an avenue for the future production, storage and application of this eco-friendly hydroxylamine product.