ABSTRACT Hydroxylamine nitrate (HAN) is a key energetic component in green monopropellant formulations and is increasingly replacing traditional highly toxic hydrazine‐based fuels, with growing applications in rocket propulsion systems. However, the microscopic mechanism underlying its decomposition remains inadequately understood. In this study, density functional theory (DFT) was used to develop a microkinetic model for the thermal decomposition of HAN in both the gas phase and on the Ir(111) surface. The results demonstrate that the Ir catalyst markedly enhances the decomposition of HAN. Given the inherent instability and autocatalytic decomposition behavior of HAN, seven possible reaction pathways were systematically investigated. Among these, Pathway 5:HNO 3 * + HNO* → NO 2 + NO + H 2 O + * + * was identified as the most favorable decomposition route, indicating that NO 2 and NO are key reaction products. Further analysis of the temperature dependence of the reaction kinetics showed that above 543.15 K, the selectivity of NO decreases after reaching a maximum of 48.3%, whereas the selectivities of NO 2 and N 2 increase significantly. Moreover, electronic structure analysis revealed electron transfer from the Ir surface to nitrogen and oxygen atoms of the adsorbates during catalysis, offering important theoretical insights into the catalytic mechanism.
Xie et al. (Tue,) studied this question.