Encapsulation of ferrocenes in microporous ZIF-67 channels for boosting their anti-migration tendency and catalytic activity in ammonium perchlorate thermal decomposition

Abstract

The enhancement of the anti-migration performance of ferrocene-based burning rate catalysts (BRCs) and their catalytic influence on ammonium perchlorate (AP) combustion in composite solid propellants through the confinement effect is acknowledged as an effective strategy. In this investigation, FcR@ZIF-67 nanocomposites were fabricated by introducing commercial ferrocenes (FcR = Cat, NBF, TBF, and NOF) into microporous ZIF-67 nanochannels. In the catalysis performance evaluations, the Cat@ZIF-67 exhibited prominent combustion catalytic efficiency on AP thermal decomposition by advancing the AP pyrolysis temperature peak by 111.4 °C and increasing its release heat by 2.3 times. Moreover, the anti-migration tests demonstrated that FcR@ZIF-67 composites remain predominantly immobile during prolonged storage at 50° C. The investigation results of in-situ solid FTIR, TG-FTIR-MS, and theoretical calculations for the AP thermal degeneration with Cat@ZIF-67 as a promoter, indicated that, in the oxygen-rich environment of AP, the thermal disintegration of Cat@ZIF-67 creates a Fe2O3-Co3O4 heterostructure that facilitated the generation of reactive oxygen species. This, in turn, accelerated the pyrolysis of AP and formed more thermodynamically stable gaseous products, advancing its exothermic degradation temperature and increasing its release heat. Based on these discoveries, a hypothetical catalytic mechanism for the thermal decomposition of AP is proposed.