Engineered ammonia nanospheres via self-assembly: Novel integrated coking suppression strategy for deep thermal cracking of hydrocarbon fuels

Endothermic hydrocarbon fuels are specialized fuels tailored for hypersonic aircraft to simultaneously achieve cooling and propulsion, yet their operational reliability is severely compromised by coking during high-temperature thermal cracking. Although the addition of ammonia to hydrocarbons has been shown great potential to enhance its anti-coking performance, practical applications remain constrained by system instability and scalability limitations. Herein, a new strategy to construct uniformly dispersed ammonia-water-in-hydrocarbon fuel systems is developed by encapsulating ammonia water within hydrocarbon-soluble nanospheres. These nanospheres self-assemble via energy-minimization principles during controlled mixing of ammonia, hydrocarbons, and surfactants (oleic acid and Tween). The resulting system exhibits enhanced heat sink and superior anti-coking performance, driven by synergistic mechanisms of ammonia and surfactants. Specifically, decomposition-derived radicals introducing oxygen/nitrogen defects into coke deposits to inhibit graphitization pathways and potentially deactivate resonance-stabilized radicals (coking precursors). This innovative approach provides a scalable platform for engineering stable, uniformly dispersed fuels tailored for hypersonic thermal management, while revealing mechanistic insights into the cooperative anti-coking effects of ammonia water nanospheres.