Molecular interpretation for the synergistic catalysis of platinum/hyperbranched polyethyleneimine composites on the pyrolysis of endothermic hydrocarbon fuels

The initiated/catalytic cracking of endothermic hydrocarbon fuels (EHFs) is a viable strategy for improving the thermal management capabilities of regenerative cooling. Either noble metal nanoparticles (NPs) or hyperbranched polymers (HPs) has been confirmed to promote the pyrolysis of EHFs but their synergistic catalytic mechanism remains unclear. Aiming to address such issues, the cooling performance of n-dodecane in the presence of platinum (Pt), decanoic anhydride modified hyperbranched polyethyleneimine (DHPEI), and their composite (DHPEI-Pt) was investigated using ReaxFF MD simulations, respectively. The results indicate that all three additives significantly reduce the initial pyrolysis temperature of n-dodecane, ultimately leading to an increase in heat sink through enhanced conversion and gas yield. The composite DHPEI-Pt demonstrates better cooling performance compared to single additive alone, with a 28 % increase in heat sink (5.89 MJ/kg at 2800 K) and a 20 % reduction in activation energy of n-dodecane compared to pure pyrolysis. This is attributed to the synergistic mechanism between the chain initiation reaction promoted by DHPEI self-cracking and the dehydrogenation reaction catalyzed by Pt. This work bridges the current gap in the microscopic understanding of the synergistic catalytic mechanism between metals and HPs, and provides reliable guidance for the development of EHFs catalytic cracking technology.