Endothermic catalytic cracking of liquid hydrocarbons for thermal management of high-speed flight vehicles

Regenerative cooling paired with catalytic cracking of hydrocarbons can address thermal management and efficient fuel combustion in supersonic air streams, as a sustainable approach in developing high-speed flight vehicles. Solid acid catalyst promoted cracking of supercritical hydrocarbon fuels can combine physical and chemical heat sink capacities which can provide the required endothermicity to utilize the excess heat as a viable solution for thermal management. Furthermore, resulting cracked hydrocarbon products exhibit shorter ignition delay times than the parent fuels leading to more efficient combustion, even at supersonic speeds. The supercritical state of the fuel also reduces the carbon deposition arising from the process by fluidising any coking products. This process would therefore address the problem of excessive vehicle body heat, while providing better combusting fuels. This review aims to provide insights from a catalysis perspective that summarise the current state of research regarding identifying suitable energy dense hydrocarbon fuels, most promising catalysts, and strategies to reduce carbon formation. The scientific understanding gained to date regarding optimal fuel conversion, selectivity to desired products, methods to minimize coking and achieve high heat sink capacity are reviewed. The use of additive manufacturing as an emerging efficient approach to intensify this process using small scale reactor geometries is also discussed.