Ultra-efficient catalysts were developed that are cost-effective to make and simple to scale. The 3D-printed catalysts could potentially be used to in future to power hypersonic flight while simultaneously cooling the system.
Only a few experimental planes have reached hypersonic speed (defined as above Mach 5 — over 6,100 km an hour or 1.7 km per second). Many challenges remain in the development of hypersonic air travel such as the extreme heat levels. Using fuel as a coolant was one of the most promising experimental approaches to the overheating problem. Fuels that can absorb heat while powering an aircraft are a key focus but they rely on heat-consuming chemical reactions that need highly efficient catalysts.
The heat exchangers where the fuel comes in contact with the catalysts must be as small as possible, because of the tight volume and weight constraints in hypersonic aircraft. To make the new catalysts, the team 3D printed tiny heat exchangers made of metal alloys and coated them with synthetic minerals known as zeolites. The researchers then replicated at lab scale the extreme temperatures and pressures experienced by the fuel at hypersonic speeds to test the functionality of their design. When the 3D-printed structures heat up, some of the metal moves into the zeolite framework — a process crucial to the unprecedented efficiency of the new catalysts.
The next steps for the research team include optimizing the 3D-printed catalysts by studying them with X-ray synchrotron techniques and other in-depth analysis methods. The researchers also hope to extend potential applications of the work into air pollution control for vehicles and miniature devices to improve indoor air quality — especially important in managing airborne respiratory viruses like COVID-19.