Scientists at McGill University in Montreal have created a new type of solid rocket fuel that they say is safer and cleaner than existing high-energy aerospace fuels.
Rocket fuels typically need to be hypergolic, combusting instantly when they come into contact with an external oxidizer. Most of the fuels used today are derived from hydrazine, a highly toxic and unstable compound of hydrogen and nitrogen that must be handled with inordinate care. Despite this, it’s estimated that around 12,000 tons of carcinogenic hydrazine-based fuels are released into the atmosphere each year by the aerospace industry.
Described in Science Advances, the McGill rocket fuel is based on zeolitic imidazolate frameworks (ZIFs), a type of metal organic framework (MOF) where metal ions are clustered together with an organic molecule called a linker. According to the researchers, the high latent energy of these MOFs can be unlocked using simple chemical triggers, producing a rapid hypergolic response and ignition within 2 milliseconds.
“This is a new, cleaner approach to making highly combustible fuels, that are not only significantly safer than those currently in use, but they also respond or combust very quickly, which is an essential quality in rocket fuel,” said co-senior author Tomislav Friščic, a professor in McGill’s Chemistry Department.
The team explored six different types of ZIFs using zinc, cobalt and cadmium ions. As well as examining hypergolic behaviour, the thermal and kinetic stability of the materials was also tested, with all six fuels demonstrating strong performance.
“Although we are still in the early stages of working with these materials in the lab, these results open up the possibility of developing a class of new, clean and highly tuneable hypergolic fuels for the aerospace industry,” said the first author Hatem Titi, a post-doctoral fellow who works alongside Friščić.
The team will now investigate commercialising the new fuels, in partnership with McGill and Acsynam, a company previously spun out of the Friščić lab.