Hyrazine is commonly used as an aerospace propellant for low to medium thrust applications. Hydrogen peroxide, however, is a much less toxic alternative. And a PhD student at Canterbury is developing a 3D printed catalyst bed that will enable more efficient use of this as a propellant for rockets.

To generate thrust from hydrogen peroxide, a catalyst is needed – often a previous metal such as silver or platinum. This catalyst then rapidly decomposes hydrogen peroxide into an energetic gas.

Simon Reid, who is studying a PhD in chemical and process engineering at the University of Canterbury, has designed his 3D printed catalyst bed with the surface coated with the catalyst for hydrogen peroxide to pass through.

“By passing liquid hydrogen peroxide over a catalyst bed it speeds up the decomposition reaction,” says Reid.

“The reaction disassociates the molecule, turning it into water and oxygen. It is the breakup of the molecule that produces a large amount of energy and heat. The heat vaporises the water and results in a high temperature gas – passing the hot gas through a nozzle provides thrust.”

The shape that Reid is using is called a gyroid – “a mathematical shape, more optimal for catalytic processes, and cannot be manufactured using traditional techniques”. It is hoped that this shape will in the catalyst bed will overcome loss of catalyst, a large pressure drop, and maximising thrust balanced against the concentration of hydrogen peroxide – as some catalysts have a low melting point relative to the temperature of the gases coming out.

“Dawn Aerospace, who are a local collaborator on the project, currently use hydrogen peroxide as a propellant for their reusable space plane that will deliver satellites into orbit. The catalyst they use is quite rudimentary and has been around since the 1960s, that is what the research is trying to improve,” says Reid.

Working with Callaghan Innovation, testing for the newly designed catalyst bed will soon begin and results of efficiency will be compared against existing designs.

“Only a few companies are seriously considering hydrogen peroxide. Hopefully by designing these efficient catalysts we can promote it as a viable alternative to hydrazine, and help make the aerospace industry that little bit safer.”