Simon Reid, an engineering student completing his Ph.D. at the University of Canterbury, in Christchurch, New Zealand, is working on a 3D printed catalyst bed that will enable more efficient use of concentrated hydrogen peroxide (a bleaching agent) as non-toxic rocket fuel for launch vehicles requiring low to medium thrust.
Reid, who completed a Bachelor of Engineering in Chemical and Process Engineering in 2019, identified hydrogen peroxide as a much less toxic alternative to hydrazine, a commonly used aerospace propellant for low to medium thrust applications. Hydrazine is a suspected carcinogen and requires additional safety equipment and protocols when in use which drives up the cost of using rocket fuel.
Alternatively, hydrogen peroxide is largely non-toxic to humans and has common household uses such as bleaching hair or cleaning wounds. However, to generate thrust from hydrogen peroxide a catalyst is needed. The catalyst used is often precious metal, such silver or platinum, which rapidly decomposes hydrogen peroxide into an energetic gas.
In Reid’s 3D printed design, the surface of the ceramic catalyst bed is 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. 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 vaporizes the water and results in a high-temperature gas – passing the hot gas through a nozzle provides thrust,” Simon explained
The aim of his research is to refine the design of the catalyst bed to maximize the generation of thrust from hydrogen peroxide as a rocket fuel while limiting the loss of catalyst from the bed and keeping the components light. Working with Callaghan Innovation’ AddLab, Simon turned 3D printing to generate novel catalytic structures for non-toxic rocket fuel with better properties – lower pressure drops and use different catalytic materials to improve the performance of the thrusters. “The shape I’m using is called a gyroid. It’s a mathematical shape, more optimal for catalytic processes, and cannot be manufactured using traditional techniques,” he explained.
The three things Simon is trying to overcome using the gyroid in the non-toxic rocket fuel catalyst bed are loss of catalyst, a large pressure drop, and maximizing thrust balanced against the concentration of hydrogen peroxide – some catalysts have a low melting point relative to the temperature of the gases coming out.
“Dawn Aerospace, a local collaborator on the project, currently uses 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,” said Reid.
Simon will begin testing the efficiency of the newly designed catalyst bed soon, comparing the results 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.”