Reaction of hydrogen peroxide vapor on platinum on alumina spheres

Abstract

An experimental and numerical study of the rates of decomposition of hydrogen peroxide vapor on catalytic surfaces was conducted. Hydrogen peroxide vapor and helium carrier gas flowed over a catalyst (platinum on alumina spheres of varying diameter) at a total pressure of <3 Torr, simulating the conditions of a flash evaporation propulsion system for space applications. After reacting on the catalyst, the product gas composition was measured using near-infrared laser absorption on a known hydrogen peroxide line in a multi-pass flow cell. Global reaction rate constants were inferred for varying catalyst surface areas, residence times, and temperatures. The combination of these experimental data with numerical simulations led to the conclusion that under the conditions employed in this study, namely low peroxide partial pressures and low Reynolds numbers, decomposition rates are transport-limited rather than reaction-limited. These results may be applicable to the development of catalyst bed designs for small satellite propulsion systems.