Synthesis and stoichiometric optimization of cobalt-manganese oxide nanocatalysts for decomposition of the green monopropellant H2O2

Nanocrystalline mixed oxides of cobalt and manganese with spinel structure were successfully synthesized via the self-combustion method using urea as fuel and tested as catalysts for the decomposition of the green monopropellant H2O2. The obtained powders were subjected to characterization by X-Ray Diffraction (XRD), Infrared Absorption Spectroscopy (FTIR), Thermogravimetric Analysis (TG), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Additionally, the catalytic activity of the obtained samples was evaluated via measurements of the volume of gas produced and the drop test. The powder XRD analysis confirmed the crystallization of a single cubic spinel-type oxide for a higher cobalt content sample, molar Co:Mn ratio of 2:1, which presented the best catalytic performance, with faster reaction induction and a higher amount of gas produced. Additionally, the effect of calcination on the microstructural and catalytic properties was studied. The results indicate that further calcination at temperatures from 600 to 800 degrees C leads to a decrease in the catalytic activity, which is probably related to the loss of surface area. Only the sample calcined at 800 degrees C showed clear signs of particle sintering. Thus, self-combustion synthesis seems an exciting route to prepare catalysts with the required properties for application in small propulsive systems based on monopropellants, such as hydrogen peroxide.

Automated summary

Nanocrystalline mixed oxides of cobalt and manganese with spinel structure were successfully synthesized using the self-combustion method. The catalytic performance of the obtained samples was evaluated, and the effect of calcination on the microstructural and catalytic properties was studied. The results showed that the sample with a higher cobalt content exhibited the best catalytic performance.