Optimization of a green bipropellant with monoethanolamine, 2-propanol, and hydrogen peroxide 90 wt% as oxidizer

Environmental and safety concerns have driven the search for green alternatives to conventional hypergolic propellants, particularly hydrazine and its derivatives. This study presents the development and optimization of a green bipropellant composed of monoethanolamine (MEA), 2-propanol, and copper(II) nitrate trihydrate, using hydrogen peroxide (H $$_2$$ O $$_2$$ ) 90 wt% as the oxidizer. A Rotatable Central Composite Design (RCCD) was applied to minimize the ignition delay time (IDT), resulting in an optimized formulation with a minimum IDT of 22 ms. The inclusion of 2-propanol enhanced ignition behavior and combustion performance. The optimized formulation exhibited a specific impulse of 168 s, a characteristic velocity of 1523 m/s, a density-specific impulse ( $$\rho _b I_\text {sp}$$ ) of 216 s $$\cdot $$ g/cm $$^3$$ , a flash point of 27.5 $$^\circ $$ C, and a calorific value of 23170 J/g. UV-Vis spectroscopy confirmed the formation of the [Cu(MEA) $$_4$$ ] $$^{2+}$$ complex, which catalyzes the decomposition of H $$_2$$ O $$_2$$ and enables hypergolic ignition. These results underscore the potential of MEA/2-propanol-based formulations as efficient, safer, and environmentally friendly alternatives to conventional hypergolic bipropellants, particularly for applications that demand reduced toxicity, improved ignition characteristics, and enhanced volumetric performance.