Atomic Perspective about the Reaction Mechanism and H₂ Production during the Combustion of Al Nanoparticles/H₂O₂ Bipropellants

Abstract

The combination of Al nanoparticles (ANPs) and hydrogen peroxide (H 2 O 2 ) can serve as environmentally friendly bipropellants and maximize the energetic benefits through harnessing heat release and chemical energy stored in H 2 . This work presents an atomic insight into the combustion mechanism of ANPs/H 2 O 2 . Two main paths, including the ANPs oxidation by H 2 O 2 to produce H 2 and Al oxides, and the catalytic decomposition of H 2 O 2 on ANP surface to generate O 2 and H 2 O, are confirmed to maintain the combustion. OH and HOO radicals as well as H 2 O, O 2 , H 2 , and Al oxides are detected as dominant intermediates and products therein. It is evidenced that higher temperature, smaller ANP size, and higher H 2 O 2 concentration enhance the combustion. Moreover, atomic details show that the H desorption from ANPs/Al clusters is a critical step for both H 2 production and ANP oxidation. In addition, microexplosion that has been confirmed in hot and dense O 2 is not observed in H 2 O 2 , even with a high concentration, possibly due to a slower heat release. Besides, the observed excellent specific impulse of the ANP/H 2 O 2 bipropellants could be attributed to the considerable H 2 production, instead of heat release. This work is expected to present an overall atomic perspective about the combustion mechanism of ANP/H 2 O 2 bipropellants.

Atomistic Insights into the Influence of High Concentration H2O2/H2O on Al Nanoparticles Combustion: ReaxFF Molecules Dynamics Simulation

“…The force field has been successfully used to reveal the influence of carbon coatings on the oxidation of ANPs and the combustion reaction of ANPs with oxidizing agents (O 2 , H 2 O, H 2 O 2 , etc.) [49,50]. First, an Al particle with a diameter of 2.8 nm and 675 atoms was constructed.…”

NOx on Al: The Unusual Adsorption Site Preference and the Attraction among Adsorbates

“…16 For H 2 O x (x = 1 or 2) molecules, both the dissociated H and O atoms diffuse into the ANPs, eventually producing H 2 and aluminum oxides. 17 Starik et al expanded the ignition and combustion study of ANPs to incorporate CH 4 in a mixture with O 2. 18 They found that the ignition delay and combustion efficiency of ANPs were ameliorated when compared to Al powder.…”

“…Meanwhile, various AlN chain products (AlN 4 , Al n N 2 n +2 , and AlN 3 O) are formed . For H 2 O x ( x = 1 or 2) molecules, both the dissociated H and O atoms diffuse into the ANPs, eventually producing H 2 and aluminum oxides . Starik et al expanded the ignition and combustion study of ANPs to incorporate CH 4 in a mixture with O 2.…”