Nature of Catalytic Activities of CoO Nanocrystals in Thermal Decomposition of Ammonium Perchlorate

Abstract

This work addresses the chemical nature of the catalytic activity of X-ray "pure" CoO nanocrystals. All samples were prepared by a solvothermal reaction route. X-ray diffraction indicates the formation of CoO in a cubic rock-salt structure, while infrared spectra and magnetic measurements demonstrate the coexistence of CoO and Co 3O 4. Therefore, X-ray "pure" CoO nanocrystals are a unique composite structure with a CoO core surrounded by an extremely thin Co 3O 4 surface layer, which is likely a consequence of the surface passivation of CoO nanocrystals from the air oxidation at room temperature. The CoO core shows a particle size of 22 or 280 nm, depending on the types of the precursors used. This composite nanostructure was initiated as a catalytic additive to promote the thermal decomposition of ammonium perchlorate (AP). Our preliminary investigations indicate that the maximum decomposition temperature of AP is significantly reduced in the presence of CoO/Co 3O 4 composite nanocrystals and that the maximum decomposition peak shifts toward lower temperatures as the loading amount of the composite nanocrystals increases. These findings are different from the literature reports when using many nanoscale oxide additives. Finally, the decomposition heat for the low-temperature decomposition stages of AP was calculated and correlated to the chemical nature of the CoO/Co 3O 4 composite nanostructures.

A New Energetic Complex [Co(2,4,3‐tpt)2(H2O)2]·2NO3: Synthesis, Structure, and Catalytic Thermal Decomposition for Ammonium Perchlorate

“…Many researchers have reported a higher E a for catalyzed AP than that of pure AP. [28,29] It is contrary to the generally observed trend of lowering E a for a reaction whose rate is increased by a catalyst. This discrepancy may be attributed to facts like strong interaction and binding between AP and the title complex and secondly along with E a the pre-exponential factor (A) also showed variations.…”

Synthesis and Characterization of CuO Nanoparticles by the Chemical Liquid Deposition Method and Investigation of its Catalytic Effect on the Thermal Decomposition of Ammonium Perchlorate

“…However, from these studies two mechanisms were proposed which are based on the proton and electron transfer theory and are associated with the LTD and HTD, respectively [38]. According to the proton transfer theory, decomposition starts through proton transfer from NH 4 + to ClO 4 ⁻ (Equation 2) and then further reactions cause partial decomposition of AP. From the electron transfer theory, the main decomposition stage, which occurs at higher temperatures, is initiated by electron transfer from anion to cation which leads to NH 4̊ and ClO 4 0 species [43]:…”

“…It is also greatly influenced by the presence of electron mediators which can facilitate electron transfer from ClO 4 ⁻ to NH 4 …”

“…Ammonium perchlorate (AP) is known as the most common oxidizer in strategic military weapons and various solid propellants, and its efficiency in such applications is highly influenced by various transition metal oxides, especially when in a nano crystalline form [3]. The catalytic activity of these nano-metal oxide systems on the thermal decomposition of AP has usually been attributed to the higher surface area of the nanoparticles, the increase in defects in the nano-structures, and synergistic effects of the catalyst and support of the nano-composites [4][5][6][7].…”

Nano-metal oxide: potential catalyst on thermal decomposition of ammonium perchlorate

“…Oxides of cobalt are also studied as catalyst in thermal decomposition of AP as reported [84]; when AP was mixed with CoO nanocrystals, the HTD process disappeared completely. CoO nanocrystals were prepared by a solvothermal reaction.…”