Triazine-Augmented Catalytic Activity of Cyclobutadiene Tricarbonyl Fe(0) Complexes for Thermal Decomposition of Ammonium Perchlorate

Abstract

The employment of combustion catalysts is an effective way to improve ammonium perchlorate (AP) decomposition performance during the combustion process of composite solid propellants. A classic half-sandwich iron carbonyl complex was proposed as the leading structure for exploring high-performance combustion catalysts, in which functionalized cyclobutadienes (Cb) tune the thermal stability and catalytic activity. The thermolysis of Fe2(CO)9 and substituted alkynes initiated [2 + 2] cyclization of alkyne triple bonds and gave η4-cyclobutadiene iron(0) tricarbonyl complexes, CbR1,R2-Fe-CO (1–6), with decent yields. A molecular structure analysis found that the conjugation of the aromatic substituents aryl, ferrocenyl (Fc), and triazinyl (Tz) finely tuned the coordination bonds around the Fe(0) center. The DSC/TG experiments found a remarkable thermal stability of CbTz,R-Fe-CO (3–6) with characteristic thermolysis temperatures (CTT) as high as 500 °C. The catalytic experiments demonstrated that the CTT of Cb-Fe-CO (2-6) overlapped with AP high-temperature decomposition (HTD). The thermal cross-coupling of HTD of AP and CTT of CbTz,Fc-Fe-CO (6) significantly augmented catalytic AP decomposition, resulting in a maximum energy release as high as 2828 J/g.

Evaluation of Mono and Bimetallic Ferrocene-Based 1,2,3-Triazolyl Compounds as Burning Rate Catalysts for Solid Rocket Motor

“…Several studies have focused on synthesizing combustion catalysts to improve CSPs’ burning rate and antimigration ability . These catalysts can be classified into four categories: transition metal oxides, , nanoparticles, − transition metal complexes, − and ferrocene (Fc)-based compounds. ,,− Transition metal oxides are inexpensive and simple to produce but have less worth in combustion. Nanoparticles have the advantage of being easier to transfer electrons and significantly reducing the decomposition temperature and activation energy for AP. , However, they are prone to aggregate and preferentially adsorbed on components during mixing, resulting in less dispersion of nano-Fe 2 O 3 particles and heat release of AP .…”