Catocene and Butacene Permanence as Ferrocenic Liquid Burning Rate Catalyst for Solid Composite Propellants and Comparison With Recent Developments

ABSTRACT A short review about ferrocene‐based burning rate catalysts (FBRC) for solid composite propellants is presented. Historically, transition metal oxides (TMO) have been utilized as burning rate catalysts (BRC) since the start of solid rocket propellant development. However, these compounds have a marked tendency to migrate through the propellant grain and crystallize at boundary surfaces. Consequently, FBRC emerged as an alternative to TMO. After reviewing recent advances in the field, we suggest that the continued use of Catocene [2,2′‐bis(ethylferrocenyl)propane] and Butacene as liquid BRC of choice is based on a trade‐off between high burning rates, limited migration from propellant, simpler synthetic pathways, and lower costs of production in comparison with later developments in the area of FBRC. Then, this work aims to contribute to the state of the art of FBRC research, highlighting the importance of Catocene and Butacene, in comparison with the most recent developments in the field of FBRC, particularly regarding their role in decreasing the decomposition temperature of ammonium perchlorate and/or increasing the burning rate.