Burning rate of solid propellants can be effectively improved by adding catalysts and using smaller size ammonium perchlorate (AP). Although few reports, the exploration of changing the size of AP primary particles by catalysts is of great significance for improving combustion performance. Here, taking Co-bipy as an example, the potential advantages of such materials as AP decomposition catalysts are reported. Due to the existence of NO 3 − combined with oxygen rich environment provided by AP, the structural self-transformation from micronrods to nanoparticles can be quickly realized during the heating process. More importantly, when Co-bipy decomposes, it can play the role of "scalpel" and in situ cut AP particles. Results show that high-temperature decomposition of Co-bipy/AP occurs at 305.8 °C, which is 137.5 °C lower than that of pure AP. Catalytic mechanism is discussed by in situ IR and TG-IR, CoO can effectively increase the content of reactive oxygen species and weaken the N-H bond, realizing the rapid oxidation of NH 3 . Eventually, the behavior of Co-bipy cutting AP particles is tested. This interesting catalyst structure self-transformation behavior can not only realize the influence on AP, but also perform a positive function in the combustion process of solid propellants, such as opening the adhesive AP interface.

The design of highly dispersed active sites of hollow materials and unique contact behavior with the components to be catalyzed provide infinite possibilities for exploring the limits of catalyst capacity. In this study, the synthesis strategy of highly open 3‐dimensional frame structure Prussian blue analogues (CoFe‐PBA) was explored through structure self‐transformation, which was jointly guided by template mediated epitaxial growth, restricted assembly and directional assembly. Additionally, good application prospect of CoFe‐PBA as combustion catalyst was discussed. The results show that unexpected thermal decomposition behavior can be achieved by limiting AP(ammonium perchlorate) to the framework of CoFe‐PBA. The high temperature decomposition stage of AP can be advanced to 283.6 °C and the weight loss rate can reach 390.03% min−1. In‐situ monitoring shows that CoFe‐PBA can accelerate the formation of NO and NO2. The calculation of reaction kinetics proved that catalytic process was realized by increasing the nucleation factor. On this basis, the catalytic mechanism of CoFe‐PBA on the thermal decomposition of AP was discussed, and the possible interaction process between AP and CoFe‐PBA during heating was proposed. At the same time, another interesting functional behavior to prevent AP from caking was discussed.

Catalytic stability is the prerequisite for the catalyst to achieve high catalytic efficiency. This study finds a new path that Prussian Blue (PB) ultrathin nanosheet assembly material (PB‐NSa) is designed and used to reach efficient catalysis through continuous interaction with ammonium perchlorate (AP, component to be catalyzed). Based on the strong oxidation environment provided by AP, the decomposition of PB occurs in advance, the product Fe2O3 accelerates the decomposition of AP that can release a large amount of gas, then reacts on Fe2O3 and disperses it near the undecomposed AP, finally realizing continuous and efficient catalysis. The results show that under the catalysis of PB‐N, “deactivation” stage of AP thermal decomposition disappears, showing two consecutive exothermic stages, high temperature decomposition peak of AP is reduced to 341.1 °C, the reduction range is 73.1 °C. Combining kinetic calculation and TG‐IR test, it is found that PB‐NSa can keep excellent catalytic stability, which depends on its special structure and interaction with AP. This research provides a design idea for the material to achieve catalytic stability, which will greatly promote its rapid industrialization.

No abstract

No abstract