Energetic metal-organic framework based on multinuclear clusters of Cu(II) and Fe(III) and its catalytic action on thermal decomposition of solid propellant components (RDX, HMX, CL-20 and AP)

Abstract

Using nitrogen-rich tetrazole derivatives with multifunctional groups and ligand sites in metal–organic frameworks (MOFs) is a strategy to enhance their energy levels and broaden their applications. In the present study, a Cu(II) and Fe(III) heteronuclear {[CuFe3O(tza)6(H2O)3]·(NO3)2·OH}n (CuFe-MOF) based on the high-energy ligand tetrazole-1-acetic acid (Htza) was synthesized and its structures and properties were evaluated. The effects of CuFe-MOF as a catalyst on the thermal decomposition performance of the solid propellant components (RDX, HMX, CL-20 and AP) were investigated. The results demonstrated that the successfully prepared compound, an infinite 3D meshwork structure composed of [Fe3O(tza)6]+ and Cu2+, is in the ortho-hexagonal crystal system, P63/m space group. CuFe-MOF exhibited good thermal stability (Tdec = 238.9 °C) and insensitivity to impact (IS > 40 J) and friction (FS > 360 J). The addition of 5 % CuFe-MOF significantly reduces the decomposition peak temperature (1.9 °C, 5.8 °C, 5.7 °C and 71.4 °C) and apparent activation energy (38.5 kJ·mol−1, 38.3 kJ·mol−1, 63.9 kJ·mol−1, and 27.0 kJ·mol−1) of the RDX, HMX, CL-20, and AP compared to the raw materials while notably enhancing the heat release (509.8 J·g−1, 613.1 J·g−1, 578.4 J·g−1 and 584.3 J·g−1). Furthermore, good compatibility with RDX, HMX, CL-20, and AP was demonstrated using VST method. This research indicates the potential of {[CuFe3O(tza)6(H2O)3]·(NO3)2·OH}n as a promising alternative to the existing inert catalysts in propellants containing RDX, HMX, CL-20, and AP components, serving as an energetic combustion catalyst.