Energetic Ligand Research Articles

Enhancing combustion performance of solid propellants using synergistic effect of energetic metal–organic framework with cage-like [Bi6(µ3-O)3(µ3-OH)5] clusters and copper-iron hetero-metallic compound

This study explores the potential of energetic metal–organic frameworks (E-MOFs) to enhance the combustion performance of solid propellants. A {[Bi6O3(tza)5(NO3)2(OH)5]·H2O}n (Bi-MOF) incorporating the energetic ligand tetrazole-1-acetic acid (Htza) was synthesized and evaluated for structural characteristics and properties. The catalytic thermal decomposition of cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX) by mixed systems was investigated. These systems consisted of Bi-MOF and copper-iron hetero-metallic compound ({[CuFe3O(tza)6(H2O)3]·Cl·(NO3)2·4H2O}n, CuFe-MOF), previously reported by our group in different ratios. The effect of the mixed system with the highest synergy index on the combustion performance of composite modified double-base propellant (RDX-CMDB) and nitrate ester plasticized polyether propellant (HMX-NEPE) was investigated. The impact of varying carbon black (CB) contents on the catalytic performance of the mixed system was also examined. The results showed that Bi-MOF exhibits good thermal stability (Tdec = 226.9 °C) and insensitivity (IS>40 J, FS>360 J). The mixed system, comprising Bi-MOF and CuFe-MOF in a 2:1 ratio (M2), exhibited the highest synergistic indices (3.35 and 3.24) on thermal decomposition for RDX and HMX. RDX-CMDB and HMX-NEPE propellant formulations containing M2 and a small amount of CB exhibited significant improvements in combustion performance. RDX-CMDB propellant exhibited up to an 80.6 % increase in burning rate and up to a 59.6 % reduction in pressure index. The pressure indices of NEPE without and with aluminum were reduced from 0.65 and 0.50 to 0.38 and 0.40, respectively (10–20 MPa, 1–20 MPa). These findings highlight the promise of the mixed system, formed by Bi-MOF and CuFe-MOF, as a potential combustion catalyst for RDX-CMDB and HMX-NEPE propellants.

Highly Dense N-N-Bridged Dinitramino Bistriazole-Based 3D Metal-Organic Frameworks with Balanced Outstanding Energetic Performance.

Due to the inherent conflict between energy and safety, the construction of energetic materials or energetic metal-organic frameworks (E-MOFs) with balanced thermal stability, sensitivity, and high detonation performance is challenging for chemists worldwide. In this regard, in recent times self-assembly of energetic ligands (high nitrogen- and oxygen-containing small molecules) with alkali metals were probed as a promising strategy to build high-energy materials with excellent density, insensitivity, stability, and detonation performance. Herein, based on the nitrogen-rich N,N'-([4,4'-bi(1,2,4-triazole)]-3,3'-dial)dinitramide (H2BDNBT) energetic ligand, two new environmentally benign E-MOFs including potassium [K2BDNBT]n (K-MOF) and sodium [Na2BDNBT]n (Na-MOF) have been introduced and characterized by NMR, IR, TGA-DSC, ICP-MS, PXRD, elemental analyses, and SCXRD. Interestingly, Na-MOF and K-MOF demonstrate solvent-free 3D dense frameworks having crystal densities of 2.16 and 2.14 g cm-3, respectively. Both the E-MOFs show high detonation velocity (VOD) of 8557-9724 m/s, detonation pressure (DP) of 30.41-36.97 GPa, positive heat of formation of 122.52-242.25 kJ mol-1, and insensitivity to mechanical stimuli such as impact and friction (IS = 30-40 J, FS > 360 N). Among them, Na-MOF has a detonation velocity (9724 m/s) superior to that of conventional explosives. Additionally, both the E-MOFs are highly heat-resistant, having higher decomposition (319 °C for K-MOF and 293 °C for Na-MOF) than the traditional explosives RDX (210 °C), HMX (279 °C), and CL-20 (221 °C). This stability is ascribed to the extensive structure and strong covalent interactions between BDNBT2- and K(I)/Na(I) ions. To the best of our knowledge, for the first time, we report dinitramino-based E-MOFs as highly stable secondary explosives, and Na-MOF may serve as a promising next-generation high-energy-density material for the replacement of presently used secondary thermally stable energetic materials such as RDX, HNS, HMX, and CL-20.

Construction of energetic metal-organic frameworks based on 5-aminotetrazole

Metal-Organic Frameworks (MOFs) have recently gained prominence as a novel class of energetic materials, owing to their systematic design and the ability to fine-tune properties such as energy content, sensitivity, and thermal stability. In this study, two new MOFs namely Cd(5-AT)3NH2(CH3)2+(1) and Zn(5-AT)(AMP) (2) (5-HAT = 5-aminotetrazole) were prepared under solvothermal conditions using 5-aminotetrazole as the high-nitrogen energetic ligand. X-ray single crystal diffraction analysis revealed that compound 1 possess an ABX3-type perovskite-like structure, whereas compound 2 forms a two-dimensional layer. The high thermal stability of both compounds were confirmed through thermogravimetry (TG) and differential scanning calorimetry (DSC). Their constant-volume combustion heat (ΔcU) was first determined by oxygen-bomb calorimetry and then the standard molar enthalpy of formation (ΔfHo) was calculated. Furthermore, both compounds demonstrated great detonation properties and low sensitivity, showing their potential application as new explosive materials (EMs).

Metal-Determined Explosive Characteristics of M(NO3)2(1-AT)x of Thermal and Laser Ignition (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+; x = 2 or 3).

Optical and thermal ignition are two common pathways to initiate the explosion of primary explosives, where laser ignition is a more reliable and safer initiation method. Caused by the current-applied laser igniter with the wavelength of 1064 or 915 nm, the energetic complexes with strong absorption in the near-infrared (NIR) region are possibly applied as laser-ignited explosives. Recently, [Cu(NO3)2(1-AT)3] complex has been synthesized with excellent NIR absorption properties, where 1-amino-5H-tetrazole (1-AT) has been proved to be a promising laser-ignited energetic ligand. To confirm the structure-thermal/optical explosive characteristics, based on the structure of synthesized [Cu(NO3)2(1-AT)3], the commonly used transition-metal cations (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) have been selected to construct the series of complexes of M(NO3)2(1-AT)x (x = 2 or 3) theoretically. Car-Parrinello molecular dynamics (CPMD) method has been applied to unveil the role of center metals in the initiation and growth pathways. Time-dependent density functional theory (TD-DFT) method is used to explore their charge-transfer (CT) characteristics. The optical characteristic of the metal complex is mainly determined by the behaviors of the 3d electrons of center metals in excitation, where the activity of β-d electrons is an important factor to affect the NIR characteristic of complexes.

Energetic metal-organic frameworks based on H2BTA and their effect on thermal decomposition of ammonium perchlorate

The effective thermal decomposition of ammonium perchlorate (AP) is an essential area of research in improving propellant combustion behavior. In this article, non-heavy metal cations such as Co(II), Mn(II), and Cu(II) were used for the preparation of a metal-organic framework based on 5,5′-tetrazole-amine (BTA). The low sensitivity of these compounds is of great importance in energy applications. XRD and FT-IR analyses were used to confirm the MOF structure. Adding MOF alters thermal decomposition processes, according to a thermal analysis obtained from the polymer DSC curve. The strong catalytic activity of the H-MOF for AP thermal decomposition is probably due to the synergistic effect of metal nodes and energetic ligands. The total heat released in the thermal decomposition of AP increased from 535.9 to 2435 J·g−1, and the high-temperature decomposition peak was dramatically reduced by 67 °C. Finally, we performed kinetic and thermodynamic studies on the thermal decomposition of AP and calculated the activation energy of AP decreased from 91.9 to 72.1 kJ·mol−1 and other parameters.

Construction of variable dimension green high energy complex and laser response

A high dimensional energetic complex [Co(OH-Tz)2(H2O)2]n was synthesis with tetrazole energetic ligand, and its single crystal structures were obtained. Compared with the previously reported complexes, it has higher density (ρ = 2.135 g·cm−3), higher energy level (D = 7.59 km·s−1) and thermal stability (Tdec = 271 ℃). In addition, the femtosecond laser and high-speed imaging results show that this compound is sensitive to laser stimulation, and under the stimulation of 808 nm femtosecond laser, the detonation process initiated by thermal mechanism can occur when the total laser energy is 224 mJ. Therefore, it is a potential environment-friendly laser detonating material.

In situ growth of copper-based energetic complexes on GO and an MXene to synergistically promote the thermal decomposition of ammonium perchlorate.

In this work, using tri(5-aminotetrazolium)triazine (H3TATT) as an energetic ligand, two new energetic complexes (ECs), Cu(HTATT)(H2O)2 (EC-Cu1) and [Cu3(TATT)2(H2O)2]n (EC-Cu2), have been synthesized under hydrothermal conditions. Their crystal structures, thermal decomposition behaviors and specific heat capacities were determined respectively. In addition, two ECs were combined with GO (graphene oxide) and an MXene (Ti3C2TX) respectively by an in situ growth strategy to obtain four carbon nanomaterials/EC composites, which were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of two ECs and four composites on the thermal decomposition of AP were studied by differential scanning calorimetry (DSC). Among them, the sample containing 8 wt% composite (GO/EC-Cu2) has the best promoting effect on AP, causing the high temperature decomposition peak to overlap with the low temperature decomposition peak of AP, reducing the decomposition peak temperature of AP from 443.6 °C to 308.9 °C, and the heat release is up to 4875 J g-1. Compared with ECs acting solely on AP, composite materials have stronger synergistic and promoting effects. This study provides a new example of the synthesis of carbon nanomaterial/EC composites and the improvement of the performance of AP-based solid propellants.

Design, preparation, and combustion performance of energetic catalysts based on transition metal ions (Cu2+, Co2+, Fe2+) and 3-aminofurazan-4-carboxylic acid.

Development of energetic catalysts with high energy density and strong catalytic activity has become the focus and frontier of research, which is expected to improve the combustion performance and ballistic properties of solid propellants. In this work, three energetic catalysts, M(H2O)4(AFCA)2·H2O (AFCA = 3-aminofurazan-4-carboxylic acid, M = Cu, Co, Fe), are designed and synthesized based on the coordination reaction of transition metal ions and the energetic ligand. The target products are characterized by single crystal X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal analysis, optical microscopy, and scanning electron microscopy. The results reveal that Cu(H2O)4(AFCA)2·H2O crystallizes in the monoclinic space group, Dc = 1.918 g cm-3. Co(H2O)4(AFCA)2·H2O, and Fe(H2O)4(AFCA)2·H2O belong to orthorhombic space groups, their density is 1.886 g cm-3 and 1.856 g cm-3, respectively. In addition, the designed catalysts show higher catalytic activity than some reported catalysts such as Co(en)(H2BTI)2]2·en (H3BTI = 4,5-bis(1H-tetrazol-5-yl)-1H-imida-zole), Co-AzT (H2AzT = 5,5'-azotetrazole-1,1'-diol), and [Pb(BTF)(H2O)2]n (BTF = 4,4'-oxybis [3,3'-(1-hydroxy-tetrazolyl)]furazan) for the thermal decomposition of ammonium perchlorate (AP). The high-temperature decomposition peak temperatures of AP/Cu(H2O)4(AFCA)2·H2O, AP/Co(H2O)4(AFCA)2·H2O, and AP/Fe(H2O)4 (AFCA)2·H2O are decreased by 120.3 °C, 151.8 °C and 89.5 °C compared to the case of pure AP, while the heat release of them are increased by 768.8 J g-1, 780.5 J g-1, 750.9 J g-1, respectively. Moreover, the burning rates of solid propellants composed of AP/Cu(AFCA)2(H2O)4·H2O, AP/Co(AFCA)2(H2O)4·H2O and AP/Fe(AFCA)2(H2O)4·H2O are increased by 2.16 mm s-1, 2.53 mm s-1, and 1.57 mm s-1 compared with the case of pure AP. This research shows considerable application prospects in improving the combustion and energy performance of solid propellants, it is also a reference for the design and preparation of other novel energetic catalysts.

Modulation of Crystal Growth of an Energetic Metal–Organic Framework on the Surfaces of Graphene Derivatives for Improved Detonation Performance

Energetic materials are a special class of energy materials composed of C, H, O, and N. Their safety always deteriorates with increasing energy. Regulating the properties of energetic materials to meet application requirements is one of the focuses of research in this field. Energetic metal-organic frameworks (EMOFs) are good candidates as primary explosives to replace lead azide (LA) and other explosives containing toxic metal elements. However, safety remains the biggest concern in applications. In this paper, crystal morphology modulation of EMOF was carried out by stepwise coordination of metal ions and energetic ligands on surfaces of graphene oxide (GO) and amino-functionalized graphene oxide (AGO). Two energetic composite materials, Cu-AFTO@GO and Cu-AFTO@AGO, were successfully synthesized and also the EMOF (Cu-AFTO). The structures and morphologies of these materials were fully characterized. The thermal decomposition behaviors, mechanical sensitivity, and electrostatic discharge sensitivity were investigated in detail. The electric ignition ability of EMOF and two composite materials was tested. This study shows that it is possible to reduce the diameter of EMOF crystals from hundreds of microns to tens of nanometers by a stepwise coordination method. The high electrical conductivity and sensitivity-reducing effect of GO and/or AGO allow the nanosized EMOF crystals to have a lower ignition threshold and lower sensitivity.

Hydrogen bond and 3D frameworks to reconcile the conflict between safety and detonation performance in energetic metal–organic frameworks

Energetic metal–organic frameworks (EMOFs), which combine energetic ligands with metal ions, hold promise as novel energetic materials to balance the sensitivity and safety of explosives. The coordinating solvent molecules have a significant effect on the energetic properties of EMOFs. Two EMOFs, [K(AFTO)·H2O]n (1) and solvent-free [K(AFTO)]n (2), were obtained at different reaction temperatures. EMOFs 1 and 2 exhibit excellent thermal stability (Td,1 = 569 K, Td,2 = 574 K), insensitivity to mechanical stimuli (FS ≥ 360 N, IS ≥ 40 J for 1; FS ≥ 360 N, IS = 35 J for 2) and satisfactory detonation performance (D1 = 8291 m s−1, P1 = 31.9 GPa; D2 = 8415 m s−1, P2 = 32.7 GPa) due to their different 3D framework structures and strong hydrogen bond networks.

Two silver energetic coordination polymers based on a new N-amino-contained ligand: Towards good detonation performance and excellent laser-initiating ability

High-nitrogen heterocycle ligands, as an important part of energetic coordination polymers (ECPs), play a dominant role on regulating the energetic performance of ECPs. In inspire of the higher enthalpy and higher nitrogen contents after amination reaction, we synthesized a novel energetic ligand, 4-(2-amino-2H-tetrazol-5-yl)-1,2,5-oxadiazol-3-amine (ATNT), which has enhanced physicochemical properties (ΔHf: 524.2 kJ mol−1; D: 8248 m s−1; P: 24.67 GPa). Based on ATNT, two Ag-ECPs, [Ag2(ATNT)2](NO3)2 and [Ag2(ATNT)4](ClO4)2, were prepared and their structures were determined by single-crystal XRD. The high energetic performance of ATNT promotes the further improvement of the energy density of ECPs in this work. With excellent crystal densities (2.405/ 2.675 g cm−3) and high heat of detonation (0.91/ 0.88 kcal g−1), the detonation properties of two ECPs are 7286 m s−1/27.89 GPa, 8085 m s−1/40.08 GPa, respectively, which are at advanced level among the reported silver-based complexes. Moreover, laser initiation experiments show that both ECPs possess low initiation delay times (<20 μs) under 70 mJ initiation energy, revealing their potential as novel laser-initiating energetic materials. Presented ECPs in our work combine the advantages of simple synthesis method, high density, good detonation performance, excellent laser-initiating ability, exhibiting the great development potentials.

Novel solvent-free energetic 3D metal-organic frameworks and their laser response

• Two new energetic complexes with the same topological structure were synthesized. • The complex has good thermal stability and detonation ability, and can detonate under laser stimulation. • Their laser response process is captured, which shows that the initiation threshold is less than 7 mJ. Two novel energetic metal–organic frameworks (EMOFs) were prepared by simple hydroxytetrazole (OH-Tz) method with hydroxytetrazole which have good oxygen balance and coordination ability as energetic ligand, namely, [Pb(OH-Tz) 2 ] n and [Pb(OH-Tz)(NO 3 )] n , were prepared by simple hydrothermal method. The two EMOFs have the same three-dimensional network structure, and there are no coordination solvent molecules in the structure, they form a dense network structure through the coordination bond length, so they have high density (3.578 and 4.154 g∙cm −3 , respectively), good thermal stability( T dec greater than 230 ℃) and detonation properties similar to those of RDX or HMX (8.62 km s −1 , 46.20 GPa and 8.13 km s −1 , 42.71 GPa, respectively). The response process of EMOFs to laser was captured by high-speed camera, and the initiation ability of EMOFs was tested by lead plate experiment, which shows that these solvent-free EMOFs have good laser-response performance and initiation ability.

Improved oxygen balance and effective energy density by coligand and dehydration strategy: Synthesis and characterization of two new energetic coordination polymers

Based on the excellent energetic ligand of N, N-bis(1H-tetrazole-5-yl)-amine (H2bta) and coligand of oxalic acid (oa), Cu(Ⅱ) as the metal center ion, a new energetic coordination polymer (ECP), {[Cu2(bta)2(oa)(H2O)2]∙4H2O}n (1), was synthesized by hydrothermal method. Single crystal X-ray diffraction indicates that 1 possess 3D supramolecular configuration. Due to the existence of a large number of lattice water and coordination water molecules in 1, however, the effective energy density of 1 is limited. To further improve the performance of 1, according to its thermal decomposition behavior, we dehydrated 1 at 280 °C to obtain a new ECP [Cu2(bta)2(oa)]n (2). The thermodynamic parameter of the decomposition process of 1 was discussed by Kissinger's and Ozawa's methods. Sensitivity tests show that 2 is more sensitivity to impact stimuli than 1, reflecting guest-dependent energy and sensitivity of ECPs. The theoretical calculation results show that 1 possess good detonation performances. The promotion effects of two ECPs on the combustion decomposition of ammonium perchlorate were studied using a differential scanning calorimetry method. Experimental results showed that 1 and 2 can be used as high energy density materials in the field of combustion promoter and the insensitive 1 can be regarded as a safe form for mass storge and transportation of sensitive 2.

Study on catalytic activity and mechanism of tetrazole-based energetic metal-organic frameworks for thermal decomposition of ammonium perchlorate

ABSTRACT In order to comprehensively improve the energy performance and combustion properties of the propellants, four energetic metal–organic frameworks (EMOFs) constructed from transition-metal ions (Ag+, Cd2+, Pb2+) and tetrazole-based energetic ligands (5-methyl tetrazole (HMtta), N,N-bis(1H-tetrazole-5-yl)-amine (H2bta), 3-(1H-tetrazol-5-yl)-1H-triazole (H2tztr)) were prepared by hydrothermal synthesis. The crystal phase and structure of the as-prepared samples were analyzed by XRD and IR characterization. Their catalytic activity on thermal decomposition of ammonium perchlorate (AP) was evaluated by DSC. The results show that as-prepared EMOFs can significantly reduce the thermal decomposition temperature of AP and increase its heat release. Under the optimal condition that the addition amount is 10 wt%, the high-temperature decomposition peak temperatures of [AgMtta]n/AP, [Cd5(Mtta)9]n/AP, [Pb3(bta)2(O)2(H2O)]n/AP, and [Pb(Htztr)2(H2O)]n/AP are decreased by 107.2°C, 94.2°C, 54.6°C, and 91.1°C compared to the case of pure AP, while the heat releases of them are increased by 1243.9 J∙g−1, 1226.2 J∙g−1, 1332.2 J∙g−1, 1444.4 J∙g−1, respectively. In addition, compared with the reported catalysts such as [Pb(BTF)(H2O)2]n, CuFe2O4, [Cu2(en)2(HBTI)2]2, and [Cu2(en)(HBTI)2]2en, the EMOFs prepared in this study show equal or even higher catalytic activity and heat release. Moreover, the catalytic mechanism of EMOFs on thermal decomposition of AP is also analyzed based on the electron transfer theory. With the excellent energy properties and catalytic performances, the prepared EMOFs may become promising energetic additives for composite solid propellant applications.

Assembling Silver Cluster-Based Organic Frameworks for Higher-Performance Hypergolic Properties.

Increasing research efforts have been focused on developing next-generation propellants. In this work, we demonstrated that assembling zero-dimensional (0D) silver clusters with energetic ligands into 3D metal organic frameworks (MOFs) not only inherited the short ignition delay (ID) time of the alkynyl-silver cluster but also significantly increased the output energy. Among them, the open cationic framework of ZZU-363 incorporating counter NO3– ions achieved a considerably reduced energy barrier and eventually the shortest ID time (26 ms), together with the highest volumetric energy density (40.4 kJ cm–3) and specific impulse (263.1 s), which is far superior to traditional hydrazine-based propellants. The underlying mechanisms are clearly revealed by theoretical calculations. This work opens a venue to significantly enhancing the hypergolic activity of metal clusters and MOFs.

Application of 3D energetic metal-organic frameworks containing Cu as the combustion catalyst to composite solid propellant

Abstract Using traditional metallic combustion catalysts in composite solid propellant (CSP) can lead to sharp energy losses of CSP due to the non-energetic properties of the catalysts. In the current study, the energetic ligands based 3D [Cu(atrz)3(NO3)2]n metal-organic frameworks (MOF(Cu)) were first used as the combustion catalysts to study their effects on the performance of CSP. It was found that the variation of MOF(Cu) content in the range of 0–5% had no significant effects on the theoretical specific impulse (Isp) and characteristic velocity (C*) of CSP. MOF(Cu) reduced the high decomposition temperature of AP to 344 °C and the complete decomposition temperature of CSP to 358 °C. It also decreased the thermal decomposition activation energy of CSP from 74.1 kJ mol−1 to 63.3 kJ mol−1. The CSP containing MOF(Cu) exhibits higher burning rates, particular flame structure and lower pressure index, as compared with that with CuO as the catalyst. The mechanical sensitivity test results reveal that MOF(Cu) can reduce the friction sensitivity and impact sensitivity of CSP from 40% and 39.4 cm to 32% and 63.5 cm, respectively. The current study is promising to develop a new kind of energetic combustion catalysts for CSP.

Constructing Strategies and Applications of Nitrogen-Rich Energetic Metal–Organic Framework Materials

The synthesis of energetic metal–organic frameworks (EMOFs) with one-dimensional, two-dimensional and three-dimensional structures is an effective strategy for developing new-generation high-energy-density and insensitive materials. The basic properties, models, synthetic strategies and applications of EMOF materials with nitrogen-rich energetic groups as ligands are reviewed. In contrast with traditional energetic materials, EMOFs exhibit some interesting characteristics, like tunable structure, diverse pores, high-density, high-detonation heat and so on. The traditional strategies to design EMOF materials with ideal properties are just to change the types and the size of energetic ligands and to select different metal ions. Recently, some new design concepts have come forth to produce more EMOFs materials with excellent properties, by modifying the energetic groups on the ligands and introducing highly energetic anion into skeleton, encapsulating metastable anions, introducing templates and so on. The paper points out that appropriate constructing strategy should be adopted according to the inherent characteristics of different EMOFs, by combining with functional requirements and considering the difficulties and the cost of production. To promote the development and application of EMOF materials, the more accurate and comprehensive synthesis, systematic performance measurement methods, theoretical calculation and structure simulation should be reinforced.

Incorporation of a nitrogen-rich energetic ligand in a {Yb} complex exhibiting slow relaxation of the magnetisation under an applied field.

Though often used as the precursor in energetic materials research and organic synthesis, 3,6-dihydrazinyl-1,2,4,5-tetrazine (dhtz) has not been previously explored in coordination chemistry. Herein, we present the first crystalline coordination compound with dhtz, [Yb2(dhtz)(fod)6] (fod- = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate). This compound exhibits Single-Molecule Magnet behaviour under an applied magnetic field, and mJ states were resolved through luminescence studies.

Synthesis of Energetic Complexes [Co(en)(H2BTI)2]2 ⋅ en, [Cu2(en)2(HBTI)2]2 and Catalytic Study on Thermal Decomposition of Ammonium Perchlorate

AbstractA nitrogen‐rich compound 4,5‐bis(1H‐tetrazol‐5‐yl)‐1H‐imidazole (H3BTI) with high energy density has been reported as ligand to make metal‐organic energetic catalysts to improve the energy of catalysts for the first time. The high energetic catalysts [Co(en)(H2BTI)2]2 ⋅ en and [Cu2(en)2(HBTI)2]2 were successfully synthesized and the structures of the complexes were confirmed by X‐ray single‐crystal diffraction. The catalytic effects of complexes on the thermal decomposition of ammonium perchlorate (AP) have been investigated separately by differential scanning calorimetry (DSC). The DSC results show that the AP can be completely decomposed at the temperature of 333.7 °C and 336.1 °C, respectively, which indicates that the pristine “two‐step” thermal decomposition of AP was transformed to a “one step” route upon addition of the copper catalysts. Besides the excellent catalytic performance of AP decomposition, the high energetic ligand HnBTI can also release a large number of heats in the decomposition process, which can significantly enhance the total released heat of the mixture of AP.

Thermostable and insensitivity furazan energetic complexes: Syntheses, structures and modified combustion performance for ammonium perchlorate

It is an important issue to balance energy and sensitivity in the construction of high energy materials. Herein, two furozacycline energetic complexes ([Zn(HTZF)(H2O)3]·H2O (1) and [Co(HTZF)(H2O)3]·2H2O (2) (HTZF = 3-hydroxyl-4-(tetrazol-5-yl)furazan)) were hydrothermally synthesized. Single crystal X-ray diffraction shows that in 1, energetic ligand adopting bidentate chelating coordination mode coordinates to Zn2+. The coordinated units Zn(HTZF)2(H2O)2 and Zn(H2O)4 are alternatively linked to an infinite chain through nitrogen atom in furazan group, and with the aid of hydrogen bonding interaction, forming 3D supramolecule structure. Different in 2, ligand coordinates to Co2+ in bidentate chelating coordination and bridging coordination modes. π⋯π interaction further supports 3D framework stabilization. The thermal decomposition temperature of 1 and 2 are up to 293.0 °C and 295.8 °C, respectively. The heat of detonation (Q), detonation velocity (D), and detonation pressure (P), were evaluated to be, for 1: 1.123 kcal·g−1, 7.971 km·s−1 and 30.8 GPa; for 2: 2.165 kcal·g−1, 8.846 km·s−1 and 35.3 GPa. 1 and 2 are insensitive to impact and friction. As combustion promoter, both of complexes can effectively accelerate the thermal decomposition of ammonium perchlorate (AP).