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Prepared composite materials based on [Zn 4 O(benzene-1,4-dicarboxylate) 3 ] (MOF-5) and graphene oxide (GO) via a simple green solvothermal method, at which GO was used as platform to load MOF-5, and applied to the thermal decomposition of AP. The obtained composites were characterized by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption, Fourier transform infrared (FT-IR), differential scanning calorimetry and thermalgravimetric (DSC-TG). The analyses confirmed that the composite material (GO@) MOF-5 can not only improve the decomposition peak temperature of AP from the initial 409.7 ° C to 321.9 ° C, but also can improve the enthalpy (△H) from 576 J g −1 to 1011 J g −1 and reduce the activation energy ( E a ), thereby accelerating the decomposition reaction. The high-specific surface area of the MOF material can provide a large number of active sites, so that the transition metal ions supported thereon can participate more effectively in the electron transfer process, and GO plays its role as a bridge by its efficient thermal and electrical conductivity. Together, accelerate the thermal decomposition process of AP.

Hematite α-Fe 2 O 3 with microrods and nanoparticles, corresponding to the predominantly exposed (110) and (104) facets, respectively, were prepared using a hydrothermal-annealing approach. The crystal plane effects of prepared α-Fe 2 O 3 on the catalytic performance towards thermal decomposition of ammonium perchlorate (AP) were investigated. Addition 2 wt% α-Fe 2 O 3 microrods and nanoparticles to AP reduce the high temperature decomposition (HTD) by 95 and 53 °C and the corresponding activation energy decreases to 170.0 and 199.1 kJ mol −1 , respectively. The big differences in the HTD of 42 °C and in the activation energy of 29.1 kJ mol −1 reveal remarkable facet effects. Compared to α-Fe 2 O 3 nanoparticles with high exposed (104) facet, the much better catalytic activity of α-Fe 2 O 3 microrods is related to the high exposed (110) facet with a larger amount of surface oxygen vacancies which are highly advantageous for improving the electron-hole separations and their transfers in surface. Graphical Abstract Hematite α-Fe 2 O 3 with microrods and nanoparticles predominantly exposing (110) and (104) facets, respectively, were prepared and their catalytic performance towards thermal decomposition of AP were investigated. The α-Fe 2 O 3 microrods show much better catalytic performance than α-Fe 2 O 3 nanoparticles due to the (110) facet with a larger amount of surface oxygen vacancies

The 3D metal–organic framework (MOF), MIL-88B, built from the trivalent metal ions and the ditopic 1,4-Benzene dicarboxylic acid linker (H 2 BDC), distinguishes itself from the other MOFs for its flexibility and high thermal stability. MIL-88B was synthesized by a rapid microwave-assisted solvothermal method at high power (850 W). The iron-based MIL-88B [Fe 3 .O.Cl.(O 2 C–C 6 H 4 –CO 2 ) 3 ] exposed oxygen and iron content of 29% and 24%, respectively, which offers unique properties as an oxygen-rich catalyst for energetic systems. Upon dispersion in an organic solvent and integration into ammonium perchlorate (AP) (the universal oxidizer for energetic systems), the dispersion of the MOF particles into the AP energetic matrix was uniform (investigated via elemental mapping using an EDX detector). Therefore, MIL-88B(Fe) could probe AP decomposition with the exclusive formation of mono-dispersed Fe 2 O 3 nanocatalyst during the AP decomposition. The evolved nanocatalyst can offer superior combustion characteristics. XRD pattern for the MIL-88B(Fe) framework TGA residuals confirmed the formation of α-Fe 2 O 3 nanocatalyst as a final product. The catalytic efficiency of MIL-88B(Fe) on AP thermal behavior was assessed via DSC and TGA. AP solely demonstrated a decomposition enthalpy of 733 J g −1 , while AP/MIL-88B(Fe) showed a 66% higher decomposition enthalpy of 1218 J g −1 ; the main exothermic decomposition temperature was decreased by 71 °C. Besides, MIL-88B(Fe) resulted in a decrease in AP decomposition activation energy by 23% and 25% using Kissinger and Kissinger–Akahira–Sunose (KAS) models, respectively.

Composites of rhenium (ReNP) and rhenium–copper nanoparticles (ReCuNP) were studied as catalysts for the decomposition of the oxidizer ammonium perchlorate (AP) for composite solid propellants. Both composites were prepared by reducing ammonium perrhenate (NH 4 ReO 4 ) and copper chloride (CuCl 2 ) in the presence of polyamidoamine (PAMAM) dendrimers. The PAMAM-based nanostructures were characterized by transmission electron microscopy (TEM), high resolution TEM, and X-ray photoelectron spectroscopy. ReNP@PAMAM samples showed rhenium clusters and partially oxidized spherical nanoparticles of approx. 1 nm in diameter, while ReCuNP@PAMAM comprised nanoparticles of 6 nm in average size with different shapes and high-size dispersion. The computational description demonstrated the higher stability of the interaction between copper and PAMAM than perrhenate anion due to the charge transfer from the dendrimer to the cation. The materials were evaluated for the catalytic decomposition of AP by calorimetry. The catalytic performance of ReCuNP@PAMAM was superior to that of ReNP@PAMAM, lowering the decomposition of AP at high temperatures. However, the latter composite increased the energy release drastically due to the exothermic oxidation of rhenium metal. Graphical Abstract

Ammonium perchlorate (AP) is the universal oxidizer for solid propellants; AP combustion is accompanied with the release of white smoke (HCl). HCl has raised an environmental concern; it could cause acidic rain and deteriorate the fertile soil. Chlorine free and eco-friendly oxidizers are highly appreciated for green solid propellants. Ammonium nitrate (AN) could be the greener substitute for AP; yet AN expose low performance. Whereas AP demonstrated exothermic decomposition with the release of -733 J/g; AN demonstrated strong endothermic decomposition process of +1707 J/g. AN with strong endothermic decomposition process could render high burning rates. Copper chromite Nano catalyst of 45 nm was developed via hydrothermal synthesis. Copper chromite was integrated into AN matrix. Catalyzed AN demonstrated advanced exothermic decomposition enthalpy of -1492 J/g. Catalysed AN experienced diminish in activation energy by - 41.5 %, and – 40.6 % using Kissinger and Ozawa models respectively. Copper chromite NPs could secure novel catalytic effect via condensed phase reactions of chromium, and copper ions with nitrate ions (NO-3) to develop NOx gases. This catalytic effect can secure alternative pathway with low energy barrier. Consequently, catalysed AN can expose novel characteristics as a green eco-friendly oxidizer.

Aluminum particles have the problems of difficult ignition, easy agglomeration, incomplete combustion, etc. Therefore, it is of great scientific significance and engineering value to find ways to improve the ignition and combustion performance of aluminum particles in order to promote the full release of energy of aluminum particles. In this paper, spherical nano-sized ferric oxide (nFe 2 O 3 ) and ammonium perchlorate (AP), a commonly used oxidizer in propellants, were used to synergistically improve the ignition and combustion performance of aluminum particles. AP modified the aluminum particles by both mixing and coating methods, respectively. On the basis of coating AP, nFe 2 O 3 was added in order to further enhance the ignition and combustion performance of the aluminum particles. Scanning electron microscope, laser particle size analyzer, thermal analysis system and laser ignition experiment system were used to test the physicochemical properties and ignition combustion performance of different samples. The results showed that AP and nFe 2 O 3 could be coated relatively uniformly on the surface of aluminum particles using the recrystallization method. The thermal reaction behavior of the samples showed that coating was beneficial to the decomposition of AP compared with mixing, and the addition of nFe 2 O 3 could further improve the decomposition efficiency of AP. Ignition and combustion experiments showed that coating AP was more conducive to improving the ignition and combustion performance of aluminum particles than mixing AP, and the addition of nFe 2 O 3 could further significantly enhance the combustion intensity and flame propagation speed of the sample. However, the addition of nFe 2 O 3 increased the ignition delay time of the sample, which may be related to the cold agglomeration phenomenon caused by the nanoparticles. The microscopic combustion flame morphology of different samples showed that coating AP and the introduction of nFe 2 O 3 could significantly reduce the agglomeration phenomenon of aluminum particles. Overall, coating AP reduces the distance between the aluminum particles and the oxidizer, thus significantly improving the ignition and combustion performance of the aluminum particles. The addition of nFe 2 O 3 can further improve the combustion performance of aluminum particles, but at the same time, it also increases the ignition delay time. Hence, the cold agglomeration problem caused by nanoparticles should be fully considered when nFe 2 O 3 is used to improve the ignition and combustion performance of aluminum particles.

In this study, a novel Cu-MOF@Carbon nanomaterial composite was prepared to catalyze the thermal decomposition of ammonium perchlorate (AP). The structure was characterized by using scanning electron microscope (SEM), X-ray energy-dispersive spectrum (EDS), and X-ray diffraction (XRD); the specific surface area was estimated by Brunauer–Emmett–Teller (BET) method; and the pore volumes and pore size distributions were derived from the adsorption branches of isotherms using the Barrett–Joyner–Halenda (BJH) model. And the thermal decomposition behavior was investigated by using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The results indicated that all products showed excellent catalytic activity. Among the samples investigated here, Cu-MOF@CNT-rGO exhibited the best catalytic activity, since the high-temperature decomposition peak of AP decreased to 313.8 °C, which is reduced nearly 100 °C than the raw material (409.7 °C). And this was attributed to the high thermal and electrical conductivities of carbon nanomaterials, and the large surface area of both Cu-MOF and carbon nanomaterials. This study provides a new choice to be used as the promising catalysts in modifying the burning performance of AP-based composite propellant.

Five nanometal catalysts of Fe, Co, Ni, Cu and Zn were prepared by single displacement reaction and evaluated their catalytic activity towards thermal decomposition of ammonium perchlorate (AP) with respect to lowering of decomposition temperature, boosting of heat energy release and larger evolution of oxidizing decomposition products. The peak temperature of high temperature decomposition was decreased by 93, 55, 47, 15 and 13 °C by adding 0.5% each of Zn, Cu, Ni, Co and Fe respectively. The highest heat energy of 1910 J g −1 was obtained for 0.5% Cu. The evolved gases analysis using thermogravimetry-mass spectrometry revealed new inputs to the catalysed decomposition of AP, especially with respect to chlorine gas evolution. Among the five catalysts studied, copper nanometal powder emerged as the most promising catalyst for thermal decomposition of AP, which can improve the burn rate of the propellant enormously with reduced mass penalties. Graphical abstract

Mn-doped Co 3 O 4 nanoparticles of 15 nm were developed via solvothermal synthesis. Mn@Co 3 O 4 microspheres were developed via controlled annealing treatment at 600 °C. Mn@Co 3 O 4 microspheres demonstrated an average diameter of 5.5 µm, with specific area (BET) of 73.7 m 2  g −1 . The pore diameter was centered at 13.1 nm, and the mean pore size was 16 nm; porous structure could secure extensive interfacial surface area. Mn@Co 3 O 4 microspheres were integrated into ammonium perchlorate (AP) matrix. The catalytic activity of Mn@Co 3 O 4 on AP decomposition was assessed via DSC and TGA/DTG. Whereas Mn@Co 3 O 4 /AP nanocomposite demonstrated decomposition enthalpy of 1560 J g −1 , pure AP demonstrated 836 J g −1 . While Mn@Co 3 O 4 /AP nanocomposite demonstrated one decomposition temperature at 310 °C,pure AP exposed two decomposition stages at 298 °C, and 453 °C. Decomposition kinetics was investigated via isoconversional (model free) and model fitting. Kissinger, Kissinger–Akahira–Sunose (KAS), integral isoconversional method of Ozawa, Flyn and Wall (FWO), and differential isoconversional method of Friedman. Mn@Co 3 O 4 /AP demonstrated apparent activation energy of 149.7 ± 2.54 kJ mol −1 compared with 173.16 ± 1.95 kJ mol −1 for pure AP. While AP demonstrated sophisticated decomposition models starting with F3 followed by A2, Mn@Co 3 O 4 /AP nanocomposite demonstrated A3 decomposition model. Mn@Co 3 O 4 can expose active surface sites; surface oxygen could act as electron donor to electron deficient perchlorate group. Furthermore, Mn@Co 3 O 4 /AP could act as adsorbent of released NH 3 gas with efficient combustion. This study shaded the light on Mn@Co 3 O 4 as potential catalyst for AP decomposition.

Ammonium perchlorate (AP) is a commonly used oxidant for rocket solid propellants. To control the thermal decomposition of AP, a new PEI-imidazole derivative (PEI-ICA) was synthesized. With the combination of Cu compound, the heat decomposition behavior of the AP’s composites was tuned, and the activation energy was also reduced. To explore the potential reason for the catalytic effect, a series of measurements were also carried out, which indicates the electrostatic self-assembly of PEI-ICA and its combination with Cu compound should be responsible for the different heat decomposition behavior of AP. Graphical Abstract