Superb catalytic activity of as-green synthesized copper ferrite's thermal decomposition of ammonium perchlorate

Spiral gas-solid two-phase flow continuous mechanochemical synthesis of salophen complexes and catalytic thermal decomposition of ammonium perchlorate

Although mechanochemistry is increasingly becoming an alternative to traditional chemical synthesis, highly efficient continuous mechanochemical synthesis techniques are still rare. In this work, a novel spiral gas-solid two-phase flow (S-GSF) synthesis technique for the mechanochemical synthesis of salophen complexes has been reported, which is an approach for continuous synthesis based solely on airflow impacting the reaction. The synthesis of salophen-Br-Cu was used as a model reaction to optimize the reaction conditions, and three other salophen complexes, namely, salophen-Br-Co, salophen-Br-Ni, and salophen-Br-Zn were synthesized on this basis. The structure and thermal stability of the obtained products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, UV-vis spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, and differential thermal analysis (DTA). The results showed that these complexes can be obtained continuously at a rate close to 4 g min-1, and the corresponding space-time yield is close to 1.2 × 105 kg m-3 day-1. In addition, DTA was used to analyze the catalytic performance of the complex for ammonium perchlorate (AP). The results showed that compared to the conditions for pure AP, salophen-Br-Co and salophen-Br-Cu could significantly reduce the high-temperature decomposition of AP pyrolysis to 77.0 and 102.1 °C, respectively. According to the method of Kissinger calculations, the Ea of AP decomposition decreased from 217.3 kJ mol-1 to 131.0 and 118.5 kJ mol-1, respectively. The TG data at different heating rates were analyzed using two isoconversion methods, i.e. Flynne-Walle-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The activation energies of AP, AP + 10 wt% salophen-Br-Co, and AP + 10 wt% salophen-Br-Cu were calculated. When the conversion degree (α) is between 0.1 and 0.9, the Ea values obtained from the two isoconversion methods are similar and exhibit certain matching. These two isoconversion methods also confirm Kissinger's calculations.

Preparation of a Chitosan-Lead Composite Carbon Aerogel and Its Catalytic Thermal Decomposition Performance on Ammonium Perchlorate

Chitosan-lead (CS-Pb) carbon aerogels were prepared by ionic cross-linking and high-temperature carbonization using chitosan (CS) as the carbon precursor. The obtained carbon aerogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The obtained aerogels have a 3D structure and a large surface area, which can effectively prevent the agglomeration phenomenon of metals. Differential thermal analysis (DTA) was used to analyze the catalytic performance of a carbon aerogel for ammonium perchlorate (AP). The results showed that the CS-Pb carbon aerogel reduced the peak temperature of AP pyrolysis from 703.9 to 627.7 K. According to the Kissinger method calculations, the E_a of AP decomposition decreased about 27.2 kJ/mol. The TG data at different warming rates were analyzed by the Flynne-Walle-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, which are two of the isoconversion methods, and the activation energies of AP and AP+CS-Pb-3.5 were calculated. Between the conversion degrees (α) of 0.1 and 0.9, the E_a values obtained by the two isoconversion methods are similar and have a certain match. Also, the two isoconversion methods confirm Kissinger's calculation. Finally, thermogravimetry-mass spectrometry (TG-MS) was used to monitor the gases generated during the thermal decomposition of the AP+CS-Pb-3.5 system in real time.

Gas–solid two-phase flow method for preparing trimesic acid series MOFs for catalytic thermal decomposition of ammonium perchlorate

The Zn–BTC, Co–BTC and Zn–Co–BTC series MOFs were prepared by using the GSF device and applied in the catalytic thermal decomposition of AP to change the high-temperature thermal decomposition peak of AP.

Recent Advances in Synthesis and Applications of MFe2O4 (M = Co, Cu, Mn, Ni, Zn) Nanoparticles

In the last decade, research on the synthesis and characterization of nanosized ferrites has highly increased and a wide range of new applications for these materials have been identified. The ability to tailor the structure, chemical, optical, magnetic, and electrical properties of ferrites by selecting the synthesis parameters further enhanced their widespread use. The paper reviews the synthesis methods and applications of MFe₂O₄ (M = Co, Cu, Mn, Ni, Zn) nanoparticles, with emphasis on the advantages and disadvantages of each synthesis route and main applications. Along with the conventional methods like sol-gel, thermal decomposition, combustion, co-precipitation, hydrothermal, and solid-state synthesis, several unconventional methods, like sonochemical, microwave assisted combustion, spray pyrolysis, spray drying, laser pyrolysis, microemulsion, reverse micelle, and biosynthesis, are also presented. MFe₂O₄ (M = Co, Cu, Mn, Ni, Zn) nanosized ferrites present good magnetic (high coercivity, high anisotropy, high Curie temperature, moderate saturation magnetization), electrical (high electrical resistance, low eddy current losses), mechanical (significant mechanical hardness), and chemical (chemical stability, rich redox chemistry) properties that make them suitable for potential applications in the field of magnetic and dielectric materials, photoluminescence, catalysis, photocatalysis, water decontamination, pigments, corrosion protection, sensors, antimicrobial agents, and biomedicine.