Decomposition Characteristics Research Articles

Warming promotes the decomposition of oligotrophic bacterial-driven organic matter in paddy soil

The ongoing global warming is causing paddy soil to come under threat by hitherto unseen levels of carbon and nitrogen loss. The mechanism of soil organic matter (SOM) components and microbial metabolism responding to increased temperature is complicated; for example, the temperature sensitivity (Q10) of SOM decomposition in rice topsoil and subsoil remains poorly understood. In this study, 0–30 cm columns of undisturbed paddy soil were collected and incubated at 5, 15, or 25 °C for 117 days to investigate the effect of temperature on SOM decomposition and microbial characteristics in different soil layers. Results showed that Q10 of subsoil (15–30 cm) was more than twice that of topsoil (0–15 cm), indicating that SOM mineralisation in subsoil was facilitated more by temperature than that in topsoil. Warming promoted the decomposition of recalcitrant SOM and reduced the fluorescent intensity of dissolved organic matter. Increased temperature exerted no significant effect on microbial biomass, but it did enhance the relative abundance of oligotrophic bacteria and promote anabolism. Therefore, recalcitrant SOM decomposition driven by oligotrophic bacteria was more sensitive to warming than labile organic matter consumption mediated by copiotrophic bacteria. Our findings revealed the underlying mechanisms by which elevating temperature promoted SOM mineralisation, thereby emphasising the need to remain vigilant regarding the threat to carbon dynamics in deep soil poised by global climate changes.

Multi-Featured Sea Ice Classification with SAR Image Based on Convolutional Neural Network

Sea ice is a significant factor in influencing environmental change on Earth. Monitoring sea ice is of major importance, and one of the main objectives of this monitoring is sea ice classification. Currently, synthetic aperture radar (SAR) data are primarily used for sea ice classification, with a single polarization band or simple combinations of polarization bands being common choices. While much of the current research has focused on optimizing network structures to achieve high classification accuracy, which requires substantial training resources, we aim to extract more information from the SAR data for classification. Therefore we propose a multi-featured SAR sea ice classification method that combines polarization features calculated by polarization decomposition and spectrogram features calculated by joint time-frequency analysis (JTFA). We built a convolutional neural network (CNN) structure for learning the multi-features of sea ice, which combines spatial features and physical properties, including polarization and spectrogram features of sea ice. In this paper, we utilized ALOS PALSAR SLC data with HH, HV, VH, and VV, four types of polarization for the multi-featured sea ice classification method. We divided the sea ice into new ice (NI), first-year ice (FI), old ice (OI), deformed ice (DI), and open water (OW). Then, the accuracy calculation by confusion matrix and comparative analysis were carried out. Our experimental results demonstrate that the multi-feature method proposed in this paper can achieve high accuracy with a smaller data volume and computational effort. In the four scenes selected for validation, the overall accuracy could reach 95%, 91%, 96%, and 95%, respectively, which represents a significant improvement compared to the single-feature sea ice classification method.

Simulation on coal combustion and calcium carbonate decomposition in a 5500 t/d full scale cement calciner

With the continuous growth of global cement production, the increasing coal consumption in the cement industry has been drawing great attention, thus adopting advanced technologies to reduce energy consumption has become an important issue. To address this problem, this study carried out 3D Eulerian-Lagrangian simulations of the coupling process of pulverized coal combustion and CaCO3 decomposition in a 5500 t/d full-scale cement calciner. On the basis of the multiphase particle-in-cell (MP-PIC) approach, reaction models including devolatilization, combustion of char and volatiles, and CaCO3 decomposition are incorporated into the scheme. Detailed combustion characteristics including temperature distribution, carbon exhaust rate, and gas emission characteristics, as well as decomposition characteristics are comprehensively analyzed. Besides, effects of different operating performances including O2 content in bottom flue gas on carbon exhaust rate, CaCO3 decomposition rate, and NOx emission are also investigated. Results show that under the typical working condition with O2 concentration in the flue gas of 1.7 %, the CaCO3 decomposition rate can reach around 96.42 %, the carbon conversion rate is up to 98.65 %, and the NOx can be controlled at around 105 ppm. The increase of O2 content promotes higher carbon conversion rates with excessive O2 leading to higher NOx emission. Appropriately increasing the proportion of raw material flow rate in upper tubes can facilitate a more complete CaCO3 decomposition.

Monopulse Parameter Estimation for FDA-MIMO Radar under Mainlobe Deception Jamming

Multiple input multiple output with frequency diversity array (FDA-MIMO) radar has unique advantages in mainlobe deception jamming suppression and target location. However, if the training sample contains the target signal, it will lead to poor jamming suppression performance and large target measurement error. To deal with the problem, a method of coarse target location in the time domain is proposed based on the cumulative sampling analysis. Taking full advantages of the strongest correlation characteristic between the expected steering vector and the true target, the feature vector and feature value corresponding to the true target are found after feature decomposition. The time domain location of the target is roughly estimated during the cumulative sampling analysis from near to far. Then, a pure jamming training sample can be obtained by avoiding the location. Noise subspace projection algorithm is used to measure the angle and range of the target while suppressing mainlobe jamming. The simulation results show that the proposed method can roughly estimate the target location in the time domain when the mainlobe deception jamming completely covers the target. Compared with conventional methods, the performance of jamming suppression and target localization error are closer to the performance of ideal sampling.

Sparse random similarity feature decomposition and its application in gear fault diagnosis

As a new signal decomposition method, sparse random mode decomposition (SRMD) does not depend on the signal sampling process and has good anti-mode aliasing performance. However, SRMD needs preset decomposition parameters and cannot perform accurate decomposition for strong noise interference signals. Thus, this paper proposes a sparse random similarity feature decomposition (SRSFD) method to overcome the problems of SRMD. Firstly, SRSFD utilizes the windowed sinusoidal function to randomly generate time–frequency features. Then, by solving sparse optimization problem, the sparse random feature approximation of the input signal can be obtained and its corresponding time–frequency features can be applied to reconstruct the initial signal components. Finally, the initial signal components are regrouped by using periodic similarity to obtain the final components. The analytical results of simulation and actual gear fault signals show that SRSFD can effectively achieve adaptive signal decomposition and has better decomposition performance and noise robustness compared with existing methods.

Thermal decomposition and combustion characteristics of molecular perovskite energetic material DAP-4 catalyzed by Co3O4 nanoclusters

Thermal decomposition and combustion characteristics of molecular perovskite energetic material DAP-4 catalyzed by Co3O4 nanoclusters

Daily runoff prediction based on the adaptive fourier decomposition method and multiscale temporal convolutional network.

The non-linearity and non-stationarity of runoff series pose significant challenges to runoff forecasting, and conventional single forecasting models struggle to accurately capture the internal dynamics of the series. To address this issue, we propose a runoff prediction model named AFDM-MTCN, which combines the adaptive Fourier decomposition method (AFDM) and multiscale temporal convolutional network (MTCN). AFDM-MTCN consists of two stages: adaptive decomposition and multi-scale feature extraction. In the adaptive decomposition stage, the improved Fourier decomposition method (IFDM) is optimized using the Sparrow Search Algorithm to enhance its ability to extract temporal patterns. In the multi-scale feature extraction stage, improvements are made to the temporal convolutional network (TCN) through the use of multi-scale convolution kernels, skip connections, and depth-wise separable convolution, to capture information from multiple angles, enhance information propagation, and reduce training parameters. The model was applied to two hydrological stations in the Weihe River Basin and compared with state-of-the-art methods to assess its accuracy and feasibility. The results demonstrate that AFDM-MTCN exhibits satisfactory performance in runoff prediction. Furthermore, compared to other decomposition techniques, AFDM demonstrates stronger capability in extracting patterns from non-stationary runoff data.

Straw Return Decomposition Characteristics and Effects on Soil Nutrients and Maize Yield

Straw return benefits soil nutrient circulation and avoids the environmental pollution caused by incineration. The straw return effect is determined by many factors, such as the returning mode and tillage method. To find the most suitable straw return mode in the hilly areas of south China, we conducted experiments with preceding maize straw in Nanchong (Sichuan Province, China) for three years. Five treatments were tested: (A) rotary tillage without straw return (RT), (B) crushed straw return with rotary tillage (CRT), (C) crushed straw return without rotary tillage (CSR), (D) whole straw return with rotary tillage (WRT), and (E) whole straw return without rotary tillage (WSR). The results indicated that CRT had the fastest decomposition rate, followed by CSR. Moreover, CRT had the fastest nutrient release rates for nitrogen, phosphorus, potassium, cellulose, hemicellulose, and lignin, as well as the highest maize yield (6.62% higher than RT). CRT increased the content of organic matter, total nitrogen, total phosphorus, and total potassium in the soil, as well as improved the soil pH. Furthermore, the numbers of bacteria, Actinomycetes, and fungi in the soil under CRT, CSR, and WSR treatments were higher than those under the other two treatments. This study has important reference value for exploring the most favourable straw return method for improving farmland fertility.

Numerical Simulation of Natural-Gas-Hydrate Decomposition in Process of Heat-Injection Production

Heat-injection production is a common technique for gas-hydrate development, and the mechanism needs further in-depth study, particularly of the decomposition characteristics of natural-gas hydrate, which are important fundamental issues. The natural gas-hydrate-reservoir model is based on a mathematical description of reservoir properties that considers the effects of hydrate decomposition and reservoir stress conditions. The aim of our investigation was to analyze the production and decomposition characteristics of natural-gas hydrates based on the results of numerical simulations of heat-injection production. The effects of different heat-injection temperatures and heat-injection rates on production were compared, and the decomposition characteristics of hydrates were evaluated qualitatively and characterized quantitatively by temperature distribution, saturation distribution, and the decomposition front in the process of heat-injection production of natural-gas hydrate. The results showed that, with the increase in the heat-injection temperature, the decomposition front moved faster, the area share of decomposition zone increased, but the increase extent decreased. The high heat-injection rate had a more significant effect than the heat-injection temperature in promoting the decomposition of natural-gas hydrate.

Power quality transient disturbances detection system based on db5 wavelet

To improve the real-time and accuracy of transient disturbance localization in the power grid, this paper designs an FPGA-based transient disturbance detection system based on the good time-frequency local analysis capability, multi-resolution analysis characteristics of wavelet decomposition, and the selection of db5 (Daubechies 5) wavelets. The system acquires the original disturbance signal through an external high-speed AD/DA board, implements the wavelet transform algorithm by the EP4CE10F17C8 FPGA, and then feeds back to the high-speed AD/DA board to output the location of the singularities in the high-frequency detail signal that corresponds to the start and end moments of the disturbance. Simulation and actual test results together show that the system can accurately and quickly locate the start and end moments of typical single disturbances such as voltage sag and short interruption, with a measurement deviation of within 3ms, meeting the real-time requirements.

Controlling size and shape of pores during metal solidification for manufacturing of functionally graded metal foams

Manufacturing of metal foams by solidification processing involves numerous challenges related to achieving localized control of porosity with a limited material selection. The objective of this work is to control the size and shape of pores during metal solidification in a casting process by harnessing the thermal decomposition of discrete polymer features upon their interaction with molten metal. The influence of geometrical parameters and physical properties of these features on the evolution of pores generated from their interaction with molten metal was studied in detail. We firstly used an analytical model to evaluate the thermal response of such features in a model molten metal medium to determine the process window within which pores can be generated and captured in place during metal solidification. Systematic experiments were conducted to demonstrate the influence of the feature geometry on the evolution of the size and shape of captured pores. We further demonstrate that the relative separation of these features can exert a strong influence on the interaction of adjacently generated pores during metal solidification. This work essentially exhibits the potential of exploiting a lattice of discrete features that can enable the spatial control of pore capture during a metal solidification process.

Decomposition and reaction characteristics of C6F12O/N2 with rubber materials based on ReaxFF

C6F12O is considered to have potential for application in medium and low voltage electrical switchgear due to its excellent insulating properties. In order to ensure the stable operation of the equipment, it is necessary to study the compatibility of C6F12O/N2 gas with the rubber sealing materials used in insulating equipment. In this paper, EPDM, NBR and FKM are selected to conduct thermal acceleration experiments under 96 % C6F12O/4 % N2 gas at 40 ℃, 90 ℃, 110 ℃ and the changes of gas mixture before and after the experiments are analyzed by GC-MS. At the same time, the molecular system of gas mixture and rubber is constructed, and the reaction process of the system is simulated and the main decomposition path of rubber and the generation path of C2F are obtained at 1000–4000 K by using ReaxFF force field. The experimental results show that C6F12O/N2 gas mixture reacts with three rubbers at 40 ℃, 90 ℃, 110 ℃ and generate gas C3F6, C3F7H and by-products CS2. The theoretical results indicate that the decomposition products of mixed gas and rubber materials at high temperature are mainly H, F, CF2, CF3, and the reaction products are mainly C2F. Through pathway tracking, it is found that the decomposition products of C6F12O and rubber may react in multiple ways to generate C3F6 and C3F7H, which originate from the complex reaction of rubber and gas mixture. The compatibility between C6F12O/N2 and FKM is greater than that of NBR and EPDM. The simulation results are consistent with the experimental results. The results can provide a theoretical reference in the selection of sealing materials for equipment using C6F12O/N2 gas mixture as the insulating medium.

An MD Simulation Study of Decomposition Characteristics of C5F10O/CO2 Gas Mixture Under the Presence of Thermal and Electric Field

C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O has outstanding insulation properties and low global warming potential, which could be potentially used as alternative gas for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> and has attracted much attention for researchers. However, there are few reports focusing on its decomposition characteristics under atrocious conditions which is closely related to its insulation performance, as well as its safety issue. In this paper, CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is selected as the buffer gas. Based on ReaxFF, the decomposition path and reaction mechanism of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas mixture were analyzed from the molecular level. The results show that under high temperature conditions C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O cleavage produces CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , F, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> O, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , CO, CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> and other by-products. The break and recombination of C-C single bond and C-F single bond are the main reasons for the formation of fluorocarbons in the products. The addition of the electric field makes the C-F single bond and the C=O double bond in C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O become more active and reactive. The conclusion is complementary to the characteristics of environmental protection insulating gas C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O in insulation and provides reference for related engineering applications.

Traditional vs. Energetic and Perchlorate vs. "Green": A Comparative Study of the Choice of Binders and Oxidising Agents.

The aim of this article is to compare rocket propellants containing a traditional binder (hydroxyl-terminated polybutadiene) and an energetic binder (glycidyl azide polymer), as well as a perchlorate oxidising agent and a "green" one, i.e., ammonium perchlorate and phase-stabilised ammonium nitrate. We have outlined the effects of individual substances on the sensitivity parameters and decomposition temperature of the produced solid propellants. The linear combustion velocity was determined using electrical methods. Heats of combustion for the propellant samples and the thermal decomposition features of the utilised binders were investigated via differential scanning calorimetry (DSC). Activation energy values for the energetic decomposition of the propellants were determined via the Kissinger method, based on DSC measurements at varied heating rates.

A comprehensive study of pyrolysis characteristics of silicone-modified phenolic aerogel matrix Nanocomposites: Kinetic Analysis, ReaxFF MD Simulations, and ANN prediction

The pyrolysis characteristics of the polymeric nanocomposites are dominantly regulated by the pyrolyzable components to accommodate a specific thermodynamic environment. The pyrolysis mechanisms of the pyrolyzable system including silicone and phenolic aerogels (SiOC/PR) of silicone-modified phenolic aerogel matrix nanocomposites are carried out by kinetic analysis, ReaxFF molecular dynamics (MD) simulations, and artificial neural network (ANN). The experimental results show that the SiOC/PR systems exhibit better thermal stability when the mass ratio of SiOC to PR is 1:3. A distributed activation energy model with five pseudo-components is employed to calculate the kinetic parameters of each decomposition stage of SiOC/PR systems for describing the decomposition characteristics. The significant pyrolysis products detected by TG-FTIR are examined by ReaxFF MD simulations. MD results reveal that the methanol evolution of SiOC/PR systems is distinct in a high-temperature oxygen-free environment, where a mass ratio 1:3 of SiOC to PR is more likely to release methanol and forms a silicon oxide-rich phase with high bond energy. Two reaction mechanisms for methanol identified by the MD trajectory are the extraction reactions of methyl intermediates as well as hydroxymethyl intermediates. The mixture ratio of the pyrolyzable system of the SiOC/PR nanocomposites with optimal thermal resistance equaling 0.22 is predicted by ANN. This work can help understand the system’s chemical features and guide the pyrolyzable system design of the SiOC/PR nanocomposites.

A Study on Greenhouse Gas (PFCs) Reduction in Plasma Scrubbers to Realize Carbon Neutrality of Semiconductors and Displays

Perfluorinated compounds (PFCs) are used for manufacturing purposes in the semiconductor and display industries, resulting in an increased need for emission reduction due to the significant global warming potential of the associated greenhouse gases. The decomposition characteristics of etch-type and water film (WF)-type plasma-wet scrubbers were investigated. The PFCs used in the study were CF4, SF6, NF3, CHF3, C2F6, C3F8, and C4F8, and the destruction removal efficiency (DRE) and by-product gas generation rate were confirmed based on the changes in the parameters (total flow rate and power) of the plasma-wet scrubber. When the total flow rate reached 100 L/min and the measured maximum power (11 kW), the reduction efficiency of CF4 in the etch type was 95.60% and the DRE of other PFCs was 99.99%. Moreover, for the WF type, the DRE of CF4 was 90.06%, that of SF6 was 96.44%, and that of other PFCs was 99.99%. When the total flow rate reached 300 L/min and 11 kW, the DRE of SF6 in the etch type was 99%, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 was 95.57%, 87.06%, 70.74%, 81.45%, and 95.59%, respectively. In addition, in the WF type, the DRE of SF6 was 94.39%, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 was 99.80%, 95.34%, 85.38%, 88.49%, and 98.22%, respectively. The decomposition efficiency was high for the etch type for gases with small flow rates or no by-product gas generation. The by-product gas generation rate was significantly lower for the WF type.

Investigation of the thermal hazard and decomposition mechanism of 1,1-di(tert-butylperoxy) cyclohexane by experiment and DFT simulation

1,1-Di (tert-butylperoxy) cyclohexane (1, 1-DTBCH), as an important organic peroxide, is commonly used as initiator, curing agent and crosslinking agent in the chemical industry. Due to the presence of peroxy bonds, the thermal instability of 1, 1-DTBCH may incur a decomposition reaction and cause further thermal runaway. The thermal decomposition characteristics and runaway reaction characteristics of 1, 1-DTBCH were investigated by differential scanning calorimetry (DSC) and accelerated rate calorimetry (ARC). The kinetic triplet and thermal safety parameters were calculated by using non-isothermal method. The gaseous products and pyrolysis products of 1, 1-DTBCH was investigated by thermogravimetric and infrared spectroscopy (TG-FTIR) and gas chromatography/mass spectrometry (GC/MS). The thermal decomposition pathway of 1, 1-DTBCH was explored with density functional theory (DFT). The exothermic dominant reaction in the thermal decomposition process of 1, 1-DTBCH was explored by combining experiment and theoretical calculation. The corresponding safety control measures were provided to reduce the thermal runaway hazard of 1, 1-DTBCH.

Experimental and theoretical studies on the kinetics of thermal decomposition and decomposition mechanism of CF3I in oxidizing environments

CF3I, as a novel “Halon” replacement fire-extinguishing agent, has the characteristics of low fire-extinguishing concentration, high efficiency, and safety. However, there are still some gaps in its thermal decomposition studies when it is released into the high-temperature fire, so the thermal decomposition of CF3I in oxidizing environments was studied to simulate its diffusive decomposition. The decomposition of CF3I was demonstrated to be accelerated by O2 through experiments in the temperature range of 100°C-800°C in air and N2 atmosphere. The effects of initial concentration, temperature, and residence time on the decomposition rate of CF3I and decomposition characteristics were investigated by tube furnace simulation. The kinetics of thermal decomposition was calculated using the Arrhenius equation in which activation energy Ea is 15.18 kJ/mol and pre-exponential factor (A) is 13.87s−1. Additionally, the thermal decomposition products were examined by GC-MS and FTIR. The experimental results showed that the pyrolysis gas products were mainly CF4, C2F6, and CF2O. Using quantum chemistry and density flooding theory (DFT) calculations, it was concluded that the main decomposition pathway was the reaction of CF3I with singlet oxygen. The reaction pathway of the thermal decomposition of CF3I under a high-temperature fire oxidation environment was proposed based on the products.

Novel insight of the thermal degradation kinetics, environmental impact and transformation behavior of heavy metals and chlorine of municipal solid waste incineration fly ash in nitrogen

Thermal treatment is an effective method to dispose of municipal solid waste incineration (MSWI) fly ash (FA), however, present research mainly focuses on the thermal behavior of FA in air, neglecting the investigation of FA pyrolysis characteristic in inert gases. The weight loss, phase transition, environmental impact, and conversion behavior of heavy metals and chlorine during the FA pyrolysis in N2 were measured using TG-FTIR-XRD-ICP-IC to increase understanding of the transformation process and decomposition features of FA in inert gas. The results demonstrated that CO2, NO, C-O(H), HCl, SO2, and H2O are emitted during FA pyrolysis due to the decomposition of inorganic salts and organic compounds. After being roasted at 1200 °C, the volatilization rates of As, Cr, Cd, Cu, Pb, and Zn were 56.71%, 34.75%, 99.56%, 83.41%, 96.22%, and 97.19%, respectively. However, the removal rate of Cl was only 51.43%, owing mostly to the formation of Ca2SiO4CaCl2 at high temperatures, which hampered chlorine volatilization. The kinetic of FA pyrolysis was investigated using FWO, KAS, and CR methods at heating rates of 10, 20, 30, and 40 °C/min, which suited the experimental data of each stage well. Chemical reaction (No. 2), assumed random nucleation and its subsequent growth (No. 11), and three-dimensional diffusion and spherical symmetry (No. 21) were the reaction control procedures of stages I, III and IV, with activation energies of 54.04, 213.03 and 280.85 kJ/mol, respectively. The degradation kinetics, environmental emissions, and reaction mechanisms of FA pyrolysis in the N2 atmosphere can provide a novel insight for pollution reduction and process optimization.

The enhancement of heterobimetallic MOFs on the pyrolysis and laser ignition of FOX-7

The hydrothermal approach had been used to synthesize two new heterobimetallic Metal Organic Frameworks (MOFs), Ba4Pb4(CH3CO2)8[(CH6CO2)4Pb](CH3CO2)4 (PbBa-MOF) and Ba2Ni(CO2H)6(OH2)4 (NiBa-MOF), their structure and surface topography were then examined with XRD and SEM. By using the TG-DSC and TG-FTIR-MS methods, the pyrolytic decomposition properties of MOFs and their catalytic activities on the 1,1-diamino-2,2-dintroethene (FOX-7) pyrolysis were investigated. The PbBa-MOF has a single thermal decomposition process with a high thermal decomposition temperature, while NiBa-MOF has a three-stage thermal decomposition process initiated from a lower temperature. Furthermore, the thermolysis peak temperature of the FOX-7/PbBa-MOF and FOX-7/NiBa-MOF mixture has a great decrease by 24.2 °C and 27.4 °C compared with the FOX-7. However, the low pyrolysis peak temperature and the pyrolysis activation energy (Ea) are almost unchanged. The selective high temperature catalytic effect of the MOFs on FOX-7 results from the activation of -NH2 in the high temperature pyrolytic decomposition of FOX-7 by the metallic ions of the MOFs. This thermal catalytic property indicates that MOFs can promote the pyrolytic decomposition of FOX-7 while ensuring the safety requirements for the compatibility of energetic mixtures in the preparation of propellants. The relationship between the features of pyrolytic decomposition and laser ignition was finally covered and defined. The two MOFs decreased the minimum ignition energy and ignition delay time of the FOX-7. Novel MOFs combustion catalyst may strengthen ignition and combustion features of the high-energy and low-sensitivity solid propellants containing FOX-7.