International Journal of Coal Preparation and Utilization
·
2024
·
IF 2
Yanrui Guo,Xiaogang Mu,Cunbao Deng,Hongfei Duan,Ling Qiao,Qianru Du,Peng Jing
Spontaneous combustion of coal is one of the main natural disasters in the process of coal mining, and spontaneous combustion of sulfur-containing coal is an urgent problem to be solved. In order to understand the influence of different sulfur structures and sulfur content on spontaneous combustion tendency of coal, the self-developed synchronous temperature compensation adiabatic oxidation experiment system was used to study the oxidation self-heating performance of a series of sulfur-containing “coal-like materials.” Through the analysis of the heating rate of coal containing specific sulfur structure, it is considered that the time of adiabatic oxidation temperature of different organic sulfur “coal” to rise to 70°C is dimethyl sulfoxide > phenylene sulfide > dibenzothiophene. By analyzing the oxidation temperature rise characteristics of organic sulfur models with different sulfur contents, it is believed that the higher sulfur content, the faster the low temperature oxidation reaction of “coal-like substance,” the faster the temperature rise rate, and the shorter the time to reach the uncontrollable self-heating temperature, so the shorter the spontaneous combustion period. In general, in the stage of low temperature oxidation, active sulfur containing small molecules (dimethyl sulfoxide) promote the oxidation temperature rise, stable structure, larger molecular weight of dibenzothiophene slow down the “coal-like” oxidation temperature rise.
研究领域:
矿业工程
·
热力学
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产品关联
DOI
高影响因子
ChemSusChem
·
2023
·
IF 8.4
Hongcai Su,Dan Xu,Tian Li,Lingjun Zhu,Shurong Wang
Graphical Selective upcycling of polyolefin waste into H 2 fuel has been limited by the relatively high temperatures. Here, we report a novel tandem hydrothermal oxidation and reforming strategy that can convert polypropylene waste into H 2 in high yield at low temperature. The entire process operated in a mild and clean way with almost no solid residue remaining and equipment contamination. Plastic waste is a promising and abundant resource for H 2 production. However, upcycling plastic waste into H 2 fuel via conventional thermochemical routes requires relatively considerable energy input and severe reaction conditions, particularly for polyolefin waste. Here, we report a tandem strategy for the selective upcycling of polypropylene (PP) waste into H 2 fuel in a mild and clean manner. PP waste was first oxidized into small-molecule organic acids using pure O 2 as oxidant at 190 °C, followed by the catalytic reforming of oxidation aqueous products over ZnO-modified Ru/NiAl 2 O 4 catalysts to produce H 2 at 300 °C. A high H 2 yield of 44.5 mol/kg PP and a H 2 mole fraction of 60.5 % were obtained from this tandem process. The entire process operated with almost no solid residue remaining and equipment contamination, ensuring relative stability and cleanliness of the reaction system. This strategy provides a new route for low-temperature transforming PP and improving the sustainability of plastic waste disposal processes.
研究领域:
环境科学
·
能源科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
PROCESS SAFETY PROGRESS
·
2022
·Vol. 41
·期 4
·783-792
·
IF 1.294
Xue Zhou,Yue Pan,Lifan Zhang,JiaJia Jiang
Epoxidized soybean oil was widely used in industrial production. However, the epoxidized soybean oil production process releases a lot of heat, which could cause a runaway reaction, resulting in fires and explosions. Therefore, the thermal risk of the soybean oil epoxidation reaction process has been studied. Differential scanning calorimetry was used to investigate the thermal stability of reaction materials. The parameters such as initial exothermic temperature and reaction heat were obtained based on heat flow diagrams. EasyMax was used to analyze the soybean oil epoxidation reaction under different reaction temperatures and dosing rate conditions. The maximum temperature of the synthesis reactions, time to maximum rate under adiabatic condition ( TMR ad ), and adiabatic temperature rise ( ∆ T ad ) were obtained by analyzing the epoxidation reaction. An adiabatic accelerating calorimeter was used to study the adiabatic decomposition of reaction products to obtain safety criteria such as adiabatic temperature rise and maximum reaction rate. The results obtained by the risk matrix evaluation method show that the risk level of the soybean oil epoxidation process was unacceptable. According to the results of the runaway scenario analysis method, the risk level of soybean oil epoxidation reaction was level 5. Therefore, the reaction process needs to be improved to ensure safe production.
研究领域:
化学工程
·
安全科学
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DOI
高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Yuli Pei,Yiheng Zhou,Xinhe Wu,Kaixu Wang,Qianhong Shen,Hui Yang,Tao Shen
Flower spherical ZnO loaded with Ag nanoparticles was synthesized by hydrothermal method. Ag/ZnO electrical contact materials were prepared by powder metallurgy combined with hot extrusion technique. During the hydrothermal reaction, Ag nanoparticles entered the interlayer gaps of flower spherical ZnO and uniformly deposited on its surface. The tensile mechanical test results indicate that the Ag/ZnO electrical contact materials prepared by ZnO, Ag@ZnO (75 wt%) and Ag@ZnO (50 wt%) exhibited elongations of 6.8 %, 13.8 % and 12.1 %, respectively. This result indicates that appropriate loading of Ag nanoparticles on flower spherical ZnO could significantly improve the mechanical properties of Ag/ZnO electrical contact materials. The contact resistance of electrical contact materials significantly affects their temperature rise characteristics. During 20, 000 cycles process, Ag/ZnO electrical contact material prepared by Ag@ZnO (50 wt%) exhibited the lowest temperature rise of 6.33 K under the conditions of DC 36 V/10 A. Considering both mechanical and electrical contact performance, Ag/ZnO electrical contact materials prepared by Ag@ZnO (50 wt%) exhibited the optimum overall performance.
研究领域:
材料科学
·
电气工程
✓ 已验证
DOI
高影响因子
JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
·
2015
·
IF 1.406
L. Zhang,W.D. Yu,X.H. Pan,J.J. Fang,M. Hua,F.M. Chen,J.C. Jiang
The exothermic oxidation of 3-methylpyridine with hydrogen peroxide was analyzed by Reaction Calorimeter (RC1e) in semi-batch operation. Heat releasing rate and heat conversion were studied at different operating conditions, such as reaction temperature, feeding rate, the amount of catalyst and so on. The thermal hazard assessment of the oxidation was derived from the calorimetric data, such as adiabatic temperature rise (ΔT ad ) and the maximum temperature of synthesis reaction (MTSR) in out of control conditions. Along with thermal decomposition of the product, the possibility of secondary decomposition under runaway conditions was analyzed by time to maximum rate (TMR ad ). Also, risk matrix was used to assess the risk of the reaction. Results indicated that with the increase of the reaction temperature, the reaction heat release rate increased, while reaction time and exotherm decreased. With the increase of feeding time, heat releasing rate decreased, but reaction time and exotherm increased. With the amount of the catalyst increased, heat releasing rate increased, reaction time decreased and exothermic heat increased. The risk matrix showed that when the reaction temperature was 70 °C, feeding time was 1 h, and the amount of catalyst was 10 g and 15 g, respectively, the reaction risk was high and must be reduced.
研究领域:
化学工程
·
安全科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2014
·Vol. 119
·期 1
·205-212
·
IF 2.206
Yang Ting,Chen Liping,Chen Wanghua,Zhou Yishan,Gao Haisu,Zhong Tingting
2-Ethylhexyl nitrate (EHN) is an important material, which is produced by concentrated HNO 3 –H 2 SO 4 nitration process. But EHN is not a stable material, especially mixed with acids. To analyze the stability of EHN with concentrated acid under serious condition, four samples (pure EHN, concentrated sulfuric acid with EHN, concentrated nitric acid with EHN, and mixed acid with EHN) and three acids (sulfuric acid, nitric acid, and mixed acid) were measured by differential scanning calorimeter (DSC) and accelerating rate calorimeter (ARC) in this paper. The results indicated that concentrated sulfuric acid, concentrated nitric acid, and mixed acid all could decrease the onset decomposition temperature of EHN, especially concentrated sulfuric acid. DSC results also showed that the heat of EHN decomposition with nitric acid is larger than other samples. Based on ARC data, the kinetic parameters and T
D24 (temperature at which TMR
ad is 24 h) were calculated. The activation energy and T
D24 of the EHN with acids, especially with concentrate sulfuric acid, were much lower than the pure EHN. It can be concluded that acids could decrease the stability of EHN and that is an important reason for frequent accidents.
研究领域:
物理化学
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安全工程
·
材料化学
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热分析
·
危险品管理
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DOI
高影响因子
JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
·
2021
·
IF 3.66
Qiang Chen,Yuqing Ni,Jun Liang,Lei Ni,Juncheng Jiang,Yong Pan,Qingsheng Wang
Esterification reactions between anhydrides and alcohols catalyzed by sulfuric acid have broad applications in the food, cosmetic, and pharmaceutical industries. However, the exothermic behavior cannot be well explained, especially in semibatch reactors with different feeding procedures. In this study, a series of esterification processes in semibatch systems were conducted with a wide range of feeding rates with two different substrates. The structures of initial catalytic substrates were characterized using in situ Fourier Transform Infrared (FTIR) spectroscopy. A total of 11 reaction pathways, including those for the initial activation of substrates and the subsequent reactions of the feeding process, were calculated by the density functional theory (DFT) method. Three possible catalytic cycles of the esterification with specific acid catalysis, protonated intermediate, and protonated intermediate and H 2 O, were established for the semibatch esterification reaction based on calculated results and experimental evidence. Thermal safety parameters such as reaction enthalpy ( Δ H r ), adiabatic temperature rise ( Δ T r , a d ), and maximum temperature of the synthetic reaction (MTSR) were determined based on Wilson equation used to calibrate mixing heat. The results reveal that mixing heat was 2.5 kJ/mol with same mole ratio of n -butanol ( n B) and propionic anhydride (PA). The reactions started by PA are dominant, no matter whether the substrate is n B or PA. The initial reaction rate is restricted by the low concentration of catalyst and active reactant when n B is used as substrate, which lead to significant reactant accumulation with high MTSR of approximately 160 °C. Furthermore, feeding n B into PA allows a controllable increase in the Δ T r , a d realized by changing the feeding rate and limiting the accumulation of reactant.
研究领域:
化学工程
·
物理化学
·
过程安全
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产品关联
DOI
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2023
·
IF 7.8
Hang Yao,Lei Ni,Yinshan Liu,Gang Fu,Juncheng Jiang,Zhen Cheng,Yuqing Ni,Zhiquan Chen
The exothermic pattern of m-xylene nitration with mixed acid in semi-batch mode was studied by reaction calorimetry . Adiabatic temperature rise ( Δ T ad ) and reaction enthalpy ( ∆ H ) were obtained to identify the thermal hazard. Process conditions including stirring rate, reaction temperature and strength of mixed acid were studied to optimize the reaction. Optimal yield (95.5%) was reached under the conditions of sufficient stirring rate, 70% strength of mixed acid and reaction temperature of 40 °C. Meanwhile, the thermal stability of nitration products was investigated by differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). Pyrolysis kinetic parameters were calculated under non-isothermal and adiabatic conditions . Furthermore, the maximum temperature of the runaway system for synthesis reaction ( MTSR ) was determined to analyze the reaction hazard. The thermal risk of nitration of m-xylene was also assessed by the risk matrix and Stoessel criticality diagram. In addition, the nitration mechanism of m-xylene was presented. The active site for the electrophilic reaction of m-xylene was predicted via theoretical approach which was in consistent with the selectivity obtained by the experiment. These findings provide guidance for the safe operation of m-xylene nitration and can be used for further scale-up.
研究领域:
化工工程
·
热安全
·
过程优化
·
反应动力学
·
风险评估
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）