JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES
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2022
·
IF 3.916
Yong Pan,Chaoqin Ren,Gan Wang,Yanjun Wang,Xin Zhang,Juncheng Jiang,Chi-Min Shu
Aiming at the green and sustainable energy substitution and supply, biomass valorization has become a potential strategy to face the energy crisis and increasing demand all over the world from long-term perspectives. Among the bio-based chemicals, γ-valerolactone (GVL) production from hydrogenation of levulinic acid (LA) and its esters has attracted great interests due to its wide applications, such as fuel, solvent, and additives. However, the safety evaluation for this hydrogenation reaction has received few attentions. To fill this gap, thermal hazard evaluation for GVL production from LA hydrogenation by using formic acid (FA) as hydrogen donor was first performed. The process conditions were optimized by using orthogonal experimental method for further calorimetry study. Thermal stability of chemicals and thermal risk of reaction process under adiabatic conditions were investigated by applying differential scanning calorimetry and accelerating rate calorimeter Phi-Tec II, respectively. The results revealed that the chemicals were stable in temperature range from 30 to 250 °C except FA due to its evaporation and decomposition with endothermic behaviors. The reaction process under isothermal and adiabatic conditions demonstrates that the decomposition of FA was rapid and followed by the hydrogenation of LA to GVL. Based on kinetic model under adiabatic conditions and risk matrix , the thermal runaway risk was found to be medium, indicating that certain safety measures should be properly designed and taken for loss prevention. This work could benefit the safety design and thermal risk prevention for GVL production by using FA as hydrogen donor.
研究领域:
化学工程
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能源科学
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安全工程
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Mengjie Chen,Qinlan Luo,Haizhou Lin,Qiang Sun,Hongxia Gao,Sen Liu,Yuanyuan Li,Zhiwu Liang
The kinetic behavior of the reaction of CO 2 with MEA-TREA in ethanol solution was studied using the stopped-flow technique. The results indicate that the zwitterion mechanism successfully correlates the experimentally measured pseudo first-order reaction constant ( k 0 ) and that the TREA participated in the deprotonation step of MEA-zwitterion as an alkaline substance after the formation of MEA-zwitterion. Then, the applicability of this proposed mechanism was investigated by using the reaction kinetics of CO 2 with MEA-DMEA, MEA-DEEA, MEA-MDEA, DEA-TREA, DEA-DMEA blended amines in non-aqueous ethanol solution, as well as MEA-TREA, MEA-DMEA, DEA-TREA, DEA-DMEA blended amines in water-lean solutions. It was found that the mechanism of the reaction of CO 2 with these mixed amines can be expressed by: k 0 = K A - A z [ A ] 2 + K A - B z [ A ] [ B ] + K 1 z [ A ] . The ethanol and water molecules which contribute to K 1 z can be used as proton transfer channels to accelerate proton transfer, but they do not directly participate in the reaction. In addition, the alkalinity and the steric hindrance effect controlled by the molecular structure of tertiary amines affected the reaction rate at the same time. The activation energies in MEA-EtOH and MEA-TREA-EtOH system were estimated by fitting the second-order rate constants to the Arrhenius expression, indicating that TREA can reduce the reaction activation energy and make the reaction more kinetically favorable.
研究领域:
化学工程
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环境科学
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产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2023
·
IF 5.2
Fupeng He,Jianbo Zhao,Qingqing Hu,Yongjie Liu,Qingyun Huang,Zhixiong You,Xuewei Lv
We investigate the isothermal kinetics of the reduction and nitridation of V 2 O 3 using NH 3 . The reaction mechanism is also discussed based on the thermodynamic and experimental results. The reaction procedure between V 2 O 3 and NH 3 can be divided into two stages. The first stage is mainly the deoxygenation process, whereas the second is the nitridation process. The deoxygenation process follows a two-dimensional phase boundary reaction model, and a modified integrated model (IM + diffusion) was proved to be the best function at temperatures above 1023 K. For the second stage, the three-dimensional diffusion model is determined as the mechanism function. Thermodynamic analysis predicts the feasibility between V 2 O 3 and NH 3 to form VN . The VN product is a solid solution (VN x O y ) (0 < x,y < 1, x + y = 1), which can be formed at 873 K. The Rietveld refinement analysis indicates the N content of VN x O y gradually increases with increasing temperature. The highest N content is approximately 15.83% at 1073 K for 2 h.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
BMC Chemistry
·
2023
·Vol. 17
·期 1
·1-17
·
IF 4.6
Liang Min,Dai Suyi,Cheng Haijun,Yu Chang,Li Weiguang,Lai Fang,Yang Kang,Ma Li,Liu Xiongmin
In this study, the oxidation characteristics of isoprene were investigated using a custom-designed mini closed pressure vessel test (MCPVT). The results show that isoprene is unstable and polymerization occurs under a nitrogen atmosphere. Under an oxygen atmosphere, the oxidation process of isoprene was divided into three stages: (1) isoprene reacts with oxygen to produce peroxide; (2) Peroxides produce free radicals through thermal decomposition; (3) Free radicals cause complex oxidation and thermal runaway reactions. The oxidation of isoprene conforms to the second-order reaction kinetics, and the activation energy was 86.88 kJ·mol −1 . The thermal decomposition characteristics of the total oxidation product and purified peroxide mixture were determined by differential scanning calorimetry (DSC). The initial exothermic temperatures T on were 371.17 K and 365.84 K, respectively. And the decomposition heat Q DSC were 816.66 J·g −1 and 991.08 J·g −1 , respectively. It indicates that high concentration of isoprene peroxide has a high risk of thermal runaway. The results of thermal runaway experiment showed that the temperature and pressure of isoprene oxidation were prone to rise rapidly, which indicates that the oxidation reaction was dangerous. The reaction products of isoprene were analyzed by gas chromatography-mass spectrometry (GC–MS). The main oxidation products were methyl vinyl ketone, methacrolein, 3-methylfuran, etc. The main thermal runaway products were dimethoxymethane, 2,3-pentanedione, naphthalene, etc. Based on the reaction products, the possible reaction pathway of isoprene was proposed.
研究领域:
化学工程
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安全科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
COMBUSTION AND FLAME
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2023
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IF 4.4
Xiaodong Wang,Lili Ye,Xiaoyuan Zhang,Zhihe Zhang,Jiuzhong Yang,Long Zhao
Acetaldehyde, ethylene oxide , and vinyl alcohol are three C 2 H 4 O isomers that are ubiquitous in combustion over a wide temperature range. A comprehensive reaction kinetics study has been performed for reactions that occur on the same C 2 H 4 O potential energy surface , mainly including the unimolecular reactions of three C 2 H 4 O isomers and the recombination reaction of CH 3 with HCO. Temperature- and pressure-dependent rate coefficients were updated or newly predicted by performing quantum chemical calculations coupled with RRKM/master equation simulations. The dominance of C C bond fission is reconfirmed for acetaldehyde decomposition at higher temperatures. The negligible contribution of CH 4 + CO channel from usual tight intramolecular H-shift transition state provides indirect evidence for previously reported roaming mechanism that was proposed to explain the observation of CH 4 + CO in acetaldehyde pyrolysis . For ethylene oxide pyrolysis , current experiment and kinetic prediction have a good consistency in branching ratios between the formation of acetaldehyde and vinyl alcohol products. The radicals of CH 3 + HCO can also be directly generated from ethylene oxide through a well-skipping reaction mechanism especially at higher temperatures. For CH 3 + HCO recombination, we highlight the importance of CH 3 CO + H channel that was often overlooked previously. Kinetic simulations show that the incorporation of updated rate coefficients and newly identified channels results in a measurable influence on C2 chemistry , indicating the possibility and necessity of further improvement of core mechanism in combustion kinetic models .
研究领域:
物理化学
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燃烧化学
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反应动力学
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量子化学计算
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分子反应机制
✓ 已验证
DOI
高影响因子
THERMOCHIMICA ACTA
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2018
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IF 2.189
Zichao Guo,Shiran Li,Peng Zhou,Liping Chen,Wanghua Chen
Semibatch reactors (SBRs) are commonly used to conduct exothermic reaction in the pharmaceutical and fine chemical industries. From the thermal safety point of view, low MTSR (maximum temperature of synthesis reactions) is desirable. We have found that MTSR vs process temperature ( T ) profile favorably present S-shape in isothermal homogeneous SBRs involving highly exothermic or slow reactions. However, the criterion to determine the dependency of MTSR on T has been not thoroughly studied. In this work, such a theoretical criterion will be developed based on the fact that the derivative of MTSR to T is zero at the reaction temperature at which the lowest value of MTSR is obtained and experimentally validated by the hydrolysis reaction of acetic anhydride. To develop such a criterion, the quantitative relationship between the maximum accumulation X ac,max and Damköhler number ( Da ) for isothermal homogeneous semibatch reactions of arbitrary kinetic orders is first developed and numerically verified.
研究领域:
化学工程
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制药工程
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反应动力学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Hongxia Liu,Jiayi Yao,Lianhong Wang,Xinghao Wang,Ruijuan Qu,Zunyao Wang
Fenitrothion (FNT), a common organophosphorus pesticide, has been regarded as a contaminant because it is adverse to the environment. In this study, we chose the highly effective technique, persulfate (PS) activation by zero-valent iron powder (Fe 0 ), to degrade FNT. The effects of several experimental parameters including PS and Fe 0 dosages, pH, temperature, and common natural water constituents were systematically investigated via kinetics studies. We found that the addition of Fe 0 significantly enhanced the FNT degradation by PS under any of the studied conditions. Under the optimal conditions of [FNT]:[PS] = 1:500 (molar ratio), Fe 0 :PS = 1:1.5 (molar ratio), pH = 3.0, and 35 °C, 10 mg L −1 of FNT could be completely degraded in 45 min and 20 μg L −1 FNT was removed 96 ± 0% in 12 h. Sulfate (SO 4 − ) radicals led the degradation of FNT in the Fe 0 /PS system. Twelve transformation products of FNT were determined by LC-MS/MS analysis, and the vulnerable sites in FNT were predicted by a density-functional-theory-based descriptor, 2∑(C ri HOMO ) 2 , to illustrate the generation of initial reaction products. The overall acute and chronic toxicity of FNT and its products, as predicted by the ecological structure–activity relationship model (ECOSAR), decreased in the Fe 0 /PS process. The present work proves that FNT could be efficiently degraded by Fe 0 -activated PS, which may also contribute to future research on the removal of other organophosphorus pesticides.
研究领域:
环境科学
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农药化学
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水处理技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2022
·Vol. 10
·期 36
·18907-18915
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IF 14.511
Xuefan Zheng,Yuqi Wu,Cheng Li,Jinxue Peng,Wu Yang,Zhongwei Lv,Haoyue Zhong,Zhengliang Gong,Yong Yang
All-solid-state lithium–sulfur batteries (ASSLSBs) are promising candidates for the development of next-generation batteries with high energy density and improved safety. Nevertheless, the sluggish reaction kinetics of the S and Li2S cathode and the low active material content hinder the further development of ASSLSBs. Herein, a Co3O4@nitrogen-doped carbon (Co3O4@NC) nanocomposite is used as an electronically conductive additive to promote the conversion kinetics of S and Li2S in the solid sulfur cathode. With a high sulfur content of 50 wt% and sulfur loading of 4 mg cm−2, ASSLSBs with the S–Co3O4@NC–Li7P3S11 (S–CoNC–LPS) composite cathode exhibit a high specific capacity of 1313 mA h g−1 at 0.2 mA cm−2, as well as a reversible capacity of 1167 mA h g−1 after 100 charge/discharge cycles. Furthermore, the S–CoNC–LPS cathode also demonstrates a high areal capacity of 16.12 mA h cm−2, corresponding to a reversible capacity of 1343 mA h g−1, and good cycling stability even with an ultra-high sulfur loading of 12 mg cm−2. Such a superior electrochemical performance can be attributed to the fact that Co3O4@NC lowers the reaction energy barrier and promotes the interconversion of S and Li2S.
研究领域:
材料科学
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电化学
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DOI
高影响因子
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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2015
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IF 3.615
Jian Wang,Xue Wang,Xiaolong Liu,Junlin Zeng,Yangyang Guo,Tingyu Zhu
In this article, we present a detailed study combining the kinetic studies and in-situ FTIR experiments to investigate the oxidation behavior of chlorobenzene over V 2 O 5 /TiO 2 catalysts. The catalytic data show the 3–5 wt.% V 2 O 5 /TiO 2 catalysts are best fit for the oxidation of chlorobenzene. The calculated apparent reaction orders are about 0.6 and 0.2, respectively. The results of in-situ FTIR provided mechanism insights into the catalytic reaction, which supports the following proposal: (i) a nucleophilic substitution on V O species and (ii) attacking by surface oxygen through a electrophilic substitution, then (iii) followed by the cracking of ring structure, and further oxidation of the resulting species to form final products. The above results further suggest that the nucleophilic substitution process and surface reaction are kinetically significant steps for chlorobenzene oxidation, determining the overall rate of the reaction. Furthermore, 1,2-dichlorobenzene, 1,3-dichlorobenzene and 1,2,4-trichlorobenzene as additional reactants were tested together with chlorobenzene in binary mixtures to examine their competition reactions.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Ruiqi Zhang,Runcheng Liu,Zhihan Ding,Jinzhu Ma,Tao Wang,Dafeng Zhang,Junchang Liu,Peiqing Cai,Xipeng Pu
Photocatalytic hydrogen evolution is regarded as an economically viable and environmentally benign strategy. However, the practical application of photocatalytic hydrogen production is constrained by the sluggish reaction kinetics and rapid recombination of photogenerated charge carriers. Herein, a Cu 3 SnS 4 /Mn 0.3 Cd 0.7 S (CTS/MCS) S-scheme photocatalyst with photothermal effect was synthesized via an ultrasound-assisted self-assembly method and applied for the first time to photocatalytic hydrogen evolution. The hydrogen production rate of CTS/MCS-5 reached 72.5 ± 0.8 mmol/h g −1 , representing a 3.44-fold increase relative to Mn 0.3 Cd 0.7 S, and the apparent quantum yield of CTS/MCS-5 reached 17.5 % at 450 nm. The photothermal effect induced by Cu 3 SnS 4 can elevate the local surface temperature of the catalyst, providing a portion of the energy required for the reaction, thereby reducing the reaction barrier and further promoting photocatalytic reactions. This research highlights the significance of the S-scheme heterojunction and the photothermal effect as an effective strategy to enhance photocatalytic activity, offering new insights for the development of photocatalytic hydrogen evolution technology.
研究领域:
材料科学
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能源化学
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环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Haoze Wang,Huizhe Zheng,Jie Jiang,Ling Zhao,Zhenhao Xi
Poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PCTG) is a high-performance engineering copolyester prepared using terephthalic acid (TPA), ethylene glycol (EG), and 1,4-cyclohexanedimethanol (CHDM). In this work, a complex reaction network of PCTG copolyesters involving homopolymerization and cross-polymerization was presented and the corresponding reaction mechanism was proposed. The reaction kinetics and mass transfer behavior were investigated using static thin film experiments, wherein the variation of the hydroxyl end-group concentrations of EG and CHDM with reaction time was separately determined. The results showed that the apparent reaction rate benefited from the high temperature, thin film thickness, and high vacuum conditions. Based on the pseudosteady-state assumption, the apparent reaction rate model coupled with mass transfer was evaluated and the model parameters including the reaction rate coefficient, equilibrium constant, and mass transfer coefficient were obtained, which were further used to simulate the polycondensation process. The concentration variation of EG and CHDM, and the rate variation of each reaction during polycondensation are discussed by combining the effects of homopolymerization, cross-polycondensation, and mass transfer. The concentration of EG was more sensitive to pressure than that of CHDM, which promoted the production of CHDM at high pressures. The proposed model is expected to provide guidance for the optimization of industrial production of PCTG/PETG and generalize to other copolyester systems.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Wei Du,Zhihua Zhang,Jundi Wang,Nan Song,Xuezhi Duan,Xinggui Zhou
Propylene epoxidation by H 2 and O 2 to propylene oxide (HOPO), as a novel method for PO production, has attracted widespread attention due to its economic and environmental advantages. Acrolein is a notable byproduct arising in HOPO reaction over Au/TS-1 catalyst, and is traditionally thought to be exclusively formed on Au site through propylene oxidation. However, on the intraporous and external surface Au sites of Au-Ti catalysts, the HOPO reaction have been shown to proceed by different mechanisms, yet the effect of active sites distribution on acrolein formation is far from being understood. Herein, we found that the reaction orders in acrolein formation on Au/TS-1 catalyst (H 2 , 0.19; O 2 , 0.44; C 3 H 6 , 0.44) relative to Au/TS-1 with blocked pores (Au/TS-1-B) catalyst (H 2 , −0.36; O 2 , 0.61; C 3 H 6 , 0.52) were quite different, suggesting a variation in the reaction pathway on the catalysts with different Au locations. Moreover, it is found that PO can be converted to acrolein by O 2 on TS-1 zeolite, which is absent on TS-1-B zeolite without micropores. Consequently, acrolein formation on Au/TS-1 catalyst can proceed through two parallel pathways: propylene hydro-oxidation on Au site, and PO conversion by O 2 inside micropores. Furthermore, by designing and preparing the Au/TS-1 catalysts with different structures, the Au locations are closely related to acrolein formation mechanism and kinetic behaviors. This work provides kinetic insights into the acrolein formation pathways in the HOPO reaction on Au/TS-1 catalyst, and is helpful to the rational design and preparation of efficient catalysts with high selectivity.
研究领域:
催化化学
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材料科学
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环境化学
✓ 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）