JOURNAL OF MOLECULAR LIQUIDS
·
2016
·
IF 2.74
Guo-Qiang Liu,Fei Wang,Sheng-Jun Luo,Dong-Yan Xu,Rong-Bo Guo
Nano metal fluids have been applied to promote the formation of natural gas hydrates . In this work, the sol of SDS@Fe 3 O 4 (named as SDS@Fe 3 O 4 ) were prepared and used as promoters in methane hydrate formation. Compared with SDS , SDS@Fe 3 O 4 produced much better promotion and the main superiority was that SDS@Fe 3 O 4 could significantly shorten the induction periods of hydrate formation. When SDS was used, the induction periods lasted about 40–60 min, while when SDS@Fe 3 O 4 was used at the same concentrations, hydrates nucleated within 10 min, especially, even no obvious induction periods were observed when SDS@Fe 3 O 4 was used in some experiments. Particle size showed significant influences on the promotion of SDS@Fe 3 O 4 to methane hydrate formation and smaller particles resulted in rapider hydrate formation. In addition, SDS@Fe 3 O 4 showed excellent repeatability during the hydrate formation-dissociation cycles.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
iScience
·
2023
·
IF 5.8
Kuo Yang,Jinzhe Li,Zhongkui Zhao,Zhongmin Liu
Selective oxidation of methane is one of the most attractive routes for methane to chemicals. However, mechanistic understanding and avoiding over-oxidation have great challenges because of its very rapid reaction rate. Herein, a capillary micro-reaction system was introduced to monitor the initial stage of methane oxidation over platinum. For the first time, an induction period is observed, during which oxygenated intermediates, such as methanol, acetone, methyl methoxy acetate, etc., are detected. Induction period can be shortened by methane pretreatment at 600°C, which generates highly active species containing unsaturated bonds. Combined these findings and observations of in situ characterizations, the evolution route of methane oxidation over Pt is prosed, i.e., the reaction starts from the formation of initial species containing Pt-C bond, followed by the generation of oxygenated intermediates, and ended with the over-oxidation of the intermediates to CO/CO 2 .
研究领域:
化学工程
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF CRYSTAL GROWTH
·
2019
·
IF 1.573
Lianlian Zhan,Yang Zhang,Shili Zheng,Ying Zhang,Binqiang Fan,Ping Li,Yi Zhang
Crystallization of ammonium polyvanadate is a key procedure for the production of vanadium pentoxide. The kinetics of nucleation of ammonium polyvanadate and the effects of impurities on the nucleation including sodium ion, potassium ion, hexavalent chromium ion, dihydrogen phosphate were studied in this research by using conductivity method. The solubility of ammonium polyvanadate was determined first, then the nucleation parameters were obtained by combining induction period with the classical primary nucleation theory. The results show the nucleation is homogeneous when with a high supersaturation degree of higher than 25. The critical nucleation radius, free energy and activation energy decrease, and the nucleation rate increases, with the increase of supersaturation degree. The existence of sodium ion, potassium ion, dihydrogen phosphate in the solution will prolong the induction period of crystallizing ammonium polyvanadate, with phosphorus showing the most significant influence. The morphology of the ammonium polyvanadate crystals will change from flake to spherical-like with the existence of phosphorus.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2021
·Vol. 38
·期 9
·1810-1817
·
IF 3.309
Luan Wenwen,Wang Chunyu,Zeng Zuoxiang,Xue Weilan,He Xuelian,Bai Yu
The hydrolysis kinetics of polyvinyl butyral (PVB) was studied in ethanol/water mixed solvents in the temperature range of 339.15-355.15 K, and a three-step hypothesis was proposed to describe the hydrolysis process. The influences of stirring speed, ethanol content and temperature on the hydrolysis of PVB were investigated, and an induction period (IP) phenomenon was found in the process of PVB hydrolysis. The ethanol content in the mixed solvents has a great influence on IP, which is due to the formation of the two kinds of water-ethanol clusters in the system. Temperature influences the IP by changing the catalytic activity of hydroxylamine hydrochloride (HH) on the hydrolysis of PVB. The shrinking core models with three controlling steps were used to fit the kinetic data, and the results indicate that the model controlled by chemical reaction is suitable to describe the kinetic behavior of PVB hydrolysis.
研究领域:
化学工程
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材料科学
✓ 已验证
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Wenchao Wang,Fashe Li,Hua Wang
The oxidative stability of Jatropha biodiesel after exposure to different wavelengths of visible light was studied and kinetic analysis of the oxidation process was carried out. The results showed that the induction period of Jatropha biodiesel was 5.12 h and visible light at different wavelengths affected the oxidation of biodiesel differently. Effect of oxidation was the strongest in the purple, where the induction period was reduced to 2.65 h. The red had the weakest effect on biodiesel oxidation, and the induction period was reduced to 4.61 h. Acid value detection, component analysis and UV characterization of biodiesel oxidized by visible light at different wavelengths. The results showed that with the decrease of light wavelength, the acid value of the biodiesel increased from 0.2577 mg KOH/g to 0.3438 mg KOH/g and the content of methyl linoleate containing two carbon–carbon double bonds decreases. UV characterization results showed that the absorption peak absorbance of conjugated double bond of Jatropha biodiesel oxidized by purple light was 5.282, while the absorption peak absorbance of conjugated double bond of Jatropha biodiesel oxidized by red light was only 2.877, and purple light was helpful to stimulate the generation of conjugate double bond. The kinetic analysis results showed that the different wavelengths had different rates of biodiesel degradation. Purple light has the fastest oxidation rate. The oxidation rate constant k 1 was 0.06011, the reaction order was n = 1, and the minimum activation energy of the oxidation reaction process was 19.79 kJ·mol −1 .
研究领域:
能源科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2014
·
IF 2.733
Hongchao Yan,Xiaofei Song,Feng Xin,Xingang Li,Guangjin Chen,Yong Wang
Storage capacities, formation rates, and induction periods of methane hydrates in slurries of solid n-tetradecane, which is a phase change material (PCM), were investigated experimentally in a semibatch hydrator with a stirrer. The hydrations were carried out at an initial temperature of 277.1 K, which was slightly lower than the melting point of n-tetradecane in a slurry; the stirring rate was 800 rpm, and the experimental pressures were in the range of 5.00–6.28 MPa. The emulsion of PCM was prepared using a high-speed disperser and then cooled to solidify the PCM droplets in an oil-in-water (O/W) emulsion. The highest storage capacity of 158.7 V/V was found at 5.26 MPa, and the corresponding hydration time was only 78 min. The hydration rates divided into three stages: a constant speed was observed initially, followed by a steep increase, and a slowing in the final step. The maximum hydration rate was 0.0096 molCH4/(molH2O min) at 5.26 MPa. The induction time of hydration was reduced largely to a few minutes. Therefore, the fast formation rate and short induction time led to free water being trapped in the hydrate and much higher pressures would make the storage capacity smaller. Therefore, the advantage of our method is improving heat transfer during hydration, which results in a fast hydration rate and high storage capacity. On the other hand, one disadvantage is that the method is somewhat complex.
研究领域:
化学工程
·
能源存储
·
热力学
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材料科学
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物理化学
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工业催化
·
多相系统
✓ 已验证
DOI
高影响因子
JOURNAL OF CRYSTAL GROWTH
·
2020
·
IF 1.632
Lu Li,Shicheng Zhao,Zhong Xin,Shuai Zhou
Nucleation kinetics of clopidogrel hydrogen sulfate polymorphs has been investigated in the mixture of 2-butanol and ethyl acetate by reactive crystallization. The effect of supersaturation and temperature on the nucleation rate was researched by measuring the induction period. The results show that the induction period decreases with the increase of supersaturation and temperature. After identifying the form of nuclei, the results disclose the metastable form seems to favor generating at a high supersaturation level. The reasons have been explained from the view of critical nucleation size. The interfacial energy of two polymorphs (20 °C, γ sl I = 4.49 m J / m 2 , γ sl I I = 4.94 m J / m 2 ; 25 °C, γ sl I = 5.60 m J / m 2 , γ sl I I = 6.27 m J / m 2 ) was also determined from induction time. The value calculated of Form II at 25 °C was close to the ones obtained from directly methods: by contact angle measurement (6.85 m J / m 2 ). The effect of different contents of ethyl acetate on the induction period at 20 °C was also explored. The results reveal the addition of a small amount of ethyl acetate can significantly promote nucleating.
研究领域:
制药工程
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Songshan Zhu,Shimin Ma,Di Song,Yunzhu Wang,Jichang Lu,Tianhao Ai,Huihui Lu,Sufang He,Yongming Luo
The dynamic relationship of TiO 2 crystal phase and strong metal-support interactions (SMSI) of Ni/TiO 2 catalyst was investigated to reveal the induction period of glycerol steam reforming. Comprehensive investigations confirmed that the SMSI between Ni 0 and anatase TiO 2 was formed by anatase TiO 2 encapsulated Ni 0 after H 2 reduction at 500 °C for the Ni/TiO 2 catalyst calcined at 500 °C (Ni/Ti-500R), which inhibited the contact of Ni 0 active sites with reactants and led to the low hydrogen yield in the initial stage of the reaction. Interestingly, the dynamic conversion of anatase to rutile during the GSR process at 600 °C caused the TiO 2 overlayers on the Ni 0 particles to gradually fade, exposing more Ni 0 sites, resulting in a gradual increase in hydrogen yield to 5.93 mol H2 /mol glycerol . In addition, Ni/Ti-500R with a dynamic SMSI inhibited Ni 0 particles sintering and encapsulated carbon deposition, resulting in relatively better stability (21 h) after induction period. In comparison, the designed Ni/TiO 2 catalyst calcined at 600 °C (Ni/Ti-600R) with rutile TiO 2 as the main component inhibited the formation of the classical SMSI, even after 600 °C H 2 reduction, and no excessive TiO 2 encapsulated Ni 0 particles were observed, so no obvious induction period occurred. This study provides new insights into the relationship of SMSI with crystal phases and the induction period in multiphase catalysis, also a new strategy for designing efficient catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Macromolecular Reaction Engineering
·
2020
·Vol. 14
·期 1
·1900048
·
IF 1.33
Jing Zhao,Bo-Geng Li,Zhi-Yang Bu,Hong Fan
The ring-opening polymerization of propylene oxide catalyzed by double metal complex (DMC) is carried out in continuous micro-reactor (C-MR). It is found that the monomer conversion at the C-MR outlet is usually 100% within 2 min of average residence time, which means that the polymerization rate in the C-MR is faster than that in a traditional semi-continuous tank reactor. However, the induction period still exists in the polymerization in C-MR, but can be shortened by increasing the reaction temperature or the micro-reactor length. The mechanism of monomer coordination and ring opening on DMC during the induction period is confirmed by the 1 H NMR analysis of the samples obtained under very short average residence time. The molecular weight distribution (MWD) of product from C-MR is generally narrow, which indicates that the process still maintain the characteristics of the “living” polymerization. That is, there is a very high rate ratio of chain transfer to chain propagation provided by the DMC catalyst. However, with the same average residence time, the MWD of product from the longer C-MR is broader, which can be attributed to the increase of the chain propagation rate caused by rise of pressure.
研究领域:
化学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2025
·
IF 3.4
Jiaqi Luo,Yingchen Wang,Qiutong Zhang,Wenhao Yan,Mingting Yuan,Yimin Jia,Qiushuo Yu,Xinyue Zhai,Yuan Zou
In order to identify the crystallization induction period precisely, this study developed a fluorescence method based on aggregation-induced emission (AIE) characteristics. Accurate identification of the early stage of nucleation was made possible by tracking molecular aggregation through monitoring of the fluorescence intensity using N-phenylanthranilic acid (NPAA) as the model compound. The results showed that the fluorescence method had a significantly greater sensitivity and detected nucleation earlier than the traditional visual inspection method. Furthermore, a combination of experimental analysis and molecular dynamics simulations was employed to investigate the regulatory effects of surfactants on the nucleation process. Tetradonium bromide (TTAB) promoted nucleation by reducing the nucleation barrier through electrostatic attraction and hydrophobic interactions, thereby accelerating crystal formation. On the other hand, by enhancing solvation effects and electrostatic repulsion, sodium dodecyl sulfate (SDS) prevented molecular aggregation and resulted in a longer induction period. This study showed the important regulating role of surfactants in the crystallization process in addition to validating the effectiveness of the fluorescence method.
研究领域:
晶体学
·
物理化学
·
材料科学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2025
·
IF 1.8
Run-Yang Zhang,Jing-Ru Jia,Peng-Xiao Chen,Wen-Xue Zhu,Hua-Min Liu
Tiger nut ( Cyperus esculentus L.) is a promising oilseed for its high-oleic oil with superior oxidative stability. However, the oxidative stability of crude tiger nut oil varies significantly between extraction batches, a phenomenon hypothesized to correlate with the raw material's moisture content. In this study, tiger nut oil (labeled as TO-4, TO-8, TO-12, TO-16, and TO-20) was obtained by solvent extraction from tiger nuts with varying moisture contents (4%–20%). All oils exhibited no obvious difference in the major triacylglycerol and fatty acids, with low acid values (1.30–1.35 mg/g) and peroxide values (0.14–0.15 mmol/kg). Phospholipids (0.71–8.61 mg/g) and phenolic compounds (24.34–70.83 mg/kg) exhibited significant inter-sample variations, whereas tocopherols, carotenoids, and sterols showed no significant differences. Notably, phospholipids and phenolic compounds demonstrated a significant positive correlation with oxidative stability as measured by induction period (21.9–105.2 h), with TO-12 displaying the longest induction period (105.2 h). Centrifugation of oils confirmed phospholipid and phenolic removal decreased induction periods. Therefore, targeted moisture adjustment for tiger nuts enhanced the oxidative stability of solvent-extracted oil through elevated levels of phospholipids and phenolic compounds in the oil. This work provides a green strategy for improving oil quality of tiger nut. Practical Applications : In this study, how the moisture content of tiger nuts influences the oxidative stability of tiger nut oil was explored, offering guidance for selecting the optimal moisture parameters during oil processing. Employing tiger nuts with 12% moisture content during oil extraction produces crude oil exhibiting optimal oxidative stability. This moisture adjustment strategy not only enhances oil quality through an environmentally benign process but also reduces production and refining expenditures.
研究领域:
食品科学
·
农产品加工
·
油脂技术
·
绿色化学
·
植物生物化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
·
2020
·Vol. 56
·期 6
·2938-2945
·
IF 2.773
Ao Li,Man-Tong Zhao,Fa-Wen Yin,Min Zhang,Hui-Lin Liu,Da-Yong Zhou,Fereidoon Shahidi
Summary The antioxidant effects of gallic acid (GA) and its alkyl esters including methyl gallate, ethyl gallate, propyl gallate, butyl gallate (GA-C4), octyl gallate, lauryl gallate, hexadecyl gallate and octadecyl gallate in frying oil (soybean oil) and oyster during frying were investigated. Rancimat induction period (RIP) assay indicated GA and its alkyl esters effectively improved the oxidative stability of soybean oil according to the ‘polar paradox’; that is, the antioxidant effects of the polyphenols decreased in lipid system with the increasing of hydrophobicity. Results also indicated that GA and its alkyl esters all effectively retarded lipid oxidation in oyster tissue according to parameters including RIP, peroxide value and electron spin resonance assays. Moreover, the antioxidant efficiency in oyster increased with the alkyl chain length until GA-C4, and thereafter, the antioxidant effects decreased, similar to the ‘cut-off effect’. This study provides basic data for improving the oxidative stability of seafood during frying.
研究领域:
食品科学
·
化学
·
营养学
✓ 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）