Catalysts
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2024
·Vol. 14
·期 1
·41
·
IF 3.8
Huajun Wang,Jingjing Ma
A series of Zn salts were used as catalysts for the reaction of glycerol and urea to produce glycerol carbonate and it was found that ZnSO4showed the highest catalytic activity. Furthermore, the effects of reaction parameters on the glycerol conversion and glycerol carbonate yield were studied in detail. The results indicated that the glycerol conversion and glycerol carbonate yield were increased with the reaction temperature, reaction time, and catalyst amount while the optimal reaction conditions were 140 °C, 240 min, catalyst amount of 5 wt% (based on the glycerol weight), and urea-to-glycerol molar ratio of 1.1:1. During the reaction, the ZnSO4catalyst is transformed into Zn(NH3)2SO4at the initial stage of the reaction and then further transformed into Zn(C3H6O3). Zn(C3H6O3) and (NH4)2SO4may be the true active species for the activation of urea and glycerol, respectively. The reaction mechanism is proposed in this article. Based on the experimental results, a reaction kinetics model considering the change in volume of the reaction system was also established, and the model parameters were obtained by fitting the experimental data. The statistical results showed that the established kinetics model is accurate.Keywords:glycerol;urea;glycerol carbonate;zinc sulfate;reaction kinetics
研究领域:
化学工程
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催化
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有机化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2020
·Vol. 95
·期 8
·2251-2260
·
IF 2.75
Yanli Xu,Pengkun Guo,Chun Chang,Pan Li,Shiqiang Zhao,Guizhuan Xu
BACKGROUND Methyl levulinate (ML) is a promising green candidate for bio-based diesel fuels and fuel additives. An effective method for synthesizing ML from levulinic acid (LA) catalyzed by cheap metal salt catalyst under mild conditions was developed. A series of metal salts were screened for the synthesis of ML from LA, and aluminum chloride was identified as a suitable catalyst for this process. RESULTS The effects of catalyst loading, the molar ratio of methanol to LA, reaction temperature and reaction time on LA conversion and ML yield were investigated. The response surface method was used to optimize the process, and the model validation experiment showed that the predicted values corresponded well with the actual ones. Under the optimum conditions of reaction temperature 343 K, reaction time 1.5 h, aluminum chloride 1.14 g and molar ratio of methanol to LA 8:1, a high ML yield of 95.0 mol% could be obtained. Moreover, a kinetic model was proposed to evaluate the reaction process at a temperature range of 30–70 °C. The first-order pseudo model was considered most suitable ( R 2 > 0.99), and the activation energy of the reaction E a was estimated to be 32.28 kJ mol −1 . Investigation of the reuse of the catalyst revealed that it retained good catalytic activity after repeated use for ten times. CONCLUSION A green and efficient process of ML production from LA catalyzed by the metal salt aluminum chloride was developed. © 2020 Society of Chemical Industry
研究领域:
化学工程
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可再生资源
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2023
·
IF 11.1
Shi Liu,Wen Cao,Fanrui Meng,Mingming Du,Wenwen Wei,Yunan Chen,Hui Jin,Liejin Guo
Supercritical water gasification (SCWG) of biomass waste as a new clean waste conversion technology is increasingly valued worldwide attributable to the unique properties of supercritical water (water: T > 374 °C, P > 22.1 MPa). However, the fate of conventionally contaminated elements such as nitrogen in this process still warrants further research to control potential contamination. In this work, uric acid was used as the model compound of nitrogenous components in chicken manure to investigate the transformation mechanism of nitrogen during the SCWG process. The effects of different temperatures (550–650 °C) and residence times (2–30 min) on the gasification characteristic of uric acid and the behaviour of nitrogen were experimentally explored. The results indicated that the higher temperatures and longer residence time significantly facilitated the uric acid gasification and nitrogen transformation. The maximum nitrogen conversion efficiency was 84.83%, and the maximum yield of NH 3 , H 2 , and CO 2 reached 20.20 mol/kg, 23.78 mol/kg, and 20.10 mol/kg at 650 °C and 30 min, respectively. Subsequently, the reaction pathways of nitrogen in uric acid were proposed in detail according to the product analysis. Finally, a kinetic model was developed to describe the SCWG process, especially the reaction kinetic of nitrogenous products. The results revealed that the hydrolysis reactions of uric acid led to a rapid increase in NH 3 yield in the initial stage of the SCWG process. As the process continued, the increase in NH 3 was mainly due to the deamidation reaction of small-molecule nitrogenous intermediates. Notably, NO x , NO 2 − , and NO 3 − were not detected in products, validating the inhibitory effects of the reducing environment of supercritical water on the generation of nitrogen oxides.
研究领域:
环境科学
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能源工程
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化学工程
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DOI
高影响因子
AICHE JOURNAL
·
2019
·Vol. 66
·期 2
·e16841
·
IF 3.463
Chong Shen,Minjing Shang,Hong Zhang,Yuanhai Su
In this work, we report a simple and inexpensive UV-LEDs based photomicroreactor assembly constructed by commercially available components. The photoisomerization of norbornadiene to quadricyclane was selected to validate this novel photomicroreactor design. Mass transport limitation was eliminated and indicated by dimensionless numbers Fo and Da II , and photons loss was evaluated considering the absorption and reflection of the microreactor walls. The solvents, photosensitizers, and light sources selections were optimized for achieving better photochemical performance and mechanistic insights. The detailed comparison between the high-pressure mercury arc lamp and the UV-LEDs strip revealed great potential of UV-LEDs as appealing light source for photochemical transformations. Moreover, the reaction mechanism was thoroughly discussed and illustrated by the Jablonski diagram indicating electronic states transitions. According to possible intermediate steps, a kinetic model was proposed with the reaction rate constant being correlated with the photon flux, which is valuable for process optimization and further understanding reaction mechanisms.
研究领域:
化学工程
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光化学
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反应动力学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
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2020
·
IF 3.35
Shaojian Hu,Jianhua Zhu,Bencheng Wu,Rui Ma,Xiaohui Li
As an eco-friendly lubricant base oil, ester base oil is receiving increasing attention. However, studies on synthetic reaction kinetics of high viscosity complex ester have been rarely reported. In this work, based on the principle of equal reactivity of all functional groups and simplified kinetics models, synthetic reaction kinetics for high viscosity complex ester was investigated in two steps. As for the esterification of trimethylolpropane with glutaric acid, the activation energies of the first and second stage were 55.3 and 73.5 kJ/mol, respectively. As for the esterification of the first step products with 2-ethylhexanoic acid, the activation energies of the first and second stage were 60.6 and 98.2 kJ/mol, respectively. As for the esterification of the first step products with n -heptanoic acid, its activation energy was 68.9 kJ/mol. A mutation phenomenon on reaction order from zero to second order was discovered, which could be explained by the strong adsorption of organic acid on catalyst surface. The conversion rate of carboxyl of synthetic reaction for mixed acid ester was estimated by simulation, and average relative error was less than 3.0%. The synthetic process of high viscosity complex ester was considered to consist of a series of parallel–consecutive reactions with addition–elimination mechanism.
研究领域:
化学工程
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环境科学
✓ 已验证
DOI
高影响因子
Journal of Environmental Sciences
·
2025
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IF 6.3
Kun Liu,Tao Wang,Guohua Zhang,Wei Sun,Ye Yang,Mingjin Tang,Xinming Wang,Xinhui Bi
Aqueous-phase reactions between carbonyls and reduced nitrogen compounds play a considerable role in the formation of secondary organic aerosols and brown carbon in the atmosphere. However, the reported reaction rate constants for these reactions have largely been limited to bulk aqueous-phase simulations, which may not accurately represent the real state of atmospheric cloud droplets. We employed an integration of optical tweezers and Raman spectroscopy to manipulate and analyze simulated cloud droplets (size range 8000-10000 nm), comprising a mixture of glyoxal and ammonium sulfate. This approach enabled us to delve into the intricate realm of their reaction kinetics at individual droplet level mimicking cloud droplets. Raman spectroscopy provided high temporal resolution (20 s) measurements of the changes in the amount of nitrogen-containing organics (or NOCs as represented by the C-N bond) within the droplets. The results indicate that the reaction follows first-order kinetics throughout the monitoring over 80-400 minutes. The average reaction rate constant for the formation of NOCs within the single droplet was determined to be (6.77 ± 0.98) × 10 -5 s -1 , up to three orders of magnitude higher than those through the bulk aqueous-phase simulations, especially at lower pH levels. Additionally, the reaction rate constant in single droplet increases with increasing pH, consistent with the trend previously reported for the aqueous-phase simulations. The results highlight the difference of the reaction rate constant between bulk aqueous phase and droplets, which would improve our understanding on the formation and impacts of secondary organic aerosols and brown carbon in atmospheric aqueous phase.
研究领域:
大气科学
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化学动力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
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2024
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IF 5.3
Yuwen Deng,Zaili Xiong,Jijun Guo,Bingzhi Liu,Meirong Zeng,Zhandong Wang,Zhongyue Zhou,Wenhao Yuan,Fei Qi
Elucidating the oxidation chemistry of polycyclic aromatic hydrocarbons (PAHs) aids in understanding the degradation reaction processes of PAHs, as well as their competitive roles in PAH growth. In this work, ozone-assisted oxidation of indene , the smallest prototype PAH molecule, was investigated in an atmospheric jet stirred reactor at 400–550 K. Ab initio quantum chemistry calculations were conducted to characterize the oxidation kinetics of indene and interpret the experimental observations. Fingerprint oxidation products including 2-(2-oxoethyl) benzoic acid, 2-(formylmethyl) benzaldehyde , 1,2-indanedione and 1-indanone were identified by synchrotron vacuum ultraviolet photoionization mass spectrometry . The initial C 9 H 8 O 3 adduct resulting from O 3 -addition to indene exhibits high instability and is primarily detected as 2-(2-oxoethyl)benzoic acid following ozonolysis reactions. Minor amounts of vinylhydroperoxide were also observed as isomeric products of the C 9 H 8 O 3 adduct. Theoretical calculations indicate that indene ozonolysis is highly structure-dependent, where the conformation of the C 9 H 8 O 3 adduct determines the configuration of the resulting Criegee intermediates (CI). The distinctive reaction pathways introduced by the bifunctionalized characteristics of indene-derived large CIs are emphasized in this study. syn -Configuration CI features more conversion pathways compared to anti -CI due to the interaction between CI functionality and the neighboring aldehyde group, among which the bicyclic ring-closure reaction yielding secondary ozonide is most favored. The dioxirane intermediates generated from anti -CIs can undergo the Crossed Acid-forming channel to yield the target acid products, which provides an alternative way for dioxirane conversion. Further theoretical analyses demonstrate that ozonolysis is not the exclusive mechanism for indene oxidation under O 3 -assisted conditions. Instead, it is accompanied by low-temperature reactions initiated by OH/O 2 , leading to key products such as 2-(formylmethyl) benzaldehyde and 1-indanone. The present work aims to unravel the elusive chemistry involved in the O 3 -initiated oxidation of indene, providing new insights into the distinctive kinetics introduced by large bifunctionalized CIs in the ozonolysis of structurally similar PAHs.
研究领域:
化学动力学
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环境科学
·
量子化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Fengqin Li,Jingjie Zhou,Yuqi Liu,Jinyuan Sun,Ke Zhang,Huibin Liang,Chunyu Wang,Tao Geng,Riccardo Tesser,Vincenzo Russo,Martino Serio
The reaction of butylene oxide with fatty alcohols produces interesting products for the surfactant industry; however, no detailed study on the kinetics of this reaction can be found in the literature. In this paper, the kinetics of butoxylation of dodecanol catalyzed by KOH was deeply investigated. An orthogonal design approach was used to determine the optimum reaction conditions, which were analyzed in conjunction with the residues of fatty alcohols and epoxidized butanes by using a combined metric analysis. On this basis, BO solubility was measured and finally compared with the UNIFAC model, and it was found that the kinetics of epoxidized butane was modeled in the same way as the ethoxylation and propoxylation of primary fatty alcohols. It is concluded that the alkoxylation reaction rate decreases mainly with the increase in the steric hindrance of the employed epoxide. Finally, the models and data in this paper can be used for industrial reactor design and production optimization.
研究领域:
化学工程
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表面活性剂工业
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Environmental Science & Engineering
·
2025
·Vol. 19
·期 3
·1-15
·
IF 6.4
Zhang Xiang,Tian Jian,Hu Tanghui,Yue Guangyong,Liu Xianlong,Zhou Wen,Liu Xiaohong,Wang Xinye
Combining pulverized coal gasifiers with cement kiln production is promising for application in low-cost and efficient NO reduction. This paper presents a pulverized coal gasifier catalytic denitration technique and investigates the homogeneous reduction (by CO and CH 4 ) and heterogeneous catalytic reduction (by coke, CaO, MgO, and Fe 2 O 3 ) of NO. A combination of Chemkin simulations and fixed-bed experiments is used to elucidate the reaction pathways and key intermediates of NO reduction by carbon-based gases. In addition, the activation energies for different catalyst combinations were analyzed via reaction kinetics. The results demonstrate that the presence of small amounts of O 2 inhibits NO reduction by CO but promotes NO reduction by CH 4 . The NCO• radical is essential for the NO reduction process, and the generation of this radical depends on the CH 4 cleavage intermediate and O• radical. CaO and Fe 2 O 3 exhibit more significant catalytic effects on NO reduction by carbon-based gases than the other catalysts tested. The presence of a small amount of O 2 in the reacting gas mixtures facilitates the NO reduction reaction. The activation energy is reduced to 1.02 kJ/mol, and the NO conversion reaches 99.80% when the catalyst is C + CaO + MgO + Fe 2 O 3 and the gas composition is CO + CH 4 + O 2 . This work provides theoretical support and data recommendations for the use of pulverized coal gasifiers for the denitrification of cement kilns.
研究领域:
化学工程
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环境科学
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2021
·
IF 9.028
Chengxue Ma,Haijun Cheng,Ruixing Huang,Yijie Zou,Qiang He,Xiaoliu Huangfu,Jun Ma
The oxidation of thallium [Tl(I)] to Tl(III) by chlorine (HOCl) is an important process changing its removal performance in water treatment. However, the role of bromide (Br–), a common constituent in natural water, in the oxidation behavior of Tl(I) during chlorination remains unknown. Our results demonstrated that Br– was cycled and acted as a catalyst to enhance the kinetics of Tl(I) oxidation by HOCl over the pH range of 5.0–9.5. Different Tl(I) species (i.e., Tl+ and TlOH(aq)) and reactive bromine species (i.e., HOBr/BrO–, BrCl, Br2O, and BrOCl) were kinetically relevant to the enhanced oxidation of Tl(I). The oxidation by free bromine species became the dominant pathway even at a low Br– level of 50 μg/L for a chlorine dose of 2 mg of Cl2/L. It was found that the reactions of Tl+/BrCl, Tl+/BrOCl, and TlOH(aq)/HOBr dominated the kinetics of Tl(I) oxidation at pH < 6.0, pH 6.0–8.0, and pH > 8.0, respectively. The species-specific rate constants for Tl+ reacting with individual bromine species were determined and decreased in the order: BrCl > Br2 > BrOCl > Br2O > HOBr. Overall, the presented results refine our knowledge regarding the species-specific reactivity of TI(I) with bromine species and will be useful for further prediction of thallium mobility in chlorinated waters containing bromide.
研究领域:
环境科学
·
水处理化学
✓ 已验证
DOI
高影响因子
ACS Omega
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2021
·
IF 3.512
Binbin Jin,Ligang Luo,Longfei Xie
The utilization of CO2, as a cheap and abundant carbon source to produce useful chemicals or fuels, has been regarded as one of the promising ways to reduce CO2 emissions and minimize the green-house effect. Previous studies have demonstrated that CO2 (or HCO3–) can be efficiently reduced to formic acid with metal Fe under hydrothermal conditions without additional hydrogen and any catalyst. However, the pathways and kinetics of the autocatalytic CO2 reduction remain unknown. In the present work, the reaction kinetics were carefully investigated according to the proposed reaction pathways, and a phenomenological kinetic model was developed for the first time. The results showed that the hydrothermal conversion of HCO3– into formic acid with Fe can be expressed as the first-order reaction, and the activation energy of HCO3– is 28 kJ/mol under hydrothermal conditions.
研究领域:
化学
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环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2019
·
IF 3.372
Yangyang Bian,Hui Li,Shufeng Shen
Water-lean absorbents have potential applications for energy-efficient CO 2 capture. In this work, the chemical kinetics of the reaction between carbon dioxide (CO 2 ) and potassium prolinate (ProK) in ethanol, ethylene glycol and water solvents was measured in a stirred cell reactor with a stable gas-liquid interface at temperatures from 275.2 to 285.2 K and ProK molar concentrations up to 2.0 M. The experiments were performed under the pseudo-first-order regime to determine the overall kinetic rate constant ( k ov ) using two-film theory. The results showed that the reaction rates in each polar solvent increase considerably as the increasing ProK concentrations and temperatures. The reaction order was found to be in the range of 1.4–2.0 with respect to ProK concentration, depending on the solvents used. The kinetic results for the reaction in ethanol were also interpreted based on zwitterion mechanism and termolecular mechanism. The calculated from the two proposed models match well with the experimental data.
研究领域:
化学工程
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环境科学
✓ 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）