Micromachines
·
2022
·Vol. 14
·期 1
·45
·
IF 3.523
Zhou Lan,Yangcheng Lu
The combination of microstructural units is an effective strategy to improve the micromixing of liquid phase systems, especially viscous systems. However, how the microstructural combination influences micromixing is still not systematically investigated. In this work, the Villermaux/Dushman reaction is used to study the micromixing performance of the viscous system of the glycerol–water in the combination of a T-type micromixer and a micropacked bed. Micromixing performances under various structural parameters and fluid characteristics are determined and summarized, and the micromixing laws are revealed by dimensionless analysis considering the specific spatial characteristics and temporal sequence in the combined microstructures. It achieves good agreement with experimental results and enables guidance for the design and scaling-up of the combined T-type micromixer and micropacked bed towards micromixing intensification in viscous reaction systems.Keywords:micromixing;micropacked bed;microstructual combination;viscous system
研究领域:
化学工程
·
流体力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
AICHE JOURNAL
·
2024
·
IF 3.5
Jingwei Zhang,Xiaohui Zhang,Jianhong Xu,Zhuo Chen
In this work, the liquid–liquid two-phase pressure drop and mass transfer characteristics in micro-packed beds with different shaped packing are investigated. The experimental results show that the liquid–liquid mass transfer performance of micro-packed bed is significantly affected by both apparent flow rates and phase ratio. By changing the characteristic size of the micro-packed bed, the experimental results show that the average volume mass transfer coefficient has no obvious correlation with the length of the bed, which indicates that the flow and dispersion behavior along the length of the micro-packed bed is basically stable. By considering dispersion strengthening, vortex strengthening and size effect, a semi-empirical model for predicting liquid–liquid mass transfer performance in a micro-packed bed is established for the first time. The model is in good agreement with the experimental results and has strong applicability to various shaped packings. In addition, by considering the contribution of inertia force, viscous force and interfacial tension to energy dissipation, a semi-empirical model of liquid–liquid two-phase pressure drop in a micro-packed bed is established. The pressure drop prediction model can also be applied to different shaped packings.
研究领域:
化学工程
·
传质与流体力学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2023
·
IF 3.7
Jingwei Zhang,Jianhong Xu,Zhuo Chen
Micro-packed beds have the advantages of excellent heat and mass transfer efficiency and high safety, which have been successfully applied to hydrogenation and oxidation reactions. The dispersion behavior of multiphase flow is closely related to mass transfer and reaction performance. However, the study of dispersion law in micro-packed beds is not sufficient. This work investigated the dispersion behavior of gas–liquid/liquid–liquid two-phase flow in micro-packed beds. The average size and distribution of droplets/bubbles were measured in different systems. Key parameters that affect the dispersion characteristics of the two phases were observed experimentally, including gas/liquid phase flow rate, size of the packing, and physical parameters of the systems. The experimental results showed that gas–liquid and liquid–liquid dispersion processes exhibited different characteristics due to the different physical parameters of liquid and gas as the dispersed phase. The fracture driving force of the gas–liquid process was mainly from the continuous liquid phase, while the fracture driving force of the liquid–liquid process came from both the dispersed phase and the continuous phase.
研究领域:
化学工程
·
传热传质学
✓ 已验证
产品关联
DOI
高影响因子
Reaction Chemistry & Engineering
·
2022
·Vol. 7
·期 8
·1827-1835
·
IF 5.2
Zipin Peng,Xuepeng Wang,Zheng Li,Xingkun Chen,Yunjie Ding,Jisong Zhang
Catalytic hydrodechlorination (HDC) is considered to be a safe and effective method to treat chlorinated organic pollutants and has always been a hot spot in basic catalysis research. It is difficult to obtain excellent catalytic performance due to the inferior mass transfer performances of traditional batch reactors, and the deactivation of catalysts can easily occur due to the poisoning effect of HCl. In this work, Pd catalysts supported on activated carbon (Pd/AC) were synthesized by the ion-exchange (IE) method. The characterization results of N2 physisorption, XRD, TEM and XPS revealed that the active Pd components were uniformly dispersed on the surface of AC in the form of nanoparticles. A continuous flow system based on a micro-packed bed reactor (μPBR) was developed for the hydrodechlorination, and the hydrogenation of chlorobenzene (CB) was selected as the model reaction. With the optimal reaction conditions, a conversion and selectivity of 100% were obtained. Importantly, no obvious deactivation of the catalysts was observed during a 100 h time-on-stream test. Moreover, Pd/AC catalysts exhibited remarkable substrate suitability in dechlorination systems. The reaction kinetics for hydrodechlorination of CB in methanol was investigated after the internal and external diffusion limitations were eliminated.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Hongda Zhang,Miao Pang,Weiyao Yang,Le Sang,Zhiping Zhao
A micro-nano coating with controllable wettability is constructed on Ni foam using the dipping coating method, incorporating organic polydopamine (PDA) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and inorganic SiO 2 nanoparticles. PDA has the properties of controlling wettability, strong adhesion, and abundant grafting sites. The water contact angle (WCA) of modified Ni foam is controlled in the range of 0–151.5°. The stability measurement displays that modified Ni foam packings exhibit excellent acid and alkali resistance as well as mechanical stability to fluid erosion under microenvironment. Compared with non-modified (131.5°) and superhydrophilic (0°) Ni foam packings, the maximum ratios of mass transfer enhancement for the superhydrophobic (151.5°) Ni foam packing are 35.6 % and 160.2 %, respectively. Empirical correlations of the gas–liquid mass transfer coefficient and friction factor are established considering the effect of the WCA, and errors between predicted values and experimental values are within ± 15 % and ± 10 %, respectively.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Flow Chemistry
·
2021
·Vol. 11
·期 2
·171-179
·
IF 2.786
Lan Zhou,Lu Yangcheng
The matching of the micro-dispersion method and the reaction kinetics is of the utmost importance for the fast and strongly exothermic nitration reaction. Taken as an example to discuss this issue, a synthesis of 3,4-dichloronitrobenzene via the nitration of o -dichlorobenzene with mixed acid of nitric acid and sulfuric acid was conducted in continuous-flow reactors in this work. Through combining the adiabatic reaction environment, the use of a micropacked-bed reactor, and introducing partial product circulation, it successfully achieved the matching of the micro-dispersion state and the reaction kinetic characteristics. The good two-phase dispersion state can be maintained throughout the micropacked-bed reactor and the reaction can be completed within 5 s with above 89% selectivity under adiabatic condition. Furthermore, the reaction activation energy was conveniently obtained by processing the temperature distribution data, providing a fundamental to realize a reliable design of the nitration reaction process with high efficiency and inherent safety. Graphical abstract
研究领域:
化学工程
·
反应动力学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Chu Zhou,Yanfu Chen,Dang Cheng
Micro packed bed reactors (MPBRs) operated by feeding with two immiscible liquids are of increasing importance in the chemical, biochemical, and energy industries. Herein, the impact of the channel- to particle-diameter ratio (N) on the liquid–liquid mass transfer and pressure drop in MPBRs is experimentally investigated. The experimental results reveal that both the overall volumetric liquid–liquid mass transfer coefficient (kLa) and pressure drop per unit length (ΔP/Lc) increase with the total flow rate (Qtot) for MPBRs of low to high N. The wall effects depend on Qtot, and the larger the Qtot, the more significant the wall effects. At small values of Qtot, kLa decreases slightly with N and increases marginally with the organic- to aqueous-phase flow rate ratio (φ); ΔP/Lc increases inappreciably with N and φ. At large values of Qtot, kLa declines significantly with N and increases appreciably with φ; ΔP/Lc increases significantly with N and φ. Correlations for calculating kLa and ΔP/Lc of the MPBRs are developed, yielding predictions that are in reasonably good agreement with the corresponding experimental data.
研究领域:
化学工程
·
生物化学工程
·
能源工程
✓ 已验证
DOI
高影响因子
AICHE JOURNAL
·
2025
·
IF 4
Hong-Da Zhang,Wei-Yao Yang,Miao Pang,Ya-Qiao Tian,Shi-Chao Su,Zhi-Ping Zhao,Le Sang
Non-modified Pd/PDA/Ni foam, hydrophobic modified F 9 -Pd/PDA/Ni foam, and F 17 -Pd/PDA/Ni foam catalysts are successfully prepared and used for NB hydrogenation in micropacked bed reactors (μPBRs). The catalytic performance increases with the addition of water in the water–methanol mixed solvent. In the mixed solvent with 50 v/v% water, F 17 -Pd/PDA/Ni foam can almost completely convert nitrobenzene (NB) with a yield of 95.9% at a mild 45°C. As the solvent contact angle of catalysts increases (87.5–141.5°), the enhancement ratios of NB conversion and AN yield are 28.9%–92.4% and 31.4%–106.5%, respectively. The space–time yield of AN in μPBRs reaches 1.873 kg·L −1 ·h −1 ·g −1 , which is 1–2 orders of magnitude higher than that of conventional reactors. The kinetic model of NB hydrogenation is established at the water–methanol system in μPBRs. The hydrophobicity of catalysts significantly improves the reaction rate of NB hydrogenation, and the reaction rate constant is increased by 69.9%.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Wei-Yao Yang,Rui-Xue Zhang,Xiao-Feng Zheng,Zhi-Ping Zhao,Le Sang
The efficient synthesis of the platform chemical 5-hydroxymethylfurfural (HMF) is of great significance for the production of downstream value-added bio-based chemicals. Herein, the highly-efficient and continuous synthesis of HMF is demonstrated in micropacked bed reactors (μPBRs) with HND-580. 95.3 % fructose conversion, 90.2 % HMF yield, and 99.3 % HMF extraction efficiency can be achieved within 26.3 s in μPBRs. The space–time yield (STY) of μPBRs is more than two times of magnitude greater than conventional fixed bed reactors (FBRs) and stirred tank reactors (STRs). The organic phase liquid holdup of liquid–liquid system is obtained at the range of 0.82–0.90, which is measured for the first time in μPBRs. The liquid–liquid mass transfer coefficient of μPBRs is 1.68 × 10 -2 to 1.68 × 10 -1 s −1 , which is 1–3 orders of magnitude larger than STRs and packed columns. In addition, a heterogeneous kinetic model for the synthesis of HMF in water-MIBK biphasic system is established in μPBRs. The fructose conversion and HMF yield were predicted and the error was within ± 20 %.
研究领域:
化学工程
·
生物化工
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Le Sang,Xudong Feng,Jiacheng Tu,Bingqi Xie,Guangsheng Luo,Jisong Zhang
In this work, the hydrogenation of α-methylstyrene to cumene over Pd catalyst is adopted to determine the external mass transfer performance under the mass transfer limited regime in micro-packed bed reactors. The operating temperature, pressure, and solvent are first confirmed for this method. Then the effects of gas and liquid superficial velocities as well as particle size on the external overall volumetric mass transfer coefficient are investigated. The external overall volumetric mass transfer coefficient in micro-packed bed reactors can reach 0.15–2.76 s −1 , which is about one to two orders of magnitude larger than those of conventional large trickle bed reactors . Furthermore, a correlation of the external overall volumetric mass transfer coefficient is proposed and the external mass transfer process analysis is carried out.
研究领域:
化学工程
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
Chemical Engineering and Processing-Process Intensification
·
2025
·
IF 3.9
Shichao Su,Yaqiao Tian,Huifeng Li,Weiyao Yang,Hongda Zhang,Feng Liu,Le Sang
The micropacked bed reactor (μPBR) with monolithic catalyst hydrogenation technology has received widespread attention due to its high efficiency, continuous operation, and safety. In this study, the Pd/PDA/foam catalyst was prepared via impregnation method and vanillin (VL) hydrogenation was investigated in green water solution based on the μPBRs. The effect of operating temperature, pressure, the number of foam catalyst block, VL concentration, liquid and H 2 flow rate on VL conversion and VA yield was discussed. The highest conversion of VL was 99.4% and product yield of vanillyl alcohol (VA) reached 84.9% with 2.8 MPa, 120°C, 22 blocks of Pd/PDA/Ni foam catalyst, H 2 flow rate of 10 mL·min −1 and liquid flow rate of 0.1 mL·min −1 , and short reaction time (0.106 h) in μPBRs. The kinetic of hydrogenation VL to VA was established. The reaction rate constant and activation energy in μPBRs were from 0.63 to 1.39 min −1 and 16.94 kJ·mol −1 . The STY of VA in μPBRs was 0.0824 kg·L −1 ·h −1 ·g −1 , which was bigger than that of batch hydrogenation devices.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2021
·
IF 4.311
Xiaonan Duan,Jiabin Yin,Mengmeng Huang,Aoxing Feng,Weisong Fu,Huaxiang Chen,Zhenfu Huang,Yagang Ding,Jisong Zhang
The hydrogenation of m -dinitrobenzene to m -phenylenediamine is a significant transformation for the synthesis of dyes and pigments in the fine chemical industry. Owing to the complexity of this reaction mechanism and negative effect of the first amino group on the reduction of the second nitro group, it is difficult to inhibit eminently the generation of side products and obtain m -phenylenediamine efficiently. Hence it is imperative to establish kinetic network and investigate the intrinsic kinetic parameters of this reaction for further optimization. In this study, a continuous flow system based on micro-packed bed reactor was developed and a kinetic model of the hydrogenation of m -dinitrobenzene was established successfully. The activation energies and pre-exponential factors were acquired using the kinetic network and the kinetic model exhibited reasonable fit for the transformation of each substance. Moreover, the influence of pressure was investigated, and the accuracy of kinetic model was validated by the comparison with the values in literature. This kinetic model enabled the accurate determination of kinetic parameters with Pt/C and Ni/SiO 2 catalysts, and provided the rate determining steps and characteristics of different catalysts for the process optimization.
研究领域:
化学工程
·
催化反应动力学
✓ 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）