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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 June 2018, Volume 26 Issue 6
    Reviews
    Polyethoxylation and polypropoxylation reactions: Kinetics, mass transfer and industrial reactor design
    E. Santacesaria, R. Tesser, M. Di Serio
    2018, 26(6):  1235-1251.  doi:10.1016/j.cjche.2018.02.020
    Abstract ( 971 )   PDF (5875KB) ( 185 )  
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    Ethoxylation and propoxylation reactions are performed in the industry to produce mainly non-ionic surfactants and ethylene oxide (EO)-propylene oxide (PO) copolymers. Both the reactions occur in gas-liquid reactors by feeding gaseous EO, PO or both into the reactor containing a solution of an alkaline catalyst (KOH or NaOH). Non-ionic surfactants are produced by using liquid starters like fatty alcohols, fatty acids or alkyl-phenols, while when the scope is to prepare EO-PO copolymers the starter can be a mono-or multi-functional alcohol of low molecular weight. Both reactions are strongly exothermic, and EO and PO, in some conditions, can give place to runaway and also to explosive side reactions. Therefore, the choice of a suitable reactor is a key factor for operating in safe conditions. A correct reactor design requires:(i) the knowledge of the kinetic laws governing the rates of the occurring reactions; (ii) the role of mass and heat transfer in affecting the reaction rate; (iii) the solubility of EO and PO in the reacting mixture with the non-ideality of the reacting solutions considered; (iv) the density of the reacting mixture. All these aspects have been studied by our research group for different starters of industrial interest, and the data collected by using semibatch well stirred laboratory reactors have been employed for the simulation of industrial reactors, in particular Gas-Liquid Spray Tower Loop Reactors.
    Inherently safer reactors and procedures to prevent reaction runaway
    Yi Fei, Bing Sun, Fan Zhang, Wei Xu, Ning Shi, Jie Jiang
    2018, 26(6):  1252-1263.  doi:10.1016/j.cjche.2018.03.017
    Abstract ( 726 )   PDF (2962KB) ( 108 )  
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    Reaction runaway has longtime been an issue in chemical industry as it often leads to severe accidents if not controlled and inhibited properly. Herein we have reviewed several key considerations and procedures to prevent such phenomena, including inherently safer reactor design, thermal risk assessment and early warning detection of runaway, and pointed out that the basic principle underlying is necessary heat management and construction of resilient processes. For inherently safer reactor design, important factors such as heat removal, heat capacitance, flow behaviors and explosive behaviors have been investigated. The survey shows that heat exchanger (HEX) reactor and microreactor outperform traditional reactors. Meanwhile, we have looked into the effect of thermal risk ranking and safety operation region determining for thermal risk assessment, and the influence of runaway criteria and construction methods for early detection of reaction runaway as well. It shows that thermal risk assessment plays a key role on process design, and early warning detection system (EWDS) is preferable on prevention of reaction runaway. In the end, perspectives regarding inherently safer designs with the measures discussed above have been provided.
    Catalysis
    Ag-Co3O4: Synthesis, characterization and evaluation of its photocatalytic activity towards degradation of rhodamine B dye in aqueous medium
    Muhammad Saeed, Majid Muneer, Nida Mumtaz, Mohsin Siddique, Nadia Akram, Muhammad Hamayun
    2018, 26(6):  1264-1269.  doi:10.1016/j.cjche.2018.02.024
    Abstract ( 855 )   PDF (1869KB) ( 157 )  
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    Synthesis, characterization of Co3O4 and Ag-Co3O4 composites and evaluation of their photo-catalytic activities towards photo-degradation of aqueous solution of rhodamine B dye under irradiation of visible light have been described in this paper. Co3O4 was prepared by solid phase mechano chemical process using Co(NO3)2·6H2O and NH4HCO3 as precursor materials. Ag was deposited on Co3O4 from AgNO3 using Calotropis gigantea extract as reducing agent. XRD, SEM and FTIR were used for characterization of prepared composites. Photo-catalytic efficiencies of as-prepared Co3O4 and Ag-Co3O4 were evaluated for aqueous phase photo-degradation of rhodamine B. It was found that deposition of Ag on Co3O4 highly enhanced the photo-catalytic activity of Co3O4. Photo-catalytic degradation followed the Eley-Rideal mechanism. About 100% and 91% photo-degradation of 40 ml dye solution achieved at 313 K in 90 and 120 min over 0.05 g of Ag-Co3O4 as photo-catalyst using 100 and 200 mg·L-1 as initial concentration of dye respectively.
    One-pot synthesis of 5-hydroxymethylfurfural from glucose over zirconium doped mesoporous KIT-6
    Chongwen Jiang, Jundong Zhu, Bing Wang, Lu Li, Hong Zhong
    2018, 26(6):  1270-1277.  doi:10.1016/j.cjche.2018.02.031
    Abstract ( 632 )   PDF (1587KB) ( 42 )  
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    Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method. Various characterization techniques confirm that highly distributed ZrO2 nanoparticles and multicoordinated Zr4+ species are incorporated in the mesoporous composites. One-pot synthesis of 5-hydroxymethylfurfura(HMF) from glucose was examined in the presence of Zr-KIT-6(20) the molar ratio of Si to Zr is 20 under aqueous system. The effects of temperature, reaction time, catalyst dosage and biphasic solvent system on the conversion of glucose and the HMF yield were investigated. It was found that the glucose conversion and the HMF yield have been improved from 54.8% to 79.0% and from 19.5% to 34.5% in the biphasic MIBK-water system, respectively. Both the acidity of Zr-KIT-6(20) and the biphasic MIBK-water system are responsible for the improved performance of glucose dehydration to HMF.
    Selective propylene epoxidation in liquid phase using highly dispersed Nb catalysts incorporated in mesoporous silicates
    Wenjuan Yan, Yuhui Wu, Xiang Feng, Chaohe Yang, Xin Jin, Jian Shen
    2018, 26(6):  1278-1284.  doi:10.1016/j.cjche.2018.03.001
    Abstract ( 726 )   PDF (1448KB) ( 166 )  
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    Selective propylene epoxidation to propylene oxide (PO) with hydrogen peroxide (H2O2) was carried out in a catalytic semi-batch reactor. High propylene epoxidation activity (44 h-1) was observed over Nb based mesoporous silicate materials Nb-TUD-1 under mild operating conditions. The physical and chemical properties of the Nb based silicates characterized using BET, FTIR, TPD, TEM and UV-Vis revealed that the site isolation and surface acidity are crucial for PO production. Catalyst synthesis methods were investigated for their effects on PO productivity, PO selectivity and H2O2 utilization efficiency. It is found that Nb-TUD-1 material synthesized by the sol-gel method is more active and selective than impregnated materials for liquid phase propylene epoxidation. Surface characterization confirms that thus synthesized Nb-TUD-1 catalysts have more Lewis acidity and less Bronsted acidity compared to the catalysts by impregnation.
    High-efficiency acetaldehyde removal during solid-state polycondensation of poly(ethylene terephthalate) assisted by supercritical carbon dioxide
    Zhenhao Xi, Tian Liu, Wei Si, Fenglei Bi, Zhimei Xu, Ling Zhao
    2018, 26(6):  1285-1291.  doi:10.1016/j.cjche.2018.03.007
    Abstract ( 720 )   PDF (1115KB) ( 84 )  
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    The concentration of acetaldehyde (AA) is the main quality index of poly(ethylene terephthalate) (PET) used in food and drink packaging. A new method for AA removal has been developed by using supercritical carbon dioxide (scCO2) during the solid-state polycondensation of PET. The influence factors of AA removal including the temperature, pressure, reaction time and the size of pre-polymer particles are systematically studied in this work. The results indicate that it is a highly efficient way to obtain high molecular weight PET with relative low concentration of AA. Correspondingly, the polymerization degree of PET could increase from 27.9 to 85.6 while the concentration of AA reduces from 0.229×10-6 to 0.055×10-6 under the optimal operation conditions of 230℃, 8 MPa and size of 0.30-0.45 mm. Thermodynamic performance tests show the increasing extent of PET crystallinity due to the fact that the plasticization of scCO2 is not obvious with extended reaction time, therefore the increasing crystallinity has no significant influence on AA removal. SEM observations reveal that the effects of scCO2-induced plasticization and swelling on PET increase significantly with the decrease of prepolymer size, and the surface of PET becomes more loose and porous in favor of the AA removal.
    A phase inversion based sponge-like polysulfonamide/SiO2 composite separator for high performance lithium-ion batteries
    Xiao Wang, Gaojie Xu, Qingfu Wang, Chenglong Lu, Chengzhong Zong, Jianjun Zhang, Liping Yue, Guanglei Cui
    2018, 26(6):  1292-1299.  doi:10.1016/j.cjche.2017.12.010
    Abstract ( 688 )   PDF (10046KB) ( 19 )  
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    In this work, a sponge-like polysulfonamide (PSA)/SiO2 composite membrane is unprecedentedly prepared by the phase inversion method, and successfully demonstrated as a novel separator of lithium-ion batteries (LIBs). Compared to the commercial polypropylene (PP) separator, the sponge-like PSA/SiO2 composite possesses better physical and electrochemical properties, such as higher porosity, ionic conductivity, thermal stability and flame retarding ability. The LiCoO2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator. Moreover, the sponge-like composite separator can ensure the normal operation of LiCoO2/Li half-cell at an extremely high temperature of 90℃, while the commercial PP separator cannot. All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO2 composite separator is really a promising separator for high performance LIBs.
    Synthesis and catalytic activity of SBA-15 supported catalysts for styrene oxidation
    Vasu Chaudhary, Sweta
    2018, 26(6):  1300-1306.  doi:10.1016/j.cjche.2018.01.025
    Abstract ( 597 )   PDF (2782KB) ( 142 )  
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    Cu (Ⅱ) and Mn (Ⅱ) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique. The support and catalysts were characterized by SEM-EDX, TEM, BET, XRD and ICP-AES methods. The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio, temperature, catalyst amount by using TBHP as an oxidizing agent. Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion (97.3%) was observed at styrene to TBHP mole ratio of 1:4, temperature at 80℃ and 20 mg of catalyst. Further, the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.
    Catalytic reactor & ISMR
    The effect of operating conditions on acylation of 2-methylnaphthalene in a microchannel reactor
    Wenpeng Li, Suohe Yang, Xiaoyan Guo, Guangxiang He, Haibo Jin
    2018, 26(6):  1307-1311.  doi:10.1016/j.cjche.2018.01.004
    Abstract ( 652 )   PDF (401KB) ( 52 )  
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    Acylation of 2-methylnaphthalene (2-MN) is a very important reaction in organic synthesis, and the effiency of the continuous reactor is more than one of the batch reactor. Considering that the Friedel-Crafts acylation is a rapid exothermic reaction, in this study, we perform the acylation of 2-MN in a stainless steel microchannel flow reactor, which is characterized by high mass and heat transfer rates. The effect of reactant ratio, mixing temperature, reaction temperature, and reaction time on product yield and selectivity were investigated. Under the optimal conditions, 2-methyl-6-propionylnaphthalene (2,6-MPN) was obtained in 85.8% yield with 87.5% selectivity. Compared with the conventional batch system, the continuous flow microchannel reactor provides a more efficient method for the synthesis of 2,6-MPN.
    Experimental study of partially decoupled oxidation of ethane for producing ethylene and acetylene
    Jiajia Luo, Jinfu Wang, Tiefeng Wang
    2018, 26(6):  1312-1320.  doi:10.1016/j.cjche.2018.02.010
    Abstract ( 797 )   PDF (1032KB) ( 32 )  
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    With increasing amount of unconventional natural gas, the production of ethane, propane and other low alkanes continues to increase. In our previous works, a partially decoupled process (PDP) was proposed for conversion of ethane based on numerical simulations, which showed higher acetylene and ethylene selectivities than the original partial oxidation process. In the current work, the PDP of ethane for producing acetylene and ethylene was studied experimentally to verify the PDP concept. In the PDP of ethane, coke-oven gas or other cheap gas combusts with stoichiometric oxygen as heat carrier, and ethane is mixed with the heat carrier and undergoes pyrolysis at high temperatures. The jet-in-cross-flow (JICF) reactor was designed and manufactured to realize the PDP. A positioning device of 0.1 mm accuracy and a mass spectrometer were used to measure the spatial profiles of the species concentrations. The maximum combined yield (52.7%) of acetylene and ethylene was obtained even at the condition of heat loss, confirming that the PDP of ethane was advantageous over the partial oxidation process and at least comparable to the steam cracking process.
    Modeling and optimization of the cyclic steady state operation of adsorptive reactors
    Mamoon Hussainy, David W. Agar
    2018, 26(6):  1321-1329.  doi:10.1016/j.cjche.2018.04.013
    Abstract ( 1262 )   PDF (609KB) ( 41 )  
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    Adsorptive reactors (AR), in which an adsorptive functionality is incorporated into the catalytic reactors, offer enhanced performance over their conventional counterparts due to the effective manipulation of concentration and temperature profiles. The operation of these attractive reactors is, however, inherently unsteady state, complicating the design and operation of such sorption-enhanced processes. In order to capture, comprehend and capitalize upon the rich dynamic texture of adsorptive reactors, it is necessary to employ cyclic steady state algorithms describing the entire reaction-adsorption/desorption cycle. The stability of this cyclic steady state is of great importance for the design and operation of adsorptive reactors. In this paper, the cyclic steady state of previously proposed novel adsorptive reactor designs has been calculated and then optimized to give maximum space-time yields. The results obtained revealed unambiguously that an improvement potential of up to multifold level could be attained under the optimized cyclic steady state conditions. This additional improvement resulted from the reduction of the regeneration time well below the reaction-adsorption time, which means, in turn, more space-time yield.
    n-Decane hydro-conversion over bi-and tri-metallic Al-HMS catalyst in a mini-reactor
    Mahdi Abdi-Khanghah, Mostafa Adelizadeh, Zahra Naserzadeh, Zhi'en Zhang
    2018, 26(6):  1330-1339.  doi:10.1016/j.cjche.2018.04.007
    Abstract ( 758 )   PDF (4433KB) ( 64 )  
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    Bi-metallic (Pt-Sn and Sn-Ni) and tri-metallic (Pt-Sn-Ni) catalysts, supported on Al-containing hexagonal mesoporous silica (Al-HMS) (Si/Al=20) materials, were synthesized. N2 adsorption-desorption, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) test, and temperature programed desorption (NH3-TPD) were used to characterize physicochemical characteristics and textural properties of the Al-HMS catalysts. Catalytic performances on hydro-cracking of n-decane at different reaction conditions were studied in a microreactor. Comparison between Pt-Sn, Sn-Ni and Pt-Sn-Ni catalyst under different hydro-cracking conditions was made. The experimental results indicate that the proper balance between the acid and metal functions is the key in synthesizing a catalyst with a better performance in hydro-cracking. Tri-metallic catalyst exhibits the best catalytic performance in n-decane hydro-cracking than two bi-metallic catalysts.
    CFD simulation of homogeneous reaction characteristics of dehydration of fructose to HMF in micro-channel reactors
    Xin Zhang, Hui Liu, Amar Samb, Guofeng Wang
    2018, 26(6):  1340-1349.  doi:10.1016/j.cjche.2018.04.024
    Abstract ( 712 )   PDF (1783KB) ( 51 )  
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    In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan (HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations. Influential factors including solvents, residence time distribution of reaction mixtures, heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices, i.e., conversion of fructose, HMF selectivity and yield. A scale-up method from a single channel to a multiple channel reactor is also proposed. It is demonstrated that:1) at the single channel scale, controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance, while different channel configurations lead to marginal improvements; 2) for the scaling-up of the reaction process, a reactor module containing 15 circular parallel channels could be used as module blocks, which can be stacked one by one to meet the required reactor performance and production capacity. The present results show that micro-reactors are quite suitable for HMF production.
    General reactor
    CFD simulation of gas-liquid flow in a high-pressure bubble column with a modified population balance model
    Bo Zhang, Lingtong Kong, Haibo Jin, Guangxiang He, Suohe Yang, Xiaoyan Guo
    2018, 26(6):  1350-1358.  doi:10.1016/j.cjche.2018.01.003
    Abstract ( 722 )   PDF (2217KB) ( 110 )  
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    In this study, based on the Luo bubble coalescence model, a model correction factor Ce for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term. Then, a coupled modified population balance model (PBM) with computational fluid dynamics (CFD) was used to simulate a high-pressure bubble column. The simulation results with and without Ce were compared with the experimental data. The modified CFD-PBM coupled model was used to investigate its applicability to broader experimental conditions. These results showed that the modified CFD-PBM coupled model can predict the hydrodynamic behaviors under various operating conditions.
    Hydrodynamics and bubble behaviour in a three-phase two-stage internal loop airlift reactor
    Dan Li, Kai Guo, Jingnan Li, Yiping Huang, Junchao Zhou, Hui Liu, Chunjiang Liu
    2018, 26(6):  1359-1369.  doi:10.1016/j.cjche.2018.03.020
    Abstract ( 782 )   PDF (2920KB) ( 63 )  
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    Local hydrodynamics of a gas-liquid-solid system, such as bubble circulation regime, gas holdup, liquid velocity and axial profile of solid concentration, are studied in a two-stage internal loop airlift reactor. Empirical correlations for gas holdup and liquid velocity are proposed to ease the reactor design and scale-up. Different bubble circulation regimes were displayed in the first (lower) and second (upper) stages. Increasing superficial gas velocity and solid loading can promote regime transition of the second stage, and the gas holdup of the second stage is higher than that of the lower stage. In addition, the effects of solid loading on bubble behaviour are experimentally investigated for each stage. It is found that bubble size in the downcomer decreases with the presence of solid particles, and bubble size distribution widens under higher superficial gas velocity and lower solid loading.
    Features of the motion of gel particles in a three-phase bubble column under foaming and non-foaming conditions
    Gabriel Salierno, Mauricio Maestri, Stella Piovano, Miryan Cassanello, María Angélica Cardona, Daniel Hojman, Héctor Somacal
    2018, 26(6):  1370-1382.  doi:10.1016/j.cjche.2018.03.026
    Abstract ( 619 )   PDF (10010KB) ( 23 )  
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    Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas-liquid systems, determined by using experiments of radioactive particle tracking (RPT), have been compared. The tracer used is a gel particle which resembles typical immobilized biocatalyst. The tracer trajectory is analyzed to extract relevant information for design purposes. The solid velocity field, turbulence parameters, dispersion coefficients, mixing times and flow transitions are determined and compared. The presence of foam significantly affects many quantified parameters, especially within the heterogeneous flow regime. The hydrodynamic stresses are reduced in the presence of foam, especially close to the disengagement. The dispersion coefficients also decrease, and the solid mixing time is only slightly affected by the presence of foam. Gas holdup, inferred both from RPT experiments and from gamma ray scanning, is higher for foaming systems and leads to a shift in the transition gas velocity towards higher values.
    Effects of rotational speed and fill level on particle mixing in a stirred tank with different impellers
    Yuyun Bao, Yu Lu, Ziqi Cai, Zhengming Gao
    2018, 26(6):  1383-1391.  doi:10.1016/j.cjche.2017.11.010
    Abstract ( 579 )   PDF (4753KB) ( 151 )  
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    The particle mixing was studied in a cylindrical stirred tank with elliptical dished bottom by experiments and simulations. The impeller types used were double helical ribbon (HR) + bottom HR, pitched blade ribbon + bottom HR, inner and outer HR + bottom HR, and pitched blade ribbon + Pfaudler + bottom HR labeled as impellers I to IV, respectively. The quantitative correlations among the rotational speed, fill level and power consumption for impeller I and impeller Ⅱ were obtained by experiments to validate the discrete element method (DEM) simulations. The particle mixing at different operating conditions was simulated via DEM simulations to calculate the mixing index using the Lacey method, which is a statistical method to provide a mathematical understanding of the mixing state in a binary mixture. The simulation results reveal that as the rotational speed increases, the final mixing index increases, and as the fill level increases, the final mixing index decreases. At the same operating conditions, impeller Ⅲ is the optimal combination, which provides the highest mixing index at the same revolutions.
    Characterization on the hydrodynamics of a covering-plate Rushton impeller
    Tenglong Su, Fengling Yang, Meiting Li, Kanghui Wu
    2018, 26(6):  1392-1400.  doi:10.1016/j.cjche.2017.11.015
    Abstract ( 615 )   PDF (3498KB) ( 35 )  
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    A modified Rushton impeller with two circular covering-plates mounted on the upper and lower sides of the blades was designed. There are gaps between the plates and the blades. The turbulent hydrodynamics was analyzed by the computational fluid dynamics (CFD) method. Firstly, the reliability of the numerical model and simulation method was verified by comparing with the experimental results from literature. Subsequently, the power consumption, flow pattern, mean velocity and mixing time of the covering-plate Rushton impeller (RT-C) were studied and compared with the standard Rushton impeller (RT) operated under the same conditions. Results show that the power consumption can be decreased about 18%. Compared with the almost unchanged flow field in the lower stirred tank, the mean velocity was increased at the upper half of the stirred tank. And in the impeller region, the mean axial and radial velocities were increased, the mean tangential velocity was decreased. In addition, the average mixing time of RT-C was shortened about 4.14% than the counterpart of RT. The conclusions obtained here indicated that RT-C has a more effective mixing performance and it can be used as an alternative of RT in the process industries.
    Comparison between the new mechanistic and the chaos scale-up methods for gas-solid fluidized beds
    Haidar Taofeeq, Muthanna Al-Dahhan
    2018, 26(6):  1401-1411.  doi:10.1016/j.cjche.2018.03.022
    Abstract ( 654 )   PDF (5070KB) ( 31 )  
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    The chaotic scale-up approach by matching the Kolmogorov entropy (EK) proposed by Schouten et al. (1996) was assessed in two geometrically similar gas-solid fluidized bed columns of 0.14 and 0.44 m diameter. We used four conditions of our validated new mechanistic scale-up method based on matching the radial profiles of gas holdup where the local dimensionless hydrodynamic parameters were similar as measured by advanced measurement techniques. These experimental conditions were used to evaluate the validity of the chaotic scale-up method, which were selected based on our new mechanistic scale-up methodology. Pressure gauge transducer measurements at the wall and inside the bed at various local radial locations and at three axial heights were used to estimate KE. It was found that the experimental conditions with similar or close radial profiles of the Kolmogorov entropy and with similar or close radial profiles of the gas holdup achieve the similarity in local dimensionless hydrodynamic parameters, and vice versa.
    Modeling of segregation in magnetized fluidized bed with binary mixture of Geldart-B magnetizable and nonmagnetizable particles
    Quanhong Zhu, Hongzhong Li, Qingshan Zhu, Qingshan Huang
    2018, 26(6):  1412-1422.  doi:10.1016/j.cjche.2017.12.011
    Abstract ( 605 )   PDF (800KB) ( 73 )  
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    For the magnetized fluidized bed (MFB) with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles, the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities (H), leading to the deterioration of the fluidization quality. The critical intensity (Hms) above which such segregation commences varies with the gas velocity (Ug). This work focuses on establishing a segregation model to theoretically derive the Hms-Ug relationship. In a magnetic field, the magnetizable particles form agglomerates. The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles. Consequently, the segregation model was established in two steps:first, the size of agglomerates (dA) was calculated by the force balance model; then, the Hms-Ug relationship was obtained by substituting the expression of dA into the basic size segregation model for binary mixtures. As per the force balance model, the cohesive and collision forces were 1-2 orders of magnitude greater than the other forces exerted on the agglomerates. Therefore, the balance between these two forces largely determined dA. The calculated dA increased with increasing H and decreasing Ug, agreeing qualitatively with the experimental observation. The calculated Hms-Ug relationship agreed reasonably with the experimental data, indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.
    Critical impeller speeds for a gas-inducing stirring tank loaded with solid particles
    Yanhong Zhang, Zhengwei Zhang, Chenwen Wei, Hualin Wang
    2018, 26(6):  1423-1429.  doi:10.1016/j.cjche.2018.04.026
    Abstract ( 681 )   PDF (2640KB) ( 76 )  
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    The influence of solid particles size, density and loading on the critical gas-inducing impeller speed was investigated in a gas-liquid-solid stirring tank equipped with a hollow Rushton impeller. Three types of solid particles, hollow glass beads with diameters of 300 μm, 200 μm, 100 μm, and 60 μm, silica gel and desalting resin, were used. It was found that the adding solid particles would change the critical impeller speed. For hollow glass beads and silica gel, whose relative densities were less than or equal to 1.5, the critical impeller speeds increased with the solid loading before reaching the maximum values, and then decreased to a value even lower than that without added solids. The size of the solids also had apparent influence on the critical impeller speed, and larger solid particles correspond to a smaller critical impeller speed. The experimental data also showed that the gasinducing was beneficial to the suspension of the solid particles.
    Stability of penicillin G in ionic liquid [Bmim]PF6
    Jingxian Qi, Qingfen Liu, Huizhou Liu
    2018, 26(6):  1430-1434.  doi:10.1016/j.cjche.2018.02.030
    Abstract ( 672 )   PDF (884KB) ( 53 )  
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    The extraction of penicillin G by ionic liquid [Bmim]PF6 has exhibited promising prospect. The stability of penicillin G is crucial for developing a green ionic liquid-based extraction technology. In this work, the stability of penicillin G in [Bmim]PF6 was systematically investigated. The results showed the stability of penicillin G was significantly influenced by pH and temperature. It tended to be more stable when pH value increased from 1.5 to 4.0 and the temperature gradually decreased. The half-life (t1/2) of penicillin G in [Bmim]PF6 was 17.7 h in the optimal technological condition (pH 2.0 and 10℃), which is enough for the requirement of extraction technology. The reaction of penicillin G in [Bmim]PF6 followed the first order kinetics in the pH range 2.0-4.0. Three isomers of penicillin G were found through rearrangement at pH 2.0, and their structures were not affected by temperature.
    A novel constant interfacial area cell for determining the extraction kinetics of Er(III) from chloride medium
    Chuanxu Xiao, Kun Huang, Huizhou Liu
    2018, 26(6):  1435-1441.  doi:10.1016/j.cjche.2018.04.016
    Abstract ( 590 )   PDF (1670KB) ( 32 )  
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    A novel constant interfacial area cell (NCIAC), by spatially separating the agitation from liquid flow circulation of organic and aqueous two phases, was suggested to obtain detailed kinetic data for Er(Ⅲ) extraction from chloride medium by 2-ethyl-hexyl-phosphonic acid mono-(2-ethylhexyl) ester (EHEHPA). Different from the traditional Lewis cell and the constant interfacial area cell with laminar flow, the concentrations of Er(Ⅲ) in organic and aqueous two phases were uniform, and the stability of the interfacial area between the two phases could be controlled effectively. Therefore, the special requirements for the design of agitators in the traditional Lewis cell and the constant interfacial area cell for minimizing the influence of diffusion resistance could be avoided. Experimental results indicated that the extraction kinetics was mainly affected by the aqueous flow rate, interfacial area between organic and aqueous two phases, and the aqueous pH values. An extraction kinetic equation was suggested based on the experimental data.