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Current Issue
2014 Vol.31 Issue.2,
Published 2014-03-15
Article
Article
1
Friedel-Crafts Acylation Reaction of Thiophene
TONG Tian-Xia, CHEN Zhi-Hua, YANG Li-Juan, JIA Peng-Fei, CHENG Jing, ZENG Ai-Wu
Through the catalytic reaction test of five kinds of catalysts, including HZSM-5, HY, 13X, ZnCl
2
and C
25
, and a higher activity zeolite C
25
was chosen as catalyst and acetic anhydride was applied as acylating agent in the Friedel-Crafts acylation reaction of thiophene at atmospheric pressure. The effects of higher reaction temperature, the raw material ratio, the additional amount of solvent acetic acid, and the different concentrations of nitric acid modified catalysts on the Friedel-Crafts acylation reaction of thiophene were investigated principally. When the reaction temperature is 80 ℃, the suitable reactive conditions are: the mole ratio of thiophene to acetic anhydride is 1∶2, reaction time 5 h, the conversion of thiophene up to 97.23%. The catalytic activity was greatly improved when the acetic acid was added; the amount of acetic acid account for 8.72% of the total materials, reaction time 5 h, the conversion of thiophene was increased by 1.3%; the catalytic activity was up to the best when the zeolite was modified by 0.5 mol/L nitric acid. Meanwhile, the research on acylation reaction of gas thiophene was conducted by fixed bed reactor, and found that the best temperature was 92 ℃. Finally, the reactive products were refined to get the purity of 2-acetyl thiophene up to 99.90%.
2014 Vol. 31 (2): 1-6 [
Abstract
] (
5396
) [
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1KB] [
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1274KB] (
2098
)
7
Synthesis of 3, 5-Dibromo-2, 6-bis(2’-oxazolinyl)phenylpalladium(II) Chloride and Its Catalytic Activity in Suzuki Coupling
LIU Fang, PENG Miao, WANG Hong-Xing
The ligand 4,6-dibromo-1,3-bis(2’-oxazolinyl)benzene was synthesized from starting material 4,6-dibromoisophthalic acid after a series of reactions including acylation, amination, chlorination as well as ring closure. Treatment of this bisoxazoline with palladium acetate(II) and then ion exchanging with lithium chloride resulted in the corresponding pincer complex,［3,5-dibromo-2,6-bis (2’-oxazolinyl)phenyl］palladium(Ⅱ) chloride. The catalytic activity of this pincer complex in Suzuki coupling between aryl chlorides and phenylboronic acid was assessed. Experimental results demonstrate that the Suzuki coupling between series aryl chlorides and phenylboronic acid all give out the expected products in high yields except the case of
p
-chloroaniline. In addition, the product yields in the coupling of aryl chlorides bearing electron-donating groups catalyzed by palladium pincer are higher than those of aryl chlorides containing electron-withdrawing substituents probably because of the character of electron-withdrawing of bromines at 3,5-positions in this pincer complex.
2014 Vol. 31 (2): 7-12 [
Abstract
] (
1738
) [
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1KB] [
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1313KB] (
1608
)
13
Progress in Preparation of Hexabromocyclododecane Flame Retardan
WU Dan, ZHANG Yu-Shan, CAI Rong-Hua, LIU Wei, ZHANG Hui-Feng, YAO Ying
The progress in reaction mechanism and preparation techniques of hexabromocyclododecane（HBCD）both at home and abroad is reviewed. According to the problems existing in the HBCD synthesis process, it is suggested that we improve the purity of the HBCD products and take post-processing measures to enhance thermal stability of HBCD, which are the future research direction of synthesis high purity and high thermal stability of HBCD. Furthermore, we can carry out kg-scale experiments to provide the reference for the industrial scale-up generation.
2014 Vol. 31 (2): 13-17 [
Abstract
] (
2552
) [
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1KB] [
PDF
1023KB] (
1729
)
18
Synthesis of Adipic Acid Dihydrazide by Two Steps
YANG Jun-Ge, SONG Bao-Dong, ZHANG Hua-Tang
The synthesis of adipic acid dihydrazide by two steps was investigated in this paper. Adipic acid was first esterified with methanol under the catalysis of KHSO
4
to give dimethyl adipate, which was further reacted with hydrazine hydrate to produce adipic acid dihydrazide (ADH) with a high purity. The optimal conditions for the esterification reaction were determined as catalyst amount was 5.5% of the weight amount of adipic acid, molar ratio of methanol to adipic acid was 4.0, reaction time was 1.0 h. Under these conditions, the purity of dimethyl adipate was as high as 998% and the yield was 77%. For the hydrazide reaction, the optimal conditions were: molar ratio of both hydrazine hydrate and methanol to dimethyl adipate was 4.0, reaction time was 1.5 h. Under these conditions, the yield of adipic acid dihydrazide reached 99% and the purity was 99.5%.
2014 Vol. 31 (2): 18-23 [
Abstract
] (
5741
) [
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1KB] [
PDF
1481KB] (
2678
)
24
Startup Characteristics of Hydraulic-Drive Rotary Energy Recovery Device
HAN Song , WANG Yue , XU En-Le , SUN Yang-Ping , XU Shi-Chang , WANG Shi-Chang
Realizing the hydraulic-drive operating is of great importance for enhancing the controlling flexibility and working reliability of energy recovery device in seawater desalination process. Based on the FLUENT software, fluid-solid coupling model for hydraulic-drive energy recovery device was built in this paper. Under the operational pressure of 6.0 MPa and entrance velocity of 5.0 m/s for high and low pressure streams, characteristics of the device’s rotating speed and flow velocity at high and low pressure regions were studied and analyzed at the startup stage. Results show that the rotating speed increases rapidly at the beginning and then tends to remain constant. The final steady rotating speed can be up to 1 395 r/min in 1.25 s of startup period. At high and low pressure regions, tangential velocity difference appears in fluid between the entrance and center of those rotor channels mantled by the end-cover wedge structure. The velocity difference is believed to be the main force that hydraulically drives the device.
2014 Vol. 31 (2): 24-30 [
Abstract
] (
1583
) [
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1KB] [
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2029KB] (
1558
)
31
Deep Concentration of Brine by Multiple-Effect Membrane Distillation at High Temperature
JIN Jun-Bao, QIN Ying-Jie, WANG Ben, WANG Bin, CUI Dong-Sheng, LIU Li-Qiang
Membrane distillation is usually operated at temperature <90 ℃. However, when dealing with concentrated salt, permeation flux (
J
) and thermal efficiency are much lower because of the reduction of vapor pressure, as well as concentration and temperature polarization effects. In this paper， multiple-effect membrane distillation (MEMD) was explored in the range of 85—105 ℃ for deep concentrating feed of NaCl solutions. The effects of cold feedin temperature
T
1
heated feed temperature
T
3
feed-in concentration and feedin flow rate on
J ,
performance ratio (PR) and retention rate were investigated. The experimental result indicated that the
J
and PR were 3.1 L/(m
2
·h) and 15.2 for 5% NaCl solution when
T
3
was 100 ℃, the values of both
J
and PR decreased with the increase of feed concentration, however, their values could still achieve 1.53 L/(m
2
·h) and 5.8 respectively for 25% NaCl solution when the value of
T
3
was 105 ℃, while the salt retention rate could reach more than 99.95%. Also, a long-tern operational stability of the MEMD process was tested for 15% NaCl solution for 60 days. The experimental results indicated that MEMD process showed good operation stability.
2014 Vol. 31 (2): 31-37 [
Abstract
] (
1714
) [
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1KB] [
PDF
1686KB] (
3064
)
38
Heat Recovery in Vacuum Membrane Distillation
LIU Xue-Jing, LI Bao-An
Vacuum membrane distillation technology has great potential applications in seawater desalination, industrial wastewater treatment and so on. This study focused on heat recovery in vacuum membrane distillation process. An integrated membrane module with a threestep heat recovery system was designed and manufactured. The results indicate that this novel membrane module can effectively recover the vapor latent heat produced in membrane distillation. The operating conditions, such as feed inlet temperature, feed linear velocity and vacuum degrees, has a certain influence on heat recovery rate. This paper laid a foundation for further studies on improving heat recovery efficiency of decompression membrane distillation and reducing operating cost.
2014 Vol. 31 (2): 38-42 [
Abstract
] (
2460
) [
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1KB] [
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1621KB] (
1905
)
43
Separation of Methanol-Benzene Binary by Extractive Distillation
GAO Xing-Na, BAI Peng, XU Xian-Shuo
Extractive distillation was used to separate methanol-benzene azeotropic mixture. First, chlorobenzene was chosen as the solvent through the UNIFAC group contribution method and empirical data. The calculation of vapor-liquid equilibrium using UNIFAC model for methanol-benzene system with chlorobenzene under atmospheric pressure was performed. The calculation results agreed well with the experimental data. In order to investigate the effectiveness of the solvent, the batch extractive distillation experiments were carried out. The results showed that chlorobenzene could eliminate the azeotropic point of methanol-benzene system. The batch extraction distillation was carried out in a packed column of 30 theoretical plates, 4 theoretical plates in the recovery section. With the reflux ratio of 3 and the solvent mass ratio of 1, the recovery rate of product reaches 98%, which revealed that the extractive distillation with chlorobenzene as solvent was useful in the separation of methanolbenzene system. Finally, Aspen Plus were used to simulate the continuous distillation process. Effects of reflux ratio, solvent flowrate on the product purity were analyzed to get the optimal operation parameters. These results can provide some reference for the industrial production.
2014 Vol. 31 (2): 43-47 [
Abstract
] (
1693
) [
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1KB] [
PDF
1710KB] (
1719
)
48
Induced Crystallization of Cefotaxime Sodium
YIN Yong-Heng, BAO Ying , WANG Yong-Li, GAO Zhen-Guo, LIU Dong
Cefotaxime sodium is easy to gelate during antisolvent crystallization. Aiming at controlling crystallization process and avoiding gelation, different seeds were used to investigate their effects on the anti-solvent crystallization of cefotaxime sodium. The effect of ultrasonic on the crystallization process was also investigated. Crystallization process was monitored using process analytical technologies. The results show that the seeds affect not only the crystal size distribution and crystal shape, but also the crystal purity and yield. The milled seeds can effectively induce nucleation and crystal growth, consume the supersaturation and then avoid gelation. The ultrasonic can induce nucleation as well. The results also shows that specific surface area and surface roughness of the seed crystal are the key factors inducing crystallization of cefotaxime sodium.
2014 Vol. 31 (2): 48-53 [
Abstract
] (
2270
) [
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1KB] [
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2024KB] (
1617
)
54
Pressure Swing Distillation with Heat Integration for Ethanol-Acetonitrile Separation
YANG Zhao-Yin
The pressure swing distillation with heat integration was employed to separate ethanol-acetonitrile mixture. It was experimentally measured that the ethanol composition of ethanol-acetonitrile azeotrope was increased significantly with increasing pressure. A serial of experiments were implemented to obtain 99.5 % ethanol/acetonitrile products, with focus on the influence of reflux ratio on the experimental separation efficiency in each column. It was found that the optimum reflux ratio of pressurized column and atmospheric column were 3 and 4，respectively. With the help of Aspen Plus simulation, it was also showed that the pressure swing distillation with heat integration could offer 35% energy saving compared with traditional pressure swing distillation.
2014 Vol. 31 (2): 54-59 [
Abstract
] (
1762
) [
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1KB] [
PDF
1814KB] (
2914
)
60
Numerical Simulation of the Flow and Heat Transfer Process of Vertical Tube Falling Film Evaporator
HAO Li, XIAO Xiao-Ming, ZHANG LyuHong, JIANG Bin , SUN Yong-Li
In this paper, theoretical analysis and Computational Fluid Dynamics (CFD) study on falling film process of vertical heating tube for falling film evaporator’s heat transferring was conducted. A three-dimensional numerical simulation of falling film flow was made using FLUENT software which had been further exploited with user defined functions (UDF) to identify the source term of mass and heat transfer. We studied the falling film evaporating and heat of vaporization process of heating liquid membranous falling along the wall. We adopted two-phase flow Mixture model and laminar flow model, Simple algorithms. The simulation results was in 3D performance of the liquid along the direction of movement of the development process of the film formation in the wall, the film thickness was calculated and compared with the theoretical and simulated. The simulation results show that the heating tube of vertical falling film evaporator with the good uniformity characteristics of thin liquid film and the tube surface is relatively easy to form columnar flow. The results show the film thickness is 1.0 mm.
2014 Vol. 31 (2): 60-65 [
Abstract
] (
5102
) [
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1KB] [
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1939KB] (
2285
)
66
CFD Study for a Novel Multi-Stage Flotation Column
WEN Xin, LIU Chun-Jiang
Novel multi-stage flotation column was developed independently in our lab and computational fluid dynamics software FLUENT6.3.26 was used for numerical simulation of gas-liquid two-phase flow. Euler-Euler multiphase flow model was used to simulate gas phase with single gas bubble size. A standard
k-ε
turbulence model was used to describe two phases in the simulations, considering the drag force for interphase momentum transfer only. The liquid velocities, axial liquid velocities and gas holdup distribution in the different radial positions were obtained through the simulations. It was shown that increasing the gas velocity would improve the gas holdup and liquid circulation rate, which means the more sufficiently gas and liquid were mixed, the better effect of flotation would be. It is significant for improving the separation efficiency in the column and the scale-up of the column. Performance of multi-stage loop packed flotation column at different conditions was tested with coal slurry in Qianjiaying Kailuan Mining Company. Under gas velocity of 1.25 m
3
/h and feed of 0.05 L/h, with residence time of 20 min，coal ash was 10.28%, tail ash of 43.39%, clean coal yield of 52.53%. It was close to coal ash of 10.58% in this company.
2014 Vol. 31 (2): 66-71 [
Abstract
] (
4089
) [
HTML
1KB] [
PDF
2003KB] (
1584
)
72
Small Molecular Electron Donors for Organic Photovoltaics
LIU Yang, YANG Le, CHEN Zhi-Jian
Small molecular photovoltaic materials, owing to their distinct chemical structures, easier purification and well-reproducible synthesis, have attracted considerable attention in recent years. Furthermore, the structureproperty relationships of these materials are better understandable in comparison with polymeric materials, indicating a better tenability of their properties. In terms of processability, vacuum deposition as well as solution process can be used for small molecular materials in device preparation. Nowadays a large number of small molecular electron-donating materials have been synthesized and applied widely in organic photovoltaics. Remarkable power convert efficiency (PCE) of 6.7% has been achieved for single-junction devices based on small molecules. In this paper, the application of different type small molecular electron donors is reviewed and the future development of these materials is discussed.
2014 Vol. 31 (2): 72-78 [
Abstract
] (
2384
) [
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1KB] [
PDF
2013KB] (
1741
)
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