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Gas phase ethylene polymerization over SiO

Liuzhong LI, Aiyou HAO, Ruihua CHENG, Boping LIU

《化学科学与工程前沿（英文）》 2011年 第5卷 第1期   页码 89-95 doi: 10.1007/s11705-010-0558-x

摘要： Although an important industrial catalyst for producing high density polyethylene, the SiO -supported organosilyl chromate UCC S-2 catalyst has not been fully investigated compared with the SiO -supported oxo chromium Phillips catalyst. In this work, gas phase ethylene polymerization by S-2 catalysts (Cat-1, Cat-2, and Cat-3) was carried out in a high-speed stirred-autoclave reactor. The effects of temperature, time, and pressure on kinetics, activity, and product properties were studied. All kinetics were typical built-up types with slow decay. Compared to the simple physical mixtures of Cat-1 and Cat-2, Cat-3 showed higher activity and its product had a broader molecular weight distribution, indicating new active species induced during blending of Cat-1 and Cat-2 in -hexane. The innovation by a simple catalyst technology created a new application to meet market demands.

关键词： UCC S-2 catalyst     Al-alkyl co-catalyst     gas-phase ethylene polymerization     high density polyethylene    

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Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites

RUN Mingtao, ZHANG Dayu, WU Sizhu, WU Gang

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 50-54 doi: 10.1007/s11705-007-0010-z

摘要： The nonisothermal and isothermal degradation processes of poly (ethylene terephthalate)/mesoporous molecular sieve (PET/MMS) composites synthesized by in-situ polymerization were studied by using thermogravimetric analysis in nitrogen. The nonisothermal degradation of the composite is found to be the first-order reaction. An iso-conversional procedure developed by Ozawa is used to calculate the apparent activation energy (), which is an average value of about 260 kJ/mol with the weight conversion from 0% to 30%, and is higher than that of neat PET. Isothermal degradation results are confirmed with the nonisothermal process, in which PET/MMS showed higher thermal stability than neat PET. The polymer in mesoporous channels has more stability due to the protection of the inorganic pore-wall. These results indicate that mesoporous MMS in PET/MMS composites improve the stability of the polymer.

关键词： polymerization     isothermal degradation     conversion     nonisothermal degradation     activation    

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Studies on the rheological, phase morphologic, thermal and mechanical properties of poly(trimethyleneterephthalate)/ethylene propylene diene monomer copolymer grafted with maleic anhydride/metallocene

RUN Mingtao, SONG Hongzan, WANG Yingjin, YAO Chenguang, GAO Jungang

《化学科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 238-245 doi: 10.1007/s11705-007-0043-3

摘要： The rheological, phase morphologic, thermal and mechanical properties of poly(trimethylene terephthalate)/metallocene polyethylene (PTT/mPE) blends in the presence of ethylene propylene diene monomer copolymer grafted with maleic anhydride (EPDM--MAH) as compatibilizer are studied by means of a capillary rheometer, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). Results suggest that the compatibility of PTT/mPE blends is improved greatly after the addition of a compatibilizer. The radius of the dispersed phase in the system decreases greatly when the compatibilizer is added into the blend. When the amount of compatibilizer exceeds 8 wt-%, the size of dispersed phase becomes larger again. This phenomena could be attributed to the higher viscosity of the EPDM--MAH phase, which is dispersed more difficulty in the PTT phase of lower viscosity, thus the mixing efficiency is apparently decreased during the melt blending process. Moreover, the melt viscosity of the blend reaches the maximal value in case of 4 wt-% compatibilizer content, above which it would decrease again. This result is associated with the generation of more and bigger dispersed phase inside the bulk phase, thus the grafting efficiency at the interface is decreased, which could result in lower viscosity. The DSC results suggest that the mPE component shows a nucleating effect, and could increase the overall degree and rate of PTT crystallization, while the addition of a compatibilizer might slightly diminish these effects. In addition, the blend with 4 wt-% compatibilizer shows the best thermal stability. Furthermore, the Izod impact strength and the tensile strength at room temperature of the blend are also markedly improved by the addition of a 4 8 wt-% compatibilizer.

关键词： /metallocene polyethylene     presence     rheological     phenomena     trimethylene terephthalate    

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Effect of PEG additives on properties and morphologies of polyetherimide membranes prepared by phase

Jian CHEN, Jiding LI, Xia ZHAN, Xiaolong HAN, Cuixian CHEN,

《化学科学与工程前沿（英文）》 2010年 第4卷 第3期   页码 300-306 doi: 10.1007/s11705-009-0280-8

摘要： This study investigated the effect of poly(ethylene glycol) (PEG) additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic properties in the phase inversion process. The membranes were prepared by using polyetherimide/-methyl-2-pyrrolidone/PEG (PEI/NMP/PEG) casting solution and water coagulant. The resulting membranes, prepared by changing the ratio of PEG to PEI, were characterized by scanning electron microscope (SEM) observations, measurements of water flux and -globin rejection. The thermodynamic and kinetic properties of the membrane-forming system were studied through viscosity. The pore radius distribution curves were especially obtained by differential scanning calorimetry (DSC). Furthermore, the membranes were characterized for pure water flux and rejection of solute and by SEM observation. The filtration results agreed well with the SEM observations. As expected, PEG with a fixed molecular weight (PEG 600) acted as a pore forming agent, and membrane porosity increased as the PEG content of the casting solution increased.

关键词： permeation     ethylene     filtration     PEI/NMP/PEG     membrane    

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Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel

ZHUGE Weilin, ZHANG Yangjun, LAO Xingsheng, CHEN Xiao, MING Pingwen

《能源前沿（英文）》 2007年 第1卷 第3期   页码 305-310 doi: 10.1007/s11708-007-0044-4

摘要： Investigation into the formation and transport of liquid water in proton exchange membrane fuel cells (PEMFCs) is the key to fuel cell water management. A three-dimensional gas/liquid two-phase flow and heat transfer model is developed based on the multiphase mixture theory. The reactant gas flow, diffusion, and chemical reaction as well as the liquid water transport and phase change process are modeled. Numerical simulations on liquid water distribution and its effects on the performance of a PEMFC are conducted. Results show that liquid water distributes mostly in the cathode, and predicted cell performance decreases quickly at high current density due to the obstruction of liquid water to oxygen diffusion. The simulation results agree well with experimental data.

关键词： diffusion     gas/liquid two-phase     management     exchange     transfer    

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茂金属催化剂催化烯烃聚合反应的研究 ——聚合物的聚集行为和热性能 Letter

吴长江, Minqiao Ren, Liping Hou, Shuzhang Qu, Xinwei Li, Cui Zheng, Jian Chen, 王伟

《工程（英文）》 2023年 第30卷 第11期   页码 93-99 doi: 10.1016/j.eng.2023.07.001

摘要：

Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes. Polyolefin elastomers (POE) are a typical example. Due to cost, only a few linear α-olefins (e.g., 1-butene, 1-hexene, and 1-octene) are used as comonomers in solution polymerization in industry. However, α-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones. Moreover, the properties of the corresponding materials may differ significantly. In this work, copolymers of ethylene with linear and end-cyclized α-olefins are synthesized using a metallocene catalyst. The copolymerization of ethylene with linear α-olefins results in a higher turn-over frequency (TOF) and lower incorporation than copolymerization with end-cyclized α-olefins, which may indicate that end-cyclized α-olefins have a higher coordination probability and lower insertion rate. In this reaction, the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization. End-cyclized α-olefins exhibit a much stronger crystallization destructive capacity (CDC) in the copolymer than linear α-olefins, possibly because linear α-olefins act mainly in the radial direction of the main chain of the polymer, while end-cyclized α-olefins act mainly in the axial direction of the main chain.

关键词： Metallocene catalyst     Ethylene copolymerization     Comonomer distribution     Crystallization destructive capacity    

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Experimental study for the stratified to slug flow regime transition mechanism of gas-oil two-phase flow

LIU Yiping, YANG Weilin, WANG Jing

《能源前沿（英文）》 2008年 第2卷 第2期   页码 152-157 doi: 10.1007/s11708-008-0012-7

摘要： Theoretical relations that predict the transition from a stratified pattern to a slug pattern, including a one-dimensional wave model that contains less empiricism than the commonly used Taitel-Dukler model, and the ideal model for stratified flow for the gas-liquid flow in horizontal pipes are presented. Superficial velocities of each phase, as the onset of slugging occurs, were predicted, and theoretical analysis was conducted on the stratified to slug flow regime transition. The friction, existing between the fluid and pipe wall, and on the interface of two phases, was especially taken into account. A theoretical model was applied to an experiment about air-oil two-phase flow in a 50 mm horizontal pipe. The effect of pipe diameter on the transition was also studied. The results show that this approach gives a reasonable prediction over the whole range of flow rates, and better agreement has been achieved between predicted and measured critical parameters.

关键词： two-phase     Superficial     reasonable prediction     one-dimensional     gas-liquid    

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Simultaneous analysis of five taste and odor compounds in surface water using solid-phase extractionand gas chromatography-mass spectrometry

Wenfeng SUN, Ruibao JIA, Baoyu GAO

《环境科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 66-74 doi: 10.1007/s11783-010-0257-3

摘要： In this paper, a method using solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2-methylisoborneol (2-MIB), 2,4,6-trichloroanisole (TCA), 2-isopropyl-3-methoxy pyrazine (IPMP), 2-isobutyl-3-methoxy pyrazine (IBMP), and -1,10-dimethyl- -9-decalol (geosmin, GSM). The mass spectrometry was operated in selective ion monitoring (SIM) mode. Three kinds of SPE columns and three eluting solvents were compared, the C18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1–200 ng·L and gave detection limits of 0.5–1.5 ng·L for individual compounds. Good recoveries (93.5%–108%) and relative standard deviations (1.58%–7.31%) were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan’s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan’s raw water.

关键词： solid-phase extraction (SPE)     gas chromatography-mass spectrometry (GC-MS)     taste and odor compounds     surface water     micropollutant    

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Catalysis of semihydrogenation of acetylene to ethylene: current trends, challenges, and outlook

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1031-1059 doi: 10.1007/s11705-021-2113-3

摘要： Ethylene is an important feedstock for various industrial processes, particularly in the polymer industry. Unfortunately, during naphtha cracking to produce ethylene, there are instances of acetylene presence in the product stream, which poisons the Ziegler–Natta polymerization catalysts. Thus, appropriate process modification, optimization, and in particular, catalyst design are essential to ensure the production of highly pure ethylene that is suitable as a feedstock in polymerization reactions. Accordingly, carefully selected process parameters and the application of various catalyst systems have been optimized for this purpose. This review provides a holistic view of the recent reports on the selective hydrogenation of acetylene. Previously published reviews were limited to Pd catalysts. However, effective new metal and non-metal catalysts have been explored for selective acetylene hydrogenation. Updates on this recent progress and more comprehensive computational studies that are now available for the reaction are described herein. In addition to the favored Pd catalysts, other catalyst systems including mono, bimetallic, trimetallic, and ionic catalysts are presented. The specific role(s) that each process parameter plays to achieve high acetylene conversion and ethylene selectivity is discussed. Attempts have been made to elucidate the possible catalyst deactivation mechanisms involved in the reaction. Extensive reports suggest that acetylene adsorption occurs through an active single-site mechanism rather than via dual active sites. An increase in the reaction temperature affords high acetylene conversion and ethylene selectivity to obtain reactant streams free of ethylene. Conflicting findings to this trend have reported the presence of ethylene in the feed stream. This review will serve as a useful resource of condensed information for researchers in the field of acetylene-selective hydrogenation.

关键词： selectivity     hydrogenation     acetylene     ethylene     palladium    

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合成橡胶化学及技术进展

武冠英

《中国工程科学》 1999年 第1卷 第3期   页码 79-85

摘要：

文章从合成橡胶的化学基础出发，叙述了合成橡胶工业二十世纪以来的过去、现状，并展望未来。着重讨论了合成化学基础及相应聚合工艺过程的进步这两方面的问题。指出合成橡胶化学基础中活性聚合、可控聚合，包括茂金属催化剂仍为近期的重点；气相聚合工艺将会得到较大的发展；高效聚合釜的研究仍是核心问题；环保问题应更受到重视。

关键词： 合成橡胶     合成化学     活性/控制聚合     气相聚合    

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Effect of counter current gas phase on liquid film

Shujuan LUO, Huaizhi LI, Weiyang FEI, Yundong WANG

《化学科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 135-137 doi: 10.1007/s11705-009-0129-1

摘要： Liquid film flow is very important in many industrial applications. However, there are few reports about its characteristics on structured packings. Therefore, in this paper, liquid film phenomena were investigated experimentally to exploit new approaches for intensifying the performance of the structured packings. All experiments were performed at room temperature. Water and air were the working fluids. The effect of counter current gas phase on the liquid film was taken into consideration. A high speed camera, a non-intrusive measurement technique, was used. It is shown that both liquid and gas phases have strong effects on film characteristics. In the present work, liquid film width increased by 57% because of increasing liquid flow rate, while it decreased by 25% resulting from the counter current gas phase.

关键词： counter current     liquid film     two phases     structured packings    

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Optimization of Venturi tube design for pipeline pulverized coal flow measurements

WU Zhansong, XIE Fei

《能源前沿（英文）》 2008年 第2卷 第4期   页码 369-373 doi: 10.1007/s11708-008-0072-8

摘要： A Venturi flow meter was designed to accurately measure the mass flow rate of pulverized coal in power plant pipelines. Numerical simulations of the dilute turbulent gas-solid two-phase flow in a horizontal Venturi tube were used to study the effects of Venturi tube geometry on the pressure distribution in the mixture. The results show that Venturi tube geometry strongly influences the metering of the dilute gas-particle two-phase flow. The geometry can be optimized to improve the precision of the measurement and ensure stable measurements. Furthermore, the geometries of three types of Venturi tubes were optimized for an experimental study of pulverized coal mass flow rate measurements.

关键词： gas-solid two-phase     geometry     gas-particle two-phase     Numerical     flow    

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Determination of selected semi-volatile organic compounds in water using automated online solid-phaseextraction with large-volume injection/gas chromatography/mass spectrometry

Yongtao LI, Christina L. MCCARTY, Ed J. GEORGE

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 417-425 doi: 10.1007/s11783-011-0310-x

摘要： A rapid, sensitive, and cost-effective analytical method was developed for the analysis of selected semi-volatile organic compounds in water. The method used an automated online solid-phase extraction technique coupled with programmed-temperature vaporization large-volume injection gas chromatography/mass spectrometry. The water samples were extracted by using a fully automated mobile rack system based on x-y-z robotic techniques using syringes and disposable 96-well extraction plates. The method was validated for the analysis of 30 semi-volatile analytes in drinking water, groundwater, and surface water. For a sample volume of 10 mL, the linear calibrations ranged from 0.01 or 0.05 to 2.5μg·L , and the method detection limits were less than 0.1μg·L . For the reagent water samples fortified at 1.0μg·L and 2.0?μg·L , the obtained mean absolute recoveries were 70%–130% with relative standard deviations of less than 20% for most analytes. For the drinking water, groundwater, and surface water samples fortified at 1.0μg·L , the obtained mean absolute recoveries were 50%–130% with relative standard deviations of less than 20% for most analytes. The new method demonstrated three advantages: 1) no manipulation except the fortification of surrogate standards prior to extraction; 2) significant cost reduction associated with sample collection, shipping, storage, and preparation; and 3) reduced exposure to hazardous solvents and other chemicals. As a result, this new automated method can be used as an effective approach for screening and/or compliance monitoring of selected semi-volatile organic compounds in water.

关键词： automated solid-phase extraction     programmed-temperature vaporization     large-volume injection     gas chromatography/mass spectrometry     semi-volatile organic compounds     water analysis    

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Detection of geosmin and 2-methylisoborneol by liquid-liquid extraction-gas chromatograph mass spectrum(LLE-GCMS) and solid phase extraction-gas chromatograph mass spectrum (SPE-GCMS)

MA Xiaoyan, CHEN Beibei, LI Qingsong, ZHANG Qiaoli, GU Guofen

《环境科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 286-291 doi: 10.1007/s11783-007-0048-7

摘要： Two sample preparation methods were introduced and compared in this paper to establish a simple, quick and exact analysis of geosmin and 2-methylisoborneol. LC-18 column was employed in solid phase extraction (SPE), 1.0 mL of hexane was adopted in liquid-liquid extraction (LLE), and the extracts were analyzed by gas chromatograph mass spectrum (GCMS) in selected ion mode. Mean recoveries of SPE were low for 2-methylisoborneol (2-MIB) and geosmin (GSM) with values below 50%. For LLE, the recoveries were satisfyingly above 50% for 2-MIB and 80% for GSM. Detection limits of the LLE method were as low as 1.0 ng/L for GSM and 5.0 ng/L for 2-MIB. A year-long investigation on odor chemicals of drinking water in Shanghai demonstrated that in the summer, there was a serious odor problem induced by a high concentration of 2-MIB. The highest concentration of 152.82 ng/L appeared in July in raw water, while GSM flocculation was minimal with concentrations below odor threshold.

关键词： summer     flocculation     simple     Shanghai     spectrum    

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Thin-film composite forward osmosis membranes with substrate layer composed of polysulfone blended with PEG or polysulfone grafted PEG methyl ether methacrylate

Baicang Liu,Chen Chen,Pingju Zhao,Tong Li,Caihong Liu,Qingyuan Wang,Yongsheng Chen,John Crittenden

《化学科学与工程前沿（英文）》 2016年 第10卷 第4期   页码 562-574 doi: 10.1007/s11705-016-1588-9

摘要： To advance commercial application of forward osmosis (FO), we investigated the effects of two additives on the performance of polysulfone (PSf) based FO membranes: one is poly(ethylene glycol) (PEG), and another is PSf grafted with PEG methyl ether methacrylate (PSf-g-PEGMA). PSf blended with PEG or PSf-g-PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaCl (1 mol?L ) and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSf with 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L?m ?h than the commercial HTI membranes (6–8 L?m ?h ) under the FO mode. Our study suggests that hydrophobic interface is very important for the formation of polyamide, and a small amount of PSf-g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.

关键词： thin-film composite     forward osmosis     amphiphilic copolymer     interfacial polymerization     poly(ethylene glycol)    

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标题 作者 时间 类型 操作

Gas phase ethylene polymerization over SiO

Liuzhong LI, Aiyou HAO, Ruihua CHENG, Boping LIU

期刊论文

Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites

RUN Mingtao, ZHANG Dayu, WU Sizhu, WU Gang

期刊论文

Studies on the rheological, phase morphologic, thermal and mechanical properties of poly(trimethyleneterephthalate)/ethylene propylene diene monomer copolymer grafted with maleic anhydride/metallocene

RUN Mingtao, SONG Hongzan, WANG Yingjin, YAO Chenguang, GAO Jungang

期刊论文

Effect of PEG additives on properties and morphologies of polyetherimide membranes prepared by phase

Jian CHEN, Jiding LI, Xia ZHAN, Xiaolong HAN, Cuixian CHEN,

期刊论文

Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel

ZHUGE Weilin, ZHANG Yangjun, LAO Xingsheng, CHEN Xiao, MING Pingwen

期刊论文

茂金属催化剂催化烯烃聚合反应的研究 ——聚合物的聚集行为和热性能

吴长江, Minqiao Ren, Liping Hou, Shuzhang Qu, Xinwei Li, Cui Zheng, Jian Chen, 王伟

期刊论文

Experimental study for the stratified to slug flow regime transition mechanism of gas-oil two-phase flow

LIU Yiping, YANG Weilin, WANG Jing

期刊论文

Simultaneous analysis of five taste and odor compounds in surface water using solid-phase extractionand gas chromatography-mass spectrometry

Wenfeng SUN, Ruibao JIA, Baoyu GAO

期刊论文

Catalysis of semihydrogenation of acetylene to ethylene: current trends, challenges, and outlook

期刊论文

合成橡胶化学及技术进展

武冠英

期刊论文

Effect of counter current gas phase on liquid film

Shujuan LUO, Huaizhi LI, Weiyang FEI, Yundong WANG

期刊论文

Optimization of Venturi tube design for pipeline pulverized coal flow measurements

WU Zhansong, XIE Fei

期刊论文

Determination of selected semi-volatile organic compounds in water using automated online solid-phaseextraction with large-volume injection/gas chromatography/mass spectrometry

Yongtao LI, Christina L. MCCARTY, Ed J. GEORGE

期刊论文

Detection of geosmin and 2-methylisoborneol by liquid-liquid extraction-gas chromatograph mass spectrum(LLE-GCMS) and solid phase extraction-gas chromatograph mass spectrum (SPE-GCMS)

MA Xiaoyan, CHEN Beibei, LI Qingsong, ZHANG Qiaoli, GU Guofen

期刊论文

Thin-film composite forward osmosis membranes with substrate layer composed of polysulfone blended with PEG or polysulfone grafted PEG methyl ether methacrylate

Baicang Liu,Chen Chen,Pingju Zhao,Tong Li,Caihong Liu,Qingyuan Wang,Yongsheng Chen,John Crittenden

期刊论文