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Effect of polymerization Temperature on Propylene polymerization with C_s-symmetric Metallocene Catalyst

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Chinese Chemical Letters 2000年第2期11卷 167-170页

作者： Zhi Qiang FAN Tariq YASIN lin xian {2. (department of polymer {2. and Engineering, zhejiang university, hangzhou 310027) zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

A novel highly active C-s-symmetric metallocene catalyst namely: meso-dimethylsilylbis (2.4,6-trimethyl-1 -indenyl)zirconium dichloride is presented. The effect of polymerization temperature (0-70 degrees C) on the catalyst performance for propylene polymerization has been investigated. This catalyst shows very high activity at 50 degrees C which is higher than the activity of the racemic analogue, and the resulted polypropylene is amorphous in nature with isotactic pentad content [mmmm] of 12.%.

关键词： polymerization metallocene catalyst propylene

STEREOCHEMICAL CONTROL IN PROPYLENE polymerIZATION CATALYZED BY UNBRIDGED METALLOCENE CATALYSTS

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Chinese Journal of polymer science 2001年第4期19卷 407-413页

作者： Yin-bang Zhu Zhi-qiang Fan Tariq Yasin lin-xian {2. department of polymer {2. and Engineering zhejiang university hangzhou 310027, China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Two unbridged metallocene catalysts, bis(2.4,7-trimethylindenyl)zirconium dichloride (met-I) and bis(2.4,6-trimethylindenyl)zirconium dichloride (met-II), which are different in the position of substituents on the six-membered ring of the indenyl ligands were synthesized. The effect of substituents in the two metallocenes on the propylene {2.ization was studied in the presence of methylaluminoxane (MAO) and triisobutylaluminium (TIBA). From the analysis of microstructure determined by C-13-NMR, it was demonstrated that the {2.s produced by met-II have higher [mmmm] isotactic sequences than that of met-I. Using a mechanism based on model statistical analysis, it was found that chain-end model was dominant for met-I. However, met-II obeys the concurrent two-sites model during {2.ization, which can be attributed to the existence of 'racemic-like' conformer in its system.

关键词： unbridged metallocene propylene polymerization elastomeric polypropylene stereochemical mechanism

Effects of Al(i-Bu)_3 on Propylene polymerization and Copolymerization by rac-Me_2.i(Ind)_2.rCl_2.MAO

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Chinese Chemical Letters 1998年第1期9卷 83-85页

作者： Zhi Qiang FAN Yong Hui ZHANG Qi WANG lin xian {2. (department of polymer {2. and Engineering, zhejiang university, hangzhou 310027) zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

The effects of adding Al(i-C_4H_9)_3 (TBA) to rac-Me2.i(Ind)2.rCl2. MAO catalyzed propylene-1-octene copolymerization were studied. At TBA /MAO (Al/AI mole ratio) of about 0.6, the polymerization activity was found to be much higher than the system without TBA. Increases of polymer molecular weight and 1-octene content from addition of TBA were also observed.

关键词： propylene-1-octene polymerization metallocene catalyst

Novel Aluminoxanes Prepared from AlEt_3/Al(i-Bu)_3 Mixture as Cocatalyst for Metallocene Catalyzed Ethylene polymerization

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Chinese Chemical Letters 1998年第9期9卷 869-872页

作者： Zhi Qiang FAN Qi WANG Jian Hua WENG lin xian {2. (institute of polymer {2. and Materials, zhejiang university, hangzhou 310027) zhejiang Univ Inst Polymer Sci & Mat Hangzhou 310027 Peoples R China

Aluminoxanes containing both ethyl and iso-butyl groups were synthesized by thehydrolysis of Al(C2.3)3 (TEA)/Al(i-C4H9)3 (TIBA) mixtures. The aluminoxane made from theTEA/TIBA mixture of molar ratio 7:3 showed cocatalyst activity of about five times as those ofethylaluminoxane or isobutylaluminoxane for ethylene polymerization catalyzed by Cp2.rCl2. Thealuminoxane was characterized and the possible reasons for its high activity were discussed.

关键词： aluminoxane cocatalyst metallocene ethylene polymerization

IMPACT PROPERTIES OF METALLOCENE - CATALYZED ETHYLENE-α-OLEFIN COpolymerS

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Chinese Journal of polymer science 2002年第5期20卷 473-480页

作者： Xu-rong Xu Jun-ting Xu lin-xian {2. department of polymer {2. and Engineering zhejiang university hangzhou 310027,China department of polymer {2. and Engineering College of chemistry & Molecular Engineering Peking {12. Beijing 100871, China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China Peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China

The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwisecrystallization improves the impact properties, especially in the crack propagation process, to a large extent. This is due to thedecrease of entanglements by stepwise crystallization, which is advantageous for the chain slip and shear. The polymer withheterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties understepwise crystallization.

关键词： Metallocene-catalyzed ethylene-butene copolymer Impact properties Molecular heterogeneities Thermal treatment

Synthesis, Purification and Characterization of Amphiphilic and Microphase Separated Graft Copolymer Polystyrene-g-Poly(ethylene oxide)

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Chemical Research in Chinese Universities 1992年第3期8卷 278-286页

作者： QIU Yong-xing, YU Xiao-jie, feng lin-{2. and YANG Shi-lin (department of polymer {2. and Engineering, zhejiang university, hangzhou)

The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional 'living' PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as 'selective dissolvation', was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the copolymerization were also studied. The results indicate that the feed ratio of macromer to styrene (M/S) was the most important factor in determining the composition of the copolymers. Thus a series of PS-g-PEO with a wide range of bulk compositions were obtained simply by adjusting the value of M/S. As clearly indicated by transmission electron microscopy, this amphiphilic graft copolymers may readily form microphase separated structures.

关键词： Poly(ethyiene oxide) macromer Polystyrene-g-poly(ethylene oxide) Pu-rification of graft copolymer Amphiphilic and microphase separated structure Biocom-patible polymer

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茶氨酸提取纯化工艺研究

天然产物研究与开发 2004年第5期16卷 442-447页

作者：林智杨勇谭俊峰尹军峰成浩杨贤强农业部茶叶化学工程重点开放实验室中国农业科学院茶叶研究所杭州310008 浙江大学茶学系杭州310029

系统研究了从茶多酚工业废液中提取纯化茶氨酸的工艺。采用絮凝、吸附、阳离子树脂交换、重结晶工艺来分离纯化茶氨酸。结果表明 ,絮凝能有效的去除茶多酚工业废液中的蛋白质等杂质 ,杂质的去除率为5 0 % ;吸附能进一步去除色素、多酚... 详细信息

系统研究了从茶多酚工业废液中提取纯化茶氨酸的工艺。采用絮凝、吸附、阳离子树脂交换、重结晶工艺来分离纯化茶氨酸。结果表明 ,絮凝能有效的去除茶多酚工业废液中的蛋白质等杂质 ,杂质的去除率为5 0 % ;吸附能进一步去除色素、多酚类物质及大分子有机物 ;阳离子交换树脂能较专一吸附氨基酸。茶多酚工业废液经絮凝→吸附→阳离子树脂交换工艺可得纯度 5 0 %的茶氨酸 ,得率为 1.8% ;通过重结晶可得到纯度90 %的茶氨酸 ,得率为 0 .8%。

关键词：阳离子树脂重结晶工艺纯度大分子化工阳离子交换树脂茶氨酸得率茶多酚

Syntheses of Substituted Indan-1-onesand Indenes

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Chemical Research in Chinese Universities 1999年第3期15卷 281-285页

作者： YASIN Tariq FAN Zhi-qiang feng lin-{2. department of polymer{2. and Engineering Zhejiang UniversityHangzhou 310027P.R.China

The syntheses of three novel substituted indanones namely 2.7 dimethylindan 1 one, 2.methyl 4,7 diethylindan 1 one and 2.4 dimethyl 7 methoxyindan 1 one are described. These indanones were prepared by different routes involving intramolecular ring closure of aryl substituted compounds by Friedel Crafts reaction. The t butyl was used as the positional protective group in the selective preparation of 2.7 dimethylindan 1 one. The corresponding indenes were prepared by reduction and dehydration reactions from these indanones.

关键词： Friedel Crafts reaction 1 Indanone Substituted indene

Regulating Ni site in NiV LDH for efficient electrocatalytic production of formate and hydrogen by glycerol electrolysis

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Rare Metals 2022年第5期41卷 1583-1594页

作者： lin Dong Guan-Ru Chang Yi feng {2.-Zhi Yao Xin-Yao Yu Key Laboratory of Structure and Functional Regulation of Hybrid Materials Institutes of Physical Science and Information TechnologyAnhui UniversityMinistry of Education.Hefei 230601China School of chemistry and Chemical Engineering Huangshan UniversityHuangshan 245041China department of polymer Materials and Engineering Academy of Chemical EngineeringHebei University of TechnologyTianjin 300130China Ningbo Research institute of Ecological and Environmental sciences Ningbo 315000China Energy Materials and Devices Key Laboratory of Anhui Province for Photoelectric Conversion Anhui UniversityHefei 230601China

Energy-saving glycerol electrolysis with lower potential than water spitting endows a promising way for the concurrent production of value-added formate and high-purity hydrogen. However, there is still lack of efficient electrocatalysts at both anode and cathode for glycerol electrolysis. Herein, we report the activation of Ni site in NiV layered double hydroxide(LDH) by electrochemical and N_(2./H_(2. plasma regulations for boosting the activity of glycerol oxidation reaction(GOR) and hydrogen evolution reaction(HER), respectively. Specifically, boosted GOR performance with a low overpotential(1.2. V at 10 mA·cm^(-2.) and a high Faradic efficiency(94%) is demonstrated by electrochemically regulated NiV LDH(ENiV LDH) with elevated valence state of Ni site. In situ Raman spectrum reveals the generation of Ni(Ⅲ) species by electrochemical regulation, and the highly active Ni(Ⅲ)can be regenerated with the process of electrochemical oxidation. Additionally, the possible reaction pathway is speculated based on the in situ Fourier transform infrared spectroscopy(FTIR) and high-performance liquid chromatography results. The plasma-regulated NiV LDH(PNiV LDH) with lower valence state of Ni site exhibits outstanding HER activity, displaying a low overpotential of 45 m V to deliver 10 mA·cm^(-2..When employing E-NiV LDH and P-NiV LDH as anode and cathode electrocatalyst, respectively, the assembled electrolyzer merely needs 1.2. V to achieve 10 m A·cm^(-2. for simultaneous production of formate and hydrogen, demonstrating remarkable 32. mV of lower potential than water electrolysis.

关键词： Glycerol electrolysis Glycerol oxidation reaction Hydrogen evolution reaction NiV LDH Formate