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Styrene epoxidation catalyzed by polyoxometalate/quaternary ammonium phase transfer catalysts: The effect of cation size and catalyst deactivation mechanism
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作者 Qiongna Xiao Yuyan Jiang +3 位作者 Weiqiang Yuan Jingjing Chen Haohong Li Huidong Zheng 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第3期192-201,共10页
Catalytic epoxidation of alkenes is an important type of organic reaction in chemical industry,and the deep insight into catalyst deactivation will help to develop new epoxidation process.In this work,series of quater... Catalytic epoxidation of alkenes is an important type of organic reaction in chemical industry,and the deep insight into catalyst deactivation will help to develop new epoxidation process.In this work,series of quaternary ammoniums bearing different cationic sizes,i.e.MTOA+(methyltrioctylammonium,[(C_(8)H_(17))_(3)CH_(3)N]+),HTMA+(hexadecyltrimethylammonium,[(C_(16)H_(33))(CH_(3))_(3)N]+) and DMDOA+(dimethyldioctadecylammonium,[(C_(18)H_(37))_(2)(CH_(3))_(2)N]+) were incorporated with polyoxometalate (POM) anions to prepare phase transfer catalysts (PTCs),which were used in the styrene epoxidations.Among them,(MTOA)_(3)PW_(4)O_(24)exhibits the best catalytic performance judged from the highest styrene conversion rate(52%) and styrene oxide selectivity (93%),during which the styrene epoxidation conditions were optimized.Meanwhile,the deactivation mechanism of this kind of PTCs was proposed firstly,i.e.in the case of low H_(2)O_(2) content,the oxidant can only be used in the styrene epoxidation,in which the catalyst can transform into stable Keggin-type POM.But when the content of H_(2)O_(2) is higher,the excess H_(2)O_(2) can reactivate the Keggin-type POM into active (PW_(4)O_(24))_(3)-anions,which can trigger the ring-opening polymerization of styrene oxide.Consequently,the catalyst is deactivated by adhered poly(styrene oxide)irreversibly,which was determined by NMR spectra.In this situation,the active moiety{PO_(4)[WO(O_(2))_(2)]_(4)}_(3)-in phase-transfer catalytic system can break into some unidentified species with low W/P ratio with the presence of epoxides.This work will be beneficial for the design of new PTCs in alkene epoxidation in fine chemical industry. 展开更多
关键词 Phosphotungstic acid phase-transfer CATALYST styrene epoxidation Catalyst deactivation mechanism Cation size effect
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Leaching of styrene and other aromatic compounds in drinking water from PS bottles 被引量:7
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作者 Maqbool Ahmad Ahmad S. Bajahlan 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2007年第4期421-426,共6页
Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packagin... Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as "purge and trap" and analysed by gas chromatograph-mass spectrometer (GC/MS). Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 μg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 μg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks. 展开更多
关键词 styrene polystyrene (PS) ethyl benzene LEACHING STYROFOAM
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SYNDIOSPECIFIC POLYMERIZATION OF STYRENE WITH MULTI-NUCLEAR TITANIUM COMPLEXES
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作者 李悦生 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2007年第3期325-329,共5页
Two multi-nuclear titanium complexes [Ti(η^5-Cp^*)Cl(μ-O)]3 (1) and [(η^5-Cp^*TiCl)(μ-O)2(η^5-Cp^*Ti)2(μ- O)(μ-O)2]2Ti (Cp^* = C5Me5) (2) have been investigated as the precatalysts for s... Two multi-nuclear titanium complexes [Ti(η^5-Cp^*)Cl(μ-O)]3 (1) and [(η^5-Cp^*TiCl)(μ-O)2(η^5-Cp^*Ti)2(μ- O)(μ-O)2]2Ti (Cp^* = C5Me5) (2) have been investigated as the precatalysts for syndiospecific polymerization of styrene. In the presence of modified methylaluminoxane (MMAO) as a cocatalyst, complexes 1 and 2 display much higher catalytic activities towards styrene polymerization, and produce the higher molecular weight polystyrenes with higher syndiotacticities and melting temperatures (Tm) than the mother complex Cp^*TiCl3 does when the polymerization temperature is above 70℃ and the Al/Ti molar ratio is in the low range especially. 展开更多
关键词 Ziegler-Natta polymerization CATALYSTS styrene POLYstyrene
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Synthesis of Syndiotactic Polystyrene/Atactic Polypropene Block Copolymer in the presnece of Half-sandwich Titanocene Catalysts
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作者 ZHU Fang-ming WU Qing, FANG YU-tang HUANG Qun-fang and LIN Shang-an (Institute of Polymer Science, Zhongshan University, Guangzhou, 510275, P. R. China) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2000年第1期83-89,共7页
Some highly active η~5-pentamethylcyclopentadienyltribenzyloxy titanium complexes [Cp Ti(OBz)_3] activated by modified methylaluminoxane (mMAO) were prepared and used as the catalyst for styrene syndiospecific polyme... Some highly active η~5-pentamethylcyclopentadienyltribenzyloxy titanium complexes [Cp Ti(OBz)_3] activated by modified methylaluminoxane (mMAO) were prepared and used as the catalyst for styrene syndiospecific polymerization and propene atactic polymerization. Styrene could be copolymerized with propene when the propene was prepolymerized for a period, to which styrene and tri-isobutylaluminum (TIBA) were then added. The titled block copolymer together with the related homopolymers was obtained. The copolymerization porducts can be divided into the homopolymers and the copolymer by successive solvent extraction with boiling butanone, heptane and tetrahydrofuran (THF), and each fraction was characterized by ~13C NMR, DSC and WAXD. It was found that aPS and aPP were soluble in boiling butanone and heptane respectively. The block copolymer (sPS-b-aPP) composed of syndiottactic polystyrene segment was soluble in boiling THF and the residue was chiefly sPS. 展开更多
关键词 Metallocene catalyst Syndiotactic polystyrene Atactic polypropene styrene and preopene coploymerization
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Synthesis of Ln-doped MCM-41 mesoporous materials and their catalytic performance in oxidation of styrene 被引量:9
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作者 詹望成 卢冠忠 +2 位作者 郭杨龙 郭耘 王筠松 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第1期59-65,共7页
Using cetyl-trimethyl-ammonium bromide (CTMAB) as the template agent and tetraethylorthosilicate (TEOS) as the silica source, the MCM-41 mesoporous materials were synthesized with La or Ce incorporated in the fram... Using cetyl-trimethyl-ammonium bromide (CTMAB) as the template agent and tetraethylorthosilicate (TEOS) as the silica source, the MCM-41 mesoporous materials were synthesized with La or Ce incorporated in the framework under hydrothermal conditions. The structure and the state of La or Ce were investigated through the analyses of XRD, nitrogen adsorption-desorption, FT-IR, and UV-Vis. XRD and N2 adsorption-desorption results showed that Ln-MCM-41 exhibited the loss of the lattice ordering of the MCM-41 construct, and larger unit cell parameter and pore diameter than pure silica MCM-41. The FT-IR and UV-Vis results indicated the presence of isolated tetra-coordinated La or Ce ions in the framework and other Ln species dispersed highly on the Ln-MCM-41 surface simultaneously. Furthermore, their catalytic behaviors in the oxidation of styrene were studied using H2O2 as the oxidant. The La-MCM-41 catalysts exhibited high reactivity and the reactivity increased with the increase of the La content in the La-MCM-41 samples. On the contrary, Ce-MCM-41 catalysts showed low reactivity in the oxidation of styrene and the conversion of styrene decreased with the increase of the Ce content in the Ce-MCM-41 samples. 展开更多
关键词 Ln-MCM-41 mesoporous materials styrene OXIDATION rare earths
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Photoreductive degradation of sulfur hexafluoride in the presence of styrene 被引量:5
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作者 HUANG Li GU Dinghong Yang Longyu Xia Lanyan ZHANG Renxi HOU Huiqi 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第2期183-188,共6页
Sulfur hexafluoride (SF6) is known as one of the most powerful greenhouse gases in the atmosphere. Reductive photodegradation of SF6 by styrene has been studied with the purpose of developing a novel remediation for... Sulfur hexafluoride (SF6) is known as one of the most powerful greenhouse gases in the atmosphere. Reductive photodegradation of SF6 by styrene has been studied with the purpose of developing a novel remediation for sulfur hexafluoride pollution. Effects of reaction conditions on the destruction and removal efficiency (DRE) of SF6 are examined in this study. Both initial styrene-to-SF6 ratio and initial oxygen concentration exert a significant influence on DRE. SF6 removal efficiency reaches a maximum value at the initial styrene-to-SF6 ratio of 0.2. It is found that DRE increases with oxygen concentration over the range of 0 to 0.09 mol/m^3 and then decreases with increasing oxygen concentration. When water vapor is fed into the gas mixture, DRE is slightly enhanced over the whole studied time scale. The X-ray Photoelectron Spectroscopy (XPS) analysis, together with gas chromatography-mass spectrometry (GC-MS) and Fourier Transform Infrared spectroscopy (FT-IR) analysis, prove that nearly all the initial fluorine residing in the gas phase is in the form of SiF4, whereas, the initial sulfur is deposited in the form of elemental sulfur, after photodegradation. Free from toxic byproducts, photodegradation in the presence of styrene may serve as a promising technique for SF6 abatement. 展开更多
关键词 SF6 184.9 nm irradiation styrene reductive radicals PHOTODEGRADATION
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Studies on the Mechanism of the Direct Synthesis of Styrene form Benzene and Ethylene 被引量:5
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作者 ZHANG Qiang , JIN Ri-guang (College of Mater, Sci, and Tech, Beijing Univ, of Them, Beijing,100029) YANG Jun (Dept. of Phys, Chem, Shenyang Pharmaceutical Univ., Shenyang,110015) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1997年第3期244-248,共5页
The adsorption behavior and description behavior of benzene , ethylene and ethylbenzene over HZSM-5 and Co/HZSM-5 catalysts were studied by means of TPSR (Temperature programmed surface reaction) technique. TPSR resul... The adsorption behavior and description behavior of benzene , ethylene and ethylbenzene over HZSM-5 and Co/HZSM-5 catalysts were studied by means of TPSR (Temperature programmed surface reaction) technique. TPSR results of ben- zene and ethylene co-adsorption show that the maian products are styrene , ethylben- zene, toluene, propane, and butane. In a separate experiment of ethylbenzene ad- sorption, styrene . toluene and benzene are formed due to cracking and dehydro- genation. The mechanism of styrene formation was proposed , i. e. , the reaction was carried out via. the dehydrogenation of mediate species ethylbenzene according to the results of TPSR-MS , activity testing and thermodynamic analysis. 展开更多
关键词 Direct synthesis TPSR-MS styrene BENZENE ETHYLENE
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MONOMER REACTIVITY RATIO AND THERMAL PERFORMANCE OFα-METHYL STYRENE AND GLYCIDYL METHACRYLATE COPOLYMERS 被引量:4
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作者 梁淑君 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2010年第3期323-330,共8页
Synthesis and characterization of the copolymers (PAG) of α-methyl styrene (AMS) and glycidyl methacrylate (GMA) are presented. The copolymers of PAG were characterized by gel permeation chromatography (GPC),... Synthesis and characterization of the copolymers (PAG) of α-methyl styrene (AMS) and glycidyl methacrylate (GMA) are presented. The copolymers of PAG were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (^1H-NMR) and thermogravimetery (TG). Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions. 展开更多
关键词 COPOLYMERIZATION α-Methyl styrene Glycidyl methacrylate Reactivity ratios DEPOLYMERIZATION
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CATALYTIC COPOLYMERIZATION OF STYRENE AND ETHYLENE BY NEUTRAL NICKEL(Ⅱ) COMPLEXES IN EMULSION 被引量:3
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作者 袁荞龙 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2009年第5期667-674,共8页
Emulsion copolymerization of styrene and ethylene catalyzed by a series of neutral nickel(Ⅱ) complexes was carried out in an aqueous system to give high-molecular-weight copolymers.The copolymers and emulsions were c... Emulsion copolymerization of styrene and ethylene catalyzed by a series of neutral nickel(Ⅱ) complexes was carried out in an aqueous system to give high-molecular-weight copolymers.The copolymers and emulsions were characterized by an array of techniques including NMR,GPC,TEM,WAXD and DSC.The results indicate that the copolymers obtained are mostly block copolymers of polyethylene with random insertion of styrene units,and their M_W is in the range of 10~5-10~6.By enhancing the electron withdrawing of the s... 展开更多
关键词 Salicylaldiminato nickel complexes Catalytic copolymerization EMULSION styrene Ethylene.
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Copolymerization of Styrene with N-phenylmaleimide by Rare Earth Coordination Catalysts 被引量:3
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作者 Yan Bing LU Wei Lin SUN Zhi Quan SHEN 《Chinese Chemical Letters》 SCIE CAS CSCD 2002年第7期685-686,共2页
Copolymerization of styrene (St) with N-phenylmaleimide (NPMI) was studied with rare earth coordination catalyst Nd(naph)3-AlEt3 in toluene. Characterization of the copolymers showed that the copolymers possess an al... Copolymerization of styrene (St) with N-phenylmaleimide (NPMI) was studied with rare earth coordination catalyst Nd(naph)3-AlEt3 in toluene. Characterization of the copolymers showed that the copolymers possess an alternating structure. 展开更多
关键词 COPOLYMERIZATION styrene N-PHENYLMALEIMIDE rare earth coordination catalyst.
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Surface Modification of Polyvinylidene Fluoride (PVDF) Membranes by Low-Temperature Plasma with Grafting Styrene 被引量:3
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作者 陈剑 李继定 陈翠仙 《Plasma Science and Technology》 SCIE EI CAS CSCD 2009年第1期42-47,共6页
In order to control the surface pore sizes of polyvinylidene fluoride membranes and their distribution, low temperature plasma-induced grafting modifications of PVDF were studied to prepare hydrophobe membranes. By ar... In order to control the surface pore sizes of polyvinylidene fluoride membranes and their distribution, low temperature plasma-induced grafting modifications of PVDF were studied to prepare hydrophobe membranes. By argon (Ar) treating and subsequent grafting reaction, a hydrophobe monomer, styrene, was introduced into the PVDF membrane. Fourier transform infrared attenuated total reflection (FTIR-ATR) was utilized to characterize the chemical and physical changes in the Ar plasma modified membrane. The surface modifications of PVDF membranes were investigated by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and differential scanning calorimeter (DSC). The water permeability and the solute rejection were measured by PVDF membrane modified in different graft conditions. Results demonstrated that the pores in the modified membranes get smaller and the distribution of pores gets narrowed with the increase in grafting reaction duration. Longer graft time caused the water flux of PVDF membrane to decrease from 578 kg/(m^2· h) to 23 kg/(m^2· h) and the solute rejection to increase from 73% to 92%. 展开更多
关键词 Ar low-temperature plasma surface grafting styrene PVDF membrane
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Research on poly(styrene-acrylic acid)-supported neodymium complex in catalytic copolymerization of styrene and 4-vinylpyridine 被引量:2
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作者 陈瑞战 李晓莉 +2 位作者 王晓菊 张永宏 赵伦 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第3期326-330,共5页
The catalytic activity of poly(styrene-acrylic acid) (PSAA) supported neodymium chloride (NdCl3) complex for the copolymerization of styrene and 4-Vinylpyridine was studied. The influence of various factors, suc... The catalytic activity of poly(styrene-acrylic acid) (PSAA) supported neodymium chloride (NdCl3) complex for the copolymerization of styrene and 4-Vinylpyridine was studied. The influence of various factors, such as Al/Nd molar ratio, reaction time, macromolecular carder (PSAA), and ratio of styrene to 4-vinypyridine (g/g), on the copolymerization yield of styrene and 4-Vinylpyridine was investigated. The results showed that the copolymerization of polar monomers with olefins occurred efficiently and the catalytic activity of polymer-supported catalyst was higher than that of the similar small molecular catalysts. The activity of PSAA.Nd complex increased with in- creasing Al/Nd molar ratios and decreased with increasing polymerization time. The highest activity of PSAA'Nd was observed at 120 min, and the highest yield was found at the ratio of styrene to 4-vinylpyridine of 4:2. DSC analysis presented that the resulted polymer had only one glass transition temperature, and showed very good thermal stability. 展开更多
关键词 rare earth catalyst styrene 4-VINYLPYRIDINE polar monomer COPOLYMERIZATION rare earths
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Effects of the crystallization time on the mesoporous structure,texture, morphology and styrene oxidation performances of V-MCM-41 被引量:2
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作者 Junqiang Xu Qiang Zhang +2 位作者 Fang Guo Jingping Hong Wei Chu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第6期1058-1063,共6页
The new V-MCM-41 molecular sieves with good ordered hexagonal mesoporous structure and crystallinity were synthesized through in-situ hydrothermal preparation method. The effects of the crystallization time were discu... The new V-MCM-41 molecular sieves with good ordered hexagonal mesoporous structure and crystallinity were synthesized through in-situ hydrothermal preparation method. The effects of the crystallization time were discussed. The synthesized samples were characterized by X-ray diffraction, N2adsorption/desorption, Fourier transformed infrared and scanning electron microscopy. The different structures, textures, morphologies of V-MCM-41 obtained with different crystallization times were observed and analyzed on the basis of the characterized results. The results showed that the V-MCM-41 molecular sieve obtained at 110 °C for 48 h crystallization times was of good spherical morphology, ordered hexagonal structure, most uniform pore size distribution and high surface area compared with other samples. Meanwhile, the V-MCM-41 molecular sieve with the high skeleton Si condensation and the good crystallinity was obtained. The heteroatom could be incorporated into MCM-41 framework with increasing crystallization times, which was beneficial to improve the catalytic activity and selectivity of pure siliceous MCM-41. The V-MCM-41 showed the good catalytic selectivity in catalytic oxidation of styrene using hydrogen peroxide, and the selectivity of the benzaldehyde and phenylacetic acid reached 30.68% and 49.44%, respectively. © 2016 展开更多
关键词 Catalyst activity Molecular sieves MORPHOLOGY Pore size Scanning electron microscopy SIEVES styrene X ray diffraction
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Synthesis and characterization of miktoarm star copolymer of styrene and butadiene using multifunctional macromolecular initiator 被引量:2
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作者 Hai Yan Zhang Xing Ying Zhang 《Chinese Chemical Letters》 SCIE CAS CSCD 2009年第9期1131-1135,共5页
A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization. At first, polydiene-stannum chloride (PD-SnCl3) was prepared by the reactio... A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization. At first, polydiene-stannum chloride (PD-SnCl3) was prepared by the reaction of n-butyl-Li (n-BuLi), stannic chloride (SnCl4) and diene. Then PD-SnCl3 was used to react with the dilithium initiator to prepare the multifunctional organic macromolecular initiators. The result suggested that the initiators had a remarkable yield by GPC, nearly 90%. By using these multifunctional macromolecular initiators, styrene and butadiene were effectively polymefized via anionic polymerization, which gave birth to novel miktoarm star copolymers. The relative molecular weight and polydispersity index, microstructure contents, copolymerization components, glass transition temperature (Tg) and morphology of the miktoarm star copolymers were investigated by GPC-UV, ~H NMR, DSC and TEM, respectively. 2009 Xing Ying Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. 展开更多
关键词 Mnitifunctional macromolecular initiator Miktoarm star copolymer styrene BUTADIENE ISOPRENE Anionic polymerization
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Preparation of ZSM-5 containing vanadium and Br?nsted acid sites with high promoting of styrene oxidation using 30% H_2O_2 被引量:2
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作者 Xianfeng Liu Fu Yang +3 位作者 Shuying Gao Bo Shao Shijian Zhou Yan Kong 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第5期1302-1310,共9页
Design and synthesis of low cost and efficacious industrial catalyst for the oxidation of styrene has been an important research project.Herein,ZSM-5 zeolite containing tetrahedral vanadium(V)and Br?nsted acid sites(V... Design and synthesis of low cost and efficacious industrial catalyst for the oxidation of styrene has been an important research project.Herein,ZSM-5 zeolite containing tetrahedral vanadium(V)and Br?nsted acid sites(V-H-ZSM-5)was prepared,and identified by characterizations such as XRD,SEM,UV–vis,NH3-TPD,H2-TPR N2-adsorption/desorption and FTIR.V-H-ZSM-5 performed extremely enhanced catalytic activity for the oxidation of styrene with 30%H2O2 at 40°C.Moreover,in-situ FTIR spectrum was used to investigate the catalytic mechanism.The results demonstrate that Br?nsted acid site could not only increase the adsorption concentration of styrene in the micropores of V-H-ZSM-5 via theπcomplex interaction between double bond of styrene and Br?nsted acid sites,but also increase the oxidation potential of H2O2.The synergetic action of tetrahedral vanadium(V)and Br?nsted acid enhanced the catalytic activity for the oxidation of styrene with 30%H2O2.Impressively,V-H-ZSM-5 performed high reusability within five runs at a low reaction temperature(40°C)for the first time. 展开更多
关键词 Selective oxidation styrene Bronsted acid BIFUNCTIONAL VANADIUM
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Enhancing the side-chain alkylation of toluene with methanol to styrene over the Cs-modified X zeolite by the assistance of basic picoline as a co-catalyst 被引量:2
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作者 Zhe Hong Guoqing Zhao +2 位作者 Fangtao Huang Xiaoxia Wang Zhirong Zhu 《Green Energy & Environment》 SCIE EI CSCD 2022年第6期1241-1252,共12页
Side-chain alkylation of toluene with methanol is a green pathway to realize the one-step production of styrene under mild conditions,but the low selectivity of styrene is difficult to be improved with by-products of ... Side-chain alkylation of toluene with methanol is a green pathway to realize the one-step production of styrene under mild conditions,but the low selectivity of styrene is difficult to be improved with by-products of ethylbenzene and xylene.In this study,a new way is introduced to improve the catalytic performance by means of assisting basic compounds as co-catalysts during the toluene side-chain alkylation with methanol to styrene.As a result,high activity of side-chain alkylation appears over the basic Cs-modified zeolite catalysts prepared by ion exchange and impregnation methods.This high performance should be mainly attributed to two co-catalysis actions:(1)the promotion of basic compounds for methanol dehydrogenation to formaldehyde as the intermediate for side-chain alkylation;(2)the suppression of the styrene transfer hydrogenation on basic Cs-modified zeolites to avoid the formation of ethylbenzene.Especially for Cs_(2)O/CsX-ex catalyst,the addition of 2%mol/mol 2-picoline in reaction mixture could achieve both 12.3%toluene conversion and 84.1%styrene selectivity.Whereas the higher concentration of 2-picoline(>6%mol/mol)caused an inhibition to the catalytic activity because the excessive basic compound poisoned the combined acid-base pathway required for the side-chain alkylation process.In addition,two possible side-chain alkylation reaction routes on Cs-modified zeolite under the different 2-picoline absorption were described. 展开更多
关键词 Basic co-catalysis TOLUENE Side-chain alkylation ZEOLITE styrene
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Controlled Radical Polymerization of Styrene in the Presence of Different Copper Complexes and Organic Halides 被引量:2
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作者 CHENG Guang-lou HU Chun-pu YING Sheng-kang 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1999年第4期358-363,共6页
The polymerization behaviors of Styrene (St) in the presence of CuX/L [X=Cl or Br; L= 2,2 bipyridine (bpy), 1,10 phenanthroline (phen) or 4,7 diphenyl 1,10 phenanthroline (DPP) ] and R X (R=trichloromethyl, benz... The polymerization behaviors of Styrene (St) in the presence of CuX/L [X=Cl or Br; L= 2,2 bipyridine (bpy), 1,10 phenanthroline (phen) or 4,7 diphenyl 1,10 phenanthroline (DPP) ] and R X (R=trichloromethyl, benzyl or allyl; X=Cl or Br) have been studied and examined. In a CuCl/bpy/RCl/St system, a bimodal GPC peak at the early stage of polymerization was observed, and a concept of multi active species was proposed to explain this phenomenon. In a CuCl/phen (DPP)/RCl/St system, the \%M\%\-n of polystyrene (PS) increased linearly with St conversion and ln[M] o/[M] also increased linearly with time, indicating the living nature of this system. Furthermore, the stability of the propagating active species in a CuBr/phen/RBr/St system is higher than that in the CuBr/phen/RBr/St system. 展开更多
关键词 ATRP 'Living'/controlled radical polymerization 1 10-PHENANTHROLINE 4 7-Diphenyl-1 10-phenanthroline Cuprous halides styrene
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Organolanthanide Compounds Containing Methanesulfonate and Pyrazinamide Ligand in Styrene Polymerization 被引量:1
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作者 Josué Garcia Quini Alessandra de Souza Maia Renata Diana Miotti Tereza Silva Martins Wanda de Oliveira 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第2期135-138,共4页
The synthesis of organolanthanide compounds identified as LnCp^*(MS)2PzA, Ln = Sm, Tb, Yb (MS = methanesulfonate, Cp^* = pentamethylcyclopentadienyl, and PzA = pyrazinamide), by the reaction of coordination comp... The synthesis of organolanthanide compounds identified as LnCp^*(MS)2PzA, Ln = Sm, Tb, Yb (MS = methanesulfonate, Cp^* = pentamethylcyclopentadienyl, and PzA = pyrazinamide), by the reaction of coordination compounds Ln(MS)3(PzA)4 with NaCp in THF was reported. The complexes were formulated according to elemental analyses, complexometric titration with EDTA (%Ln), and ^1H NMR. IR spectroscopy revealed that PzA coordinates with lanthanide (Ⅲ) ions and methanesulfonate coordinates via oxygen atoms in a non-equivalent manner. In preliminary catalytic studies, these compounds were active in styrene polymerization that used MAO as a cocatalyst with an activity of 12.3 kg PS molSm^-1h^-1. Differential scanning calorimetry (DSC) of polystyrene showed that the polymer was mainly atactic. 展开更多
关键词 ORGANOLANTHANIDES PENTAMETHYLCYCLOPENTADIENYL METHANESULFONATE PYRAZINAMIDE styrene polymerization rare earths
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Polymerization of Styrene by Neutral Ni (II) Acetylide Complex 被引量:1
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作者 Hong Mei SUN Mu Jie YANG Qi SHEN 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第11期1033-1036,共4页
Neutral nickel sigma -acetylide complex [Ni(C=CPh)(2)(PBu3)(2)] is a novel initiator for the polymerization of styrene in CHCl3 over a range of polymerization temperature from 40 degreesC to 60 degreesC. The polystyre... Neutral nickel sigma -acetylide complex [Ni(C=CPh)(2)(PBu3)(2)] is a novel initiator for the polymerization of styrene in CHCl3 over a range of polymerization temperature from 40 degreesC to 60 degreesC. The polystyrene obtained was a syndio-rich atactic polymer and its weight-average molecular weight reached 279000. The mechanism of the polymerization was discussed and a radical mechanism was proposed. 展开更多
关键词 styrene nickel acetylide complex INITIATOR POLYMERIZATION syndio-rich
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Morphology and crystal-plane effects of Zr-doped CeO2 nanocrystals on the epoxidation of styrene with tert-butylhydroperoxide as the oxidant 被引量:1
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作者 Jia Ren Xin Liu +1 位作者 Ruihua Gao Wei-Lin Dai 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2017年第4期681-687,共7页
The morphology effect of Zr-doped CeOwas studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zrdoped CeOnanor... The morphology effect of Zr-doped CeOwas studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zrdoped CeOnanorods exhibited the highest catalytic performance(yield of styrene oxide and TOF value)followed by nanoparticles and nanocubes. For the Zr-doped CeOnanorods, the apparent activation energy is 56.3 k J/mol, which is much lower than the values of catalysts supported on nanoparticles and nanocubes(73.3 and 93.4 k J/mol). The high resolution transmission electron microscopy results indicated that(100) and(110) crystal planes are predominantly exposed for Zr-doped CeOnanorods while(100)and(111) for nanocubes,(111) for nanoparticles. The remarkably increased catalytic activity of the Zrdoped CeOnanorods is mainly attributed to the higher percentage of Cespecies and more oxygen vacancies, which are associated with their exposed(100) and(110) crystal planes. Furthermore, recycling studies proved that the heterogeneous Zr-doped CeOnanorods did not lose its initial high catalytic activity after five successive recycles. 展开更多
关键词 Morphology effect Zr-doped CeO2 styrene Selective oxidation Oxygen vacancies
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