第三组分Et2Mg对二茂锆/铝氧烷体系催化乙烯聚合反应的影响

研究发现在二茂锆-铝氧烷催化体系中添加少量Et2Mg能够明显促进在低Al/Zr摩尔比条件下乙烯高聚.以MAO作为助催化剂,Al/Zr/Mg摩尔比为1012时,得到高聚物,粘均分子量(Mv)为1.37×105,催化活性为2.83×104g聚合物/mol(Zr)h.而在同样的反应条件下,Cp2ZrCl2-MAO和-EAO二组份催化体系在如此低的Al/Zr摩尔比条件下无催化活性或以很低的催化活性生成低碳烯烃.对于这类三组份烯烃高聚催化体系的研究目前仍在进行中,以期得到有效的低Al/Zr比乙烯高聚茂金属催化体系.     

茂金属催化乙酸与丁醇酯化反应

以二茂铁、二茂钛、二茂锆和取代茂锆为催化剂用于催化酯化合成乙酸丁酯, 探讨了不同茂金属、反应时间和催化剂用量对反应性能的影响. 结果表明, 低含量的茂金属就可高效催化酯化反应. 当催化剂为二茂钛, 其含量为 0.049%(摩尔比)时, 反应 30 min 产物乙酸丁酯的分离收率达到 90%, 纯度达到 98%. 以 400 目不同温度活化的硅胶为载体, 考察了负载二茂锆催化剂的性能. 当硅胶在 400 ℃ 焙烧 4.0 h, 负载二茂锆催化剂用量为 Zr/丁醇 = 0.487% (摩尔比), 反应后乙酸丁酯收率为 90.6%, TOF = 318 h-1. 该反应的产物后处理不需要用水洗涤, 无废水排出, 催化剂易回收利用, 是一个绿色的反应过程.     

锆-铬黑T络合物的极谱研究

在0.02mol/l HNO_3、0.002%铬黑T和0.08%酒石酸钠的底液中,Zr(Ⅳ)-EBT络合物有一灵敏的吸附催化波,峰电位为-0.45V(vs.SCE)。Zr(Ⅳ)浓度在4.4×10~(-8)～3.1×10~(-6)mol/l范围内与峰电流成线性关系,检测限0.002μgZr/ml。探讨了该波的性质和机理。方法用于测定矿石中的微量锆,结果满意。     

SiO2负载的后过渡金属配合物／三乙基铝催化乙烯聚合研究

将后过渡金属配合物{[2,6-ArN=C(Me)2C5H3N]FeCl2} ( Ar=2,6-iPr2C6H3) Ⅰ负载于SiO2上, 并与三乙基铝(AlEt3)组成催化剂体系并催化乙烯聚合. 考察了Al/Fe比(AlEt3/催化剂摩尔比)、聚合温度对催化剂活性、聚乙烯(PE)分子量、熔融温度以及结晶度的影响. 在Al/Fe比为750、聚合温度为40 ℃时, 催化剂活性达到7.07×105g PE·(mol Fe·h)-1. 实验所得聚合物的分子量为1.05×105～2.33×105 g/mol, 熔融温度高达132 ℃左右,结晶度在44.2%～77.8%之间.     

Zr(Ⅳ)-桑色素络合物在碳糊电极上的二次导数吸附伏安法测定Zr的研究

研究了Zr(Ⅱ)-桑色素络合物在碳糊电极正电位区的吸附伏安行为,并利用其在0.74V处的二次导数吸附氧化峰电流与Zr(Ⅳ)浓度为6.0×10-9～2.0×10-6 mol/L呈线性而测定Zr;检出限为3.0×10-9 mol/L(S/N=3).最佳测定条件为2.0 mol/L HCl、1.0×10-5 mol/L桑色素;富集电位为0V(vs.SCE);扫描速度为250 mV/s.该法不需萃取分离,可直接用于岩石样品中Zr的测定,结果满意.     

锆(Ⅳ)-邻苯二酚紫络合物碳糊电极阳极吸附伏安法研究

研究了锆(Ⅳ)-邻苯二酚紫(PV)络合物在碳糊电极上的吸附伏安行为。测定锆最佳条件为:0.08mol/L的HNO3为底液,于0.4V富集50s,从0.4至1.4V以100mV/s的速率线性扫描。在0.85V(vs.SCE)的二次导数氧化峰电流与锆的浓度在3.0×10-9～5.0×10-8mol/L(5.6×10-7mol/LPV)和1.0×10-8～1.0×10-7mol/L(5.6×10-6mol/LPV)成线性关系。富集80s,检出限为1.0×10-9mol/L(S/N=3)。该法用于标准岩石样品中锆的测定,不需萃取分离和掩蔽,直接测定,结果满意。铪(Ⅳ)在同样的实验条件下也于0.85V产生一络合吸附峰,灵敏度稍低于锆。     

ZrC-桑色素络合物在碳糊电极上的二次导数吸附伏安法测定Zr的研究

研究了Zr 桑色素络合物在碳糊电极正电位区的吸附伏安行为 ,并利用其在 0 .74V处的二次导数吸附氧化峰电流与Zr(Ⅳ )浓度为 6 .0× 10 -9～ 2 .0× 10 -6mol/L呈线性而测定Zr;检出限为 3.0× 10 -9mol/L(S/N =3)。最佳测定条件为 :2 .0mol/LHCl、1.0× 10 -5mol/L桑色素 ;富集电位为 0V(vs .SCE) ;扫描速度为2 5 0mV/s。该法不需萃取分离 ,可直接用于岩石样品中Zr的测定 ,结果满意     

新试剂7-(2,4,6-三羟基苯偶氮)-8-羟基喹啉-5-磺酸光度法同时测定微量锆和铪

本文研究了新试剂7-(2,4,6-三羟基苯偶氮)-8-羟基喹啉-5-磺酸(THBAQS)与锆、铪的显色反应.酸性条件下锆、铪均可形成 M-THBAQS-CTMAB三元络合物,ε_(315nm)~(Zr)=3. 27×10~4,ε_(515nm)~(HI)=3.8×10~4,适量H_2O_2使锆络合物吸光度显著降低,据此实现了锆铪的同时测定.本法简便快速、适用范围为0～30μgZr/25 mL,0～25μg Hf/25 mL,且X_(Zr)+X_(Hf）<35μg/25 mL.     

以硼化物为活化剂制备负载茂金属催化剂催化乙烯均聚和乙烯/α-烯烃共聚合（英文）

以硅胶为载体,以Cp2ZrC l2为主催化剂,分别以甲基铝氧烷(MAO)、三五氟苯基硼(B(C6F5)3)、N,N-二甲基苯铵四(五氟苯基)硼酸盐([HNMe2Ph][B(C6F5)4])、三苯碳鎓四(五氟苯基)硼酸盐([Ph3C][B(C6F5)4])、三五氟苯基硼/三甲基铝(B(C6F5)3/TMA)为活化剂制备了负载茂金属催化剂,考察了它们对乙烯均聚、乙烯/α-烯烃共聚合的影响.实验结果表明,当硼化物用量为5.1×10-4mol/g SiO 2,B/Zr在14.10~19.04之间时,负载茂金属催化剂催化烯烃聚合活性达107g/(molZ r·h),是相同条件下以MAO为活化剂时活性的511~1 090倍,同样达到107g/(molZ r·h)的催化活性,硼化物用量仅仅为MAO用量1/16;和B(C6F5)3相比,以[HNMe2Ph][B(C6F5)4]和[Ph3C][B(C6F5)4]为活化剂制备的负载茂金属催化剂活性较高,并且以[Ph3C][B(C6F5)4]为活化剂制备的负载茂金属催化剂所得共聚物分子量分布最窄,乙烯/1-己烯共聚物中共单体含量最高,为2.97%;采用硼化物为活化剂制备的负载茂金属催化剂催化乙烯/1-己烯、乙烯/1-辛烯共聚合所得共聚产物分子量分布较窄,密度在0.91~0.92 g/cm3之间,属于mL LDPE范畴.     

负载双核茂金属催化剂催化乙烯聚合反应动力学研究

以SiO2为载体,制备了负载的双核茂金属[（η5-C5H5）Zr Cl2]2[μ,μ-（SiMe2）2（η5-allyl C5H2）2]/MAO/SiO2催化剂,以己烷为溶剂进行了淤浆条件下乙烯聚合反应,研究了扩散因素、乙烯聚合压力和聚合温度对乙烯淤浆聚合动力学参数的影响,测定了聚合反应级数和表观活化能,采用动力学和相对分子质量法计算了负载催化剂的活性中心浓度,并对链增长速率常数等动力学参数进行了计算.结果表明,以负载双核茂金属催化剂催化乙烯淤浆聚合反应速率对单体浓度呈1.11级依赖,反应活化能Ea为72.47 kJ/mol,活性中心浓度C＊为0.33 mol/mol,链增长速率常数Kp为1.06×106L.（mol.h）-1.     

Polymerization of ethylene by using zirconocene catalyst anchored on silica with trisiloxane and pentamethylene spacers

New supported catalysts on the basis of cyclopentadienylindenylzirconium dichloride (CpIndZrCl₂) anchored on silica with a trisiloxane spacer (ZATS) and a pentamethylene spacer (ZAPM) were prepared and used for ethylene polymerization with modified methylaluminoxane (MAO) as cocatalyst. ZATS and ZAPM produce polyethylene with lower molecular weight but show higher activity than silica-supported CpIndZrCl₂ which was prepared by reacting zirconocene directly with silica, i.e., the activity of silica-supported CpIndZrCl₂ is enhanced by introducing a spacer between silica surface and metallocene species.     

MgCl2·6H2O-BASED ZIRCONOCENE CATALYST FOR ETHYLENE POLYERIZATION

Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2O with AlMe_3 show good activity for ethylene polymerization similar to that of anhydrousMgCl_2 supported zirconocene catalyst.     

新型二茂锆化合物(1,2-Ph2-4-PrCp)2ZrCl2的合成及催化烯烃聚合反应研究

3,4-二苯基环戊-2-烯-1-酮与丙基锂反应,经酸化脱水得新环戊二烯衍生物1,2-二苯基-4-丙基-1,3-环戊二烯(1).用丁基锂处理1得到相应的环戊二烯基锂,再与ZrCl₄在甲苯中反应,生成大立体阻碍二氯二茂锆化合物(1,2-Ph₂-4-PrCp)₂ZrCl₂(2).化合物1和2均经元素分析和核磁共振谱学表征.经甲基铝氧烷(MAO)活化,化合物2在较低Al/Zr比条件下既可有效地催化乙烯聚合,生成高分子量、高熔化温度聚乙烯.2/MAO体系对丙烯聚合表现出高活性,生成低分子量齐聚物,其分子量随聚合温度的降低而升高.     

In situ polymerization of ethylene using metallocene catalysts: Effect of clay pretreatment on the properties of highly filled polyethylene nanocomposites

Highly filled polyethylene (PE)‐based nanocomposites were obtained by insitu polymerization technique. An organically modified montmorillonite, Cloisite® 15A (C15A), was previously treated with methylaluminoxane (MAO) to form a supported cocatalyst (C15A/MAO) before being contacted with a zirconocene catalyst. The main features of C15A/MAO intermediates were studied by elemental analysis, TGA, TGA‐FTIR, WAXD, and TEM. MAO reacts with the clay, replaces most of the organic surfactant within the clay galleries and destroys the typical crystrallographic order of the nanoclay. The catalytic activity in the presence of C15A/MAO is higher than in ethylene polymerization without any inorganic filler and increases with MAO supportation time. This indicates that part of the polymer chains grows within the clay galleries, separates them, and makes it possible to tune the final morphology of the composites. The polymerization results and the influence of C15A pretreatment and polymerization conditions on thermal and morphological properties of the hybrid PE/C15A nanocomposites are presented. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5390–5403, 2008     

Metal content determination in polymerization catalysts by direct methods

Metal contents in polymerization catalysts were comparatively determined by Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) spectroscopy. Catalysts were prepared by grafting metallocene onto bare silica or onto silica chemically modified with methylaluminoxane (MAO). Catalysts were compressed as self-supporting pellets (RBS and XRF), or mounted on adhesive copper tape (XPS). The proximity of the mass of the atomic nuclei did not allow resolution by RBS of the signals corresponding to Zr and Nb, nor Si and Al in catalyst systems such as (nBuCp)₂ZrCl₂/Cp₂NbCl₂/MAO/SiO₂. On the other hand, Zr, Nb, Si and Al lines were completely resolved in an XRF spectrum. For supported metallocenes on bare silica, XPS measurement was ca. 40% higher than that obtained by RBS. Silica-supported zirconocene showed good agreement in Zr content determination by XRF and RBS.     

Effects of methylaluminoxane immobilization on silica on the performance of zirconocene catalysts in propylene polymerization

Investigation of the characteristics and performance in propylene polymerization of silica‐immobilized methylaluminoxane (MAO), in combination with a moderately and a highly isospecific zirconocene catalyst, has revealed that a simple impregnation of silica with MAO at ambient temperature is insufficient to obtain uniform distribution of MAO throughout the support particle. Homogeneous Al distribution throughout the support, giving increased catalyst activity, was achieved by a more rigorous impregnation of silica with MAO at elevated temperatures. The highest catalyst activities were obtained by precontacting the MAO with the zirconocene to generate the activated species before immobilization on silica. Polymer particle morphology was strongly dependent on the characteristics of the silica used for catalyst immobilization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2734‐2748, 2005     

Synthesis and characterization of polyethylene/clay–silica nanocomposites: A montmorillonite/silica‐hybrid‐supported catalyst and in situ polymerization

A novel approach to the preparation of polyethylene (PE) nanocomposites, with montmorillonite/silica hybrid (MT‐Si) supported catalyst, was developed. MT‐Si was prepared by depositing silica nanoparticles between galleries of the MT. A common zirconocene catalyst [bis(cyclopentadienyl)zirconium dichloride/methylaluminoxane] was fixed on the MT‐Si surface by a simple method. After ethylene polymerization, two classes of nanofillers (clay layers and silica nanoparticles) were dispersed concurrently in the PE matrix and PE/clay–silica nanocomposites were obtained. Exfoliation of the clay layers and dispersion of the silica nanoparticles were examined with transmission electron microscopy. Physical properties of the nanocomposites were characterized by tensile tests, dynamic mechanical analysis, and DSC. The nanocomposites with a low nanofiller loading (<10 wt %) exhibited good mechanical properties. The nanocomposite powder produced with the supported catalyst had a granular morphology and a high bulk density, typical of a heterogeneous catalyst system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 941–949, 2004     

Preparation and application of a novel core–shell‐particle‐supported zirconocene catalyst

The use of functional groups bearing silica/poly(styrene‐co‐4‐vinylpyridine) core–shell particles as a support for a zirconocene catalyst in ethylene polymerization was studied. Several factors affecting the behavior of the supported catalyst and the properties of the resulting polymer, such as time, temperature, Al/N (molar ratio), and Al/Zr (molar ratio), were examined. The conditions of the supported catalyst preparation were more important than those of the ethylene polymerization. The state of the supported catalyst itself played a decisive role in both the catalytic behavior of the supported catalyst and the properties of polyethylene (PE). IR and X‐ray photoelectron spectroscopy were used to follow the formation of the supports. The formation of cationic active species is hypothesized, and the performance of the core–shell‐particle‐supported zirconocene catalyst is discussed as well. The bulk density of the PE formed was higher than that of the polymer obtained from homogeneous and polymer‐supported Cp₂ZrCl₂/methylaluminoxane catalyst systems. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2085–2092, 2001     

茂锆载体催化剂下的乙烯／辛烯共聚及聚合物的^13C NMR研究

茂锆载体催化剂下的乙烯／辛烯共聚及聚合物的~（１３）ＣＮＭＲ研究刘胜生，于广谦，黄葆同（中国科学院长春应用化学研究所长春１３００２２）关键词茂锆载体催化剂，共聚，序列分布，~（１３）ＣＮＭＲ由于茂锆催化剂具有高活性，单一活性中心等特点［１，２］，并且能...     

Preparation of functionalized montmorillonites and their application in supported zirconocene catalysts for ethylene polymerization

Ethylene polymerization was carried out with zirconocene catalysts supported on montmorillonite (or functionalized montmorillonite). The functionalized montmorillonite was from simple ion exchange of [CH₃O₂CCH₂NH₃]⁺ (MeGlyH⁺) ions with interlamellar cations of layered montmorillonites. The functionalized montmorillonites [high‐purity montmorillonite (MMT)‐MeGlyH⁺] had larger interlayer spacing (12.69 Å) than montmorillonites without treatment (9.65 Å). The zirconocene catalyst system [Cp₂ZrCl₂/methylaluminoxane (MAO)/MMT‐MeGlyH⁺] had much higher Zr loading and higher activities than those of other zirconocene catalyst systems (Cp₂ZrCl₂/MMT, Cp₂ZrCl₂/MMT‐MeGlyH⁺, Cp₂ZrCl₂/MAO/MMT, [Cp₂ZrCl]⁺[BF₄]/MMT, [Cp₂ZrCl]⁺[BF₄]^?/MMT‐MeGlyH⁺, [Cp₂ZrCl]⁺[BF₄]^?/MAO/MMT‐MeGlyH⁺, and [Cp₂ZrCl]⁺[BF₄]^?/MAO/MMT). The polyethylenes with good bulk density were obtained from the catalyst systems, particularly (Cp₂ZrCl₂/MAO/MMT‐MeGlyH⁺). MeGlyH⁺ and MAO seemed to play important roles for preparation of the supported zirconocenes and polymerization of ethylene. The difference in Zr loading and catalytic activity among the supported zirconocene catalysts is discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1892–1898, 2002