二茚基二芳氧基锆催化乙烯齐聚

直链低碳α 烯烃是生产线性低密度聚乙烯 (ＬＬＤＰＥ)和高密度聚乙烯 (ＨＤＰＥ)的共聚单体 .Ｋａｍｉｎｓｋｙ型催化剂是 80年代发展起来的烯烃高效聚合催化剂[1].近年来亦有文献报道该类催化剂催化乙烯齐聚合成低碳α 烯烃[2～ 5].而以茚基锆化合物与氯化烷基铝所组成的催化体系催化乙烯齐聚还未见文献报道 .本文考查了茚基锆化合物和一氯二乙基铝所组成的二元催化体系对乙烯齐聚的催化性能 ,合成了Ｉｎｄ2 Ｚｒ(ＯＣ6 Ｈ4 ｐ Ｍｅ) 2 、Ｉｎｄ2 Ｚｒ(ＯＣ6 Ｈ5) 2 、Ｉｎｄ2 ＺｒＣｌ2 和Ｃｐ2 Ｚｒ(ＯＣ6 Ｈ4 ｐ Ｍｅ) 2 4个化合物 ,…     

乙烯线性齐聚研究Ⅺ.Kaminsky催化剂催化乙烯齐聚

乙烯线性齐聚研究　Ⅺ．Ｋａｍｉｎｓｋｙ催化剂催化乙烯齐聚沈玉梅，何仁（大连理工大学化工学院，大连１１６０１２）关键词乙烯，齐聚，Ｋａｍｉｎｓｋｙ催化剂，络合催化直链低碳α－烯烃是线性低密度聚乙烯的共聚单体，也是合成高级醇、高级润滑油、增塑剂和表面活性...     

蒙脱土负载（acac）2ZrCl2催化乙烯齐聚研究

利用蒙脱土（MMT）与(acac)2ZrCl2反应,制备了负载于H－蒙脱土层间的(acac)2ZrCl2催化剂,以AlEt2Cl为助催化剂时,该负载催化剂体系对乙烯剂聚具有很高的催化选择性,产物主要为α－烯径,如C6^=和C8^=。     

Kaminsky型催化剂催化乙烯环齐聚反应的研究

研究发现Cp~2ZrL~2(L=Cl,Me,OC~6H~4-p-Me)/EAO(乙基铝氧烷)可同步催化乙烯齐聚-环化反应,不仅给出链状烯烃,而且生成环状剂聚物－－亚甲基环戊烷。环状齐聚物的选择性取决于主催化剂的结构和浓度,反应介质,预反应温度和反应温度,反应时间,Al/Zr比及烷基铝水解程度等因素,加入碱性第三组分对催化活性和选择性亦有一定影响。在优化反应条件下,亚甲基环戊烷的选择性达到37%。     

Kaminsky型催化剂催化乙烯环齐聚反应的研究

研究发现Cp~2ZrL~2(L=Cl,Me,OC~6H~4-p-Me)/EAO(乙基铝氧烷)可同步催化乙烯齐聚-环化反应,不仅给出链状烯烃,而且生成环状剂聚物－－亚甲基环戊烷。环状齐聚物的选择性取决于主催化剂的结构和浓度,反应介质,预反应温度和反应温度,反应时间,Al/Zr比及烷基铝水解程度等因素,加入碱性第三组分对催化活性和选择性亦有一定影响。在优化反应条件下,亚甲基环戊烷的选择性达到37%。     

过渡金属络合物催化乙烯齐聚

综述了乙烯齐聚的最新成果,重点阐述了用于乙烯齐聚的新型催化剂,讨论了烯烃高聚与齐聚催化剂的关系,烯烃高聚与齐聚的反应机理相同,。差别主要在于烯烃插入与β－H消除反应的速率,第IV副族金属络合物主要催化乙烯齐聚,第Ⅲ副族金属主要催化乙烯高聚,改变茂金属催化体系的助催化剂和反应条件可得到齐聚产物,选择体积较小配体的第Ⅷ族金属络合物,有利于β－H消除得到齐聚产物。     

吡啶亚胺基酞菁镍系催化剂催化乙烯齐聚性能及其动力学研究

以四氨基镍酞菁、吡啶-2-甲醛和NiCl2·6H2O为原料,先后经过席夫碱反应和络合反应得到一种新型吡啶亚胺基酞菁配体及其镍系催化剂。合成产物的结构通过红外光谱(FTIR)、紫外(UV-Vis)、核磁共振氢谱(¹H-NMR)、电感耦合等离子体质谱(ICP-MS)、同步热分析(TG-DSC)及电喷雾电离质谱(ESI-MS)等方法进行表征。对其催化乙烯齐聚性能进行考察,并研究了该反应的动力学。催化乙烯齐聚实验结果表明,当溶剂为环己烷、助催化剂为甲基铝氧烷(MAO)、催化剂用量为5μmol/L、齐聚压力为1.0 MPa、齐聚温度为35℃、Al/Ni摩尔比为500时,吡啶亚胺基酞菁镍系催化剂的活性可达8.82×10⁵ g/(mol Ni·h),丁烯和己烯的含量分别为58.22%和39.85%。对吡啶亚胺基酞菁镍系催化剂催化乙烯齐聚反应动力学方程进行拟合计算,结果表明该反应对催化剂摩尔浓度的反应级数为1.24,对齐聚压力的反应级数为0.95,当活性中心的浓度为5μmol/L、齐聚压力为1.0 MPa、齐聚温度为5～35℃时,该反应的表观活化能为71.4...     

Kam insky型催化剂催化乙烯齐聚──二酚基二茂锆的催化作用

通过改变 Ａｌ／ Ｚｒ 比、反应温度及反应时间, 分别考察了 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２／ Ｅ Ａ Ｏ （ Ａｒ＝ Ｃ６ Ｈ５、ｐ  Ｃ６ Ｈ４ Ｍ ｅ、ｍ  Ｃ６ Ｈ４ Ｎ Ｏ２、ｐ  Ｃ６ Ｈ４ Ｎ Ｏ２） ４ 种体系对乙烯齐聚的催化作用． 发现用 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２ 代替 Ｃｐ２ Ｚｒ Ｃｌ２ 作为主催化剂, 对于 Ｋａｍ ｉｎｓｋｙ 型体系 Ｃｐ２ Ｚｒ Ｌ２／ Ｅ Ａ Ｏ 催化乙烯齐聚, 具有调变作用,在提高催化活性的同时, 可使低碳烯烃的选择性明显改善． 在 Ｃｐ２ Ｚｒ（ Ｏ Ａｒ）２／ Ｅ Ａ Ｏ 的４ 种催化体系中, 当酚基对位带有强吸电子基团时（ Ａｒ＝ ｐ  Ｃ６ Ｈ４ Ｎ Ｏ２）, 对乙烯齐聚的催化性能最佳．     

Efficient intramolecular hydroamination of aminoalkynes catalyzed by a zirconium(IV) complex

The neutral zirconium(IV) bis(thiophosphinic amidate) complex was demonstrated to be an effective precatalyst for 5-exo-, 6-exo-, and 7-exo-dig intramolecular hydroamination of aminoalkynes, producing the cyclic imines in excellent yields (92-98%).     

The effect of cocatalysts on the oligomerization and cyclization of ethylene catalyzed by zirconocene complexes

Under certain conditions (150°C, P(C₂H₄)=1.4 MPa), the oligomerization of ethylene catalyzed by Cp₂ZrCl₂/EAO (ethylaluminoxane), Et₃Al or (i-Bu)₃Al afforded methylenecyclopentane (MCP) along with chain oligomers. The nature of cocatalysts and the Al/Zr ratios as well as the hydrolysis extent of Et₃Al have tangible effects on the selectivity of the cyclic oligomer. With Et₃Al as cocatalyst under optimal conditions, the oligomerization of ethylene gave MCP and C₄–C₁₀ chain olefins in a ratio of 45/55.

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Preparation and structures of 6- and 7-coordinate salen-type zirconium complexes and their catalytic properties for oligomerization of ethylene

A series of salen-type zirconium complexes of the general formula LZrCl₂ (L = N,N′-ethylenebis(salicylideneiminate), 3a; N,N′-ethylenebis(3,5-di-tert-butylsalicylideneiminate), 3b; N,N′-ethylenebis(5-methoxysalicylideneiminate), 3c; N,N′-ethylenebis(5-chlorosalicylideneiminate), 3d; N,N′-ethylenebis(5-nitrosalicylideneiminate), 3e; N,N′-o-phenylenebis(salicylideneiminate), 4a; N,N′-o-phenylenebis(3,5-di-tert-butylsalicylideneiminate), 4b; N,N′-o-phenylenebis(5-methoxysalicylideneiminate), 4c; N,N′-o-phenylenebis(5-chloro-salicylideneiminate), 4d) were prepared. The crystal structures of 6- and 7-coordinate zirconium complexes 4b and [4b · OCMe₂] were determined by X-ray crystallography, which reveals that a salen-type zirconium complex possesses a labile coordination site on the Zr center with a relatively stable framework and that the coordination and the dissociation of O-donor molecules occur readily at this site. The catalytic properties of 3(a-e) and 4(a-d) were studied for ethylene oligomerization in combination with Et₂AlCl as co-catalyst. Complex 3c featuring a methoxy-substituted salen ligand displayed higher activity than its analogous precursors having chloro and nitro groups as substituents. The catalytic reactions by 3(a-e) and 4(a-d) gave C₄-C₁₀ olefins and low-carbon linear α-olefins in good selectivity.     

Synthesis, structure and ethylene polymerization behavior of zirconium complexes with chelating ketoiminate ligands

Mixed ketoiminate/ketoimine/pentamethylcyclopentadienyl (Cp*) complex of zirconium, [(η⁵-Cp*){CH₃C(O)CHC(NHR)CH₃}{CH₃C(O)CHC(NR)CH₃}ZrCl₂] (R=4-CF₃Ph) (3) has been prepared in high yield by the reaction of one equivalent of 4-CF₃-phenyl-β-ketoimine (1a) and one equivalent of lithium 4-CF₃-phenyl-β-ketoiminate (2a) with one equivalent of Cp*ZrCl₃ in Et₂O. Bis(ketoiminate)zirconium dichloride complexes, 4 and 6, have been also prepared in high yield by the reaction of amine elimination of ketoimine ligands, respectively 1a and 1b, with Zr(NMe₂)₄ and followed by chlorination reaction with TMSCl. The X-ray crystallography reveals that the compound 3 is based on distorted octahedral geometry containing a ketoimine and a ketoiminate. The ketoiminate ligand coordinates to the zirconium as a bidentate ligand, leaving the metal center coordinatively unsaturated and thus leading to an additional binding of a ketoimine ligand to the metal to stabilize the complex 3. The zirconium complexes 3, 4 and 6 provide the moderate activity for the polymerization of ethylene in the presence of MMAO cocatalyst. Low molecular weight and high density polyethylene was obtained.     

A series of new zirconium complexes bearing bis(phenoxyketimine) ligands: Synthesis, characterization and ethylene polymerization

A series of new zirconium complexes bearing bis(phenoxyketimine) ligands, bis((3,5-di-tert-butyl-C₆H₂-2-O)R₁CN (2-R₂-C₆H₄))ZrCl₂ {R₁ = Me, R₂ = H (2a); R₁ = Et, R₂ = H (2b); R₁ = Ph, R₂ = H (2c); R₁ = 2-Me-Ph, R₂ = H (2d); R₁ = 2-F-Ph, R₂ = H (2e); R₁ = 2-Cl-Ph, R₂ = H (2f); R₁ = 2-Br-Ph, R₂ = H (2g); R₁ = Ph, R₂ = Me (2h); R₁ = Ph, R₂ = F (2i)}, have been prepared, characterized and tested as catalyst precursors for ethylene polymerization. Crystal structure analysis reveals that complex 2c has a six coordinate center in a distorted octahedral geometry with trans-O, cis-N, cis-Cl arrangement which possesses approximate C₂ symmetry. When activated with methylaluminoxane (MAO), complexes 2a-2i exhibited high ethylene polymerization activities of 10⁶-10⁸ g PE (mol M h)⁻¹. Compared with the bis(phenoxyimine) zirconium analogues bis((3,5-di-tert-butyl-C₆H₂-2-O)CHNC₆H₅)ZrCl₂ (3), the introduction of substituent on the carbon atom of the imine double bond enhanced the catalytic activity and molecular weight of prepared polyethylene. Especially, when the H atom at the carbon atom of the imine double bond was replaced by 2-fluoro-phenyl with strong electronic-withdrawing property, complex 2e displayed the highest catalytic activity, and the polyethylene obtained possessed the highest molecular weight and melt point.     

Pyrrolide-imine benzyl complexes of zirconium and hafnium: synthesis, structures, and efficient ethylene polymerization catalysis

A series of pyrrolyl-imines HL^1-6 was prepared by the condensation of pyrrole-2-carboxyaldehyde with different amines. The reaction of 2 equiv of pyrrolyl-imine with tetrabenzyl complexes of hafnium and zirconium M(CH₂Ph)₄ (M=Hf or Zr) gave dibenzyl complexes (L^3-6)₂M(CH₂Ph)₂, which were characterized by NMR spectroscopy and crystal structure analysis. NMR spectra of the complexes with secondary alkyl substituents at the imine nitrogen (isopropyl: 3a, 4-tert-butylcyclohexyl: 4a and 4b) suggest that rapid racemization between Δ and Λ configurations occurs in solution on the NMR time scale. The complexes with pyrrolide-imine ligands with a tertiary alkyl group such as tert-butyl (5a and 5b) or 1-adamantyl (6a and 6b) at the imine nitrogen possess cis-configured benzyl groups. Hafnium complexes 5a and 6a react with B(C₆F₅)₃ in bromobenzene-d₅ to give the corresponding cationic benzyl complexes, which exhibit high activity for ethylene polymerization (5a: 2242 kg-polymer/ mol-Hf h bar, 6a: 2096 kg-polymer/ mol-Hf h bar). Zirconium complexes 5b and 6b display a remarkably high ethylene polymerization activity when activated with methylaluminoxane (5b: 17,952 kg-polymer/mol-Zr h bar, 6b: 22,944 kg-polymer/mol-Zr h bar).     

Synthesis of and ethylene oligomerization with binuclear palladium catalysts having sterically modulated bis-imine ligands with methylene spacer

Sterically modulated bis-imine ligands (L¹-L³) were prepared by reacting 4,4′-methylene bis-(2,6-dialkyl aniline) and antipyrine-4-carboxaldehyde in a 1:2 stoichiometric ratio. The reactions of L¹-L³ with dichloro(cycloocta-1.5-diene)palladium(II) [PdCl₂(cod)] yield the corresponding binuclear palladium complexes with the general formula Pd₂Cl₄L (L = L¹, L², and L³). The binucleating ligands bind to the palladium ion via the lone pair on the imine nitrogen and amide oxygen atoms, resulting in a square-planar geometry around the metal center. All the palladium catalysts efficiently oligomerize ethylene to produce C₄-C₂₀ fractions at activities of up to 1308 kg-oligomer mol-Pd⁻¹ bar⁻¹ h⁻¹ at 30 °C in combination with ethylaluminum sesquichloride. The formation of active sites by the change in geometry of the metal complexes could be traced using spectroscopic and electrochemical techniques.     

磷酸锆催化甘油气相脱水制备丙烯醛

以沉淀法、水热合成法和浸渍法制备了磷酸锆催化剂,通过X射线衍射、热重分析、氮气物理吸附、红外光谱和Hammett指示剂法对催化剂进行了表征,并将该催化剂用于甘油气相脱水反应.研究表明,由沉淀法得到的磷酸锆经过400℃焙烧后能达到最佳催化活性,在温和条件下,甘油可完全转化,丙烯醛选择性为81%,反应24h内催化剂失活不明显.不同方法制备的磷酸锆其结构和表面酸性显著不同,催化剂表面酸性对催化剂活性、丙烯醛选择性和催化剂的寿命均有较大影响.     

无定形硅铝负载镍催化剂上乙烯齐聚反应的活性位点结构鉴定

镍(Ni)基催化剂在低碳烯烃聚合领域具有重要的地位,也是该领域研究的热点.自Johnson等报道(J.Am.Chem.Soc.,1995,117,6414–6415)二亚胺配体络合的Ni(Ⅱ)催化剂可有效降低烯烃聚合度,降低产物中非线性烯烃的选择性,甚至可以生成α-烯烃以来,掀起了Ni基催化剂在烯烃聚合领域的研究热潮.从均相到负载型多相Ni基催化剂,从载体类型到配体性质,从Ni纳米粒子的粒径调控到金属表面价态,关于Ni活性中心的研究工作一直存在争论.本课题组之前研究结果表明,曾明确了无定形硅铝(ASA)载体负载的Ni催化剂,经惰性气氛(N2)预处理得到的一价Ni是烯烃齐聚反应的主要活性中心(J.Chem.Soc.Chem.Commun.,1991,126–127).本文进一步深入研究了不同Al2O3含量的ASA载体上Ni活性位点的结构及其在乙烯齐聚反应中的活性.27Al NMR结果表明,催化剂中的铝存在三种配位方式,分别为AlⅣ、AlⅤ和AlⅥ,其中AlⅣ含量随Al2O3含量的增加而增加.载体中铝配位方式的不同,导致其表面金属负载的金属Ni活性位点所处的结构亦不同.原位FTIR-CO和H2-TPR实验结果表明,催化剂表面存在两种不同结构分布的Ni位点,分别是接枝在弱酸性硅醇上的Ni2+阳离子和Si?(OH)?Al桥式羟基离子交换位置的Ni2+阳离子.多数研究者认为,位于离子交换位置处孤立的Ni阳离子是反应的活性中心.然而,近期有研究者提出负载在酸性硅烷醇表面孤立的Ni2+阳离子为反应的活性中心物质.本文研究发现,随着Al2O3负载量的降低,处于离子交换位置处的Ni2+离子含量逐渐减少,而处于硅醇缺陷位点处的Ni2+离子含量则逐渐增多.原位FTIR-CO分析结果表明,处于硅醇缺陷位点处的Ni2+离子物种在惰性气氛中更易于转化为活性中心Ni+.相应的催化反应结果表明,相比于离子交换位置的Ni2+物种,具有与硅醇缺陷位点相连的Ni2+离子结构更有利于表现出更高的乙烯齐聚化活性.由此可知,处于硅醇缺陷位点的Ni2+物种是乙烯齐聚反应的活性中心的前驱体.本文进一步研究了硅醇缺陷位点处的Ni2+离子物种更易于转化为活性中心Ni+的原因.H2-TPR结果表明,相比于离子交换位置的Ni2+物种,处于硅醇缺陷位点的Ni2+物种与载体之间的相互作用力更弱.C2H4-TPD结果进一步表明,具有这种相对较弱的金属载体间作用力结构的催化剂对反应物C2H4分子的吸附作用力相对更强,吸附量也相对增多,因此其乙烯齐聚的催化性能更优.本研究结果对理解活性中心结构和合理设计催化剂提供参考.