超支化铬系催化剂的合成及乙烯齐聚性能研究

以不同端基烷基链长度的1.0G超支化大分子为桥联基,通过对其端基氨基进行催化功能改性,合成了系列具有不同桥联基长度的超支化PNP铬系催化剂。采用红外光谱(IR)、核磁共振氢谱(1H-NMR)、核磁共振磷谱(31P-NMR)、紫外光谱(UV)和质谱(MS)等表征方法证明合成催化剂的结构与理论结构相符。详细考察了溶剂种类、反应温度、Al/Cr摩尔比、反应压力、催化剂用量和催化剂结构对催化剂乙烯齐聚性能的影响。实验结果表明,当以甲苯为溶剂,甲基铝氧烷(MAO)为助催化剂时,超支化PNP铬系催化剂表现出良好的催化乙烯齐聚性能,产物以低碳烯烃为主。最佳条件下,催化活性最高可达到1.69×105g/mol Cr·h,己烯和辛烯的选择性为43.3%以上。相同聚合条件下,其催化活性随着端基烷基链长度的增加而下降。     

超支化PAMAM桥联乙烯齐聚用镍系催化剂的合成与表征

以系列直链脂肪胺为核的低代超支化聚酰胺-胺(PAMAM)和水杨醛为原料,通过席夫碱反应制备系列新型超支化PAMAM桥联水杨醛亚胺配体;以无水Ni Cl2为络合试剂,通过络合反应合成系列超支化PAMAM桥联镍催化剂,采用FT-IR和1H NMR证实合成的系列新型配体和镍系催化剂的结构与其理论结构相符.对系列超支化PAMAM桥联镍催化剂催化乙烯齐聚的性能进行了研究,结果表明,超支化PAMAM桥联镍系催化剂配体骨架烷基链长度对其催化活性和选择性影响较小,助催化剂和溶剂影响较大;倍半乙基氯化铝为助催化剂,甲苯为溶剂时,聚合活性较高,产物中C8以上的高碳产物的含量最高;其中以十四胺为核的超支化PAMAM桥联镍催化剂为主催化剂、倍半乙基氯化铝为助催化剂、甲苯为溶剂时,催化乙烯齐聚活性高达1.96×106 g/(mol·h),齐聚产物中C8以上的高碳产物含量为98.77%.     

新型树枝状PNP铬催化剂的合成及催化性能

以1.0代聚酰胺-胺(PAMAM)为配体骨架,氯代二苯基膦为原料,通过取代反应合成了1种含有较大空间位阻的新型树枝状PNP配体,再以Cr Cl3(THF)3为络合试剂,通过络合反应合成树枝状PNP铬催化剂.采用傅里叶变换红外光谱(FTIR)、紫外-可见分光光度计(UV-Vis)、核磁共振波谱(NMR)、电喷雾电离质谱(ESI-MS)和元素分析等手段证实合成的新型树枝状PNP配体及其铬催化剂的结构与理论设计的结构一致.以甲基铝氧烷(MAO)为助催化剂,对乙烯齐聚反应进行了研究,考察了溶剂种类、反应温度、反应压力及Al/Cr摩尔比对该催化剂活性和选择性的影响.结果表明,以甲苯为溶剂,MAO为助催化剂,当反应温度为25℃,反应压力为0.9 MPa,Al/Cr摩尔比为500时,该催化剂的活性高达2.15×105g/(mol Cr·h),催化剂对乙烯三聚、四聚反应的选择性共达到36.76%.     

新型链行走烯烃聚合催化剂的合成及其催化活性

以二氯化镍为原料制得配合物(DME)Ni Cl2(1);以2,6-二异丙基苯胺和丁二酮为原料,经缩合反应制得α-二亚胺配体(2);1与2经络合反应合成了一种用于乙烯齐聚制备超支化聚乙烯的新型链行走催化剂(3),其结构经IR,XRD和元素分析表征。以乙烯齐聚为探针反应,考察了助催化剂,反应温度和反应时间对3催化活性的影响。结果表明:在较优反应条件[Al Et30.14 mol,n(Al)∶n(Ni)=600,于20℃反应0.5 h]下,3催化活性为2.5×106g PE·(mol·Ni·h·MPa)-1。齐聚产物为支化聚乙烯,部分支链中碳原子数大于4。     

MixMOFs接枝PNP铬系催化剂的合成及催化乙烯齐聚性能

以对苯二甲酸、2-氨基对苯二甲酸和六水合硝酸锌为原料,合成出一种含有氨基的混合金属有机骨架(MixMOFs),然后以MixMOFs、氯代二苯基磷和CrCl_3(THF)_3为原料,依次经后合成修饰法和络合反应,合成出一种新型的MixMOFs接枝PNP铬系催化剂。利用红外光谱、X-射线衍射、扫描电镜、元素分析和电感耦合等离子体质谱等方法对产物的结构进行表征,并考察了催化体系和反应条件对催化乙烯齐聚性能的影响。结果表明,MixMOFs接枝PNP铬系催化剂具有较好的催化乙烯齐聚性能,以环己烷为溶剂、一氯二乙基铝(Et_2AlCl)为助催化剂,当反应温度为25℃、Al/Cr摩尔比为600、乙烯压力为1.0MPa时,该催化剂的活性可达4.33×10~4g/(mol Cr·h),聚合产物主要是C_8以下的低碳烯烃,含量高达90%以上。并且催化剂重复使用3次,活性和选择性没有明显变化,表现出较好的重复利用性。     

Ti(Ⅳ)/PNP/MAO体系催化乙烯齐聚的研究

合成了三种PNP配体,并与Ti(Ⅳ)作用形成催化剂,利用核磁共振氢谱、元素分析及质谱对配体及催化剂进行了结构表征。在助催化剂甲基铝氧烷(MAO)存在的条件下,催化乙烯齐聚。试验结果表明:钛(Ⅳ)剂催化活性最高可达2.58×105g/(molTi.h),α-烯烃选择性达80.72%。     

芳氧基锆系催化剂催化乙烯齐聚与Friedel-Crafts烷基化的串联反应

从锆系催化剂的结构修饰出发,合成了一系列具有Zr(OAr)nCl4-n·m Ar OH(n=1~4,m=0~7)结构的芳氧基锆系催化剂,并研究了锆酚配比及游离Ar OH含量等对乙烯齐聚行为的影响.结果表明,Zr(OPh)3Cl·m Ph OH/TEA/Et Al Cl2催化体系具有较高的齐聚催化活性[6.8×104g/(mol Zr·h)],所得产物主要为C4~C24的α-烯烃,无高聚物生成.研究发现,游离酚的存在对体系的催化性能有较大影响.该系列芳氧基锆系催化剂可催化乙烯齐聚与Friedel-Crafts烷基化的串联反应,即齐聚反应产物α-烯烃与甲苯溶剂发生烷基化反应而生成多取代芳香烃,压力越大烷基化反应程度越高.     

超支化分子桥联水杨醛亚胺镍配合物的合成及对乙烯齐聚反应的催化性能

合成了一种具有超支化结构的新型水杨醛亚胺配体及其Ni(Ⅱ)配合物, 利用元素分析、 电喷雾电离质谱(ESI-MS)、 傅里叶变换红外光谱(FTIR)、 紫外-可见光谱(UV-Vis)、 氢核磁共振谱(¹H NMR)和碳核磁共振谱(¹³C NMR)对其结构进行了表征. 以甲基铝氧烷(MAO)为助催化剂, 考察了超支化水杨醛亚胺镍配合物对乙烯齐聚反应的催化活性及聚合条件(Al/Ni摩尔比、 聚合温度)对催化剂活性及聚合产物分布的影响. 结果表明, 在反应温度为25 ℃、 Al/Ni摩尔比为500时, 该催化剂的活性最高达到5.59×10⁵ g/(mol Ni·h), 得到的聚合产物为全馏分烯烃, 其中高碳烯烃C₁₀~C₁₈的含量最高达91%.     

The Research of Novel Ti（IV）/PNP/MAO Catalyst System for Ethylene Oligomerization

合成了三种PNP配体,并与Ti（IV）作用形成催化剂,利用核磁共振氢谱、元素分析及质谱对配体及催化剂进行了结构表征。在助催化剂甲基铝氧烷（MAO）存在的条件下,催化乙烯齐聚。试验结果表明：钛（IV）剂催化活性最高可达2．58×105g／（molTi·h）,α-烯烃选择性达80．72％。     

树枝状吡啶亚胺铬催化剂的合成及其催化性能研究

以1. 0代聚酰胺-胺树枝状大分子为配体骨架、吡啶二甲醛为原料,合成了一种新型树枝状吡啶亚胺(DPI)配体,再以CrCl_3·6H_2O为络合试剂,制备DPI-Cr催化剂。采用IR、UV-Vis、MS、元素分析等确证了产物结构。考察溶剂种类、助催化剂种类、反应温度、乙烯压力以及Al/Cr摩尔比对DPI-Cr催化乙烯齐聚性能的影响。结果表明,DPI-Cr催化剂表现出良好的催化活性和烯烃选择性,优化反应条件下,催化效率可达4. 91×10~4g/mol Cr·h,C_6和C_8选择性为73. 90%。     

Synthesis and application of chromium complexes bearing hyperbranched PNP ligands in the ethylene oligomerization

Series of hyperbranched PNP ligands ( L1 – L3 ) were prepared using three low-generation hyperbranched molecules with the same branching chains and functional groups but different alkyl chain length as backbones in a mixed solvent of acetonitrile and dichloromethane. The chromium complexes ( Cr1 – Cr3 ) were obtained by reacting with CrCl₃(THF)₃ and the corresponding ligands ( L1 – L3 ). Both L1 – L3 and Cr1 – Cr3 were characterized by elemental analysis, Fourier transform infrared and electrospray ionization–mass spectrometry as well as ¹H nuclear magnetic resonance (NMR) and ³¹P NMR measurements in the case of the ligands. When activated with different aluminum co-catalysts, all three chromium complexes were able to catalyze the ethylene oligomerization, but the products of the ethylene oligomerization were mainly dependent on ethylene pressure, co-catalyst and ligand backbone. Upon activation with methylaluminoxane, the catalytic activity and the selectivity of C8 olefin increased with increasing of ethylene pressure for Cr1 , the catalytic activity was 13.83 × 10⁵ g·(mol Cr·h)⁻¹ and the main product was C8 olefin (50.68%) at the ethylene pressure of 4.0 MPa. When activated with diethylaluminium chloride, ethylaluminium dichloride and ethylaluminum sesquichloride, Cr1 showed the lower catalytic activity and the higher selectivity of C4 olefin in toluene. An increase in the length of alkyl chain in the hyperbranched PNP ligand backbone caused a decrease in the catalytic activity and an increase in the selectivity of C8 + olefin. The PNP chromium complexes exhibited higher selectivity for higher carbon number olefins compared with the dendritic PNP chromium complex ( Cr5 ).     

Selective ethylene oligomerization bearing hyperbranched bispyridylamine chromium catalyst

Two new hyperbranched bispyridylamine ligands and multinuclear chromium complexes were synthesized with 1.0?G hyperbranched macromolecules, 2-chloropyridine, 2-chloro-4-methylpyridine and CrCl₃(THF)₃ as raw materials. The structures of hyperbranched ligands and chromium complexes were characterized by UV, FT-IR, ¹H NMR, ESI-MS, and elemental analysis. These hyperbranched chromium complexes were evaluated as catalyst precursors by using MAO as activator in the oligomerization of ethylene. Effects of reaction temperature, reaction pressure, Al/Cr molar ratio, concentration of catalyst, solvent, and the structure of catalysts on the catalytic activity and product selectivity were investigated. The oligomerization results showed that with increase of reaction temperature, reaction pressure, and Al/Cr molar ratio, the catalytic activity increased and then decreased; the catalytic activity continuously decreased as the amount of catalyst increased. The products were mainly based on C₆ and C₈. Under optimized conditions, the catalytic system of hyperbranched NNN/Cr(III)/MAO led to activity of 1.26?×?10⁵ g/(mol·Cr·h) and 63.34% selectivity for C₆ and C₈.     

Hyperbranched bisphosphinoamine ligands: synthesis,characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph₂PCl) and CrCl₃(THF)₃ as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, ¹H NMR, ³¹P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10⁵ g/(mol Cr·h) and 37.71% selectivity for C₆ and C₈.     

Novel Dendritic PNP Chromium Complexes: Synthesis,Characterization, and Performance on Ethylene Oligomerization

Three dendritic PNP ligands with ethylenediamine, 1,4‐butanediamine, 1,6‐diaminohexane as bridged groups are synthesized in good yields, respectively. Three dendritic PNP chromium complexes ( C1  –  C3 ) are prepared with the ligands and chromium(III ) chloride tetrahydrofuran complex (CrCl₃(THF )₃) as materials. The dendritic PNP ligands and the synthetic chromium complexes are fully characterized by spectroscopic and analytical methods. All chromium complexes activated with methylaluminoxane (MAO ) exhibited moderate activities on ethylene oligomerization (7.90 × 10⁴ – 2.15 × 10⁵ g (mol Cr h)⁻¹] and had better selectivity for C₆ and C₈ oligomer, reaching up to 81%. The chromium complex ( C1 ) activated with diethylaluminium chloride (Et₂AlCl) has higher catalytic activity than the chromium complex C1 activated with MAO , although the chromium complex ( C1 ) activated with Et₂AlCl had lower selectivity for C₆ and C₈ oligomer. The effects of solvent and reaction parameters on ethylene oligomerization are also studied using the chromium complex C1 as pre ‐ catalyst and MAO as co ‐ catalyst. Under optimized conditions ([complex] = 2 μmol, Al/Cr = 500, 25 °C, 0.9 MP a ethylene, 30 min), the catalytic activity of complex C1 in toluene is 2.15 × 10⁵ g (mol Cr h)⁻¹ and the selectivity for C₆ and C₈ oligomer is 36.76%. In addition, the structure of complexes significantly affects both the catalytic activity and the selectivity on ethylene oligomerization.     

Synthesis and application of bidentate nickel complexes bearing hyperbranched salicylaldimine ligands in ethylene oligomerization

Three bidentate salicylaldimine nickel complexes containing different long-chain alkyl groups in their ligand backbone were synthesized in good yield. All the bidentate salicylaldimine ligands and their nickel complexes were fully characterized by FT-IR, ¹H NMR, UV spectroscopies, and mass spectrometry. Three bidentate nickel complexes were evaluated as catalyst precursors in ethylene oligomerization. Upon activation with methylaluminoxane (MAO), the catalytic activity was 5.75 × 10⁵ g/(mol Ni·h) and the oligomers were mainly butenes (52.10%) and octenes (32.63%) for bidentate nickel complex with 1-tetradecyl as core in the ligand backbone (R₁₄-complex) using toluene as solvent. However, bidentate nickel complex with 1-octadecyl as core in the ligand backbone (R₁₈-complex) produced mainly octenes (59.38%) and C10 + olefins (29.01%) and the catalytic activity was 2.23 × 10⁵ g/(mol Ni·h). After activation with ethylaluminum sesquichloride (EASC) in toluene, three nickel complexes yielded mainly C10 + products which contained Friedel-Craft alkylated-toluene, and their catalytic activities were above 1.5 × 10⁶ g/(mol Ni·h). For the bidentate salicylaldimine nickel catalysts with hyperbranched molecules as ligand backbones, the solvent and the reaction conditions had a large effect on catalytic activity as well as oligomerization distribution except the structure of the catalyst and the co-catalyst.     

Synthesis of short straight-chain alkylamine based hyperbranched nickel complexes and their catalytic performance of ethylene oligomerization

Short straight-chain alkylamine based hyperbranched molecules and their corresponding salicylaldimine nickel complexes have been synthesized in high yield and characterized by FTIR, ¹H-NMR and mass spectrometry. The optimal reaction parameters were determined under the catalytic system of methylaluminoxane (MAO) as co-catalyst and toluene as solvent. Under these conditions, the effect of catalyst structure, solvent and co-catalyst were determined. Upon activation of MAO in toluene, ethylene oligomerization products were homogeneous distribution of butene, hexene and octene with trace higher olefin. The same catalytic system under cyclohexane and methyl cyclohexane as solvent, however, produced majority of butene. Under the activation of EtAlCl₂, Et₂AlCl and EASC as co-catalyst in toluene, ethylene oligomerization reaction was tandem with Friedel-Crafts reaction in catalytic system.     

Influence of the ligand structure on the properties of bidentate salicylaldimine nickel(II) complexes in ethylene oligomerization

Three nickel(II) complexes (C1–C3) bearing diamine-bridged 4-hydroxysalicylaldehyde ligands (L1–L3) were successfully synthesized, and all the compounds were characterized by physicochemical and spectroscopic methods. The influence of the oligomerization parameters on the catalytic properties of complex C2 was systematically investigated. The results showed that oligomerization parameters played an important role in the catalytic properties and the catalytic activity was 19.90?×?10⁴ g/(mol·Ni·h) and the selectivity of C₈₊ olefins was 60.25% when the precatalyst dosage was 5 μmol, the Al/Ni molar ratio was 500, the temperature was 25 °C, the reaction time was 30 min and the pressure of ethylene was 0.7 MPa. Complexes C1–C3 with different lengths of the bridged group were evaluated for ethylene oligomerization, and the results showed that the length of the alkyl chain in the ligand had little influence on the catalytic properties. Complex C4 based on ethanediamine-bridged salicylaldimine and C5 based on the hyperbranched salicylaldimine in our previous work were also investigated to study the influence of the ligand structure on the catalytic properties. The catalytic activity [31.80?×?10⁴ g/(mol·Ni·h)] and the content of the low-carbon oligomers (70.16%) for complex C4 were higher than complex C2 with hydroxyl substituent in benzene ring. The catalytic activity and the content of the low carbon oligomers for complex C5 were far higher than other four complexes.

     

Cobalt complexes based on hyperbranched salicylaldimine ligands as catalyst precursors for ethylene oligomerization

Three hyperbranched salicylaldimine ligands with tetradecyl as core, with hexadecyl as core and with octadecyl as core were synthesized in good yields. These ligands were reacted with cobalt chloride hexahydrate to form three complexes ( C1 – C3 ). The compounds were characterized using Fourier transform infrared, ¹H NMR, mass and UV spectroscopies and thermogravimetric and differential thermal analyses. The catalytic properties of the hyperbranched cobalt complexes were evaluated for ethylene oligomerization. The effects of solvent and reaction parameters (Al/Co molar ratio, temperature and reaction pressure) on ethylene oligomerization were studied using the cobalt complex C3 as pre‐catalyst and methylaluminoxane (MAO) as co‐catalyst. Under these conditions ([Co] = 5 μmol, Al/Co = 500, 25 °C, 0.5 MPa ethylene, 30 min), the catalytic activity of complex C3 in toluene was 1.85 × 10⁵ g (mol Co)⁻¹ h⁻¹ and the selectivity for C₈₊ oligomers was 55.72%. The complex structure also had a significant influence on both the catalytic activity and selectivity. All three cobalt complexes, activated with MAO, showed moderate activities towards ethylene oligomerization and the activity of cobalt complex C1 was up to 1.99 × 10⁵ g (mol Co)⁻¹ h⁻¹. The kinds of metal center of complexes (cobalt complex C1 and nickel complex with tetradecyl as core) and their catalytic properties were investigated in detail under the same conditions.