酚硝酮为配体的锆催化剂合成与表征及催化乙烯聚合的研究

以水杨醛与苯基羟胺缩合制备的酚硝酮为配体制备了Zr的配合物,采用IR、NMR、元素分析、质谱等表征手段对酚硝酮配体以及催化剂的结构进行了表征.研究了以酚硝酮为配体的Zr的配合物与MAO组成的催化体系催化乙烯聚合的行为.研究结果表明,该催化剂乙烯均聚活性较高且具有较好的耐温性,乙烯均聚的活性大于106g/(molZr·h),催化剂的活性随着温度的升高有较大幅度的提高且在100℃条件下活性仍无明显衰减.另外,采用凝胶渗透色谱以及示差扫描量热法对制备的一系列聚乙烯的分子量、分子量分布以及热性能进行了表征,催化得到的聚乙烯分子量可达到105,熔点在132℃左右.

SYNTHESIS AND CHARACTERIZATION OF Zr CATALYST WITH PHENOL NITRONE LIGAND FOR ETHYLENE POLYMERIZATION

A new non-metallocene early transition metal catalyst with phenol nitrone ligand for ethylene polymerization was designed and successfully synthesized by the reaction of phenol nitrone ligand with zirconium tetrachloride.Phenol nitrone ligand was obtained by the reaction of phenolic aldehyde with hydroxylamine.The structure of the catalyst and the phenol nitrone ligand were characterized by infrared spectrum (IR),nuclear magnetic resonance (1H-NMR),elemental analysis and mass spectrometry (MS).The catalytic behavior of the catalyst for the ethylene homopolymerization has been investigated with methyl aluminoxane (MAO)as cocatalyst.The catalyst exhibits a high ethylene homopolymerization activity ( > 106g / (molZr·h)) and good thermal stability.The catalytic activity of the catalyst increases with the increment of the temperature and keeps at 105 g /( molZr·h ) even under 100℃ .Besides,the molecular weight and the molecular weight distribution of the polyethylene were characterized by gel permeation chromatography (GPC).The molecular weight of the resulting polymers reaches 105,and the molecular weight distribution (Mw /Mn) is around 2.The thermal properties of the obtained polymers were also investigated with differential scanning calorimetry (DSC),the Tm of the polymer was around 132℃ .Based on the above results,it can be concluded that the early transition metal catalyst with phenol nitrone ligand synthesized in this report is a single active site homogeneous catalyst with good thermal stability and high catalytic activity in ethylene polymerization.