新型超支化镍系催化剂的合成及对乙烯齐聚的催化性能

摘要

以直链十二胺为核的0.5代超支化大分子（R12-0.5G）和丁二胺为原料，合成出一种新型的1.0代超支化大分子（R12-1.0G）。然后以R12-1.0G、水杨醛和NiCl2·6H2O为原料，依次经过希夫碱反应和络合反应合成了一种新型的超支化水杨醛亚胺镍系催化剂。FTIR、1H NMR、UV和MS证实合成产物的结构与理论结构相符。在合成的基础上，并对该催化剂催化乙烯齐聚的性能进行了研究。考察了溶剂种类、反应温度、反应压力、Al/Ni比等条件对该催化剂催化乙烯齐聚性能的影响。结果表明，该催化剂具有良好催化乙烯齐聚的性能，当以甲苯为溶剂，在甲基铝氧烷（MAO）活化下，随着反应压力和 Al/Ni 比增加，催化活性增加；而催化活性随着反应温度的增加先升高后下降；在反应温度为25℃、反应压力为0.5MPa、Al/Ni比为1500时，该催化剂的活性可达5.03×105g/(molNi·h)，聚合产物主要是 C6以下的低碳烯烃，含量高达89%以上。相同条件下，其催化乙烯齐聚的活性低于与其具有类似结构的“扫帚型”镍系催化剂。%1.0G hyperbranched macromolecule was synthesized with R12-0.5G and butanediamine as starting materials. Then a novel hyperbranched salicylaldimine nickel catalyst was synthesized by Schiff’s reaction and complex reaction with salicylaldehyde,nickel chloride hexahydrate and the 1.0G hyperbranched macromolecule as raw materials. The structure of the 1.0G hyperbranched macromolecule,salicylaldimine ligand and catalyst were characterized by FTIR,1H NMR,UV and MS. The performance of the hyperbranched nickel catalyst in ethylene ologomerization was also investigated. The effects of solvents,reaction temperature,reaction pressure and ratio of Al/Ni on catalytic performance in ethylene oligomerization were investigated. The results showed that the complex displayed high catalytic activity in selective ethylene oligomerization with toluene as solvent and MAO as the cocatalyst. The catalytic activity always increased with the increase of reaction pressure and Al/Ni ratio,but firstly increased and then decreased with the increase of reaction temperature.The highest activity of 5.03×105g/(mol Ni·h) was achieved and 89% of the product were C4 and C6 olefins. The reaction conditions were that temperature was 25℃,pressure was 0.5MPa,and the Al/Ni ratio was 1500. Under the same polymeric conditions,the catalytic activity of novel hyperbranched salicylaldimine nickel catalyst was lower than that of the “Broom molecule” nickel catalyst with a similar structure in ethylene oligomerization.