Synthesis Of Hyperbranched Molecule Bridged Nickel Catalyst With Long-chain Alkyl As Core And Performance For Ethylene Oligomerization

A series of hyperbranched macromoelcules with long-chain alkyl as core were synthesized with long chain fatty amines, methyl acrylate and ethylene diamine as raw materials through Michael addition reaction and amidation reaction. A series of hyperbranched salicylaldehyde imine ligands were synthesized with hyperbranched macromolecules as bridged groups by Schiff reaction. A series of hyperbranched salicylaldehyde-imine ligands metal complexes were synthesized using anhydrous nickel chloride, nickel chloride hexahydrate and cobalt chloride as materials, respectively. The structure of the ligands and the catalysts were characterized by FT-IR, UV and 1H NMR and the results showed that the structure of synthetic products conformed to the design structure.On the basis of the synthesis, the properties of a series of hyperbranched molecule bridged nickel catalysts for ethylene oligomerization were studied, and the effects of the polymeric system and polymeric conditions on the oligomerization activity and product distribution were investigated. The results showed that the optimum synthetic conditions of a series of hyperbranched molecule bridged nickel catalysts were as follows: the reaction temperature was 25℃, the reaction pressure was 0.5MPa and the Al/Ni value was 1000. Under the conditions, the hyperbranched molecule bridged nickel catalysts had highest catalytic activities for ethylene oligomerization. Moreover, the main products was high carbon compounds when the hyperbranched molecule bridged nickel catalysts being activated by ethyl aluminum sesquichloride. The main products was low carbon compounds when the hyperbranched molecule bridged nickel catalysts being activated by MAO.The effect of the length of alkyl chain on the catalytic activities was also studied. The results showed that the effect rule was similar, and the catalytic activities were increased first and then decreased with the increase of the length of alkyl chain. The catalytic activities of the hyperbranched molecule bridged nickel catalysts with 1-aminotetradecane as core for ethylene oligomerization was highest, and the catalytic activity was 1.96×106g/(mol·Ni·h) with ethylaluminum sesquichloride as co-catalyst. On the basis of synthesizing the hyperbranched molecule bridged nickel, a series of hyperbranched molecule bridged cobalt catalysts were synthesized with cobalt chloride hexahydrate as material, and the catalytic activity was 9.93×10~5g/(mol Ni·h) with ethylaluminum sesquichloride as co-catalyst.