Research On Catalysts For Olefin Oligomerization With Transition Metals

This paper mainly synthesizes different ligands and complexes:2,6-bis[1-(2,6-dimethylphenylimine)ethyl]pyridine(ligand 3),[(2,6-bis Ethylphenyl)imino]-naphthone(ligand 4),Hdpa(1),Hdpza(2)Six kinds of complexes were obtained by reacting ligands 1,2 and transition metal salts,and the structure of the complexes was characterized and studied.The ethylene oligomerization and carbon dioxide polymerization tests were performed using six complexes,respectively.The first part is based on the ligands 2,2'-dipyridylamine(Hdpa)and bis(2-pyrazolyl)amine(Hdpza),the neutral molecular complex[Co(Hdpa)2(NCS)2](1)and[Co(Hdpza)2(NCS)2](2)is synthesized.DFT calculation of complex 1 was performed to analyze the electron density distribution.The magnetic properties of complex 1 were calculated.The magnetic results show that the gradual decrease of xMT over the entire temperature range indicates that the high-spin Co(?)ion in 1 has a strong zero-field splitting ability.The effects of complex 1 and 2/MAO catalyst systems on the oligomerization catalysis of ethylene were analyzed.Complexes 1 and 2 were used for the cycloaddition of CO2 and propylene oxide with a catalytic activity of Ll>L2.Under mild conditions,complex 1 exhibits excellent catalytic performance and can convert CO2 to cyclic carbonate.In the second part,two different ligands were synthesized by Schiff reaction with pyridine and perylene quinone as raw materials.Two different ligands were synthesized by UV,elemental,infrared and thermogravimetric methods to verify the ligands.The synthesis result was successful.A catalytic system was formed with Fe(acac)3/MAO to test the ethylene oligomerization reaction.The results showed that the pressure of ethylene oligomerization was 1 MPa,the temperature was 60 0 C,and the reaction time was 60 min.2/Fe(acac)3 catalyst,the catalyst ratio Al/Fe is 400,and the overall activity of the oligomerization catalyst is 3.91,4.587(unit:105g/mol·h).Increasing the reaction pressure to 4 MPa,without changing the reaction time,temperature,and catalyst ratio,the ethylene oligomerization catalytic activity of both was improved,but at the same time,the content of polyethylene wax as a by-product was also increased.Relative rise.In the third part,four different complexes were synthesized from ligand 3 and transition metals Fe(?),Co(?),Ni(?),and Cu(?),and elemental analysis was performed on the four complexes.,IR,UV,TG-DTG characterization tests,proved that the four metal complexes were successfully synthesized.The catalytic reactions of ethylene oligomerization and CO2 to PC were tested by using four kinds of imperfect metal complexes.The effects of reaction temperature,reaction pressure,co-catalyst ratio Al/M,and reaction time on the catalytic reaction were discussed.The results showed that the activity of ethylene oligomerization complexes la and lb was higher than that of complexes lc and Id.When the temperature is 40?,the reaction pressure is 1 MPa,and the assisting ratio Al/M is 800,the optimal reaction conditions are as follows.The catalytic activity of the complexes(3a,3b,3c,and 3d)can reach 6.93,5.18,3.72,2.57.×105(g/mol-h).For PC-catalyzed reactions at a reaction temperature of 80 0 C,a reaction pressure of 1.5 MPa,and a reaction time of 2 h,the activity of complexes 3b and 3c is higher than that of complexes 3a and 3d,and the yield of PC can reach 67.36%and 71.54.%.