Study On Oligomerization Of Ethylene To Linear Low Carbon α-olefins By ⅣB,Ⅷ Groups Metal Complexes

Linear low carbon a-olefins are used primarily as comonomers for production of linear low-density polyethylene and high-density polyethylene. There are great, demands of comonomers in the world, but until now there is no modern a-olefin industry in our country. In this dissertation, the linear low carbon olefins have been synthesized using ethylene oligomerization catalyzed by. â…¦B and â…§ complexes.The catalytic performance of (Ind)₂ZrCl₂, (n⁵-l-But-Ind)₂ZrCl₂ (n⁵-4,7-Me₂-Ind)₂ZrCl₂ complexes with EtiAlCl as co-catalyst has been studied. They displayed medium catalytic activity and high selectivity to low a-olefms. Introducing electron donor group into an indene ligand increased the catalytic activity, however the selectivity of linear low a-olefins was enhanced with the bulky group.The ethylene oligomerization catalyzed by a series of alkyl coordinating zirconium complexes, such as (n⁵-4,7-Me₂-Ind)₂ZrMe₂(n⁵-4,7-Me₂-Ind)₂Zr(CH₂Ph)₂ and (n₅-4,7-Me₂-Ind)₂ZrPh₂ with Et₂AlCl, was studied The results showed that (n⁵-4,7-Me₂-Ind)₂ZrCl₂/ Et₂AlCl was the best one with the catalytic activity of 1714 g/g.Zr.h, selectivities of C⁼_4-10 and linear l-C⁼_4-10 are 97.6% and 90.3% respectively, on the optimal conditions.Preliminary results indicated that ethylene oligomerization was catalyzed by (C₆H₄-0-R-N=C-C₆H₄-0-O-)₂ZrCl₂(R=-Me, -H, -Cl)/Et₂AlCl. The effect of R in complexes has the following order: R=Me > R=H > R=Cl. The best catalyst war: (C6H4-o-Me-N=C-C6H4-o-O-)2ZrCl2/Et2AlCl with the catalytic activity of 5590p/ g-Zr-h, and the selectivities of C4-io and linear l-C4-io up to 96.4% and 91.2%.The catalytic behavior of (dppe)MCl2(M= Fe( II), Co(II) , Ni( II) )/EAO k. ethylene oligomerization has been studied. The results showed that these catalytic systems have medium catalytic activity and high selectivity to low carbon olefins. The catalytic activity of (dppe)CoCl₂/EAO was 4021 g / g.Co. h with the selectivity of 95.5% to C_4-10lefins and 75.4% to linear C_4-10 a-olefms at 200℃. The catalytiosystems of (dppp)FeCl₂, (dppp)CoCl₂ and (dppp)NiCl₂ with EAO displayed the similar behavior, but the catalytic activity of the complex with a six-membered ring was slightly lower than that with a five-membered ring under the same reaction conditions.The effect of adding of Ph₃P or dppe as a third-component for the catalytic system of (dppe)MCl₂/EAO (M= Fe(â…¡) , Co(â…¡) > Ni(â…¢) on ethylene oligomerization has been studied.The catalytic performance of (bipy)CoCl₂, (C₆H₄-o-R-N=C-C₆H₄-o-O-)₂M (M= Fe,Co) and (acac)₂Co with EAO as co-catalyst for ethylene oligomerization has been studied. The results showed that the catalytic activity of (bipy)CoCl₂/EAO was 2441g/g.Co.h, which is the highest one with selectivity of 95.9% to C_4-10 olefins at 1807The catalytic center of (dppe)FeCl₂/EAO was characterized by UV and Mossbauer spectrum. The information of cationic (dppe)Fe+Et has been observed. The construction data of zirconocenes were investigated by molecular mechanics and molecular orbital models, and were correlated to the catalytic performance. A cationic mechanism of ethylene oligomerization was suggested.