III International Conference

PP-I-7KINETIC STUDY OF ETHYLENE POLYMERIZATION OVER HOMOGENEOUSAND SUPPORTED CATALYSTS BASED ON 2,6-BIS(IMINO)PYRIDYL COMPLEXOF IRON AND COBALTBarabanov A.A., Bukatov G.D., Zakharov V.A., Semikolenova N.V.,Mikenas T.B., Matsko M.A., Echevskaya L.G.Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: barabanov@catalysis.ruMethod of polymerization inhibition by radioactive carbon monoxide ( 14 CO) has beenused to determine the number of active centers (C P ) and propagation rate constant (k P ) forethylene polymerization with homogeneous and supported on the different supports (SiO 2 ,Al 2 O 3 , MgCl 2 ) catalysts based on the bis(imino)pyridine complexes of iron and cobalt.Methylalumoxane (MAO) or Al(i-Bu) 3 , were used as co-catalyst. In the case of homogeneoussystem with both activators the rate profile of polymerization was unstable: high activity ofthe initial period sharply decreases. Rapid catalyst deactivation with polymerization time isshown to be connected with the decrease of the active sites number and average propagationrate constant (for instance, for catalysts based on Fe-complex in 1.5-2 and 3 times for C P andk P values, respectively). In contrast to homogeneous systems based on bis(imino)pyridinecomplexes of iron and cobalt, the supported catalysts are highly active and stable in ethylenepolymerization at 70-80 0 C. Data on the effect of hydrogen over the calculated C P and k Pvalues were obtained. Molecular-mass distribution (MMD) of polyethylenes produced wasdetermined by gel-permeated chromatography method. Polyethylene with broad MMD wasdivided by using Temperature Rising Elution Fractionation (TREF) on separate fractions withnarrow MMD and the distribution of C P and k P values on polymer fractions were determined.The obtained C P and k P values and data on the polymer molecular mass and MMD lead toconclusion that the nature of the support has almost no effect on the active centers structureand distribution of their reactivity. This work was supported by the Russian Foundation forBasic Research, project No. 03-03-33034.19