Polymerization of ethylene and propylene with catalysts based on zirconocenes and methylaluminoxane synthesized on a zeolite support

The reaction of trimethylaluminum. with the internal water of a zeolite (the Na form of ZSM-5, SiO2: Al2O3 = 24) yielded immobilized methylaluminoxanes which, in the absence of other organoaluminum cocatalysts, reacted with metallocenes (Cp2ZrCl2, Et(Ind)(2)ZrCl2) to form heterogenized complexes active in the polymerization of ethylene and propylene. The kinetics of ethylene and propylene polymerization in the presence of zeolite-supported zirconocene catalysts was studied. The reaction order of ethylene and propylene polymerization with respect to the concentration of the monomer changes from 2 to I as the concentration of the monomer in the reaction zone increases. The apparent activation energies of ethylene and propylene polymerization with the ZSM-5(H2O)/AlMe3/Et(Ind)(2)ZrCl2 catalyst were found to be 32 and 48.5 kJ/mol, respectively. It is inferred that the synthesis of methylaluminoxane directly on the surface of a support and the formation of catalytic complexes in the absence of free methylaluminoxane reduce the probability of leaching active centers from the support surface to a solution.