Abstract: Two kinds of Ti-Mg supperted catalysts for gas-phase polymerization of ethylene were studied.The Ti³⁺ content in the milling-made catalyst (CMtype) containing titanium 3-4%-4.0% by mass is 15%-25% of the total titanium.The surface area of the catalyst and catalytic activity for the polymerization are 130m²/g and 9.20 kg PE/(gTi.h).The polymerization showed quickly decaying kinetics.The Ti³⁺ content in the reacting-made cat-alyst(MG-2 type) containing titanium 7.0%-8.0% by mass is 55 %-69% of the total tita-nium.The surface area of the catalyst and catalytic activity are 78 m²/g and 4.45 kgPE/(gTi.h).The polymerization was relative steady.The average value of diameter (D_av) and D_avmax/D_avmin of the CMand MG-2 catalyst particles are 6.8 pm, 33 pm and 9.2, 7.0, respec-tively, and corresponding values of polymerization product PEparticles are 155μm, 263μm,and 10.8, 9.0, respectively.The results indicated that the morphology of the polymerization product reproduced that of the catalyst particle.

Key words: Ti-Mg catalyst, Gas-phase polymerization of ethylene, Morphology of particles