Two catalysts were prepared using reaction method with or without dibuthylphalate(DBP). The surface area

X-ray diffractions and kinetic behavior for ethylene polymerization of these catalysts have been compared. It was found that when the catalyst without DBP(WY-1 system)

the kinetic curves for ethylene polymerization show decaying type; however

when the catalyst with DBP(WY-2 system)

the kinetic curves are accelerating type. The specific number of active centers [C*] are almost same in the two systems. The value of kp of WY-2 system was much greater than that of WY-1 system

but the apparent activation energy of WY-2 system was much lower than that of WY-1 system.It leads to that the catalytic activity of the catalyst with DBP increased greatly in comparision with that of the catalyst without DBP.