A novel organic/inorganic support for immobilizing a hybrid catalyst used in ethylene polymerization was devised.The composition of the hybrid catalyst was as follows：styrene and acrylic copolymer (PSA) was the organic part for binding (n-BuCp)2ZrCl2

and SiO2/MgCl2 was the inorganic part to immobilize TiCl3.As an alternative to a tandem or cascade type process

a two-step polymerization method was carried out in a single reactor on a laboratory scale.Utilizing this two-step polymerization process

reactor blends of high molecular weight (made in the first step) copolymer and low molecular weight homo-polymer (made in the second step) were produced that were similar to industrial resins.The results showed that polymer blends had bimodal molecular weight distribution and broad melt flow rate (MI21.6/MI2.16=79).Besides

the melting point and crystallinity of the blends were in the range of polymers made separately in the first and second polymerization steps

indicating that the polymer obtained by the hybrid catalyst had good co-crystallinity.Catalyst kinetic curves in each polymerization step showed that the introduction of PSA facilitated gradual generation of the active sites of catalyst.Thus

the activity could be maintained in a long time in each polymerization step.