SIMULATION MODELING ON THE COORDINATION MECHANISM OF ETHYLENE MONOMER ON VARIOUS PREREDUCED Cr（Ⅱ）Ox/SiO2 PHILLIPS POLYETHYLENE MODEL CATALYSTS

As one of the most important catalysts in polyethylene industry,Phillips catalyst(CrO_x/SiO_2)was quite unique for its activation by ethylene monomer without using any activator like alkyl-aluminium or MAO.In this work,the density functional theory(DFT)calculation combined with paired interacting orbitals(PIO)method was applied for the theoretical studies on coordination reaction mechanism between ethylene monomer and two model catalysts namely Cr(Ⅱ)(OH)_2(M1) and silsesquioxane-supported Cr(Ⅱ)(M2)as surfac...

Ti,Al改性Phillips乙烯聚合催化剂的结构及性能研究

通过添加钛(Ti)、铝(Al)对Cr/SiO_(2) Phillips催化剂进行改性,制备出了Cr-Ti/SiO_(2)和Cr-Ti-Al/SiO_(2)两种改性催化剂,考察了改性催化剂的结构及催化乙烯聚合性能。结果表明,添加Ti和Al后,催化剂表面变得粗糙,孔径变小,比表面积增大;催化活性增加,最高活性分别为55.36和82.55g(PE)/g(Cat),而Cr/SiO_(2)仅为45.39g(PE)/g(Cat)。改性催化剂的PE产品分子链变长,结晶度增加,高分子量组分增多,分子量分布变宽。