Temperature programmed decomposition of sillica-supported MgCl2/THF/TiCl4 catalyst and effect of thermal treatment on ethylene polymerization rate

Silica supported MgCl₂/THF/TiCl₄ catalyst (SiO₂/MgCl₂/THF/TiCl₄) was prepared, and then decomposed thermally. The amount of produced gas [tetrahydrofuran (THF) and 1,4-dichlorobutane (DCB)] was measured with gas chromatography (GC) and mass spectrometer. SiO₂/MgCl₂/THF/TiCl₄ catalyst started to decompose around 85‡C, and further decomposed at 113, 150 and 213‡C. THF was mainly produced, but very small amount of DCB evolved during temperature programmed decomposition (TPD), while unsupported MgCl₂THF/TiCl₄ produced DCB significantly. Polymerization rate of ethylene with SiO₂/MgCl₂/THF/TiCl₄ decreased when it was preheated at 85 and 110‡C for 5 and 60 min, respectively, while that of unsupported MgCl₂/THF/TiCl₄ increased after same pretreatment condition. It can be suggested that Mg/Ti bimetallic complex anchored on the surface of silica through OH group of it has weak interaction between Mg and Ti species.