Nanosized silica-supported metallocene/MAO catalyst for propylene polymerization

A nanosized silica particle was used as the support to prepare an Et[Ind](2)ZrCl2/MAO catalyst for propylene polymerization of polypropylene. The catalyst and the polymer produced were characterized with nitrogen adsorption, 1CP, DSC, SEM, TEM, XRD, solution viscometer, C-13 NMR and optical microscopy. The effects of polymerization temperature and [Al]/[Zr] ratio on catalyst activity and polymer melting point were investigated. Under identical reaction conditions, nanosized catalyst exhibited better polymerization activity than the microsized catalyst (e.g., the former had 64% higher activity than the latter at the optimum polymerization temperature (50 degrees C) and [Al]/[Zr] = 570). DSC results indicated that polymer melting point increased with the increase of [Al]/[Zrl ratio and with the decrease of polymerization temperature. XRD results showed that the percentage of gamma crystals increased with decreasing [Al]/[Zr] ratio. Electron microscopic results showed that the polymer particle size increased with increasing polymerization temperature. (c) 2006 Wiley Periodicals, Inc.