MgCl2·6CH3OH: A Simple Molecular Adduct and Its Influence As a Porous Support for Olefin Polymerization

Abstract

A single phase molecular adduct, MgCl2·6CH3OH has been synthesized using MgCl2 and the simplest alcohol, methanol. Structural, spectroscopic, and morphological studies have been carried out for a better understanding of the single phase MgCl2·6CH3OH adduct. 13C CPMAS solid state NMR studies show all six methanol molecules are magnetically equivalent and present in a single environment around the Mg2+ center. Raman spectral analysis of the characteristic peak at 708 cm–1 substantiates octahedral coordination of six CH3OH molecules around Mg2+. Solid state 13C NMR measurements, made after heat treatment at different temperatures, have been utilized to understand the variations in CH3OH stoichiometry and coordination around Mg2+ with temperature. A titanated active catalyst, TiCl4 on MgCl2·6CH3OH, has also been synthesized and subjected to detailed characterizations. The active catalyst shows high surface area (102 m2/g) and mesoporosity. The titanated catalyst has been screened for ethylene polymerization reactions using different cocatalysts (R3Al; R= −CH3, −CH2CH3, and −CH2CH(CH3)2). A total of 7.25 kg of polyethylene per gram of catalyst has been obtained with Me3Al cocatalyst, which is six times higher in activity compared with commercial Me3Al/TiCl4/ MgCl2·6EtOH-supported catalyst. Although porosity influences the catalytic activity, other factors also seem to contribute to the total catalytic activity.