Surface organometallic investigation of the mechanism of ethylene polymerization by silica-supported Cr catalysts

Effect of surface hydroxylation on the catalytic activity of a Cr(II)/SiO2 model system of Phillips catalyst

“…As an example, for the sample activated at 823 K, the resulting polymerization rate is of about 55 s À1 mol Cr À1 (corresponding to about 5.5 Á 10 6 g PE h À1 mol Cr À1 ). These values are of the same order of magnitude of those reported in the literature for similar systems [28].…”

High resolution X-ray photoelectron spectroscopic analysis of transformation of surface chromium species on Phillips CrOx/SiO2 catalysts isothermally calcined at various temperatures

“…Phillips CrO x /SiO 2 catalyst is still extracting both academic and industrial interests due to its great importance in the field of industrial polyolefin production [1][2][3][4][5][6][7][8][9][10]. With its unique product properties, the catalyst is still quite competitive against Ziegler-Natta and metallocene catalysts in some application areas like blow molding HDPE products [11,12].…”

Morphological modifications of Cr/SBA-15 and Cr/Al-SBA-15 ethylene polymerization catalysts: Influence on catalytic behaviour and polymer properties

“…Conventional preparation methods for Phillips catalysts involve the impregnation of an inorganic support (silica, alumina, aluminophosphates, etc.) with an inorganic or organometallic chromium compound, followed by calcination at high temperature (500-1000°C) to produce Cr(VI) active species [2][3][4]. Nowadays, it is well known that physicochemical properties of the solid supports play an important role on the resulting properties of the polyethylene produced [2,3,[5][6][7].…”