Supported Chromium Catalysts for Ethylene Polymerization

Surface chromium single sites: open problems and recent advances

“…The Cr/SiO 2 Phillips catalyst for ethylene polymerization is by far one of the simplest single-site heterogeneous catalysts (McDaniel 1985;Groppo et al 2005b;McDaniel 2010). The common synthesis receipt is very simple, as shown in figure 1.…”

“…In addition, the possibility of changing the catalytic activity of Cr/SiO 2 by altering the chemical composition of the support has been known since the 1970s. Ti, fluorine, boron or alkali metal ions have been investigated, but Ti is by far the most studied modifier (McDaniel 1985;Cheng et al 2010). Depending on the choice of support, Cr catalysts can produce anything from liquid oligomers and low molecular weight wax to ultrahigh molecular weight grades.…”

Olefin polymerization over supported chromium oxide catalysts

“…The heart of the Phillips polymerization process is a supported chromium oxide catalyst, which is usually prepared by impregnation of a chromium oxide on a wide pore silica [2,5]. The impregnated material is subsequently heated in air at high temperature, cooled down,¯ushed with nitrogen, and stored under dry nitrogen until loaded in the polymerization reactor.…”

“…However, no attempt will be given to cover the whole ®eld, and in this respect, we refer to several excellent review papers, most notably the review paper of McDaniel published in 1985 [2]. For background, a general description of the Phillips polymerization process will be given.…”

Models for heterogeneous catalysts: studies at the atomic level

“…One such system, envisioned is the Philips catalyst, where chromia is grafted to typically amorphous silica catalyzing the polymerization of ethene to poly-ethylene (McDaniel 1985(McDaniel , 2010. Our research in this direction had been inspired by work at the group of Adriano Zecchina in Torino (Groppo et al 2005).…”