Business and Technology of the Global Polyethylene Industry: An In-depth Look at the History, Technology, Catalysts, and Modern Commercial Manufacture of Polyethylene and Its Products

Chapter 3

Chromium-Based Catalysts

3.1 Part I – The Phillips Catalyst

Ethylene polymerization catalysts based on chromium as the active center are primarily used in the low-pressure manufacture of high density polyethylene (HDPE) with a relatively broad molecular weight distribution. This type of polyethylene is primarily used for blow-molding applications for bottles and large containers and for extrusion applications for pipe and HDPE film for merchandise bags.

Table 3.1 summarizes a few examples of end-use applications for chromium-based polyethylene in terms of the density, molecular weight distribution and molecular weight of the HDPE for various product applications.

Table 3.1 Examples of product applications for HDPE.

3.1.1 Early History of the Phillips Catalyst

The first chromium-based ethylene polymerization catalyst [1] was discovered by John P. Hogan and Robert L. Banks of Phillips Petroleum Company. On March 4, 1958, an historic U.S. Patent 2,825,721 was issued to them, and assigned to the Phillips Petroleum Company, in which an olefin polymerization catalyst based on the interaction of chromium compounds with high surface area inorganic supports was reported¹.

The catalyst, designated since the mid-1950s as simply the “Phillips” catalyst, was prepared in a two-step process in which the chromium compound was impregnated into silica and/or alumina to provide an intermediate ...