2. Chromium catalysts

2.1 Phillips catalysis

Phillips catalysis (also known as chromium catalysis) was discovered in 1951 by J. Paul Hogan and Robert L. Banks of Phillips Petroleum. It is still used on a large scale today, producing almost 5 Mt of polyethylene.

The main disadvantage of these Phillips catalysts is that they cannot polymerize monomers other than ethylene. Indeed, propylene, 1-hexene or 1-butene can copolymerize with ethylene, but only lead to ill-defined homopolymers with low molecular weights.

2.1.1 Catalyst...