Advanced Catalyst/Process Combinations for Polyethylene

Advanced catalyst classes are divided according to chemical structure and transition metal. The format first covers metallocenes (the standard biscyclopentadienyl ligand framework and substituted analogs), and the so-called metallocene analogs. These analogs retain the overall general structural features of a metallocene, with substitution of a heteroatom containing aromatic ring system replacing one or both cyclopentadienyl ligand(s). A second division of catalyst type is the non-metallocene single-site catalyst (SSC). These catalysts have one, or fewer, cyclopentadienyl ligands. The SSCs are then further subdivided into the more Lewis acidic early transition metals, and the late transion metals, notably Ni and Fe based catalysts. This paper deals with the resent developments in catalyst/process technology for the production of polyethylene.