PEP Review 81-2-2
Polypropylene, El Paso Process Using Mitsui/Montedison Catalyst
Published: April 1982
In the El Paso polypropylene process, propylene is polymerized as slurry in liquid propylene, and product is recovered by flashing off excess monomer at the reactor exit. With first generation catalysts, both catalyst residues and atactlc polypropylene are then extracted from the polymer before final pelletization. Use of the highly active, highly stereospecific Mitsui Petrochemical/Montedison catalysts renders the catalyst residue and atactic removal steps unnecessary, thereby greatly simplifying the process and improving production economics. In addition, the polypropylene product has enhanced properties.
Comparison of the new El Paso process with Montedieon's (see PEP Report 128) indicates significantly lower production costs for El Paso's process in homopolymer and copolymer production. El Paso's process has a lower utilities requirement and a lower investment, particularly for the copolymerization system.