Monomer and solvent recovery in polymerization processes

Abstract

Abstract Improvements in the process for preparing copolymers of ethylene, higher alpha-olefins and, optionally as termonomer, a nonconjugated diene include subjecting the reactor effluent containing polymer cement, unreacted monomers, catalyst composition, and diluent-solvent to a first stripping operation, wherein recycled vaporous diluent-solvent is used as stripping medium, whereby substantially all unreacted light monomers and some diluent-solvent are taken as overhead. The first stripper bottoms are deashed and subjected to a second stripping operation employing steam as stripping medium. The overhead of this second operation, containing substantially all remaining diluent-solvent and some steam, is condensed; most water is withdrawn therefrom and the remaining water-saturated diluent-solvent is fractionated separating as overhead, any remaining water and any light impurities, and, as bottoms dry diluent-solvent and any heavy impurities. These bottoms are again fractionated separating as overhead, pure hot vaporous diluent-solvent which is recycled to the first stripping operation as stripping medium, and, as bottoms heavy impurities and any heavy termonomer. The overhead of the first stripping operation may be partially condensed, separating as overhead light monomers, any light impurities, and some diluent-solvent. The condensate containing a major portion of diluent-solvent and minor amounts of light monomer may be directly recycled to the reactor. The noncondensed portion may be fractionated, thereby separating substantially all unreacted light monomer as overhead which may be recycled directly to the reactor. The bottoms, containing diluent-solvent and light impurities, may be combined with the overhead from the second stripping operation. This process results in improved and simplified monomer and diluent-solvent recycle and significant investment and operating cost savings due to improved heat integration and reduction of required processing equipment.

Inventors

• 👤 J Faure
• 👤 J Love
• 👤 H Rosenbaum
• 👤 B Tegge

Bibliographic Details