CIRCULAR ECONOMY FOR PLASTIC WASTE TO POLYPROPYLENE AND LUBRICATING OIL VIA REFINERY FCC AND ISOMERIZATION DEWAXING UNITS

摘要

A continuous process for converting waste plastic into recycle for polypropylene polymerization is provided. The process integrates refinery operations to provide an effective and efficient recycle process. The process comprises selecting waste plastics containing polyethylene and polypropylene and then passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a refinery FCC unit, from which is recovered a liquid petroleum gas C₃ olefin/paraffin mixture. The C₃ paraffins and C₃ olefins are separated into different fractions with a propane/propylene splitter. The C₃ olefin fraction is passed to a propylene polymerization reactor. The C₃ paraffin fraction is optionally passed to a dehydrogenation unit to produce additional propylene and then the resulting C₃ olefin is passed to a propylene polymerization reactor. The heavy fraction of pyrolyzed oil is passed to an isomerization dewaxing unit to produce a lubricating base oil.