Chemical upcycling of polyethylene, polypropylene, and mixtures to high-value surfactants

Conversion of plastic wastes to fatty acids is an attractive means to
supplement the sourcing of these high-value, high-volume chemicals.
Herein, we report a method for transforming polyethylene (PE) and
polypropylene (PP) at ~80% conversion to fatty acids with number average
molar masses up to ~700 Da and 670 Da, respectively. The process is
applicable to municipal PE and PP wastes and their mixtures.
Temperature-gradient thermolysis is the key to controllably degrading PE
and PP into waxes and inhibiting producing small molecules. The waxes are
upcycled to fatty acids by oxidation over manganese stearate and
subsequent saponification. PP ꞵ-scission produces more olefin wax and
yields higher acid-number fatty acids than PE. We further convert the
fatty acids to high-value, large-market-volume surfactants.
Industrial-scale technoeconomic analysis suggests economic viability
without subsidies.