Catalytic process upcycles polyethylene into propyleneS. Himmelstein | October 04, 2022
Polyethylene (PE), the most widely produced plastic, can be transformed into polypropylene (PP), the second-most widely produced plastic, by application of a catalytic conversion process. By using ethylene to convert PE to propylene, the commodity monomer used to make PP, the tandem catalysis strategy offers a scalable approach to keeping waste plastics out of landfills and curbing greenhouse gas emissions.
The PE is subjected to a catalyst to remove hydrogen from the material and create a reactive location in the chain of molecules, after which another catalyst splits the molecules at this location and caps the exposed ends using ethylene. A third catalyst then shifts this reactive location along the chain so the process can be repeated so that molecules of propylene remain as the end-product for use as building blocks for a virgin version of PP.
The researchers from the University of Illinois Urbana-Champaign, University of California Santa Barbara and Dow Chemical Company have engineered a reactor that supports a continuous flow of propylene for conversion into PP easily using current technology, making this development scalable and rapidly implementable.
The study published in the Journal of the American Chemical Society establishes a proof-of-concept for upcycling PE plastic with more than 95% selectivity into propylene.