Challenges and opportunities of light olefin production via thermal and catalytic pyrolysis of end-of-life polyolefins: Towards full recyclability

• DOI: 10.1016/j.pecs.2022.101046
• Publication Date: 2023-02-14T11:38:56Z
• Authors: Mehrdad Seifali A...; Yannick Ureel; Andreas Eschenbacher; Florence H. Vermeire; Robin John Varghese; Jogchum Oenema; Georgios D. Stefa...; Kevin M. Van Geem
• Keywords: Polyolefin; Thermal Stability

Is full recyclability of polyolefins via chemical recycling a dream, or can it become reality? The main problem in plastic waste is that its composition highly heterogeneous while sorting and purifying solutions to obtain mono-streams are complex require large investments, thereby hampering the economy scale. Ideally, novel processes designed have mixed wastes as input higher value products produced such C2–C4 olefins aromatics instead low oil. In this review we show directions how realize these objectives. Classical thermal pyrolysis offers some possibilities but requires very high temperatures exceeding 800 °C transform back into desired temperatures. Nevertheless, because robustness, polyolefinic currently intensively studied first industrial applications operated at medium temperature range maximize oil product. Catalytic still under development, ideal lab-scale conditions around 85 wt.% be when pure polyolefin feeds used. With improved catalyst design should possible get number further up without affecting stability. As yield light impacted by both process (reactor type, efficiency prior conversion, flexibility towards feed composition) experimental parameters (temperature, catalyst/feed ratio, contact mode, residence time, addition inert reactants) also improvements respect. To industrialize waste, short times (<1 s) crucial avoid secondary reactions by-products methane, coke, aromatics. Pyrolysis reactors according principles, downers, spouted fluidized bed, vortex reactors, envisaged result optimal yields olefins. However, coke formation seems inevitable reactor designs need sufficiently robust allow for in-situ removal. For future research will viability improve purification stream, optimize catalysts selectivity stability, suitable reactor. It innovations three areas eventually reaching 90 target.