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

Abstract

Conversion of plastic wastes to fatty acids is an attractive means to supplement the sourcing of these high-value, high-volume chemicals. We report a method for transforming polyethylene (PE) and polypropylene (PP) at ~80% conversion to fatty acids with number-average molar masses of up to ~700 and 670 daltons, 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 the production of small molecules. The waxes are upcycled to fatty acids by oxidation over manganese stearate and subsequent processing. PP ꞵ-scission produces more olefin wax and yields higher acid-number fatty acids than does PE ꞵ-scission. We further convert the fatty acids to high-value, large–market-volume surfactants. Industrial-scale technoeconomic analysis suggests economic viability without the need for subsidies.

Design of Copolymer‐Based Blend Compatibilizers for Mixed Plastic Recycling

“…Over the past years, there are many emerging technologies for addressing mixed plastic waste, including pyrolysis-based and using catalytic reactions. [207][208][209][210] We believe blend compatibilization using mechanical recycling can still be particularly useful to address postindustrial wastes, which are typically clean and high quality, such as multi-layer packaging films composing of PET and polyolefin; these materials are difficult to separate due to their alternating layer structures. Furthermore, scaled implementation of a blend compatibilization technology necessitates a clear understanding about their economic and environmental benefits.…”

Precise activation of C–C bonds for recycling and upcycling of plastics

“…1,2,6 The rapid accumulation of plastic waste, which is challenging to handle, has resulted in severe environmental pollution, ultimately posing a threat to both Earth's ecosystems and human health. 5,7–10 Meanwhile, plastic waste represents one of the most significant potential carbon resources in the modern era. 3,11 Approximately 59% of all plastics ever manufactured, equivalent to around 8600 million metric tons, are directly discarded, ultimately ending up in landfill sites, or infiltrating natural ecosystems, such as rivers and oceans.…”

“…3,11 Approximately 59% of all plastics ever manufactured, equivalent to around 8600 million metric tons, are directly discarded, ultimately ending up in landfill sites, or infiltrating natural ecosystems, such as rivers and oceans. 8,12 Only approximately 17% of these plastics are fortunate enough to be reclaimed and used as an energy source. 12 Consequently, the imperative lies in achieving environmentally sustainable plastic waste treatment through methods such as physical, chemical, or biological recycling/ upgradation.…”

Review on Catalytic Depolymerization of Polyolefin Waste by Hydrogenolysis: State-of-the-Art and Outlook

“…Some of the methods used for upcycling of plastic wastes include pyrolysis, − solvolysis, − hydrogenolysis, , cracking, − combustion (incineration), − hydrothermal liquefaction, , and gasification . Even though chemical recycling is more expensive compared to mechanical recycling, it still has advantages over the latter and is more suitable for many commercial and industrial applications. ,− Even the rate of the depolymerization as an upcycling techniques is also investigated today . The chemical recycling process is applicable to a mixture of plastic waste and does not generate greenhouse gases.…”