Waste polyethylene to long-chain unsaturated esters and alcohols via alkene cross-metathesis

The conversion of waste polyethylene into valuable long-chain functional molecules offers a contemporary solution to the global plastic waste challenge. This study presents a two-step catalytic approach, comprising of polyethylene (PE) dehydrogenation followed by cross-metathesis with renewable resource-derived functional olefins, catalyzed by the Grubbs-II catalyst (G-II). A dehydrogenated polyethylene (DHP) was subjected to a tandem catalytic cross-alkene metathesis with functional olefins under mild conditions to achieve approximately 36% conversion of DHP into valuable long-chain building blocks with controlled product distribution. Comprehensive characterization of intermediates and products was performed using NMR, GC, GC-MS, GPC, and DSC. In the alkene cross-metathesis with methyl-10-undecenoate, the product distribution consisted of 23% lower alkenes (C8-C14), 40% unsaturated long-chain mono-esters (C12-C18), and 37% unsaturated di-esters. In the case of 10-undecen-1-ol, the distribution included 20% lower alkenes (C8-C11), 32% unsaturated long-chain (C12-C18) mono-alcohols, and 48% unsaturated di-alcohols. This strategy opens up new opportunities for converting waste polyethylene into high-value chemical intermediates, enabling resource recovery and delivering environmental benefits.