Value‐Added Upcycling of PET to 1,4‐Cyclohexanedimethanol by a Hydrogenation/Hydrogenolysis Relay Catalysis

Abstract

We present an innovative process for directly transforming poly(ethylene terephthalate) (PET), a polymer extensively used in food and beverage packaging, into trans‐isomer‐enriched 1,4‐cyclo‐ hexanedimethanol (CHDM), a key ingredient in advanced specialty polymers. Our approach leverages a dual‐catalyst system featuring palladium on reduced graphene oxide (Pd/r‐GO) and oxalate‐gel‐derived copper‐zinc oxide (og‐CuZn), utilizing hydrogenation/hydrog‐ enolysis relay catalysis. This method efficiently transforms PET into polyethylene‐1,4‐cyclohexanedicarboxylate (PECHD), which is then converted into CHDM with an impressive overall yield of 95% in a two‐stage process. Our process effectively handles various post‐consumer PET plastics, converting them into CHDM with yields between 78% and 89% across different substrates. Additionally, we demonstrate the applicability and scalability of this approach through a temperature‐programmed three‐stage relay process on a 10‐gram scale, which results in purified CHDM with an isolated yield of 87% and a notably higher trans/cis ratio of up to 4.09/1, far exceeding that of commercially available CHDM. This research not only provides a viable route for repurposing PET waste but also enhances the control of selectivity patterns in multistage relay catalysis.