Catalytic upcycling of PVC waste-derived phthalate esters into safe, hydrogenated plasticizers. Issue 2 (6th December 2021)

• Record Type: Journal Article
• Authors: Windels, Simon; Diefenhardt, Thomas; Jain, Noopur; Marquez, Carlos; Bals, Sara; Schlummer, Martin; De Vos, Dirk E.
• Is Part Of: Green chemistry. Volume 24:Issue 2(2022)
• Page Start: 754
• Page End: 766
• Publication Date: 2021-12-06
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/d1gc03864h
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : Recycling of end-of-life polyvinyl chloride (PVC) calls for solutions to deal with the vast amounts of harmful phthalate plasticizers that have historically been incorporated in PVC. Abstract : Recycling of end-of-life polyvinyl chloride (PVC) calls for solutions to deal with the vast amounts of harmful phthalate plasticizers that have historically been incorporated in PVC. Here, we report on the upcycling of such waste-extracted phthalate esters into analogues of the much safer diisononyl 1, 2-cyclohexanedicarboxylate plasticizer (DINCH), via a catalytic one-pot (trans)esterification–hydrogenation process. For most of the virgin phthalates, Ru/Al2 O3 is a highly effective hydrogenation catalyst, yielding >99% ring-hydrogenated products under mild reaction conditions (0.1 mol% Ru, 80 °C, 50 bar H2 ). However, applying this reaction to PVC-extracted phthalates proved problematic, (1) as benzyl phthalates are hydrogenolyzed to benzoic acids that inhibit the Ru-catalyst, and (2) because impurities in the plasticizer extract (PVC, sulfur) further retard the hydrogenation. These complications were solved by coupling the hydrogenation to an in situ (trans)esterification with a higher alcohol, and by pretreating the extract with an activated carbon adsorbent. In this way, a real phthalate extract obtained from post-consumer PVC waste was eventually completely (>99%) hydrogenated to phthalate-free, cycloaliphatic plasticizers.