Recycling of post-use starch-based plastic bags through pyrolysis to produce sulfonated catalysts and chemicals

• Published in: Journal of analytical and applied pyrolysis 2021-05, Vol.155, p.105030, Article 105030
• Main Authors: Samorì, Chiara, Parodi, Adriano, Tagliavini, Emilio, Galletti, Paola
• Format: Article
• Language: English
• Subjects: Building blocks; Chemical recycling; Heterogeneous acid catalyst; Pyrolysis; Starch-based plastic bags
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2021.105030

[Display omitted] •Pyrolysis and sulfonation convert starch-based plastic (SBP) bags into SO3H-catalyst.•SO3H-catalyst from SBP-bags well-catalyzes the esterification of fatty acids.•SO3H-catalyst from SBP-bags is robust and recyclable for more than 7 cycles.•Highly pure terephthalic acid self-precipitates from SBP-bags pyrolysis liquid.•Pyrolysis liquid is enriched in levoglucosan, adipic acid and monobutenyl esters. Pyrolysis was explored as a technology for depolymerizing and charring starch-based plastic bags in a novel valorization perspective based on a chemical recycling strategy, alternative to anaerobic digestion or composting. The char obtained from the thermal treatment (420°C for 15 h) was sulfonated to give a highly active and recyclable heterogeneous acid catalyst (10 wt% yield based on starch-based plastic bags subjected to pyrolysis), comparable in terms of catalytic activity and reusability to the analog catalyst prepared from potato starch and tested on a model esterification reaction. From pyrolysis liquid of starch-based plastic bags, highly pure terephthalic acid (4 wt% yield) was isolated through self-precipitation, whereas the remaining pyrolysis liquid produced (21 wt%) was solvent-fractionated to give a polar fraction (7 wt% yield) enriched in levoglucosan, and a less polar fraction (14 wt% yield) enriched in monobutenyl adipate and terephthalate.