Performance comparison and sustainability assessment of mesoporous FAU zeolites for the plastic upcycling

Azam, Muhammad Usman, Kim, Nanbyen George, Fernandes, Auguste, Ribeiro, M. Filipa, Afzal, Waheed and Graça, Inês 2026. Performance comparison and sustainability assessment of mesoporous FAU zeolites for the plastic upcycling. Chemical Engineering Journal 527 , 172045. 10.1016/j.cej.2025.172045

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Abstract

This study investigates the influence of hierarchical modification of zeolites, synthesized via top-down (surfactant-templating via basic solution of CTAB) and bottom-up (use of organosilane, TPOAC) approaches, on the hydrocracking of linear and branched chain plastics. Unlike traditional comparisons exclusively based on catalytic performance, this study further provides an insight into the simultaneous comparison of conversion with environmental and economic benefits. Overall, top-down hierarchical zeolites (CT-HY) showed higher conversions than bottom-up modified (ST-HY) and HY zeolites for the hydrocracking of virgin HDPE and mixed post-consumer plastic waste, suggesting that improved textural properties play a dominant role for the hydrocracking of plastics. Interestingly, while conversion increases progressively with mesoporosity when branched plastics are present, a plateau in conversion is reached after a certain mesoporosity development for linear-chain plastics. However, product quality improves steadily with the increase in mesoporosity in both cases. A 27 % higher Pareto front optimisation score was obtained for the prolonged treated top-down hierarchical HY zeolite (CT-HY-2) than HY when processing mixed post-consumer plastic waste. Finally, the sustainability assessment showed the benefits of top-down hierarchically modified Y zeolites as compared to previous literature, with both zeolites showing high productivity of middle distillates (6.96–8.35 gC5-C18 gcat−1 h−1). Overall, the present study shows the contribution of mesoporosity in hierarchical zeolites to the upcycling of different types of plastic chains. Similarly, the demonstration of sustainability assessment helps to optimise the physiochemical properties of hierarchical zeolites and reaction conditions for improved catalytic results and provides decision makers a standardised approach when studying industrial-scale processes.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering
Publisher:	Elsevier
ISSN:	1385-8947
Date of First Compliant Deposit:	12 January 2026
Date of Acceptance:	17 December 2025
Last Modified:	13 Jan 2026 13:00
URI:	https://orca.cardiff.ac.uk/id/eprint/183807

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