Fig. 1. Pathways for processing plastic wastes.

Fig. 2. (A) Key features of zeolites. (B) Economic and sustainability evaluation of zeolites in the field of plastic waste recycling.

Fig. 3. The role of zeolites in various routes of chemical transformation.

Fig. 4. General effects of zeolite features and reactor characteristics on catalytic recycling of polyolefins.

Fig. 5. Catalytic cracking mechanism of alkanes: (A) Haag-Dessau cracking mechanism for an alkane molecule (RH) proceeding via a carbonium ion transition state. (B) Classic cracking mechanism for an alkane molecule (RH) consisting of a hydride transfer step to a smaller carbenium ion (R1+) followed by β-scission. Reprinted with permissiom from Ref. [124]. Copyright 2008, Elsevier Inc. (C) Reaction mechanism in the catalytic cracking of polyolefins mixture. Reprinted with permissiom from Ref. [126]. Copyright 2000, American Chemistry Society.

Fig. 6. Overall tandem catalytic processes for upcycling PE. (A) Hydrocracking of PE over metal-zeolite catalysts. (B) Degradation of PE through catalytic CAM with light alkanes. Reprinted with permission from Ref. [139]. Copyright 2019, American Chemistry Society. (C) One-pot hydrogenolysis-aromatization conversion of PE. Reprinted with permission from Ref. [12]. Copyright 2020, American Association for the Advancement of Science.

Fig. 7. Hydrocracking mechanism of polyolefins over bifunctional catalysts. Reprinted with permission from Ref. [143]. Copyright 2012, Wiley-VCH.

Fig. 8. (A) Yield and degree of branching of products using Pt/WO3/ZrO2+HY catalyst. (B) Depiction of aim intermediates diffusing over Pt/WO3/ZrO2+HY. Reprinted with permission from Ref. [153]. Copyright 2021, American Association for the Advancement of Science. (C) Yield of methane and conversion of PE using Ru/HY catalyst. (D) Methanation of plastic over Ru/HY catalyst. Reprinted with permission from Ref. [154]. Copyright 2021, Elsevier Inc.

Fig. 9. Enhancements of mass transfer of substrates. (A) Distribution of the LDPE cracking products using layer-like Y as catalysts. Reprinted with permission from Ref. [32]. Copyright 2022, American Chemical Society. (B) LDPE conversion versus temperature during pyrolysis tests over the parent, steamed, and alkaline-treated ferrierite zeolites. Reprinted with permission from Ref. [163]. Copyright 2009, Elsevier Inc. (C) Product distribution of HDPE over ultrathin ZSM-5 zeolite (bottom) and SEM images of ZSM-5 nanosheets (top). Reprinted with permission from Ref. [134]. Copyright 2022, American Chemical Society. (D) Comparison of yields for the catalytic cracking of LDPE over the beta zeolites of different particle sizes. Reprinted with permission from Ref. [164]. Copyright 2024, Royal Society of Chemistry.