Polyolefins, the largest used commodity plastics in the world, find extensive application in many fields. However, most end up in landfills or incineration, leading to severe ecological crises, environmental pollution, and serious resource waste problems. As representatives on chemical upcycling of polyolefin plastics polyolefin waste to fuels and bulk/fine chemicals, polyolefin catalytic cracking and hydrocracking based on zeolite or metal/zeolite composite catalysts are considered the most effective paths due to their large capacity and strong adaptability to existing petrochemical equipment. After an overview of the reaction mechanisms of pyrolysis and catalytic cracking, this review aims to comprehensively discuss the influence of zeolite catalyst structure (acidity, pore structure, and morphology) on the catalytic activity, selectivity, and stability of polyolefin cracking, particularly emphasizing the importance for matching acidity and pore structure for target product formation. Subsequently, the structure–activity relationship between the metal site and zeolite’s acid site in polyolefin hydrocracking is also discussed. In the end, emerging opportunities and challenges are proposed to promote a more efficient way for polyolefin chemical upcycling.

The interzeolite transformation approach has been used extensively for the quick synthesis of zeolites at a lower cost. Herein, an interzeolite transformation method for the quick synthesis of co-crystalline ZSM-5/ZSM-11 (CDM-5) nanoaggregates has been developed by precisely controlling the synthesis parameters and using 1,6-hexamethylenediamine as an organic structure-directing agent. In contrast, the irregular CDM-5 zeolite block obtained from an amorphous aluminosilicate gel takes a longer crystallization time using the conventional method. Combined with the related results of characterization, UV-Raman spectra show that double 6-membered rings in the parent USY zeolite framework are broken, and an ordered aluminosilicate aggregate species (OAAS) containing 4membered rings (4Rs) are formed during the interzeolite transformation. HRTEM and SEM images demonstrate that the block OAAS is dissolved into amorphous nanoparticles, followed by converting into CDM-5 nanoaggregates. These results reveal that an OAAS is essential for the synthesis of CDM-5 nanoaggregates via the interzeolite transformation method. In addition, the CDM-5 nanoaggregate catalyst exhibits superior stability and resistance to carbon deposition in the alkylation reaction of benzene with ethanol compared with the irregular block CDM-5 catalyst.

A series of Beta zeolite catalysts with controllable particle sizes and similar Si/Al ratios were prepared by introducing imidazole (IMD) into the synthesis system and used for a liquid-phase transalkylation...