A Review on Catalyst Chemical Recycling Technologies for Production of Light Gaseous Compounds from Polyolefin Waste

Chemical recycling of polyolefins is essential to mitigate plastic waste accumulation and promote circular economy strategies. Among the various chemical recycling pathways, catalytic pyrolysis, tandem catalyst systems, ethenolysis, hydrocracking, and hydrogenolysis have emerged as promising approaches for converting polyolefin waste into valuable hydrocarbons, including gaseous, liquid, and solid products. This review provides a survey of recent research on these methodologies, with a particular focus on the production of light gaseous hydrocarbons (C1–C4), bypassing the intermediate pyrolysis oil stage, which is often associated with contaminants and increased processing costs. The novelty of the present work lies in its emphasis on gaseous fractions, in contrast to most existing studies that primarily target oil recovery. Aspects such as catalyst selection, reaction conditions, and product distribution are analyzed. Additionally, the current Technology Readiness Level (TRL) of the studied processes, their relative advantages, limitations, and perspectives for industrial applications are discussed. The analysis highlights catalytic pyrolysis with zeolites as the most mature and scalable technological alternative for manufacture of light compounds directly from polyolefin waste, while tandem catalyst systems and ethenolysis constitute promising but still emerging alternatives for targeted gas production.