Upgrading of waste polyolefins with non-noble metal catalysts

Abstract

The rapid growth of waste polyolefin plastics poses a great threat to the environment and human health; hence there is an urgent requirement of efficient and environment-friendly upgrading methods. Aiming to utilize these hazardous substances and reduce energy consumption in a green way, most of the current studies use noble metal catalysts for the conversion of plastic waste, while non-noble metal catalysts have gradually attracted attention in the upgrading of waste polyolefins due to their abundant reserves, low cost, and potential to offer more sustainable alternatives. This paper provides a comprehensive review of Ni and Co-based and other catalysts in the hydrocracking, hydrogenolysis and tandem catalysis of polyolefins in recent years. It highlights the significance of the catalyst composition and support structure, which are key factors in determining the efficiency and selectivity of the conversion processes. The structure–activity relationships of these catalysts are also discussed to reveal how active site and structure design can influence the yield of desirable products while minimizing by-product formation and environmental impact. In addition, the challenges and prospects of non-noble metal catalysts in the selective upgrading of waste polyolefins in a circular economy are described to provide a theoretical foundation for the design and development of more efficient and stable catalysts, while inspiring further research in the green upgrading of waste polyolefins.