Sustainable polyolefin upcycling using liquid organic hydrogen carrier based hydrogen delivery and hydrocracking

Globally, 89% of post-consumer plastic waste is landfilled or incinerated, exacerbating environmental pollution, while less than 0.1% is chemically recycled. Polyolefin plastics, nearly half of global plastic production, can be converted into liquid fuels via hydrogenolysis or hydrocracking but require external hydrogen gas. Here, we report a tandem catalytic process combining decalin dehydrogenation with polyethylene hydrocracking, eliminating the need for external hydrogen by using decalin as a liquid organic hydrogen carrier. Among several Pt/zeolite catalysts evaluated, a bifunctional Pt/HZSM-5 catalyst is identified as the most effective, achieving high PE conversion and selectivity toward liquid fuels. Comprehensive techno-economic and life-cycle assessments are conducted for three configurations: a one-step tandem reaction that directly integrates decalin utilization, a two-step process where dehydrogenation and hydrocracking occur sequentially under hydrogen-rich conditions, and an H₂-direct process that supplies hydrogen externally. The results demonstrate that utilizing in situ-generated hydrogen from decalin significantly enhances both economic viability and environmental performance compared to conventional external hydrogen methods, with the one-step tandem approach emerging as the most efficient and sustainable pathway. This tandem catalytic system provides a sustainable and economically viable pathway for upcycling abundant polyolefin waste into valuable liquid fuels, advancing circular economy goals and mitigating plastic pollution.