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. Most plastic waste is landfilled, and polyolefin recycling needs external H₂. This work couples decalin dehydrogenation with polyethylene hydrocracking, using in situ H₂ to yield liquid fuels efficiently, improving both economic and environmental sustainability.