(661h) Mechanistic Study of Selective Hydrogenolysis of Polyethylene at Mild Conditions over Ruthenium Catalysts

Plastics waste has become a major environmental threat, with polyethylene being one of the most produced and hardest to recycle plastic^1-3. Hydrogenolysis is potentially the most viable catalytic technology for recycling. Ruthenium (Ru) is one of the most active hydrogenolysis catalysts but yields too much methane^4,5. Here we introduce ruthenium supported on selected supports for hydrogenolysis of low-density polyethylene (LDPE). We show that the highlighted Ru catalysts suppress methane formation and produce a product distribution in the diesel and wax/lubricant base-oil range unattainable by other Ru counterparts. Importantly, the enhanced performance is showcased for real-world, single-use LDPE consumables. Reactivity studies combined with characterization and density functional theory calculations reveal a novel mechanism that enables the hydrogenation and desorption of long alkyl intermediates that would otherwise undergo further C-C scission to produce methane.

References

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2 Giacovelli, C. Single-Use Plastics: A Roadmap for Sustainability (Rev. ed., pp. vi; 6). UNEP (2018).

3 OECD. Improving Plastics Management: Trends, policy responses, and the role of international co‐operation and trade. Environ. Policy Pap. 12, 20 (2018).

4 Rorrer, J. E., Beckham, G. T. & Román-Leshkov, Y. Conversion of Polyolefin Waste to Liquid Alkanes with Ru-Based Catalysts under Mild Conditions. JACS Au 1, 8-12, doi:10.1021/jacsau.0c00041 (2020).

5 Sánchez-Rivera, K. L. & Huber, G. W. Catalytic Hydrogenolysis of Polyolefins into Alkanes. ACS Central Science 7, 17-19, doi:10.1021/acscentsci.0c01637 (2021).