2021 Annual Meeting

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

Authors

Cong Wang - Presenter, University of Delware
Tianjun Xie, Clemson University
Pavel Kots, University of Delaware
Brandon Vance, University of Delaware
Kewei Yu, University of Delaware
Pawan Kumar, University of Pennsylvania
Jiayi Fu, University of Delaware
Eric A. Stach, Purdue University
Weiqing Zheng, University of Delaware
Dionisios Vlachos, University of Delaware - Catalysis Center For Ener
Abstract

Plastics waste has become a major environmental threat, with polyethylene being one of the most produced and hardest to recycle plastic1-3. Hydrogenolysis is potentially the most viable catalytic technology for recycling. Ruthenium (Ru) is one of the most active hydrogenolysis catalysts but yields too much methane4,5. 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

1 Agency, U. S. E. P. Advancing Sustainable Materials Management: Facts and Figures Report. (2020).

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).