Polyethylene Hydrogenolysis at Mild Conditions over Ruthenium on Tungstated Zirconia

Cong Wang; Tianjun Xie; Pavel A Kots; Brandon C Vance; Kewei Yu; Pawan Kumar; Jiayi Fu; Sibao Liu; George Tsilomelekis; Eric A Stach; Weiqing Zheng; Dionisios G Vlachos

doi:10.1021/jacsau.1c00200

Polyethylene Hydrogenolysis at Mild Conditions over Ruthenium on Tungstated Zirconia

JACS Au. 2021 Aug 30;1(9):1422-1434. doi: 10.1021/jacsau.1c00200. eCollection 2021 Sep 27.

Authors

Cong Wang¹, Tianjun Xie¹, Pavel A Kots¹, Brandon C Vance^{1

2}, Kewei Yu², Pawan Kumar³, Jiayi Fu², Sibao Liu⁴, George Tsilomelekis⁵, Eric A Stach³, Weiqing Zheng¹, Dionisios G Vlachos^{1

2}

Affiliations

¹ Center for Plastics Innovation, University of Delaware, 221 Academy Street, Newark, Delaware 19716, United States.
² Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware 19716, United States.
³ Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
⁴ Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
⁵ Department of Chemical and Biochemical Engineering, School of Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States.

Abstract

Plastics waste has become a major environmental threat, with polyethylene being one of the most produced and hardest to recycle plastics. 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. Here we introduce ruthenium supported on tungstated zirconia (Ru-WZr) for hydrogenolysis of low-density polyethylene (LDPE). We show that the Ru-WZr catalysts suppress methane formation and produce a product distribution in the diesel and wax/lubricant base-oil range unattainable by Ru-Zr and other Ru-supported catalysts. Importantly, the enhanced performance is showcased for real-world, single-use LDPE consumables. Reactivity studies combined with characterization and density functional theory calculations reveal that highly dispersed (WO _x )_n clusters store H as surface hydroxyls by spillover. We correlate this hydrogen storage mechanism with hydrogenation and desorption of long alkyl intermediates that would otherwise undergo further C-C scission to produce methane.