Deconstruction of high-density polyethylene into liquid hydrocarbon fuels and lubricants by hydrogenolysis over Ru catalyst

Abstract

Polyethylene (PE) is the most popular plastic globally, and the widespread use of plastics has created severe environmental issues. High energy consumption in the current process makes its recycling a challenging problem. In our report, the depolymerization of high-density PE was conducted in various liquid-phase solvents with the Ru/C catalyst under relatively mild conditions. The maximum yields of the jet-fuel- and lubricant-range hydrocarbons were 60.8 and 31.6 wt %, respectively. After optimization of the reaction conditions (220°C and 60 bar of H 2 ), the total yield of liquid hydrocarbon products reached approximately 90 wt % within only 1 h. The product distribution could be tuned by the H 2 partial pressure, the active-metal particle size, and the solvents. The solvation of PE in the different solvents determined the depolymerization reaction kinetics, which was confirmed by the molecular dynamics simulation results. • Ru/C was a highly active catalyst for the liquid-phase hydrogenolysis of HDPE • Solvent effects were prominent in the depolymerization of HDPE • H 2 partial pressure played a significant role in the HDPE depolymerization pathway • Total yield of liquid products reached around 90 wt % within 1 h at 220°C Plastic pollution has become one of the most pressing environmental issues now that the rapidly increased production of disposable plastic products is far beyond the world's capacity for recycling and upcycling waste plastics. Although recent studies have provided a few catalytic strategies for producing value-added fuel and chemical products from polyethylene (PE) waste, the kinetic rates and/or selectivities are unsatisfactory, even with extended processing time (24 h) and high temperatures (>280°C). This work reports a liquid-phase catalytic hydrogenolysis process that highly efficiently converts high-density PE to jet-fuel- and lubricant-range hydrocarbons under relatively mild conditions. The application of this efficient liquid-phase catalytic hydrogenolysis process could provide a promising approach for selectively producing high-value products, such as lubricants, from waste PE and other polyolefin polymers. Plastic pollution has become one of the most pressing environmental issues and needs to be tackled imminently. Here, Lin and coworkers report a liquid-phase catalytic hydrogenolysis process that highly efficiently converts high-density polyethylene (PE) to jet-fuel- and lubricant-range hydrocarbons under relatively mild conditions. Solvents profoundly affect the depolymerization reaction kinetics and product selectivity. This work provides a promising approach for selectively producing high-value products, such as jet fuel and lubricants, from waste PE and other polyolefin polymers.