Continuous hydrogenolysis of polyolefins at ambient pressure

Abstract

Recycling and upcycling of plastic waste are typically energy-intensive and reducing their energy demand is crucial for the success of a sustainable plastic-to-resource transition. Hydro-conversion is a leading route for plastic waste valorization but typically requires high H2 pressures, especially for upcycling polyolefins, the largest class of plastics. Here we report an efficient and selective catalyst, Ru/ND@G, that enables continuous hydrogenolysis of waste polyolefins at ambient H2 pressure. Guided by mechanistic insights into hydrogenolysis, we design small Ru nanoparticles with optimized hydrogen- and hydrogen–alkane competitive adsorption, shifting the optimal reaction window to 1 bar while suppressing methanation. The catalyst delivers a metal-specific activity of 48 g gRu−1 h−1 at 220°C and converts diverse polyolefin wastes into liquid alkanes (C5–C34) with about 80% selectivity. In a representative semi-flow operation, 2.25 g of agricultural mulch film is transformed into 1.31 g of liquid and 0.42 g of gaseous alkanes. By eliminating the reliance on high-pressure H2, this work establishes design principles for low-pressure-favorable Ru catalysts and demonstrates a practical, energy-efficient pathway for continuous chemical upcycling of plastic waste.