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"... Researchers ... recently introduced a new approach to convert polystyrene (PS), a plastic widely used to pack some foods and other products, into toluene, a hydrocarbon that is of value in industrial and manufacturing settings. Their proposed strategy, outlined in a paper ... entails heating polystyrene waste in hydrogen and breaking it down into smaller vapor molecules, a process known as hydro-pyrolysis. ..."
From the abstract:
"Converting plastic waste into valuable products mitigates plastic pollution and lowers the carbon footprint of naphtha-derived aromatics. However, the difficulties of precisely controlling complex multiphase systems and the catalyst inefficiencies hinder process viability.
Here we report a vapour-phase hydrogenolysis strategy catalysed by Ru single atoms on Co3O4 (RuSA/Co3O4), decoupling depolymerization from hydrogenolysis to overcome the toluene yield–selectivity trade-off.
In a pressurized dual-stage fixed-bed reactor, polystyrene undergoes hydropyrolysis at 475 °C, followed by vapour-phase hydrogenolysis at 275 °C (0.4 MPa H2, 2.4 s), yielding toluene with 99% selectivity, 83.5 wt% yield and 1,320 mmol gcat.−1 h−1 rate.
The RuSA/Co3O4 catalyst demonstrates excellent stability, maintaining >99% conversion and selectivity during 100 h continuous operation (turnover number 24,747), and effectively processes diverse real-world polystyrene wastes.
Life-cycle assessment shows a 53% carbon footprint reduction over fossil-based methods, while techno-economic analysis estimates a competitive minimum selling price of US$0.61 kg−1, below the US$1 kg−1 industry benchmark."
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