Fig. 5: Environmental and techno-economic assessment of large-scale hydrogenolysis of plastic caps over 2.5Ru5Ni.

a Process flow sheet for recycling 20 t h⁻¹ of plastic bottle caps via hydrogenolysis, including downstream catalyst recycle and product separation. b Global warming potential (GWP) for different sources of hydrogen, i.e., fossil hydrogen from steam methane reforming (fossil) and green hydrogen from water splitting produced in a proton-exchange membrane electrolyzer powered by either off-shore wind power or solar photovoltaic panels. The business-as-usual scenario (BAU) represents the case where caps are produced via the conventional route and incineration is applied as end-of-life treatment, whilst gas and liquid hydrocarbons are separately obtained from oil. c Sankey diagrams for the main contributions to the three scenarios displayed in (b), where the current mixed geographical origin of HDPE is considered. The diagrams illustrate the contribution of processes embedded in the supply chain of the three scenarios (cradle-to-gate), with background data from Ecoinvent 3.8⁹¹ considering the geography “Global”. Only streams exceeding 5% are represented. d Production cost of the process described in a against the market price of the respective product portfolio. The margin between the total cost and market price indicates the potential profit. FOC = fixed operating costs, CAPEX = capital expenditures, RoW = rest of the world. Breakdowns are available in Supplementary Tables 17–22.