Engineering topics
Publications and source records attributed to Moura, Pedro.
Here, a critical component of plastics waste, polyvinyl chloride, is tough to recycle efficiently and sustainably owing to its high chlorine content. Now, research shows how to convert polyvinyl chloride mixed with polypropylene, at room temperature, into chlorine-free hydrocarbons.
We explore hydrogenolysis over ruthenium supported on zirconia (Ru/ZrO 2 ) and hydrocracking over platinum (Pt) supported on zeolites as an effective end-of-life strategy for ethylene vinyl acetate (EVA)–a widely used performance heat sealant in hard-to-recycle multilayer packaging. For Ru/ZrO 2 hydrogenolysis, EVA reacts slower than low-density polyethylene (LDPE) and the catalyst deactivates due to carbonaceous deposits originating from polyenes generated in situ during EVA thermal degradation. High H 2 pressures and temperatures can overcome catalyst deactivation; however, CH 4 yields are excessive due to cascade hydrogenolysis stemming from strong C=C/metal interactions. Polyene hydrogenation allows chains anchored by C=C to desorb from Ru, shifting product selectivity from CH 4 to higher-value liquids. Hydrogenolysis of mixed EVA and linear low-density polyethylene (LLDPE), mirroring typical frozen food packaging formulations, results in comparable catalyst activity and CH 4 yield as the pure EVA resin. For Pt/zeolite hydrocracking, pure EVA and EVA:LLDPE mixtures are deconstructed to propane or light naphtha with minimal CH 4 production. Among catalysts tested, Pt/HY gives the highest liquid productivity (g C5+products /g cat ·h). Furthermore, these findings showcase the recalcitrant nature of EVA and its associated mixtures for Ru/ZrO 2 hydrogenolysis, highlighting that hydrocracking catalysts may be superior for complex packaging waste.