Biologically bound nickel accelerated de-polymerization of polyethylene to high value hydrocarbons and hydrogen

The goal of a carbon-neutral society can be realized by utilizing a circular carbon pathway, which combines recycling, biomass utilization, carbon capture and utilization. Inspired by the potential of metal-contaminated biomass and plastic waste as valuable feed-stocks, we have developed a biologically-bound nickel catalyst (Ni-phytocat) to accelerate de-polymerization of polyethylene into high value chemicals. The synergistic effect of microwaves, together with Ni-phytocat as microwave absorbers, accelerate the catalytic de-polymerization process at low temperature (250 degrees C). The single step process typically takes up to 70 s to transform a sample of low-density polyethylene into liquid hydrocarbons (40-60% oil yield), hydrogen (11-30% gas yield) and filamentous carbon (25-37% solid yield), depending on varying catalyst to polymer weight ratios. The Ni-phytocat enhanced the production of C6-C12 aliphatics (up to 56% selectivity) and favored the aromatization of linear alkanes to form monocyclic aromatics (up to 33% selectivity), thereby releasing more H2 (up to 74% selectivity) as gaseous fractions. The enhancement of (de)hydrogenation, de-carboxylation and cyclization, utilizing Ni-phytocat can be established as a proof of concept to advance and enable selective transformation of polymeric consumer products, paving the way to harness complete circular chemical potential of these future feed-stocks. The synergy of Ni-phytocat and microwave driven process leads to highly desirable monocyclic aromatics and low molecular weight hydrocarbons, and H2, thereby paving the way to harness complete circular chemical potential of plastic waste.