Single-atom calcium catalysts with C-N-Ca coordination improve the efficiency of preparing olefins from plastics

Catalytic pyrolysis of waste plastics to high-value olefins offers a sustainable route to address pressing global white pollution and realize plastic resource recycling, yet it faces a long-standing core dilemma limiting industrial application: low-cost calcium-based catalysts suffer from critical activity and stability defects under high-temperature conditions, while high-performance single-atom catalysts rely heavily on expensive noble or transition metals with poor industrial scalability. Notably, alkaline-earth metal single-atom catalysts remain largely underexplored for this high-temperature plastic pyrolysis application, with no mature catalytic system reported to date. Herein, we designed and fabricated a calcium single-atom catalyst with a well-defined carbon-nitrogen-calcium coordination structure through a facile synthetic strategy, to address these technical bottlenecks and enable efficient polypropylene pyrolysis for targeted olefin production. Calcium atoms are atomically dispersed and stably anchored on nitrogen-doped carbon supports via C-N bonds, fully overcoming the sintering-induced deactivation and active site loss of traditional calcium oxide-based catalysts. This catalyst exhibits an outstanding pyrolysis oil yield of 96.19 wt% with 73.82 wt% olefin selectivity; it also markedly reduces reaction activation energy, promotes selective β-scission of polymer chains, suppresses undesired byproduct formation, and retains atomic-level dispersion even after multiple cyclic reactions. This work provides a low-cost, high-efficiency catalyst for waste plastic upcycling, and lays a critical theoretical foundation for the rational design of alkaline-earth metal single-atom catalysts for high-temperature pyrolysis systems.