Electronic Waste-to-Catalyst Upcycling: Selective Lignin C–O Bond Hydrogenolysis and RCF over a Cu–Iron Oxide/P-Doped Carbon Catalyst

Abstract

The development of sustainable catalysts from secondary waste resources provides an attractive strategy for addressing both electronic-waste management and biomass valorization challenges. In this work, a multifunctional heterogeneous catalyst (ML@ATP₁/CP₂-60) was constructed by integrating copper recovered from a discarded motherboard, toner powder-derived iron oxide, and phosphorus-doped carbon derived from chitosan as a heteroatom-engineered support. Comprehensive structural and surface characterization using XRD, Raman spectroscopy, XPS, HR-TEM, EPR, and temperature-programmed desorption analyses confirmed the formation of mixed-valence Cu species anchored on a defect-rich spinel iron oxide framework with interfacial acidic sites associated with iron oxide and P–O functionalities. The catalyst exhibited excellent activity and selectivity for the hydrogenolysis of benzyl phenyl ether, achieving complete conversion with exclusive formation of phenol and toluene via selective cleavage of the benzylic C(sp³)–O bond without aromatic ring hydrogenation. Mechanistic investigations, including selective poisoning experiments, revealed a cooperative dual-site pathway involving Cu-mediated hydrogen activation and adjacent acidic centers responsible for ether bond polarization. Importantly, the catalyst demonstrated effective performance in the reductive catalytic fractionation of wheat straw, affording aromatic monomers with molecular-weight distributions comparable to those obtained using conventional 5 wt % Ru/C while suppressing deep aromatic hydrogenation. CHEM21 green metrics analysis confirms the near-ideal intrinsic reaction efficiency of the protocol (AE ≈ 100%, RME = 97.6%), with solvent usage identified as the primary contributor to process-level mass intensity. These results highlight a strategy for transforming multiple waste streams into efficient catalytic platforms for selective lignin valorization.