Bimetallic Synergy in Hydroxyapatite-Supported NiRe Nanocatalysts for Mild and Efficient Arene Hydrogenation

Abstract

The development of cost-effective catalysts for mild arene hydrogenation is essential for the advancement of sustainable chemical processes. We present a rhenium-promoted nickel catalyst supported on hydroxyapatite (NiRe_0.5/HAP) that enables efficient arene hydrogenation under mild conditions (50–130 °C, 0.5–2.0 MPa of H₂). Using toluene hydrogenation as a model reaction, NiRe_0.5/HAP (4.81 h^–1 TOF) demonstrates nearly 13 and 30 times the catalytic activity of monometallic Ni/HAP (0.36 h^–1 TOF) and Re/HAP (0.16 h^–1 TOF), respectively, at 50 °C and 1.0 MPa of H₂. Structural and mechanistic studies reveal a trifunctional role of Re: (1) geometrically isolates Ni sites, preventing sintering and forming a highly dispersed NiRe bimetallic species that enhances surface accessibility of metal active sites; (2) modulates the electronic properties of Ni via Ni-to-Re electron transfer, accelerating H₂ dissociation and promoting hydrogenation; and (3) increases Lewis acidity, facilitating aromatic ring adsorption. The NiRe_0.5/HAP catalyst exhibits broad substrate compatibility, efficiently hydrogenating functionalized aromatics and heterocycles in yields of up to 99%. Notably, it enables the complete hydrogenation of aromatic polyester polyethylene terephthalate (PET), yielding (bio)degradable polyethylene-1,4-cyclohexanedicarboxylate (PECHD), highlighting the robustness of this system. This work presents a synergistic electronic-geometric design strategy for non-noble bimetallic catalysts, delivering noble-metal-like performance with the cost advantages of transition metals for sustainable arene valorization.