Single-atom Cu catalyst in a zirconium MOF for highly selective hydrogenation of unsaturated aldehydes to unsaturated...

Achieving nearly 100% selectivity in the hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols, while maintaining complete conversion, remains a significant challenge in heterogeneous catalysis, especially with non-noble metals. Herein, we report an efficient single-atom Cu catalyst (Cu₁@MOF-808) constructed by covalently anchoring Cu atoms onto defective sites of Zr oxide clusters in MOF-808, where Cu species are chelated and stabilized via coordination with oxygen atoms from dangling -OH/-OH₂ groups. The unique configuration enables preferential adsorption of the C[double bond, length as m-dash]C bond at isolated Cu sites and the capture of H* by neighboring coordinated oxygen. This synergistic, spatially dispersed adsorption mechanism drives highly selective C[double bond, length as m-dash]O bond hydrogenation. The resultant Cu₁@MOF-808 catalyst achieves nearly 100% selectivity toward cinnamyl alcohol (COL) with full conversion of cinnamaldehyde (CAL). Mechanistic studies revealed that the high oxidation state of single-atom Cu sites, coupled with electron-rich oxygen coordination and Lewis acid sites, enables spatial separation between reactant adsorption and proton transfer, thereby effectively regulating the product desorption and optimizing the reaction pathway.