Heterogeneous tandem catalysis for regioselective hydroaminomethylation of olefins to linear amines by a composite catalyst

Abstract

Hydroformylation of olefins followed by reductive amination is a key route to aliphatic amines, yet industrial processes suffer from energy-intensive aldehyde isolation and side reactions. Hydroaminomethylation offers a one-pot alternative, but heterogeneous catalysts have long struggled to combine high linear regioselectivity with chemoselectivity due to mismatched kinetics and unselective hydrogenation. Here we report a heterogeneous tandem catalytic system comprising Rh@MFI zeolite for selective hydroformylation of α-olefins to linear aldehydes and Pd1Cu1/SiO2 for subsequent imine hydrogenation. The confined Rh species within the MFI framework deliver exceptional linear regioselectivity. In the PdCu alloy, Cu disrupts Pd ensembles, weakens multi-coordinated CO adsorption, and increases Pd electron density, thereby accelerating imine hydrogenation while suppressing competitive hydrogenation of olefins and aldehydes. This kinetic coupling enables the direct conversion of α-olefins and amines into linear secondary and tertiary amines with >99% regioselectivity and high yields (typically 85–98%) across a broad substrate scope. In situ X-ray absorption fine structure, infrared spectroscopy, and density functional theory calculations elucidate the origins of the (regio)selectivity and efficient tandem catalysis. The ligand-free, easily separable composite catalyst offers a practical, atom-efficient, and sustainable platform for producing high-value linear amines from abundant olefins.