Abstract:

Amines, especially primary amines, are value-added fine chemicals widely used in modern industries. Here, a PtCo/CeO₂ catalyst is designed for the hydrogen-borrowing amination of alcohols, especially the conversion of cyclopentanol to cyclopentanylamine. CoO_x decoration over Pt/CeO₂ is able to enhance both selectivity to primary amine and catalytic activity. These CoO_x species play two roles in alcohol amination, enhancing alcohol dehydrogenation and inhibiting overhydrogenation of a Schiff base intermediate (cyclopentyl cyclopentylidene amine). Comprehensive characterization demonstrates that promotional effects of the CoO_x additive have two causes: (1) CoO_x species provide an additional Pt-CoO interface for the rate-determining dehydrogenation step; (2) CoO_x species block low-coordinated Pt sites for H₂ activation in the overhydrogenation of the Schiff base intermediate, thus suppressing the formation of undesirable secondary amines. This work provides an in-depth understanding of the role of the CoOx additive in PtCo/CeO₂ and new insights into the design of Pt-based catalysts for primary amine production via hydrogen-borrowing amination.

Full paper link: https://doi.org/10.1016/j.jcat.2019.08.024