Dual functions of CoOx decoration in PtCo/CeO2 catalysts for the hydrogen-borrowing amination of alcohols to primary amines

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. CoOx decoration over Pt/CeO2 is able to enhance both selectivity to primary amine and catalytic activity. These CoOx 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 CoOx additive have two causes: (1) CoOx species provide an additional Pt-CoO interface for the rate-determining dehydrogenation step; (2) CoOx species block low-coordinated Pt sites for H-2 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. (C) 2019 Elsevier Inc. All rights reserved.