Synergistic Roles of Hexagonal Boron Nitride-Supported Cu0 and Cu+ Species in Dehydrogenation of Ethanol to Acetaldehyde: A Computational Mechanistic Study

Abstract

Copper-based catalysts have been widely used in the dehydrogenation of ethanol to acetaldehyde due to their high activity. However, the inhibition of sintering and the identification of active sites remain challenging. In this work, by means of periodic density functional theory calculations, the catalytic mechanism is reported at the molecular level. The strong metal–support interaction between Cu 3d orbitals and O 2p orbitals and the electron transfer determine the high stability of copper clusters supported on h-BN. The enhancement of the interfacial interaction (binding energies of −11.0 and −12.5 eV on Cu+/BN and Cu0/BN, respectively) resists the sintering of copper clusters and benefits the retention of their active states. The free energy barriers to the C–H bond cleavage are 1.20, 0.90, and 0.53 eV on Cu(111), Cu0/BN, and Cu+/BN, respectively, and the barriers to the dihydrogen formation are 0.42, 1.51, and 2.36 eV, respectively. The results show the promotion of the d-band in the supported Cu+ and Cu0 species and introduce a synergistic effect of the two species, with Cu+ participating in the dehydrogenation of ethanol to acetaldehyde and Cu0 in the formation of H2. This work explains the origin of the resistance of h-BN-supported copper clusters against their sintering and identifies the synergistic roles of the Cu+ and Cu0 species in ethanol dehydrogenation This knowledge is expected to contribute to the rational design of heterogeneous copper-based catalysts for efficient ethanol dehydrogenation.