Intensifying Hydrogen Heterocracking via Regulating the ZnO Overlayer for Enhanced Fatty Acid Ester Hydrogenation

Abstract

Hydrogenation of renewable fatty acid esters represents a clean route to synthesize fatty alcohols, crucial building blocks in fine chemicals. Nevertheless, the sluggish H2 dissociation and C═O bond activation significantly hinder the reaction rate in this approach. Herein, we successfully developed an inverse Ni-ZnO interface to intensify H2 heterocracking for enhanced hydrogenation of fatty acid esters to fatty alcohols. By regulating the calcination temperature of supports, a tunable degree of ZnO overlay coating on Ni nanoparticles is obtained in the Ni/ZnO catalysts. In particular, the partially coated Ni/ZnO calcinated at 500 °C exhibits typical characteristics of Frustrated Lewis acid–base pairs, where the Ni cluster serves as the Lewis acid and nearby Zn–Ov serves as the Lewis base, to promote the heterolytic cleavage of H2 at the Ni-ZnO interface. The as-formed Hδ-/Hδ+ pairs attack the positively charged C and negatively charged O atoms in the C═O bond, leading to superior hydrogenation activity. This work gives deep insight into the structure–activity relationship governing polar functional group hydrogenation and spots some opportunities for the design of highly efficient interfacial catalysts.