Selective Hydrogenation of Lignin-Derived Phenols by Ultrafine Co–Ni Bimetallic Alloy Embedded on Dendritic Mesoporous Silica Nanoreactor

Abstract

The rational design of catalyst structure to enhance the hydrogenation activity of lignin-derived phenols is crucial but remains challenging. In this paper, an efficient dendritic mesoporous silica capsulated ultrafine Co-Ni alloy catalyst (CoNi₃@DMSN) was constructed for hydrogenation of phenol to cyclohexanol, and a 99% yield was achieved under relatively mild conditions (150 °C, 1 MPa, 4 h). The characterization results confirmed that the introduction of Ni species to construct Co-Ni alloy sites could adjust the electronic structure and acidity of the catalyst, thereby improving the catalytic performance. The theoretical calculation results revealed that the adsorption energy of phenol on the catalyst changed from −1.647 to −2.187 eV, the adsorption energy of H₂ changed from −2.943 to −1.642 eV, and the d-band center shifted from −1.894 to −1.941 eV after the introduction of Ni species. The Gibbs free energy changes of the reaction process further verified that the CoNi₃@DMSN catalyst exhibited high catalytic performance. In addition, the as-prepared CoNi₃@DMSN catalyst showed good stability within six cycles, which was also applicable to other lignin-derived phenolic compounds with similar structures. This study provides new ideas for the design of hydrogenation catalysts with high selectivity.