Highly efficient hydrogenation of phenol to cyclohexanol over Ni-based catalysts derived from Ni-MOF-74

Abstract

The design of highly efficient noble-metal-free catalysts for fast hydrogenation of phenol to cyclohexanol is of great significance and quite challenging. Nickel-based Ni@C-T catalysts derived from Ni-MOF-74 with different pyrolysis temperatures (T) were prepared and characterized by various methods. The effect of T on the selective hydrogenation of phenol over Ni@C-T was studied. The results showed that metallic Ni is identified as the main activity site for the hydrogenation of phenol and the active metallic Ni was formed at the pyrolysis temperature higher than 400 °C. Ni@C-400 exhibited the best performance under mild conditions. The conversion of phenol reached 100% with a cyclohexanol selectivity of 100% under the reaction conditions of a temperature of 120 °C, a H₂ pressure of 2.0 MPa and a time of 2 h, which are more excellent than those of reported catalysts. Furthermore, Ni@C-400 showed perfect reusability. The excellent catalytic performance of Ni@C-400 was associated with its high surface area and better dispersion of active sites due to the metal–organic framework.