Efficient hydrogenation of biomass-derived phenol to cyclohexanol over 3D mesoporous silica-supported Ni catalysts in a continuous gas phase conditions

High surface area three-dimensional (3D-cubic SBA-16) and two-dimensional mesoporous silica (2D-hexagonal SBA-15) supported Ni composities were employed as active catalysts for industrially important cyclohexanol synthesis via phenol hydrogenation. Among synthesised porous materials, Ni/SBA-16 catalysts were dramatically displayed a superior activity compared to Ni/SBA-15 catalysts. It was obviously due to three-dimensional Ni/SBA-16 catalysts were exhibited unusual surface textural properties, like adequate surface area, interconnected-cage type pore structure and thermal stability. Moreover, uniformly distributed smaller size Ni nanoparticles results in efficient utilisation of external H-2 source for highest phenol reduction on porous SBA-16 material, compared to SBA-15 catalyst. Hence, 20 (wt.%) Ni/SBA-16 catalyst afforded a remarkable activity in terms of 91% phenol conversion and 79% cyclohexanol yield even after 8-h time-on-stream study. In contrast, 20 (wt.%) Ni/SBA-15 catalyst showed low catalytic activity about 28% phenol conversion and 19% cyclohexanol yield during the 8-h time-on-stream. All synthesized catalysts were characterised by X-ray diffraction (XRD), H-2 temperature-programmed reduction (H-2-TPR), scanning electron microscopy (SEM), BET surface area, transmission electron microscopy (TEM) techniques and inductive coupled plasma-optical emission spectroscopy (ICP-OES).