Phyllosilicate-derived Ni/SiO2 catalyst for liquid-phase hydrodeoxygenation of phenol: Synergy of Lewis acid sites and Ni0

Abstract

Designing effective catalysts using non-noble metals for bio-oil hydrodeoxygenation (HDO) into liquid fuels is greatly sought after, yet it remains a great challenge. Contrary to the prevailing belief that monometallic nickel lacked activity in the HDO of oxygen-containing compounds, this study demonstrates a remarkable catalytic performance over monometallic Ni catalyst. Herein, a Ni/SiO2 catalyst having both nickel phyllosilicate and Ni0 was synthesized by the ammonia evaporation (AE) method. The Ni-PS-400 catalyst reduced at 400 ℃ achieves a significant high activity and yields 97 % cyclohexane at a low reaction temperature of 190 ℃, surpassing both Ni-IMP-400 prepared by impregnation method and most of the reported other non-noble metal catalysts which are generally used at high temperature of above 240 ℃. It was found that the reduction temperature of Ni-PS-X influences the catalytic activity, as more dispersed Ni nanoparticles and acidic sites can be produced on the surface of the support at an appropriate temperature. The outstanding catalytic performance can be ascribed to the collaborative effect of well-scattered Ni nanoparticles and the significant presence of Lewis acidic sites, which result from coordinatively unsaturated Ni2+ sites situated within the remaining nickel phyllosilicate.