Enhanced demethylation of aromatic ether to phenol over NiAl hydrotalcite-derived nickel sulfide catalyst

The production of phenol from lignin or its model compounds, instead of cumene oxidation is very interesting from the viewpoint of sustainability and economics. The selective demethylation of anisole was an efficient but challenging route to produce phenol. In this work, we demonstrated the fabrication of nickel sulfide (Ni9S8+NixS6) nanoparticles on Al2O3 matrix by a facile in situ sulfidation of NiAl hydrotalcite and announced that nickel sulfide can serve as efficient active site for the demethylation of anisole for the first time. The asdesigned 4Ni1Al-S catalyst exhibited a hierarchical morphology with a high particle density and high dispersion, affording a 95.6% yield of phenol in the demethylation of anisole under relative milder reaction temperature (270 degrees C) when compared to the reported state-of-the-art results. By comprehensive characterizations and experiments, we inferred that the nickel sulfide exsolved from the LDH structure exhibited stronger metalsupport interaction than that obtained from the impregnation method, which not only benefits the uniform dispersion of active nickel sulfide but also results in the electronic transfer from Ni center to Al2O3 support. As a consequence, enhanced demethylation activity was achieved on 4Ni1Al-S in comparison to Ni-S/Al2O3-IM.

Automated summary

This study successfully used nickel sulfide as a catalyst for the demethylation of anisole, achieving a high yield of phenol (95.6%) at a relatively low reaction temperature. Through comprehensive characterization and experiments, it was found that the strong metal-support interaction between nickel sulfide and alumina support on the catalyst facilitated the dispersion of nickel sulfide and enhanced the demethylation activity.