Facile water-free synthesis of noble metal-containing hydrotalcites-derived materials and their application for hydrotreatment of anisole

A novel, solvent-free, atom-efficient, and environmentally friendly method for preparing nickel-based hydrotalcite (HT) materials containing group VIII metals was established. A series of nickel-based (NiRu, NiRh, NiIr, NiSn, NiFe, NiCo, NiIn, and NiAl) HT-type materials were successfully synthesized using a facile water-free solid-state grinding method. The precursor-gel obtained by solid-state grinding facilitates efficient hydrolysis of metal salts by the use of ammonium hydroxide and results in the formation of layered HT materials. The presence of layered HT structure was evident from the powder X-ray diffraction (XRD) analysis. The method provides the complete conversion of metal precursors into the corresponding HT materials in an atom-efficient manner. The developed nickel-based HT materials were highly efficient and reusable catalysts for the hydrotreatment of the lignin-derived model compound, anisole. Among the several catalysts prepared, the one based on nickel-ruthenium catalysts showed complete conversion of anisole with 86% selectivity toward cyclohexane under optimum reaction conditions. The presence of in-situ generated metallic nickel‒ruthenium species on the surface of the catalyst, as evident from XPS, TEM, and XRD analysis of the spent catalyst, was responsible for the observed superior catalytic activity.