NiO x -promoted Cu-based catalysts derived from CuNi phyllosilicates were synthesized, characterized, and tested in the selective hydrogenation of adipic acid to 1,6-hexanediol. The reduction of the CuNi phyllosilicate allows finely dispersed Cu0 and Cu+ on the surface. The reduced Cu36Ni5PS catalyst was found to have a higher turnover frequency for the selective hydrogenation of adipic acid than the reduced Cu41PS, Cu40Ni1PS, and Cu31Ni10PS catalysts. This catalyst is also effective at hydrogenation of succinic acid, glutaric acid, butyric acid, pentanoic acid, and hexanoic acid to their respective alcohols. The higher activity of the reduced Cu36Ni5PS catalyst is attributed to a higher oxidation state of Cu cations.

A reduction–silylation–reduction method was developed to synthesize hydrophobic Cu catalysts derived from Cu phyllosilicates (CuPS). Triethoxy­(octyl)­silane (OTS) was used as the coupling agent. The OTS-grafted, reduced CuPS catalysts were applied in the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The most promising catalyst was synthesized by reducing CuPS at a high temperature (350 °C for 3 h), followed by OTS grafting, and then by repeating the previous reduction step. High LA conversion (95.7%), GVL yield (85.2%), and stability (3 cycles with a 7.5% loss of initial activity) were obtained at a mild reaction condition (130 °C with a H2 pressure of 12 bar). A high reduction temperature not only leads to a low oxidation state of Cu species but also suppresses the formation of silylation-induced acids. Moreover, the intrinsic activity of a reduced CuPS catalyst was nearly intact after subjecting to silylation and the second reduction treatment.