In Situ Hydrogenation of Methyl Palmitate to Hexadecanol on TiO2- and ZrO2‑Supported Ni–In Catalysts in the Aqueous Phase Using Methanol as a Hydrogen Donor

Selective hydrogenation of fatty acids/esters is an efficient way to produce fatty alcohols, and it is very promising to provide in situ H2 generated via aqueous phase reforming of hydrogen donors. Here, the supported Ni–In intermetallic compounds (IMCs) were prepared for in situ aqueous phase hydrogenation of methyl palmitate to hexadecanol using methanol as a hydrogen donor. First, the effects of Ni/In atomic ratio and metal loading on the performance of ZrO2-supported Ni–In IMCs were investigated. Different from metallic Ni that favors decarbonylation/decarboxylation generating n-pentadecane, all of the Ni2In, NiIn, and Ni2In3 IMCs facilitate the selective hydrogenation to yield hexadecanol. Therein, the ZrO2-supported NiIn IMC with a total metal loading of 40 wt % gives the best performance with a hexadecanol yield of 87.6%. Second, the performance of Ni–In IMCs on different supports [ZrO2, TiO2, Al2O3, SiO2, and activated carbon (AC)] was compared. ZrO2- and TiO2-supported NiIn IMC (especially TiO2) show higher stability than others. This is ascribed to their higher hydrothermal stability and interaction with the NiIn IMC, restraining the sintering and leaching of the NiIn IMC. During the four times recycling, the hexadecanol yield maintains ∼80% on the TiO2-supported NiIn IMC, while it slightly decreases from 87.6% to ∼83% on the ZrO2-supported NiIn IMC, the slight deactivation of which is due to carbon deposition. In contrast, Al2O3 is converted to boehmite under a hydrothermal condition, and there is remarkable leaching of Ni and In species from SiO2 and AC, all of which are detrimental to the catalyst stability.