Cobalt Nanocluster Supported on ZrREnOx for the Selective Hydrogenation of Biomass Derived Aromatic Aldehydes and Ketones in Water

In this study, rare earth (RE) metal doped ZrO 2 was prepared by a surfactant-assisted coprecipitation/hydrothermal crystallization method and used to load Co as catalyst for the hydrogenation of aromatic carbonyl compounds in water. Furfural was hydrogenated to furfural alcohol in water with up to 95 mol % yield over Co/ZrLa 0.2 O x at 40 °C, 2 MPa H 2 in 10 h. The doping of rare earth metal oxide has three advantages: (I) it promotes the ZrO 2 to reach a small-sized, stable, and high-activity tetragonal phase zirconia and thus lead to a high specific surface area for metal loading; (II) it interacts with Co to reach an ultrasmall average particle size of 1.1 nm; and (III) it modifies the ZrO 2 surface to increase the amount of acidic sites for the adsorption of carbonyl feedstock. The adsorption experiment indicated a tight interaction between not only the carrier and C═O bond but also the Co clusters and C═O bond, which were of benefit for the hydrogenation of carbonyl groups. The surfactant addition during the carrier preparation improves the strong metal–support interactions (SMSI) to promote Co dispersion and stability. Various rare earth metals including La, Pr, Nd, and Ce could modify ZrO 2 with a similar mechanism. The as-prepared Co catalyst could also catalyze the selective hydrogenation of various aromatic aldehydes and ketones (such as 5-hydroxymethyl furfural, benzaldehyde, and acetophenone) in water, and 100% yield to corresponding alcohols was achieved. The catalyst remained stable and showed little deactivation during the recycling tests. This study not only presented a high-efficient, low-cost, and stable catalyst for the selective hydrogenation of various aromatic aldehydes and ketones but also give rise to an understanding of rare earth metal oxide doped ZrO 2 supported nano Co ternary catalysts.