Chemoselective Hydrogenation of Benzoic Acid over Ni–Zr–B–PEG(800) Nanoscale Amorphous Alloy in Water

A Zr and polyethylene glycol 800 [PEG(800)] modified Ni–B [Ni–Zr–B–PEG(800)] amorphous alloy catalyst showed excellent catalytic performance, comparable to noble metal catalysts, in the chemoselective hydrogenation of benzoic acid to cyclohexane carboxylic acid. The synergistic effect between Zr and PEG(800) is suggested to decrease significantly the agglomeration of the active Ni species, causing the Ni–Zr–B–PEG(800) to have a larger BET area, smaller particle size, and the greatest number of Ni active centers, accounting for its high activity in water. The solvent effect on the selectivity was studied in detail. The high polarity of the water favors the orientation of carboxyl group toward the solvent, resulting in the selective hydrogenation of the aromatic ring, thus leading to a high selectivity for production of cyclohexane carboxylic acid compared to that occurring in the low polarity cyclohexane.