Nickel-based heterogeneous catalysts for nitroarene reduction

Abstract

Silica-supported nickel (Ni/Q6) and silica-supported nickel phosphide (Ni₂P/Q6) catalysts were synthesized via wetness impregnation method using different metal loading amounts. The synthesized materials were characterized and confirmed the successful preparation of catalysts using X-ray diffraction (XRD), N₂ adsorption-desorption, and CO chemisorption. The characterization results showed that the use of 6% loading amount of Ni gave the highest surface area, highest pore volume, and highest metal dispersion among the synthesized materials. The synthesized catalysts were tested for their catalytic capabilities via the reduction reactions of 4-nitrophenol and several other nitroarenes to their corresponding aminoarenes. The catalytic results showed that the supported nickel phosphide catalyst with 6% nickel loading (6NiP-Q6) exhibited the highest catalytic activity and the reaction was completed within 5-6 min. The high reaction rate using 6NiP-Q6 as the catalyst could be mainly due to its higher metal dispersion and higher surface area. Lastly, the reusability test was performed to determine the sustainability and efficiency of the synthesized catalysts. It was confirmed that the catalysts could be reused up to four times without a significant loss in efficiency.