Preparation of Bimetallic Cu.sub.xAg.sub.y Nanoparticles and their Catalytic Performance in Hydrogenation of 4-Nitrophenol with H.sub.2 to 4-Aminophenol

Bimetallic Cu.sub.xAg.sub.y (x, y = 1â9) nanoparticles were successfully prepared by a successive precipitation and reduction method using copper nitrate and silver nitrate as metal precursors, sodium hydroxide as a precipitant, and hydrazine hydrate as a reductant at 30 °C. In the bimetallic Cu.sub.xAg.sub.y nanoparticles, Ag nanoparticles well anchored at the surfaces of Cu nanoparticles. There exists an interaction between metallic Ag and Cu components through the electron transfer from Ag nanoparticle to Cu nanoparticle, which effectively improves the catalytic activities of the bimetallic Cu.sub.xAg.sub.y nanoparticles in the hydrogenation of 4-nitrophenol with gaseous hydrogen to 4-aminophenol. When the bimetallic Cu.sub.7Ag.sub.3 nanoparticles catalyzed the hydrogenation reaction at 90â150 °C, the experimental data could be well fitted by a powder type reaction kinetic model. The simulated activation energy, Ea, is 40.8 kJ·mol.sup.â1, which reveals that the catalytic hydrogenation of 4-nitrophenol with gaseous hydrogen to 4-aminophenol on the bimetallic Cu.sub.7Ag.sub.3 nanoparticle catalyst can be conducted under a mild reaction condition.