Preparation and catalytic evaluation of Au/γ-Al2O3 nanoparticles for the conversion of 4-nitrophenol to 4-aminophenol by spectrophotometric method

A set of catalysts having gold nanoparticles deposited on gamma-Al2O3 (Au/gamma-Al2O3) with lowest effective amount of gold content were prepared by successive impregnation and hydrogen reduction method. The structural features of prepared catalysts were analysed by X-ray diffraction (XRD), N-2 physisorption, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). The catalytic activity was evaluated for the reduction of an organic pollutant 4-nitrophenol (4NP) to 4-aminophenol (4AP) by spectrophotometric analysis. Supported catalyst presented excellent catalytic ability to convert 4NP to 4AP in the presence of sodium borohydride (SBH) due to synergistic effect of Au NPs and mesoporous gamma-Al2O3 support. The reduction reaction was also performed at a range of temperatures to calculate kinetic parameters. The development of highly stable Au/gamma-Al2O3 catalysts with lowest noble metal content and recyclability made the process cost effective and may promote their applications in various fields including removal of organic pollutants in industrial waste water and high-temperature gas-phase reactions.