Copper-based nanoparticles supported on functionalized kaolinite for catalytic reduction of nitroaromatic compounds

A catalyst was synthesized by in situ reduction of Cu(II) ions on kaolinite particles. The clay mineral was modified by grafting propane sultone, to promote the stability of the catalyst and the good distribution of metal particles. Physicochemical characterizations revealed that the abundant synthesized metallic particles (mainly copper(I) oxide (Cu2O) although metallic copper particles were also present)) were of nanometric sizes. The catalyst was successfully applied for the catalytic reduction of three nitroaromatic compounds (4-nitrphenol, 4chloronitroaniline, and 4-nitrocatechol). The variation of some experimental parameters was performed and marked effects on reaction rates were observed (increase with the catalyst concentration and decrease with the concentration of nitroaromatic compounds). An attempt to elucidate the mechanism of the catalytic reaction revealed that the adsorption of dihydrogen on the metal particles controlled the reaction rate while the adsorption of the nitroaromatic compounds controlled the induction time preceding the reduction reaction.