Comparative Study on the Effect of Support for Nanonickel Catalyst in Reduction of Nitrophenols

Abstract

THE CATALYTIC reduction of para- and ortho- nitrophenols to the corresponding aminophenols was investigated over Ni/TiO 2 catalysts prepared by reduction method. Hydrazine hydrate in the presence of nickel ions supported on TiO2 was used in the preparation of nanonickel catalyst over rutile and anatase. Further decomposition of the hydrazine hydrate on the nickel atoms surfaces yields nascent hydrogen atoms that efficiently reduce the nitro groups. Many techniques such as XRD, IR, TEM and UV-Visible absorption spectroscopy have been used. TEM shows the formation of nanonickel clusters on TiO2. IR analysis confirms the appearance of the characteristic peaks of only ortho or para aminophenols. The kinetics of reduction reaction was studied. Catalyst recovery and factors affecting the reduction reaction such as phenol concentration, pH, catalyst loading and temperature have been studied. The obtained data and kinetic results show that the conversion percentage reaches 100% within few minutes. The results indicate that the nanonickel loaded over rutile or anatase TiO2 exhibit nearly the same catalytic activity in reduction of nitrophenols but more active than nanonickel in zeolite catalyst.

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