Reduction Of Nitrobenzene With Hydrazine Hydrate By The Iron Oxide Catalysts Modified By PVP

In this paper, a series of different proportions of FeCl₃/PVP colloid nanoparticles catalyst has been successfully synthesized through the hydrothermal process using polyvinyllpyrroh -done (PVP) as protective agent. Effects of hydrothermal time and protective agent dosage on the performance of FeCl₃/PVP colloidal catalyst for the reduction of nitrobenzene were investigated. The yield of aniline was studied by reaction temperature, hydrazine hydrate dosage, and catalyst dosage. The structure and morphology of the colloidal catalysts were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the hydrothermal treatment time,PVP and FeCl₃ molar ratio made the catalyst particles size, morphology and the stability different. Under hydrothermal treatment conditions, n(PVP):n(FeCl₃)=1:40, temperature 100℃, time 2 h, the high-stability, high-dispersion, club-shaped colloidal catalyst with a size of 70⁹0 nm were prepared. The FeCl3/PVP colloidal catalyst exhibits high catalytic activity for reduction of nitrobenzene reduced by hydrazine hydrate under the conditions: nitrobenzene 4.89 mmol, absolute alcohol 5 mL, 2.0 mL FeCl3/PVP colloidal catalyst(nFe=0.1500mmol), n(hydrazine hydrate):n(nitrobenzene) =2.5, 80℃for 80 min, the yield of aniline could reach 100.00%.Meanwhile, we prepared Fe3O4 modified by PVP, focused on exploration effect of hydrazine hydrate dosage when prepared the catalyst, reducing agent added approach and the catalyst treatment to remove the PVP for reduction of nitrobenzene, the results showed that the presence of PVP greatly enhanced the catalytic activity of Fe₃O₄/PVP.We also tried to prepare FeCl3/PVP colloid and then supporting on activated carbon .we found that free-transition metal exist in the catalyst, the activated carbon still had effection. Especially the activated carbon treated by the hydrochloric acid and in nitrogen atmosphere under the conditions of high temperature calcination, the yield of aniline could reach 100.00% in 2.5h.