Hydrogenation of m‐dinitrobenzene to m‐phenylenediamine over La2O3‐promoted Ni/SiO2 catalysts

Abstract BACKGROUND: Liquid‐phase catalytic hydrogenation of m‐dinitrobenzene is an environmentally friendly routine for m‐phenylenediamine production. The key to increasing product yield is to develop catalysts with high catalytic performance. In this work, La 2 O 3 ‐modified Ni/SiO 2 catalysts were prepared and applied to the hydrogenation of m‐dinitrobenzene to m‐phenylenediamine. The effect of La 2 O 3 loading on the properties of Ni/SiO 2 was investigated. The reaction kinetic study was performed in ethanol over Ni/3%La 2 O 3 –SiO 2 catalyst, in order to clarify the reaction mechanism of m‐dinitrobenzene hydrogenation. RESULTS: It was found that the activity of the silica supported nickel catalysts is obviously influenced by La 2 O 3 loading. Ni/3%La 2 O 3 –SiO 2 catalyst exhibits high activity owing to its well dispersed nickel species, with conversion of m‐dinitrobenzene and yield of m‐phenylenediamine up to 97.1% and 94%, respectively. The results also show that Ni/3%La 2 O 3 –SiO 2 catalyst can be reused at least six times without significant loss of activity. CONCLUSION: La 2 O 3 shows strong promotion of the effect of Ni/SiO 2 catalyst for liquid‐phase hydrogenation of m‐dinitrobenzene. La 2 O 3 loading can affect the properties of Ni/SiO 2 catalyst. Based on the study of m‐dinitrobenzene hydrogenation kinetics over Ni/3%La 2 O 3 –SiO 2 catalyst, a possible reaction mechanism is proposed. Copyright © 2009 Society of Chemical Industry