科研之友
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摘要
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, La2O3-modified Ni/SiO2 catalysts were prepared and applied to the hydrogenation of m-dinitrobenzene to m-phenylenediamine. The effect of La2O3 loading on the properties of Ni/SiO2 was investigated. The reaction kinetic study was performed in ethanol over Ni/3%La2O3-SiO2 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 La2O3 loading. Ni/3%La2O3 -SiO2 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%La2O3 -SiO2 catalyst can be reused at least six times without significant loss of activity. CONCLUSION: La2O3 shows strong promotion of the effect of Ni/SiO2 catalyst for liquid-phase hydrogenation of m-dinitrobenzene. La2O3 loading can affect the properties of Ni/SiO2 catalyst. Based on the study of m-dinitrobenzene hydrogenation kinetics over Ni/3%La2O3-SiO2 catalyst, a possible reaction mechanism is proposed.
