Abstract
The catalytic transfer hydrogenation of dimethyl-nitrobenzene (DN) to Dimethyl-aniline (DA) was studied in the temperature range 343–403<i>°K</i>, pressure range of 4–10 bar H<sub>2</sub> and ethanol as solvent using Ni on alumina-silicate as catalyst above agitation speed 800 rpm. The substrate feed concentration was varied in the range from 0.124 to 0.745 kmol/m<sup>3</sup> while catalyst loading was in the range 4–12% (w/w) of dimethyl-nitrobenzene. Dimethyl-aniline was the only reaction product, generated through the hydrogenation of the Nitro group of dimethyl-nitrobenzene. The effects of hydrogen partial pressure, catalyst loading, dimethyl-nitrobenzene concentration and temperature on the reaction conversion have been reported. Near first-order dependence on dimethyl-nitrobenzene concentration and hydrogen pressure were observed for the initial rate of dimethyl-nitrobenzene hydrogenation over the Ni catalyst. Furthermore, an increase in the catalytic activity as the reaction temperature, pressure and weight of catalysts was observed. Conventional Arrhenius behavior was exhibited by catalyst, Ni showed activation energies of 808 J/mol.
Highlights
Aromatic amines, widely used as important intermediates in the synthesis of chemicals such as dyes, antioxidants, photographic, pharmaceutical and agricultural chemicals, can be obtained by the reduction of corresponding aromatic nitro compounds using catalytic hydrogenation and a variety of other reduction conditions
The main purpose of this study was to evaluate the effects of parameters such as hydrogen pressure and temperature on the rate of dimethylnitrobenzene hydrogenation over a Ni catalyst in ethanolwater two components solvent
The following assumption was made while studying the heterogeneous catalytic hydrogenation reactions: 1. The activity of the catalyst is maintained throughout in all the experiment, that is, that no poisoning or deactivation of the catalyst occurs
Summary
Widely used as important intermediates in the synthesis of chemicals such as dyes, antioxidants, photographic, pharmaceutical and agricultural chemicals, can be obtained by the reduction of corresponding aromatic nitro compounds using catalytic hydrogenation and a variety of other reduction conditions. The selective hydrogenation of nitro compounds is commonly used to manufacture amines, which are important intermediates for dyes, urethanes, agro-chemicals and pharmaceuticals. Hydrogenation of nitro aromatics are used to produce aniline derivatives, which can be carried out in gas or liquid phase by using supported metal catalysts and organic solvents such as alcohols, acetone, benzene, ethyl acetate, or aqueous acidic solutions [4]. The use of these solvents has some drawbacks owing to their toxicity, flammability, or environmental hazards. Solvents are known to have a Mansoor Kazemimoghadam: Catalytic Hydrogenation of Dimethyl-Nitrobenzene to Dimethyl-Aniline in a
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