PROCESS FOR PREPARING 4-AMINODIPHENYLAMINE
A process for preparing 4-aminodiphenylamine having the steps of reacting nitrobenzene and aniline in the presence of a complex base catalyst, hydrogenating the reaction mixture with hydrogen, a powdery composite catalyst, and a hydrogenation solvent; separating, recovering, and reusing the complex base catalyst and the powdery composite catalyst from the reaction mixture; separating, recovering, and reusing aniline, and optionally water, from the reaction mixture; refining the reaction mixture to obtain 4-aminodiphenylamine. The complex base catalyst comprises tetraalkyl ammonium hydroxide, and tetraalkyl ammonium salt.
1 . A process for preparing 4-aminodiphenylamine comprising
reacting nitrobenzene and aniline in presence of a complex base catalyst to form a reaction mixture;
hydrogenating the reaction mixture in presence of hydrogen, a powdery composite catalyst, and a hydrogenation solvent;
separating, recovering, and reusing the complex base catalyst and the powdery composite catalyst from the reaction mixture;
separating, recovering, and reusing aniline, and optionally water, from the reaction mixture;
refining the reaction mixture to obtain 4-aminodiphenylamine,
wherein the complex base catalyst comprises tetraalkyl ammonium hydroxide, and tetraalkyl ammonium salt.
2 . The process of claim 1 , where the complex base catalyst further comprises alkali metal hydroxide.
3 . The process of claim 1 , wherein the powdery composite catalyst comprises nickel, aluminum, and a component A that is at least one selected from the group consisting of Fe, Cu, Co, Mn, Cr, Mo, B and P.
4 . The process according to claim 1 , wherein the condensation reaction is carried out under conditions of a molar ratio of nitrobenzene to aniline of from 1:1 to 1:15, a reaction temperature of from 20 to 150° C., a reaction pressure of from 0.005 to 0.1 MPa (absolute pressure), and a reaction time of from 3.5 to 6 hours.
5 . The process according to claim 1 , wherein a molar ratio of hydroxide ion in the complex base catalyst to nitrobenzene is in a range of from 1:4 to 4:1.
6 . The process according to claim 1 , wherein the reaction of aniline and nitrobenzene is carried out in the absence of oxygen.
7 . The process according to claim 1 , wherein proton material is not controlled during the reaction of aniline and nitrobenzene.
8 . The process according to claim 1 , wherein the hydrogenation reaction is carried out at a volume ratio of hydrogen gas to a sum of the hydrogenation solvent and the reaction mixture in a range of from 10:1 to 1500:1, a weight ratio of the powdery composite catalyst to the sum of the hydrogenation solvent and the reaction mixture in a range of from 0.5:100 to 16:100, and a weight ratio of the hydrogenation solvent to the reaction mixture in a range of from 1:10 to 5:10.
9 . The process according to claim 8 , wherein a reaction temperature of the hydrogenation reaction ranges from 50 to 100° C., a reaction pressure of the hydrogenation reaction ranges from 0.2 to 3.0 MPa (absolute pressure), and the reaction time ranges from 2 to 7 hours.