Study On The Technology And Apparent Kinetics Of Continuous Liquid-Phase Condensation Of Aniline

Diphenylamine is a vital intermediate product of fine chemicals which has a multifarious range of uses such as rubber aids, explosive stabilizing agent,medicament, dye, and etc. In the synthesis technology of diphenylamine, the method of continuous liquid-phase condensation of aniline to diphenylamine in fixed bed tubular reactor is chosen as the research object and the technological conditions and apparent kinetics on the H-type of beta-zeolite molecular sieve catalyst (FD-20) is studied. Some progress has been made in the study on improving the conversion of aniline by the combination of ammonia separation and condensation reaction, and appropriate apparent kinetics model containing ammonia concentration has been achieved.A certain amount of H-type of beta-zeolite molecular sieve catalyst (FD-20) was packed in the fixed bed tubular reactor and the space time of aniline (input quantity of aniline), reaction temperature and pressure were changed in order to get the rules of per pass conversion of aniline and the selectivity of diphenylamine in the continuous liquid-phase condensation reaction. As a result, the optimal technological conditions of the reaction temperature, pressure and space time were confirmed.It is good to enhance the conversion of aniline by separating the ammonia from the reaction mixture in that the condensation reaction of aniline is a reversible reaction. The reaction mixture gained under the different reaction temperature, pressure and space time was tackled by the method of reduced pressure distillation, and then the influence on improving the fraction conversation of aniline by ammonia separation in the case of the same space time was researched after carrying out the condensation reaction with the tackled mixture at a second time. The experimental result declared that ammonia separation has a good effect in enhancing conversion of aniline and the technique of producing diphenylamine by coupling the ammonia separation and condensation is feasible.That the liquid-phase condensation reaction of aniline is a secondary reversible reaction has been conformed by analyzing the mechanism of liquid-phasecondensation of aniline on the solid catalyst surface and the apparent kinetics model containing the term of ammonia concentration was established. The hypothesis as plug flow was introduced, thus the model parameters and the rules of effect of reaction temperature on ammonia concentration have been estimated from the experimental data gained in the fixed bed tubular reactor. The feasibility and reliability of the established kinetics model has been proved by comparison between model values and experiment values. Furthermore, the necessity of ammonia concentration in the model is confirmed by testing the feasibility of the model reported by document.The research results have some values in developing new technological process about coupling liquid-phase condensation reaction and ammonia separation, intensifying the process of condensation reaction and designing the industrial reactor.