Initial rate study on the vapor‐phase condensation of aniline to diphenylamine

The vapor‐phase condensation of aniline to diphenylamine has been studied in a downflow differential reactor at 370–426°C and under atmospheric pressure using H‐151 ALCOA catalyst. An initial rate equation based on the Langmuir‐Hinshelwood model, i.e. surface reaction control with a similar dual site mechanism, has been proposed: r o = (k 1 K A 2 p Ao 2 )/ (1 + K A p Ao ) 2 The effects of different mass transfer resistances, of longitudinal and of radial dispersion have been taken into consideration. The rate constant value at 404°C is 1.488 × 10 −7 (k mol)/ (s) (kg cat) [5.358 × 10 −4 (mol)/ (h) (g cat)] and the activation energy is calculated to be 123.3 kJ/mol [29.45 k cal/mol] in the working temperature range.