On the Principles of Modelling of Homogeneous−Heterogeneous Reactions in the Production of Fine Chemicals. A Case Study:  Reductive Alkylation of Aromatic Amines

A kinetic model for the reductive alkylation of aromatic amines, which implies a combination of homogeneous and heterogeneous reactions, was developed. The kinetic model was combined with a reactor model for a semibatch reactor, traditionally used for the reductive alkylation on both laboratory and industrial scale. The system was modelled as a three-phase system, with mass-transfer limitations at the gas−liquid interface. The mass-transfer resistances at the outer surface of the catalyst and inside the catalyst were considered to be negligible, since very finely dispersed catalyst particles were used. The kinetic parameters were determined for a system containing an aromatic amine with one alkyl substituent and an aldehyde. The results revealed that it is possible to describe this kind of complex reaction system with very few parameters.