The catalytic hydrogenation of adiponitrile is generally carried out industri-ally at high temperature and pressure over Ni-Raney catalysts, which have thedisadvantages of possessing low mechanical resistance and of being pyrophoric.In this work adiponitrile was hydrogenated in a three phase stirred slurry reactorusing rhodium over alumina powder as a catalyst instead. Catalysts were pre-pared with a ion exchange technique by contacting 100 micron alumina powderwith a solution of hydrate rhodium cloride for 36 h. The reaction runs were con-ducted in a 100 cc vessel at a pressure of 3 MPa and temperatures of 72 92?C varying the initial concentration of adiponitrile. A variety of series-parallelreactions took place when adiponitrile was contacted with hydrogen in our reac-tor. Attention was concentrated on hexamethylenediamine, the final product, andon aminocapronitrile, a very interesting intermediate which could be used subse-quently for caprolactam production (and from this the direct synthesis of nylon).Samples were withdrawn from the reactor at fixed interval of time and analysedwith a gas-chromatograph so that time dependency of reactant conversion andproduct selectivity could be determined. The results showed the expected quali-tative behaviour: adiponitrile conversion increased with time, as did the hexam-ethylenediamine selectivity, whereas aminocapronitrile selectivity showed a clearmaximum and then decreased to negligible values. The Chemical reaction en-gineering approach was used and proved sufficient to describe quantitatively theobserved kinetic behaviour of the reactor.
