Nitrobenzene was hydrogenated at a H-2-pressure of 0.5...4MPa and a te
mperature of 310...370K, using Ni/SiO2, and Pt/C as catalysts. During
the hydrogenation the catalyst's electrochemical potential was kept at
a given level by regulation of the nitrobenzene feed (potential contr
olled hydrogenation). If the substrate concentrations are increased to
values about some percent the hydrogenation rate decreases. Reaction
instabilities caused by this effect can be reliably avoided by potenti
al controlled substrate supply.