HYDROGENATION OF NITROTOLUENES CONTROLLED BY THE ELECTROCHEMICAL POTENTIAL OF THE CATALYST

The hydrogenation of 2-nitrotoluene, 2,4-dinitrotoluene and 2,4,6-trin itrotoluene on Pd/C, Pt/C and Ni/SiO2 catalysts was investigated in a liquid phase batch reactor at pressures between 0.4 and 2.5 MPa. The r eaction was controlled by regulating the substrate supply in such a wa y that the electrochemical potential of the catalyst and, consequently , the surface concentration of active hydrogen was kept at a constant level. The observed hydrogenation rate dependence on the concentration of active surface hydrogen shows that the hydrogen activation is at l east one of the rate determining steps. Additionally, controlling the reaction by the potential of the catalyst allows one to prevent danger ous feed concentrations and fast deactivation, too.