CATALYST POTENTIAL CONTROLLED HYDROGENATI ON OF 2,4,6-TRINITROTOLUENE

Catalytic hydrogenation of trinitrotoluene over Ni/SiO2, Pd/SiO2 and P d/C catalysts has been studied in a liquid phase batch reactor at pres sure of 2.5 MPA and temperature of 368 K. The surface concentration of atomic hydrogen was estimated by measuring the electrochemical potent ial of the catalyst and was held on certain different values (potentia l controlled hydrogenation). In regard of the metal content the activi ty of Pd-catalysts were higher and related to the catalyst weight the Ni-samples were more active. It has been shown that rapid catalyst dea ctivation takes place at values below 1% of the equilibrium surface co ncentration of atomic hydrogen. The observed relation between hydrogen ation rate and surface concentration of atomic hydrogen can be discrib ed by a reaction order of n = - 0.8. This negative order points at a s trong influence of hydrogen activation on the rate of trinitrotoluene hydrogenation.