Deactivation Kinetics Model of Pt/C Catalyst for Hydrogenation of Nitrobenzene to p-Aminophenol

The deactivation kinetics of Pt/C catalyst for hydrogenation of nitrobenzene in acid medium to p-aminophenol (PAP), with aniline as a by product, was investigated in a batch reactor. Caused by carbonaceous fouling and poisoning in the nitrobenzene phase, deactivation of Pt/C catalyst is regarded as independent deactivation. Based on experimental results, a simple power law expression (SPLE) model for the deactivation kinetics is proposed. The kinetic parameters for the deactivation were determined by theoretical analysis and data fittings and the following model for the system progressing with time-on-stream is obtained: r(PAP) = (-r(PAP))(0).a, -da/dt = k(d0) exp(-e(d)/RT)a(m) = 2.614exp(-25.57/RT)a(0.0198). The kinetic parameters evaluated from a batch reactor model were found to represent the observed experimental data very well. That is the deactivation order in = 0.0198, k(d0) = 2.614, the apparent activation energy for the deactivation E(d) = 25.57 KJ/mol. Regarding the deactivation as a pore mouth fouling/poisoning model, the selectivity for p-aminophenol to aniline can be explained.