(621e) Liquid-Phase Hydrogenation of Chloronitrobenzene over PdCu Catalyst

Selective hydrogenation of nitro group in chloronitrobenzene is an important step in the preparation of various fine chemicals. The reaction is even more challenging because the reduction of the N=O double bond is thermodynamically restricted. Hydrogenation of chloronitrobenzene over a PdCu/TiO₂ catalyst was investigated in a stirred batch reactor. In the present study, the influence of mass transfer in the liquid-phase hydrogenation of chloronitrobenzene was studied. A combined experimental/theoretical approach was used to elucidate the impact of gas/liquid, liquid/solid, and pore diffusion. To determine the kinetic region area, the catalytic performance at different reaction conditions was evaluated. The complex evaluation presented comprises all important factors such as catalyst mass, stirring speed, liquid load, catalyst particle size, etc., that might contribute to mass-transfer limitations. Theoretical calculations were confirmed by experimental results showing its applicability.