Cooperative adsorption based kinetics for dichlorobenzene dechlorination over Pd/Fe bimetal

Pd/Fe bimetal has been used in dichlorobenzene treatment with high efficiency. In order for an industrial application of this process, the dechlorination kinetics was studied. As a catalytic reaction, the overall dechlorination process can be characterized by the step of adsorption and surface reaction. A cooperative adsorption theory was applied to describe the adsorption behaviors in this system. Four chemicals: dichlorobenzene, chlorobenzene, benzene and hydrogen, are adsorbed on the catalyst surface, where active centers provide the space for adhesion. Two groups of active centers, "σ" and "σ*", are divided by size in order to distinguish the capability of capturing aromatic compounds. Apparent multilayer adsorption was used to model the cooperative adsorption behaviors in this system. The adsorption sites were characterized by two energy levels. Based on the cooperative adsorption theory, a kinetic model was built for the dechlorination process under adsorption limitation. There are five parameters in the final model including the concentration of active sites, Cσ, one reaction rate constant: kDCB and three equilibrium constants: K1,K2 and Ke. The resultant model was found to describe the experimental data well.