Abstract:

By dynamic technique, the dependence of adsorption and surface reaction rate coefficients for α-methyl styrene hydrogenation on the properties of active sites of Pd/Al_2O_3 catalyst was studied. The results showed that there were two kinds of active sites on the surface of Pd/Al_O_3. Their number N_t, active frequency AF and the number of active atoms in an active site m were obtained and their variations were also studied. The coefficients of adsorption equilibrium, overall reaction rate and adsorption and surface reaction rate coefficients for a single active site κ~*, κ_0~*, κ_0~* and κ_r were calculated. Their changes with Pd content were as same as that of active frequency AF except for κ_r and the change of κ_r was consistent with that of m value. In summary, the kinetic parameters of a catalytic reaction depend not only on the number of active sites, but also on some properties of the active site, such as AF and m value.