The Intrinsic Kinetics of Catalytic Hydrogenation of Rosin Using Pd/C Catalyst

The intrinsic kinetics of catalytic hydrogenation of rosin using Pd/C catalyst was investigated at temperature range of 403K to 433K and under pressure range of 3.0MPa to 7.0Mpa. The effects of both internal and external diffusions were eliminated by reducing catalyst size and increasing stirrer rotational speed. The changes of concentration of reactants and products with reaction time were traced on-line during hydrogenation of rosin. Based on the experimental data, a suitable reaction mechanism was screened by EVIEWS software from 10 possible reaction mechanism models. The model indicated that the main component, abietic-acid, in rosin is not adsorbed, the reaction between atomically adsorbed hydrogen on catalyst surface and abietic-acid is the controlling step. The intrinsic kinetic equation can be written as: HH2SS(1)kPrbCa=+. The model parameters related with reaction rate and adsorption equilibrium were correlated from experimental data. The Arrhenius equations, i.e. H5.695exp(2498.5/)kTa=-, )/8.1920exp(104.93STb-=, can be used to describe the relationships between model parameters and reaction temperature. The model should be very useful to provide a theoretical explanation of reaction mechanism and to be applied in the development of industrial process.