Abstract
The performances of a supported liquid phase catalyst are investigated under unsaturated vapor pressures of the solvent, in contrast with the conditions of previous studies where the presaturated reacting gas mixtures were applied for preventing vaporization of the solvent. In the present work, oxidation of ethylene to produce acetaldehyde is carried out by the catalyst system of aqueous solution of PdCI2 and CuCl2 supported on porous particles. It is found that the reaction takes place at much higher rates when the reactant gas is not saturated with the water solvent than when it is saturated. The increase in activity of the reaction is considered to be brought about by the dual features of mass transfer and chemical reaction. The effectiveness factor of the catalyst is, in the case of unsaturated gas, increased by rapid gas diffusion through the empty space in the pore volume which otherwise is filled with liquid. The activity for the unsaturated gas becomes sometimes about two orders of magnitude greater than even the mass transfer free activity for the saturated gas. An attempt is made to propose a reaction model which explains both qualitatively and quantitatively the kinetic data obtained experimentally under the unsaturated conditions.
