Oxidation of Propylene over Pd(II)-Cu(II)-Y Zeolite Catalyst in the Presence of Steam

Abstract

The Pd(II)-Cu(II)-Y zeolite catalyst was prepared by two-step ion exchange of Na⁺; in the first place with Pd(NH₃)₄Cl₂ aqueous solution, and in the second with CuCl₂ aqueous solution. Vapor phase oxidation of propylene in the presence of steam over the catalyst in the temperature range of 100∼150°C at atmospheric pressure gives acetone with good yield comparable to the homogeneous catalytic systems. Selectivity of acetone formation was higher than 80 %. By-products were carbon dioxide, acetaldehyde, propionaldehyde and trace amount of acids. These results suggested that electron transfer occurred from Pd(0) to Cu(II) existing in the definite sites of the zeolite structure. The catalyst deactivation by ammonia addition and the low catalytic activity of the Pd(NH₃)₄(II)-Cu(NH₃)₆(II)-Y zeolite catalyst suggested that the active species were the partially aquated Pd(II), and Cu(II) ions.