SELECTIVE SYNTHESIS OF ACETALDEHYDE APPLYING A FUEL-CELL SYSTEM IN THE GAS-PHASE

The partial oxidation of ethylene applying a fuel cell system (C2H4 + H2O, Pd/silica wool disk holding H3PO4 (aq.)/Pd or Pt, O2) produces acetaldehyde very selectively (>97%) in the gas phase. Palladium is the unique electrocatalyst for this selective synthesis of CH3CHO. This method could solve a number of disadvantages of the Wacker process. The electrode prepared by hot-pressing a mixture of Pd black or Pt black with graphite and Teflon powder improved the current and the rate of formation of CH3CHO as compared to the electrode of the metal black alone. The kinetic results showed that the higher the pressure of oxygen in the cathode compartment, the better for synthesis of CH3CHO. However, the optimum pressure of C2H4 in the anode compartment is 30 kPa. The optimum reaction temperature for the synthesis of CH3CHO is 373 K. The applied potential across the cell enhanced the rate of formation of CH3CHO remarkably without lowering selectivity. © 1990, The Electrochemical Society, Inc. All rights reserved.