Oxidation of Ethylene over Palladium Sulfate-Active Charcoal Catalysts

Abstract

Oxidation of Ethylene was studied in vapor phase over palladium sulfate-active charcoal catalysts. Major product was acetaldehyde and minor products were butenes and carbon dioxide. Palladium sulfate catalysts exhibited fairly high activities but they lost their activities fairly rapidly with the reaction time. The deactivated catalyst was reactivated by the treatment with concentrated nitric acid at the reaction temperature. While the catalytic activity increased with the increase in free sulfuric acid content in the catalyst up to about 10 wt %, above it, the activity decreased depending on a squre of the sulfuric acid concentration. The apperent activation energy of acetaldehyde formation increased with increasing sulfuric acid content from 8 kcal/mol (at sulfuric acid free) to 8.5 kcal/mol (at 100 wt % sulfuric acid based on active charcoal). The reaction order in the steam decreased with the increase in the sulfuric acid concentration from about 2.0 to zero. The effect of the sulfuric acid concentration on the apparent activation energy and the reaction order were interpreted on the basis of the hydrophlicity of the catalyst. The catalysis of the palladium sulfate catalyst was concluded as a redox system and it was found that the reoxidation step of the reduced palladium was slower than that of the palladium chloride catalyst. t Oxidation of Olefins with Metallic Salts-Active Charcoal Catalysts.