The Activities of Platinum Group Metal Catalysts on Carriers and the Course of the Reaction in the Vapor Phase Oxidation of Mixtures of Ethylene and Benzene

Abstract

The vapor phase oxidation of mixtures of ethylene and benzene has been investigated with platinum metal catalysts supported on carriers. Reaction products were styrene, carbon dioxide, chlorobenzene (Cl from residual Cl in catalyst), benzaldehyde, phenel, acetaldehyde, and a trace amount of ethylbenzene. The order of metals with respect to initial activity for the formation of styrene was Rh Ir Pd Pt Ru, while that for the formation of carbon dioxide was lr Pt Pd Ru Rh under the same reaction conditions (Table 1). The order of the ratios of the activities for the formation of carbon dioxide to those of the formation of styrene among the metals was found to agree with those of the redox potential and of the work function of the metals. Changes of activity with reaetion time were examined with Rh, lr and Pd-catalysts (Fig.1). The effects of preparation conditions of Pd-catalyst on activity (Table 2, 3, Fig.2, 3, 4) were examined. The reaction pathes to the products (Table 4) as well as effects of oxygen pressure upon the rates of formation (Fig.5) were also investigated.
It is concluded that the active state of the catalysts for styrene formation is metal chloride and that for carbon dioxide, probably fermed by the complete oxidation of benzene, is metallic state.