Oxychlorination of propylene on supported palladium and other platinum group metal catalysts

Abstract

Oxychlorination of propylene was studied on platinum groups metal catalysts. Main product was allyl chloride on all catalysts studied. The catalylic activity was in the following order: Rh > Pd > Pt > Ir . Ru. Details of the reaction were studied on palladium catalysts. By-products were isopropyl chloride, 1,2-dichloropropane, chloropropenes and carbon dioxide. Isopropyl chloride and 1,2-dichloropropane were formed parallel to allyl chloride and major part of carbon dioxide was formed successively from allyl chloride. Among others active charcoal was the best support for the palladium catalyst. The high efficiency of active charcoal support is explained by its catalytic action for palladium oxidation. Hydrogen chloride was chemically adsorbed on the catalyst in the presence of oxygen and a significant amount of palladium chloride was formed during the reaction. The concentration of palladium chloride under working conditions was measured by a novel method. The PdCl 2 concentration reached a steady state, which was controlled by the feed composition. On a fully chlorinated palladium catalyst little allyl chloride was formed and 1,2-dichloropropane was formed instead. Allyl chloride was considered to be formed through a reaction of π-allyl species of propylene on the reduced palladium with the chlorides of palladium.