DEACTIVATION OF SUPPORTED COPPER-BASED CATALYSTS DURING POLYOL CONVERSION IN AQUEOUS-PHASE

Degradations and cyclodehydration of polyols in aqueous solution were studied on copper deposited on charcoal unmodified or modified by addi tion of chloride and a second metal (Pt or Au). These catalysts had pr operties very close to those of Raney copper based catalysts. Their de activation was studied in a dynamic flow three-phase reactor. Sinterin g of copper particles, surface oxidation and copper(I) hydroxide dehyd ration were responsible for the deactivation of the unmodified Cu/C. I n the cases of modified Cu/C, decrease of the cyclodehydration selecti vity was attributed to the loss of chloride. Addition of chloride ions to the polyol solution to be converted increased the cyclodehydration selectivity but strongly decreased the activity.