Julie L. d’Itri

Hydrodechlorination of 1,2-dichloroethane catalyzed by Pt-Cu/C: effect of catalyst pretreatment

Abstract The catalytic performance of Pt–Cu/C with Pt/Cu atomic ratios of 1:1 and 1:3 in the reaction of 1,2-dichloroethane dechlorination at 200°C and atmospheric pressure was investigated to understand the molecular phenomena governing the change in ethylene selectivity with time on stream (TOS). When the Pt1–Cu3/C catalyst is prereduced in H 2 at 220°C, ethane is the major product at early TOS, while ethylene is the major product at longer TOS. Pretreatment in flowing He at 220°C eliminates the transient behavior and significantly increases steady state selectivity toward ethylene for both Pt–Cu catalysts. The transient behavior is also eliminated after reduction at 220°C followed by treatment with HCl at the same temperature. Quite different behavior is observed with a Pt/C catalyst in that ethane is the major product regardless of the type of pretreatment. The results are interpreted via a molecular scheme including the formation of mixed PtCuCl x species during the non-reductive pretreatment. These PtCuCl x particles are converted into the corresponding alloy during subsequent reduction by H 2 or reaction mixture. The enrichment of the catalysts’ surface with Cu results from the pretreatment with HCl.