Reference : Palladium-silver sol-gel catalysts for selective hydrodechlorination of 1,2-dichloroe...
Scientific journals : Article
Engineering, computing & technology : Materials science & engineering
Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Chemical engineering
http://hdl.handle.net/2268/9427
Palladium-silver sol-gel catalysts for selective hydrodechlorination of 1,2-dichloroethane into ethylene - IV. Deactivation mechanism and regeneration
English
Heinrichs, Benoît mailto [Université de Liège - ULg > Département de chimie appliquée > Chimie physique appliquée > >]
Noville, Francis mailto [Université de Liège - ULg > Département de chimie appliquée > Chimie physique appliquée > >]
Schoebrechts, Jean-Paul [Solvay S.A. > Laboratoire Central > > >]
Pirard, Jean-Paul mailto [Université de Liège - ULg > Département de chimie appliquée > Chimie physique appliquée > > >]
15-Nov-2003
Journal of Catalysis
Academic Press Inc Elsevier Science
220
1
215-225
Yes (verified by ORBi)
International
0021-9517
San Diego
[en] hydrodechlorination ; 1,2-dichloroethane ; Pd-Ag catalyst ; deactivation ; regeneration
[en] The activity and selectivity of a 1.9% Pd-3.7% Ag/SiO2 catalyst during selective hydrodechlorination of 1,2-dichloroethane into ethylene have been followed in the course of time. The deactivation curves show two distinct periods: an initial period at the very beginning of catalyst operation, that is, during the first 20 operating hours, characterized by a sharp decrease of the rates of both reactions involved in the process (1,2-dichloroethane hydrodechlorination and undesired ethylene hydrogenation) and a second period, after the first 20 operating hours and investigated for more than 600 h, characterized by a clearly slower deactivation. During the initial period, the hydrodechlorination rate decreases less quickly than the hydrogenation rate and this results in a fast increase of ethylene selectivity which reaches a maximum at the end of this period. After the initial period, the hydrodechlorination rate decreases faster than the hydrogenation rate and this results in a slow decrease of ethylene selectivity. A comparison between the physico-chemical properties of the fresh catalyst and of the deactivated one suggests a deactivation mechanism by poisoning or coking of silver sites at the surface of the active Pd-Ag alloy particles whereas palladium sites would remain intact. The selectivity evolution during the second period, that is, after the very first operating hours, is in agreement with such a mechanism. However, the sharp ethylene selectivity increase during the initial operating hours suggests, in addition to the deactivation by silver sites disappearance, the presence of a further nonidentified phenomenon. The characterization of the catalyst after a regeneration treatment including an oxidation step followed by a reduction step shows that this treatment allows restoration near to the physico-chemical properties of the fresh catalyst. (C) 2003 Elsevier Inc. All rights reserved.
http://hdl.handle.net/2268/9427

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