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Palladium-catalyzed aqueous hydrodehalogenation in column reactors: Modeling of deactivation kinetics with sulfide and comparison of regenerants

Paper ID Volume ID Publish Year Pages File Format Full-Text
48565 46513 2007 10 PDF Available
Title
Palladium-catalyzed aqueous hydrodehalogenation in column reactors: Modeling of deactivation kinetics with sulfide and comparison of regenerants
Abstract

Palladium (Pd) based catalysts are increasingly important in environmental applications; however, sulfide, a known poison, has been identified as a potential issue in laboratory and field studies. This paper develops a quantitative model for deactivation kinetics with aqueous sulfide; investigates the effects of pH on a catalyzed dehalogenation reaction and sulfide deactivation; and characterizes regeneration with acids, bases, and oxidizing agents. Results obtained with trichloroethylene show no inherent catalyst deactivation in deionized water. Deactivation increased with sulfide concentration and exposure time. Deactivation was slowly reversible by flushing the catalyst with deionized water at pH 10.4. Treatment with 20 mM sodium hypochlorite quickly and completely regenerated the catalyst, and was significantly more effective than hydroxide, hydrochloric acid, hydrogen peroxide, and air-saturated water. The time required for regeneration increased with increasing sulfide concentrations and exposure times. These results have important implications for maintaining catalyst activity with Pd or bimetallic catalyst systems.

Keywords
Palladium (Pd); Sulfide deactivation kinetics; Sulfur diffusion; Regeneration; Groundwater remediation; Trichloroethene (TCE); Zero valent iron; Bimetallic catalysts
First Page Preview
Palladium-catalyzed aqueous hydrodehalogenation in column reactors: Modeling of deactivation kinetics with sulfide and comparison of regenerants
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 75, Issues 1–2, 29 August 2007, Pages 1–10
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis