title: Ligand-enhanced reduction of perchlorate in water with heterogeneous Re-Pd/C catalysts.
abstract: New bimetallic heterogeneous catalysts for the reduction of perchlorate in water with dihydrogen have been prepared in two ways: (1) by impregnating 5 wt % Pd on activated carbon powder with one of the complexes trans-[ReO(2)(py-X)(4)](+) (py-X = 4-substituted pyridine; X = H, Me, OMe, NMe(2)) or (2) by adsorbing perrhenate onto the Pd/C powder in the presence of the pyridine ligand under a hydrogen atmosphere. Both sets of catalysts are highly active at pH 2.7-3.0 (HCl), with observed rates increasing with varying X in the order H < Me < OMe < NMe(2), which supports a rate-determining oxygen atom transfer reaction involving the Re(V) centers. However, the materials prepared by method (1) show evidence of facile formation of perrhenate from handling under ambient conditions. A system prepared by method (2) with 2 equiv of dimethylaminopyridine per Re is especially active and stable up to pH 4.5.
authors.affiliation: Department of Chemistry and Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Keith D
authors.initials: KD
authors.lastname: Hurley
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Zhang
authors.forename: John R
authors.initials: JR
authors.lastname: Shapley
mesh_terms: D002384:Catalysis; D008024:Ligands; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D010472:Perchlorates / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D008024:Ligands; D010472:Perchlorates; D014867:Water; D010165:Palladium; D012211:Rhenium