title: Novel catalytic and mechanistic studies on wastewater denitrification with hydrogen.
abstract: The present work reports up-to-date information regarding the reaction mechanism of the catalytic hydrogenation of nitrates in water media. In the present mechanistic study, an attempt is made, for the first time, to elucidate the crucial role of several catalysts and reaction parameters in the mechanism of the NO(3)(-)/H(2) reaction. Steady-state isotopic transient kinetic analysis (SSITKA) experiments coupled with ex situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were performed on supported Pd-Cu catalysts for the NO(3)(-)/H(2) and NO(3)(-)/H(2)/O(2) reactions. The latter experiments revealed that the formation and surface coverage of various adsorbed active intermediate N-species on the support or Pd/Cu metal surface is significantly favored in the presence of TiO(2) in the support mixture and in the presence of oxygen in the reaction's gaseous feed stream. The differences in the reactivity of these adsorbed N-species, found in the present work, adequately explain the large effect of the chemical composition of the support and the gas feed composition on catalyst behaviour (activity and selectivity). The present study leads to solid mechanistic evidence concerning the presence of a hydrogen spillover process from the metal to the support. Moreover, this study shows that Cu clusters are active sites for the reduction of nitrates to nitrites.
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: C P
authors.initials: CP
authors.lastname: Theologides
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: G G
authors.initials: GG
authors.lastname: Olympiou
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: P G
authors.initials: PG
authors.lastname: Savva
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: N A
authors.initials: NA
authors.lastname: Pantelidou
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: B K
authors.initials: BK
authors.lastname: Constantinou
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: V K
authors.initials: VK
authors.lastname: Chatziiona
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: L Y
authors.initials: LY
authors.lastname: Valanidou
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: C T
authors.initials: CT
authors.lastname: Piskopianou
authors.affiliation: Department of Environmental Science and Technology, Cyprus University of Technology, P.O. BOX 50329, 3603 Limassol, Cyprus E-mail: costas.costa@cut.ac.cy.
authors.forename: C N
authors.initials: CN
authors.lastname: Costa
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry; D058440:Denitrification; D006859:Hydrogen / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D062065:Wastewater / Q000737:chemistry*
chemical_list: D003300:Copper; D006859:Hydrogen; D009584:Nitrogen; D010165:Palladium; D062065:Wastewater