Catalytic reduction of nitrate and nitrite ions by hydrogen: investigationof the reaction mechanism over Pd and Pd-Cu catalysts

The catalytic behavior of mono- and bimetallic catalysts with Pd and/or Cu supported over gamma-Al2O3 in the reduction of aqueous nitrate and nitrite ions by hydrogen was investigated. The composition of the supported metal c atalysts was analysed using secondary ion mass spectroscopy (SIMS) and X-ra y diffraction (XRD) techniques. Surface enrichment of the bimetallic Pd-Cu particles in copper was revealed. Interactions of NO (possible intermediate in reduction of nitrate and nitrite ions) with H-2 over Pd were studied by thermal desorption spectroscopy (TDS) under high-vacuum conditions. The mo lecular mechanism of NO3- and NO2- reduction by H-2 as well as the role of Pd and Cu active sites are discussed. (C) 2000 Elsevier Science B.V. All ri ghts reserved.