ZrO2-modified Al2O3-supported PdCu catalysts for the water denitrification reaction

Monometallic Pd and bimetallic Pd-Cu catalysts supported on alumina, zirconia and ZrO2-Al2O3 mixed oxides of different composition were prepared and evaluated in the catalytic denitrification of water. The supports were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray (SEM/EDX), NH3-adsorption thermogravimetry and specific surface areas measured by the BET method. XRD studies showed that the predominant phase in the ZrO2-modified Al2O3 supports is the metastable tetragonal phase (57%) of zirconia. SEM/EDX results indicated that ZrO2 crystals are distributed homogeneously on the supports. Temperature-programmed reduction (TPR) experiments carried out on bimetallic PdCu catalysts showed that Pd is well dispersed on the modified supports and that there is a strong interaction between both metals. The modification of Al2O3 by the addition of ZrO2 not only improved the activity but also the selectivity to N-2 of the PdCu catalysts. (C) 2014 Elsevier B.V. All rights reserved.