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

Abstract

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 N2 of the PdCu catalysts.