Pt-zeolites as active catalysts for the removal of chlorate in water by hydrogenation reactions

Abstract

Catalytic hydrogenation is used to remove chlorate ions from water streams by using platinum catalysts supported on zeolites with different topologies (FAU, BEA, MWW, MFI and MOR), Si/Al ratio and compensating cation. It is observed that there is an important influence of the zeolite characteristics on the catalytic activity. The best results have been obtained with the catalyst supported on zeolites with a high number of acid centres, this is with a low Si/Al ratio and with protons, as counter-cation species compensating aluminium charge. The acid sites favour the interaction of the catalyst with the reactants and influence the neighbouring Pt species improving the redox properties of the catalyst. It is shown that with an adequate number of acid sites it is possible to decrease the metal content, keeping the same catalytic activity, by increasing the metal dispersion. The highest activity is obtained with an acidic FAU zeolite, with low Si/Al ratio and 1 wt% of Pt added by ion exchange. This catalyst is able to simultaneously reduce chlorate and chlorite ions and chlorate and bromate ions indicating that it is a multifunctional catalyst that can be utilized for removing different pollutants in water.