The use of a cation exchange resin for palladium–tin and palladium–indium catalysts for nitrate removal in water

Abstract

A sulfonated poly(styrene–divinylbenzene) (Sty–DVB) was used for preparing bimetallic palladium–tin or palladium–indium catalysts by successive impregnation and catalytic reduction. The use of this acidic support allows increasing the selectivity to molecular nitrogen without external control of the pH, as compared to a classical alumina catalyst. The preparation by successive impregnation led to the most active and selective catalysts while the indium-based catalysts were more active for nitrate reduction and less selective to nitrogen than the tin-based ones. The best performances were obtained with the 5%Pd2.6%Sn/Sty–DVB prepared by successive impregnation. This finding was related to the role of the support in decreasing the final pH, as well as to the buffering properties of the support near the active metal sites.