Investigation of PdSn-catalysts for nitrate removal in drinking water processing

PdSn catalysts prepared by various methods and used for nitrate reduction w ere investigated by means of in situ Sn-119m Mossbauer spectroscopy. Charac terization by Sn-119m Moss-bauer spectroscopy revealed significant differen ces concerning the modification of the palladium particles supported on alu mina. The controlled surface reaction preparation method (CSR) leads to for mation of PdSn alloys with different tin contents besides small amounts of Sn(II) species and unalloyed metallic Sn. On the other hand the impregnatio n method leads to a small amount of PdSn alloys and higher contents of Sn(I I) species. Sn(IV) species were found in both kinds of catalysts. The CSR p repared PdSn catalysts showed an improved activity and selectivity compared to the catalysts obtained by the impregnation method.