Catalytic reduction of nitrates using Pt/CeO2 catalysts in a continuous reactor

The increasing pollution of natural sources of drinking water encourages the development of new emerging technologies and processes for water remediation. The present study demonstrates that monometallic Pt catalysts provide high conversion on the nitrate reduction reaction when ceria is used as support. However, the presence of ammonium was detected in all the catalysts. In order to control the formation of ammonium, the acid–base character of the support was modified, introducing several fluoride species into the CeO2, using two different methods: impregnation and combustion. The introduction of fluoride species in the CeO2 support by combustion produces a slight decrease in the reduction of nitrates. However, an important decrease in ammonium formation was observed. The capability of the reduction of surface CeO2 and the acid–base properties of the support, after the addition of fluoride species, play an important role in the control of both activity and selectivity. The incorporation of fluoride species into the CeO2, represents an alternative way to improve the selectivity of nitrate reduction toward nitrogen without the use of additional molecules such as CO2 to control pH.