Cu/SiO2 CATALYSTS OBTAINED BY CATIONIC ADSORPTION FROM DIFFERENT PRECURSOR SALTS

In this work the effect of different copper precursor salts (acetate, nitrate, sulfate) on the physicochemical characteristics of Cu/SiO2 catalysts is studied. The catalysts were prepared by the cationic adsorption method and analyzed by several characterization techniques (TGA, DSC, FTIR, XRD, AAS, SEM-EDS, N2-sorptometry and TPR). The results showed that the copper acetate precursor generated highly dispersed nano-sized copper oxide species on the silica surface, while the copper nitrate precursor leaded to bulk-type copper oxide strongly interacting with the silica, and the copper sulfate precursor did not decompose completely during the catalyst preparation. Besides, the acetate precursor produced the highest copper content, due to lower acidity of its solution, which generated a higher density of negative charge on the silica surface and a higher affinity for cupric ions. In conclusion, the great influence of the nature of the precursor salt on the physicochemical characteristics of silica-supported copper catalysts is established.