Relationships between surface compositions and properties of surfaces of mixed fumed oxides

Fumed oxides SiO2/Al2O3 (SA), SiO2/TiO2 (ST) and Al2O3/SiO2/TiO2 (AST) at different content of alumina and titania were investigated by one-pass temperature-programmed desorption (OPTPD) time-of-flight mass-spectrometry (TOFMS), Auger electron spectroscopy (AES), NMR, FTIR, thermally stimulated depolarization current (TSDC), microcalorimetry, adsorption of nitrogen, water, (dimethylamino)azobenzene (DMAAB) and metal ions (Pb(II) and Ni(II)). It was shown that all the studied adsorption/desorption and energetic properties of mixed fumed oxides depend strongly on the surface content of alumina CAl2O3s (shown as a surface content of aluminum, CAls) in SA and AST and titania CTiO2s (shown as a surface content of titanium, CTis) in ST and AST. Many of these properties demonstrate clear correlations with the CAls and CTis values over the total range of alumina and titania content in the materials.