Incipient wetness impregnation, noble metals

Ceria-modified SBA-15 oxides with increased surface acidity and high reducibility were prepared. The specific surface area was ranging between 620-385 m /g, and well dispersed ceria crystalUtes (mean diameter <5 nm) were obtained. The so far reported results suggest that CexSBA oxides, prepared by incipient wetness-impregnation approach, are suitable supports for preparation and stabilization of noble metal nanoparticles. 

Preparation of Pt-TiOx/Pd membranes. It was also desirable to prepare metalloceramic membranes in which the catalytic activity of the ceramic phase was enhanced through the addition of a noble metal. The very low surface area of the titania films prepared as described above made them difficult to impregnate with adequate dispersion by traditional incipient wetness techniques. Instead, finely ground titania (>200 mesh) was impregnated with platinum via the incipient wetness method with a chloroplatinic acid solution. This powder was then sprinkled onto the surface of a freshly dipped membrane, which was dried and heat treated as described. These materials were activated before use at 350°C in hydrogen for three hours. 

This is the classical method used to make supported noble metal catalysts and consists of impregnating a support with a solution of a metal salt. This usually involves suspending the support in a larger volume of solution, from which the solvent is then removed. An alternative variation is the so-called incipient wetness (IW) technique, in which the pores of the support are filled with the solution [61-63]. 

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