(513a) Towards Tailoring of Highly Active and Stable Nanocomposite Catalysts

Nanomaterials have become the focus of intense catalysis research after first reports on nanosized gold particles indicated that nano-scaled materials can show fundamentally different properties from their bulk (macroscopic) equivalent. Furthermore, the large surface-to-volume ratio of nanoparticles makes such materials highly interesting for catalytic applications. However, the thermal stability of particles decreases strongly with decreasing diameter, which currently restricts the application of metallic nanoparticles to low and moderate temperatures (T< 500oC).

Previously we have demonstrated the first successful approach to overcome this barrier by anchoring noble metal nanoparticles in a high-temperature stabilized alumina matrix. In this way, we were able to synthesize exceptionally active and sinter-resistant platinum-barium hexaaluminate (Pt-BHA) powders which combine the high reactivity of nanosized Pt metal particles with the excellent high-temperature stability of structured aluminas.

The focus of the current work is to investigate the flexibility of this approach by applying it to the synthesis of a wide range of catalytic metal nanoparticles and ceramic matrices. Here, we report on the successful embedding of Rh, Ni, Cu, Co and Fe in these nanocomposites, as well as the extension onto silica matrices. In particular the silica-based nanocomposites appear very interesting due to very homogeneous dispersion of metal nanoparticles and very large surface areas (up to 675 m2/g) even after calcination at temperatures as high as 600°C. Synthesis, characterization, and high-temperature reactive tests of these nanocomposites will be discussed in detail.