Mullite Foam Flame-Coated Catalysts
Titania containing 10 wt.% vanadia nanoparticles were produced in single step by flame spray pyrolysis having a sub-monolayer, monomeric V2O5 on the titania surface. Direct deposition of flame-made vanadia/titania on mullite foams was controlled by the pressure drop over foam/filter, resulting in patchy to nearly homogeneous coatings of V2O5/TiO2 on the foam. The coated-foam catalyst revealed higher catalytic activity and similar selectivity to phthalic anhydride at high o-xylene conversion compared to a wet-made catalyst. The high vanadia distribution and its monomeric composition on the open foam structure facilitated vanadia accessibility. Homogeneous/patchy coatings of V2O5/TiO2 with low specific surface area showed slightly higher yield than the homogeneous coatings with high specific surface area but with lower space-time-yield. Directly coated foam catalysts combine high accessibility, high catalytic yield with favorable support structures (low pressure drop, enhanced heat transfer) and fast production routes, making them attractive for catalytic reactions.
Recent, relevant references:
- B. Schimmoeller, H. Schulz, S. E. Pratsinis, A. Bareiss, A. Reitzmann, B. Kraushaar-Czarnetzki, Ceramic foams directly-coated with flame-made V2O5/TiO2 for synthesis of phthalic anhydride, J. Catal., 243, 82-92 (2006).
- B. Schimmoeller, H. Schulz, A. Ritter, A. Reitzmann, B. Kraushaar-Czarnetzki, A. Baiker and S.E. Pratsinis; "Structure of flame-made vanadia/titania and catalytic behavior in the partial oxidation of o-xylene", Journal of Catalysis, 256 74-83 (2008).