Perovskite powders of the type La0.5Ca0.5AlyM1-yO3-δ (y = 0.25 to 0.5), M = Fe, Cr, Mn, Co, were prepared via sol-gel route according to modified Pechini method. Calcination of the resins at 350 ◦C in air was performed before final sintering at temperature 1000 ◦C for 6 hours. La, Ca, Fe, Al, Cr, Mn and Co contents in the solid were determined by microprobe attached to the electron microscope. The phase composition of the products was established by X-ray diffraction analysis and the lattice parameters were calculated using the Rietveld analysis. The shape and size of particles were determined via scanning electron microscopy. The specific surface of powder perovskites was established by the BET method. Perovskites with Co and Cr content (y= 0.75) crystallized in rhomboedric structure with R3cH space group, perovskites with a medium Fe and Mn content in orthorhombic structure with Pbnm spatial group, and the perovskite with the lowest Fe content (y=0.5) in cubic structure with Pm3m space group. The primary particles were about 200 nm in size and formed agglomerates larger than 1.0 μm. For catalytical investigations we used the experimental set up which was published in [1]. The catalytic performance was measured in the most cases at atmospheric pressure with 3 g of catalyst. The partial pressure of propane was 0.4 kPa with air as the carrier gas in all runs. Flow rates were controlled by electronic mass flow controllers (Tylan^®, FC‑260‑2s). The flow rate was 0.4 L h^-1 for propane, 100 L h^-1 for air.

First results show a strong dependency of catalytical and heating behavior on the nature of B-atom.

Conclusions and outlook

Nanoscaled perovskites of the type La0.5Ca0.5AlyM1-yO3-δ (y = 0.25 to 0.5), M = Fe, Cr, Mn, Co are interesting materials for microwave-assisted heterogeneous gas phase catalysis. We could found a strong dependency between the catalytical and the heating behaviour of the materials and the nature of B atom. Correlation between TPD and oxidation behavior of the materials has to be done in the next future

[1] Will, H., Scholz P., Ondruschka B.,

"Heterogeneous gas-phase catalysis under microwave radiation - A new multi-mode microwave applicator", Topics Catal., 29 (2004), 175

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