Preparation of Highly Active CO-Oxidation Catalysts Based on Cobalt Prussian Blue Analogues

Abstract A simple method to synthesize catalytically active, noble metal free cobalt ferrites with mesopores and high activity for CO-oxidation at low temperatures will be presented in the following work. Fe 4 [Fe(CN) 6 ] 3 (Prussian blue, PB) and Co 3 [Fe(CN) 6 ] 2 (Co- Prussian blue-analogue, PBA) are first synthesized by a co-precipitation reaction and subsequently heat treated to form the catalytically active oxide CoFe 2 O 4 . Solvent modification with DMF and a salt-filler-calcination method with MgSO 4 will be employed for the first time to modify and protect the pore system of CoFe 2 O 4 . The as obtained mesoporous material has a specific surface area of 76 m 2 g − 1 , pore sizes ranging from 10 to 70 nm and a specific mesopore volume of 0.4 cm 3 g − 1 . In a fixed bed-setup with dry air, the material shows 90% CO-conversion (T 90 ) at room temperature. When coating the catalyst onto a honeycomb support and using moisture containing air, T 90 of 320 °C can be achieved, remaining constant or increasing to 380 °C after hydrothermal or SO 2 -aging respectively. Noble metal free CO-oxidation catalysts, still active after exposure to H 2 O and SO 2 , can thus be synthesized by a simple and cost-efficient method. Graphical Abstract CoFe 2 O 4 is prepared via Prussian Blue/Prussian Blue Analogue (PB/PBA) co-precipitation method with subsequent calcination. Mesopores within the structure are preserved by using a pore-filling salt during calcination. CoFe 2 O 4 is used as a CO-oxidation catalyst that remains active even avert exposure to water and SO 2 .