Flame-made Pt/ceria/zirconia for low-temperature oxygen exchange

The preparation of platinum (0-2 wt %) supported on ceria/zirconia (Ce0.5Zr0.5O2) by flame synthesis resulted in materials with good thermal stability and improved dynamic oxygen exchange capacity at low temperatures. Comparison to a conventionally prepared material (precipitation and incipient wetness impregnation) showed an increased specific surface area for the flame-made catalysts after sintering at 1100 degrees C for 6 h in air. For low Pt content (0.1-0.5 wt %), the onset in low-temperature oxygen exchange activity of flame-made materials was even improved after a first redox test run. Repeated test runs up to 1100 degrees C deactivated the reference material for oxygen exchange below 300 degrees C, while the flame-made materials showed improved activity down to around 150 degrees C. Fluorescence EXAFS revealed the presence of oxidized Pt on the pre-sintered materials and confirmed the role of reduced Pt on the hydrogen activation prior to oxygen exchange. It further uncovered pronounced differences in Pt reducibility depending on the Pt loading.