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AIChE Journal, Vol.66, No.5, 2020
Mesoporous Co-Al oxide nanosheets as highly efficient catalysts for CO oxidation
We report mesoporous Co-Al oxide nanosheets (CoxAl-Ns, where x denotes the Co/Al ratio in the samples) prepared by calcination of CoAl-hydrotalcite and subsequent alkaline treatment. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements show that the prepared Co-Al oxide nanosheets (CoxAl-Ns) are very thin (10-15 nm) and exhibit high mesoporosity (3-5 nm). Catalytic CO oxidation tests reveal that the CoxAl-Ns exhibit excellent catalytic performances at relatively low temperatures: for example, the Co2.5Al-Ns catalyst could achieve 99% CO conversion at -98 degrees C. Kinetic studies and experimental investigations indicate that the high activity of the Co2.5Al-Ns sample is strongly related to the abundance of active sites associated with the large Brunauer-Emmett-Teller surface area. The Co2.5Al-Ns catalyst also achieves full conversion of CO in tests performed with a gas mixture simulating automobile exhaust gas at 200 degrees C. After loading the Co2.5Al-Ns on a porous ceramic substrate, the obtained Co2.5Al-Ns/PC shows high activity and stability in CO oxidation process. These features are potentially important for future industrial applications of these catalysts.