Rod-like and mushroom-like Co3O4–CeO2 catalysts derived from Ce-1,3,5-benzene tricarboxylic acid for CO preferential oxidation: effects of compositions and morphology
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Rod-like and mushroom-like Co3O4–CeO2 catalysts were synthesized using CeBTC MOFs as self-sacrifice templates. The two kinds of Co3O4–CeO2 catalysts with different shapes were characterized by SEM, TEM, N2 physical-sorption, XRD, TPR, Raman, XPS. The effects of compositions and morphology on the catalytic activity were investigated. The catalytic activities of Co3O4–CeO2 are correlated with the results of SEM, TEM, N2 physical-sorption, XRD, TPR, Raman, XPS to give insights into the catalytic sites. The results indicate the obtained Co3O4–CeO2 catalysts exhibit rod-like and mushroom-like, replicating the morphology of CeBTC templates. The catalytic activities of Co3O4–CeO2 were arranged in this sequence: Co1Ce > Co6Ce > Co2Ce > Co4Ce > Co8Ce, regardless their different catalyst morphology. The mushroom-like catalysts are superior to the rod-like ones due to their high surface areas and small Co3O4 crystal sizes. The sequence of catalytic activity versus Co/Ce ratio are coincidence with the order of Co–Ce synergistic interaction and Co3+/Co deduced from results of XRD, TPR, Raman, XPS. This evidence revealed that the Co–Ce synergistic interaction and Co3+ ions are responsible for the high activity of Co3O4–CeO2 catalysts. The highest CO conversion of 99% catalyst was achieved over M-Co1Ce catalyst with 12.5% CO2 and 15% H2O at 215 °C, 20,000 mL g−1 h−1. In addition, CO conversion of M-Co1Ce catalyst maintained more than 99% for 54 h in the atmosphere of simulated reformate at 20,000 mL g−1 h−1, suggesting the M-Co1Ce catalyst demonstrates potential in practice application.
KeywordsMetal organic frameworks CO preferential oxidation Cobalt oxide Ceria Template
The financial supports from National Natural Science Foundation of China (21406053), Natural Science Foundation of Hebei province of China (B2014208141) are gratefully appreciated. In addition, the authors acknowledged Engineering Research Center of Catalytic Oxidation Process and Technology of Shijiazhuang Hebei Province.
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