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CO oxidation at mild condition is significant for industrial process but still challenging nowadays, especially for the non-noble metal catalysts. The preparation method significant affect the catalytic activity of the catalyst. Comparing with cobalt supported on tantalum oxide prepared by impregnation method, Co/Ta2O5 prepared by deposition–precipitation method with urea in this study has smaller particle size, higher specific surface area and better redox properties, and these features make the catalyst exhibit higher catalytic activity for CO oxidation at mild condition. 90% CO conversion was achieved at 130 ℃, and CO was fully converted at 150 ℃. The XPS and DRIFTs results show that Co/Ta2O5 has more oxygen vacancies, and the absorbed CO will react with oxygen. The study may provide a new thought for the preparation of catalysts with high activity at mild condition. [ABSTRACT FROM AUTHOR]

• Co 3 O 4 loaded on different forms of Ta 2 O 5 (amorphous, mesoporous, crystalline, crystalline mesoporous) are used for CO oxidation. • Crystalline mesoporous structure of Co/Ta-cm could promote CO conversion. • Co/Ta-cm exhibited the good CO conversion, and the temperature of 90% CO conversion was approximately 130 ℃ at the high space velocity of 780,000 h−1. Because the combination of Co and common support (Al, Ti, et al.) usually shows poor catalytic activity, tantalum has been introduced for CO conversion as a novel carrier due to the excellent performance. In this work, Co 3 O 4 was loaded on four forms of tantalum support (amorphous, mesoporous, crystalline and crystalline mesoporous, abbreviated as Co/Ta-am, Co/Ta-me, Co/Ta-cry and Co/Ta-cm, respectively). And among these four states, Co/Ta-cm presents the highest CO conversion rate. The temperature of 90% CO conversion rate of Co/Ta-cm is approximately 130 ℃ at the high space velocity of 780,000 h−1, which is 70%, 82% and 88% higher than that of Co/Ta-cry, Co/Ta-me and Co/Ta-am, respectively. Moreover, the characteristics of the catalyst have been studied by XRD, SEM, BET, TGA, and H 2 -TPR, and the results reveal that Co/Ta-cm has the excellent crystallinity and stability, and the morphology is regular. X-ray photon spectroscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) have been performed to investigate the reaction mechanism, which indicates that Co3+ is the active component and lattice oxygen plays a critical role in CO oxidation. [ABSTRACT FROM AUTHOR]

Small size cobalt nanoparticles are highly dispersed on different crystalline forms of Ta 2 O 5 (amorphous, T, M, H) by impregnation method, which is then introduced to catalytic oxidation of CO. The experimental results show that Co 3 O 4 /M-Ta 2 O 5 exhibits the highest CO conversion efficiency compared with Co 3 O 4 loaded on amorphous-, T-, and H-Ta 2 O 5 , and the pure Co 3 O 4 and M-Ta 2 O 5. The temperature of 90 % CO conversion rate is approximately 170 °C at the high space velocity of 780,000 h−1. Besides, the effect of oxygen concentration, space velocity, CO concentration, as well as different ratio of Co: Ta on CO conversion have been studied. Moreover, XRD, SEM, TGA, BET and H 2 -TPR characterizations reveal that Co 3 O 4 is uniformly distributed and does not change the structure crystalline of Ta 2 O 5 , and there is strong interaction between cobalt active component and Ta 2 O 5 support, which might be beneficial for CO conversion. Furthermore, the reaction mechanism has been investigated by X-ray photon spectroscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs), which suggest that Co3+ is the active component and lattice oxygen as well as adsorbed oxygen play a critical role in CO oxidation. [ABSTRACT FROM AUTHOR]