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• 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]