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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]

In view of the unsatisfactory synergy between plasma technology and catalyst, a series of M-BTC MOFs (M=Mn, Cu, Ce) were introduced to couple with non-thermal plasma using for toluene degradation. M-BTC MOFs containing multi-carboxylic groups were successfully synthesized and presented the excellent crystallinity, morphology and thermal stability. DBD-catalysis systems presented the more excellent toluene degradation performance than single DBD alone system. Due to the porous structure and the multivalent form of manganese, the highest toluene degradation efficiency of 96.27%, the energy efficiency of 22.32 g/kW·h, the CO 2 selectivity of 53.5% and the mineralization degree of 70.17% were acquired for DBD coupled with Mn-BTC under SED of 766.35 J/L. Besides, DBD/Mn-BTC had the lowest ozone and NOx production. Moreover, the toluene degradation mechanism was analyzed by plasma emission spectra analysis, XPS spectra and GC-MS diagram analysis. It indicated plasma discharge can produce abundant free radicals and reactive species to decompose toluene firstly, and the residual toluene and intermediates in the gas can be then adsorbed on Mn-BTC and further oxidized by metal active species. Furthermore, more reactive oxygen species will be generated by activating ozone through Mn-BTC, which was beneficial for toluene degradation. [Display omitted] [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]

• Ta 2 O 5 with rich oxygen vacancies was synthesized by hydrothermal method. • Co 3 O 4 anchored in oxygen vacancies formed highly dispersion Co 3 O 4 /Ta 2 O 5. • Co 3 O 4 /Ta 2 O 5 exhibited the good CO conversion, and the temperature of 90% CO conversion was approximately 150 ℃ at the high space velocity of 156,000 h-1. To solve the problem of uneven dispersion of catalysts, Ta 2 O 5 with oxygen vacancy was introduced for CO conversion. In this work, cobalt was anchored in oxygen vacancies of Ta 2 O 5 to form highly dispersion Co 3 O 4 /Ta 2 O 5. The characteristics results of XRD, SEM, BET, TGA, ESR and H 2 -TPR show that cobalt was anchored in oxygen vacancies forming high dispersion Co 3 O 4 /Ta 2 O 5 and a strong interaction between Co 3 O 4 and Ta 2 O 5. The CO conversion was tested at 150 ℃ and resulted in a 90% conversion rate, which is significantly higher than that of pure Co 3 O 4 and Ta 2 O 5. The main mechanism of Co 3 O 4 /Ta 2 O 5 contributed to CO conversion was investigated by XPS and In-situ DRIFTs, revealing that Co3+ and activated oxygen play a vital role in CO conversion. [Display omitted] [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]