Ce-Co catalyst with high surface area and uniform mesoporous channels prepared by template method for Hg0 oxidation

Zhang, Xiaopeng; Wang, Jinxin; Tan, Bojian; Li, Zhuofeng; Cui, Yuezong; He, Gaohong

doi:10.1016/j.catcom.2017.04.024

Cited by 12 publications

(7 citation statements)

References 21 publications

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“…(Yang et al, 2014) The Hg 0 removal temperature windows of the Ce-Co catalyst and Co3O4 nanorods synthesized by He et al were 150-350 ℃ and 100-300 ℃, respectively. (Zhang et al, 2017;Zhang et al, 2019b) Therefore, users need to create a specific temperature environment for Co3O4 to achieve its best performance. In the meanwhile, the internal environment of the flue gas purification system was complicated.…”

Section: Introductionmentioning

confidence: 99%

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Zhou

Shen

Yang

et al. 2021

Environ Sci Pollut Res

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Co3O4 is a promising Hg 0 removal catalyst for industrial application. Operating temperature and low sulfur resistance are two of the main problems that hinder its industrial application in Hg removal. Herein, a metal-organic framework (Co-BDC) was introduced as a sacrificial template to obtain the catalyst nano-sized Co3O4@C by calcination. Part of the organic ligands carbonized during the calcination. Carbon wrapped Co3O4 and reduced metal agglomeration. The optimal Hg 0 removal temperature of the existing cobalt oxides catalysts was always around 150 ℃, but H2-TPR showed that the oxygen atoms on the Co3O4@C were more active than those on commercial Co3O4, causing the Hg 0 removal temperature window of Co3O4@C to shift to lower temperatures. The Hg 0 removal efficiency of Co3O4@C could reach almost 100% even at 25 ℃. In the meanwhile, Co3O4@C also showed a strong SO2 resistance at ambient temperature. Experimental results and characterization proved that SO2 did not compete with Hg 0 on the surface of Co3O4 at low temperatures. On the contrary, it participated in the oxidation of Hg 0 . This is a great improvement for Co3O4 catalyst in Hg 0 removal. It reduces the restrictions on the application of Co3O4 in Hg 0 removal. Co3O4@C shows considerable potential as an Hg 0 removal catalyst.

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Section: Introductionmentioning

confidence: 99%

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Zhou

Shen

Yang

et al. 2021

Environ Sci Pollut Res

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“…Various transition-metal oxides, such as VO x , , WO x , , , MnO x , , , ZrO x , RuO 2 , CoO x , , and CeO x , , , have been widely used as catalysts for Hg 0 oxidation. CoO x with the favorable features of low cost, earth abundance, and good stability has been considered to be a promising catalyst .…”

Section: Introductionmentioning

confidence: 99%

“…Metal iron doping is a general method to increase the amount of surface-active oxygen . Zhang et al reported that Ce-doped Co 3 O 4 could obtain 50% more surface-active oxygen when compared to single Co 3 O 4 , resulting in a 30% higher Hg 0 oxidation efficiency below 150 o C. In the meanwhile, decreasing catalyst particle size can increase the number of low-coordination atoms located at the edges and corners, , which will capture and activate more gaseous oxygen leading to a better Hg 0 oxidation performance. Esswein et al researched Co 3 O 4 nanoparticles with different particle sizes contrastively and found the small-sized Co 3 O 4 exhibits better performance .…”

Section: Introductionmentioning

confidence: 99%

“…6 It has been proven that converting Hg 0 to an easily removed form of Hg 2+ is a feasible way to control the Hg 0 emission from flue gas. 7,8 Various transition-metal oxides, such as VO x , 9,10 WO x , 11,1211,12 MnO x , 13,1413,14 ZrO x , 15 RuO 2 , 1616 CoO x , 17,18 and CeO x , 19,2019,20 have been widely used as catalysts for Hg 0 oxidation. CoO x with the favorable features of low cost, earth abundance, and good stability has been considered to be a promising catalyst.…”

Section: Introductionmentioning

confidence: 99%

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Co₃O₄ Nanorods with a Great Amount of Oxygen Vacancies for Highly Efficient Hg⁰ Oxidation from Coal Combustion Flue Gas

Zhang

Zhu

et al. 2019

Energy Fuels

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Oxidizing elemental mercury (Hg0) to Hg2+ is an effective way to remove Hg0 from flue gas. Surface-active oxygen species are considered to be important active sites in Hg0 oxidation process. The concentration enhancement of surface-active oxygen species is a primary challenge for this technology. Oxygen vacancies can easily capture and activate gaseous oxygen, forming more surface-active oxygen species, which may lead to a better Hg0 oxidation efficiency. Co3+ in Co3O4 can generate oxygen vacancies through the reduction of Co3+ to Co2+, and the oxygen vacancies formation process is controlled by Co2+/Co3+ ratio. Inspired by this, Co3O4 nanorods exposing (220) facet with a high Co3+/Co2+ ratio were successfully synthesized. Raman and X-ray photoelectron spectroscopy (XPS) results show that the high concentration of Co3+ leads to more oxygen vacancies. It results in a better catalytic performance for Co3O4 nanorods whose Hg0 oxidation efficiency remains above 90% at 180 000 h– in the temperature range of 100–300 °C. After 2880 min reaction, the Hg0 oxidation efficiency of Co3O4 nanorods reduces to about 72%, and it recovers to the original level after in situ thermal treatment at 550 °C, suggesting a great renewable property. Furthermore, XPS results of Co3O4 nanorods before and after the reaction show that the concentrations of Co3+ and surface-active oxygen decrease after the reaction. The reaction mechanism was revealed based on these results. Hg0 reacts with surface-active oxygen forming HgO, and the consumed oxygen is replenished by gaseous O2. Co3+/Co2+ redox couple can improve the electron-transfer activity to enhance the Hg0 oxidation efficiency in the presence of O2. The effects of flue gas components on the Hg0 oxidation efficiency are also investigated. O2 and NO have positive effects, while H2O and SO2 have negative effects on the Hg0 removal process. However, Co3O4 nanorods still have an efficiency of 75% even in the presence of 8% H2O and 200 ppm SO2.

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“…Meanwhile, CoO x has usually been used as a catalyst modifier due to its excellent redox ability, such as the better catalytic activities of magnetosphere with Co modification . Our previous study shows that Co modified Ce based catalysts have an excellent Hg 0 adsorption capacity and Hg 0 oxidation efficiency …”

Section: Introductionmentioning

confidence: 99%

Removal of elemental mercury by Ce and Co modified MCM‐41 catalyst from simulated flue gas

et al. 2018

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Co and Ce based catalysts have been proven to possess a high Hg 0 removal efficiency. However, these catalysts have a low dispersion of active components and low mass transfer rate, which limits their catalytic activity. MCM-41 has a large surface area and a highly ordered mesoporous structure, which can improve the dispersion of Co and Ce, resulting in a high mass transfer rate. In this paper, different amounts of Co and Ce were loaded on MCM-41 to synthesize Co x -Ce x /MCM-41. The characteristic results of the catalyst showed that catalysts with a lower Co and Ce loading amount had a high dispersion and a low crystallinity, leading to more activity sites on the catalyst surface. Hence, the Hg 0 removal efficiency of the catalysts first increased with the increase of the Co and Ce loading amount. However, with the further increase of the Co and Ce loading amount, the crystallinity of the catalysts increased, which might cause the blockage of the pores and the decrease of BET surface areas, leading to a low Hg 0 removal efficiency. Along with the factors mentioned above, Co 0.15 -Ce 0.15 /MCM-41 had the best catalytic activity, which showed above 85 % Hg 0 removal efficiency in the temperature range of 200-300 8C at 180 000 h À1 . Flue gas components had different effects on catalytic activity. O 2 and NO could promote, but H 2 O and SO 2 inhibit the Hg 0 removal efficiency. The simulated flue gas of 300 ppm SO 2 , 400 ppm NO, 6 % H 2 O, and 5 % O 2 have serious effects on catalytic activity leading to a lower Hg 0 removal efficiency of 20 % for Co 0.15 -Ce 0.15 /MCM-4.

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Ce-Co catalyst with high surface area and uniform mesoporous channels prepared by template method for Hg0 oxidation

Cited by 12 publications

References 21 publications

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Co₃O₄ Nanorods with a Great Amount of Oxygen Vacancies for Highly Efficient Hg⁰ Oxidation from Coal Combustion Flue Gas

Removal of elemental mercury by Ce and Co modified MCM‐41 catalyst from simulated flue gas

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Ce-Co catalyst with high surface area and uniform mesoporous channels prepared by template method for Hg0 oxidation

Cited by 12 publications

References 21 publications

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Co3O4 Nanorods with a Great Amount of Oxygen Vacancies for Highly Efficient Hg0 Oxidation from Coal Combustion Flue Gas

Removal of elemental mercury by Ce and Co modified MCM‐41 catalyst from simulated flue gas

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Co₃O₄ Nanorods with a Great Amount of Oxygen Vacancies for Highly Efficient Hg⁰ Oxidation from Coal Combustion Flue Gas