In this study, we used a simple impregnation method to prepare Fe-Ce-O<sub> x </sub> catalysts and tested them regarding their low-temperature (200-300 °C) selective catalytic reduction (SCR) of ...In this study, we used a simple impregnation method to prepare Fe-Ce-O<sub> x </sub> catalysts and tested them regarding their low-temperature (200-300 °C) selective catalytic reduction (SCR) of NO using NH<sub>3</sub>. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO<sub>2</sub>/H<sub>2</sub>O resistance of the catalysts. The results showed that the FeCe(1:6)O<sub> x </sub> (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O<sub> x </sub> catalyst had the highest NO conversion with an activity of 94-99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h<sup>−1</sup>. The NO conversion for the FeCe(1:6)O<sub> x </sub> catalyst also reached 80-98% between 200 and 300 °C at a space velocity of 204,000 h<sup>−1</sup>. In addition, the FeCe(1:6)O<sub> x </sub> catalyst demonstrated good stability in a 10-h SCR reaction at 200-300 °C. Even in the presence of SO<sub>2</sub> and H<sub>2</sub>O, the FeCe(1:6)O<sub> x </sub> catalyst exhibited good SCR performance.展开更多
The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond ...The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond nitrogen-coordinated atomic metal species due to the fact that the M-O bond is weaker than the M-N bond.Herein,a series of metal-oxygen-carbon structured low-nucleus clusters(LNCs)are successfully anchored on the surface of multiwalled carbon nanotubes(M-MWCNTs,M=Ni,Co,or Fe)through a foolproof low-temperature gas transfer(300℃)method without any further treatment.The morphology and coordination configuration of the LNCs at the atomic level were confirmed by comprehensive characterizations.The synthetic Ni-MWCNTs electrocatalyst features excellent OER activity and stability under alkaline conditions,transcending the performances of Co-MWCNTs,Fe-MWCNTs and RuO_(2).Density functional theory calculations reveal that the moderate oxidation of low-nucleus Ni clusters changes the unoccupied orbital of Ni atoms,thereby lowering the energy barrier of the OER rate-limiting step and making the OER process more energy-efficient.This study demonstrates a novel versatile platform for large-scale manufacturing of oxygen-coordinated LNC catalysts.展开更多
基金supported by the National Natural Science Foundation of China (No.21206108)Tianjin Municipal Science and Technology Commission (No.14JCYBJC21200)
文摘In this study, we used a simple impregnation method to prepare Fe-Ce-O<sub> x </sub> catalysts and tested them regarding their low-temperature (200-300 °C) selective catalytic reduction (SCR) of NO using NH<sub>3</sub>. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO<sub>2</sub>/H<sub>2</sub>O resistance of the catalysts. The results showed that the FeCe(1:6)O<sub> x </sub> (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O<sub> x </sub> catalyst had the highest NO conversion with an activity of 94-99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h<sup>−1</sup>. The NO conversion for the FeCe(1:6)O<sub> x </sub> catalyst also reached 80-98% between 200 and 300 °C at a space velocity of 204,000 h<sup>−1</sup>. In addition, the FeCe(1:6)O<sub> x </sub> catalyst demonstrated good stability in a 10-h SCR reaction at 200-300 °C. Even in the presence of SO<sub>2</sub> and H<sub>2</sub>O, the FeCe(1:6)O<sub> x </sub> catalyst exhibited good SCR performance.
基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang,Grant/Award Number:2019R01006National Key R&D Program of China,Grant/Award Number:2018YFB0104300。
文摘The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond nitrogen-coordinated atomic metal species due to the fact that the M-O bond is weaker than the M-N bond.Herein,a series of metal-oxygen-carbon structured low-nucleus clusters(LNCs)are successfully anchored on the surface of multiwalled carbon nanotubes(M-MWCNTs,M=Ni,Co,or Fe)through a foolproof low-temperature gas transfer(300℃)method without any further treatment.The morphology and coordination configuration of the LNCs at the atomic level were confirmed by comprehensive characterizations.The synthetic Ni-MWCNTs electrocatalyst features excellent OER activity and stability under alkaline conditions,transcending the performances of Co-MWCNTs,Fe-MWCNTs and RuO_(2).Density functional theory calculations reveal that the moderate oxidation of low-nucleus Ni clusters changes the unoccupied orbital of Ni atoms,thereby lowering the energy barrier of the OER rate-limiting step and making the OER process more energy-efficient.This study demonstrates a novel versatile platform for large-scale manufacturing of oxygen-coordinated LNC catalysts.
