Iron doped effects on active sites formation over activated carbon supported Mn-Ce oxide catalysts for low-temperature SCR of NO

Hydrocarbons as reductants show promising results for replacing NH3 in SCR technology. Therefore, considerable interest exists for developing low-temperature (<200 °C) and environmentally friendly HC-SCR catalysts. Hence, C2H4 was examined as a reductant using activated-carbon-supported MnOx-based catalyst in low-temperature SCR operation. Its sensitivity to Mn concentration and operating temperature was parametrically studied, the results of which showed that the catalyst activity followed the order of 130 °C > 150 °C > 180 °C with an optimized Mn concentration near 3.0 wt.%. However, rapid deactivation of catalytic activity also occurred when using C2H4 as the reductant. The mechanism of deactivation was explored and is discussed herein in which deactivation is attributed to two factors. The manganese oxide was reduced to Mn3O4 during reaction testing, which contained relatively low activity compared to Mn2O3. Also, increased crystallinity of the reduced manganese and the formation of carbon black occurred during SCR reaction testing, and these constituents on the catalyst’s surface blocked pores and active sites from participating in catalytic activity.

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Low Temperature deNOx Catalytic Activity with C2H4 as a Reductant Using Mixed Metal Fe-Mn Oxides Supported on Activated Carbon

Energies ◽

10.3390/en12224341 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4341 ◽

Cited By ~ 1

Author(s):

Fang Liu ◽

Li Yang ◽

Jie Cheng ◽

Xin Wu ◽

Wenbin Quan ◽

...

Keyword(s):

Activated Carbon ◽

Low Temperature ◽

Mixed Oxide ◽

Active Sites ◽

Mixed Oxides ◽

Catalytic Reduction ◽

Oxide Catalysts ◽

Catalyst Stability ◽

No Conversion ◽

Mixed Oxide Catalysts

The selective catalytic reduction of NOx (deNOx) at temperatures less than or at 200 °C was investigated while using C2H4 as the reductant and mixed oxides of Fe and Mn supported on activated carbon; their activity was compared to that of MnOx and FeOx separately supported on activated carbon. The bimetallic oxide compositions maintained high NO conversion of greater than 80–98% for periods that were three times greater than those of the supported monometallic oxides. To examine potential reasons for the significant increases in activity maintenance, and subsequent deactivation, the catalysts were examined by using bulk and surface sensitive analytical techniques before and after catalyst testing. No significant changes in Brunauer-Emmett-Teller (BET) surface areas or porosities were observed between freshly-prepared and tested catalysts whereas segregation of FeOx and MnOx species was readily observed in the mono-oxide catalysts after reaction testing that was not detected in the mixed oxide catalysts. Furthermore, x-ray diffraction and Raman spectroscopy data detected cubic Fe3Mn3O8 in both the freshly-prepared and reaction-tested mixed oxide catalysts that were more crystalline after testing. The presence of this compound, which is known to stabilize multivalent Fe species and to enhance oxygen transfer reactions, may be the reason for the high and relatively stable NO conversion activity, and its increased crystallinity during longer-term testing may also decrease surface availability of the active sites responsible for NO conversion. These results point to a potential of further enhancing catalyst stability and activity for low temperature deNOx that is applicable to advanced SCR processing with lower costs and less deleterious side effects to processing equipment.

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Low-temperature SCR of NO with NH3 over CeO2 supported on modified activated carbon fibers

Catalysis Communications ◽

10.1016/j.catcom.2010.10.028 ◽

2011 ◽

Vol 12 (6) ◽

pp. 394-398 ◽

Cited By ~ 52

Author(s):

Lili Zhu ◽

Bichun Huang ◽

Wenhui Wang ◽

Zhengle Wei ◽

Daiqi Ye

Keyword(s):

Activated Carbon ◽

Low Temperature ◽

Carbon Fibers ◽

Activated Carbon Fibers ◽

Modified Activated Carbon ◽

Scr Of No ◽

Low Temperature Scr

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Manganese Oxide Catalysts Supported on TiO2, Al2O3, and SiO2: A Comparison for Low-Temperature SCR of NO with NH3

Industrial & Engineering Chemistry Research ◽

10.1021/ie060484t ◽

2006 ◽

Vol 45 (19) ◽

pp. 6436-6443 ◽

Cited By ~ 158

Author(s):

Panagiotis G. Smirniotis ◽

Pavani M. Sreekanth ◽

Donovan A. Peña ◽

Robert G. Jenkins

Keyword(s):

Low Temperature ◽

Manganese Oxide ◽

Oxide Catalysts ◽

Manganese Oxide Catalysts ◽

Scr Of No ◽

Low Temperature Scr

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Surface characterization studies of TiO2 supported manganese oxide catalysts for low temperature SCR of NO with NH3

Applied Catalysis B Environmental ◽

10.1016/j.apcatb.2007.05.010 ◽

2007 ◽

Vol 76 (1-2) ◽

pp. 123-134 ◽

Cited By ~ 361

Author(s):

Padmanabha Reddy Ettireddy ◽

Neeraja Ettireddy ◽

Sergey Mamedov ◽

Punit Boolchand ◽

Panagiotis G. Smirniotis

Keyword(s):

Low Temperature ◽

Manganese Oxide ◽

Surface Characterization ◽

Oxide Catalysts ◽

Manganese Oxide Catalysts ◽

Scr Of No ◽

Characterization Studies ◽

Low Temperature Scr

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Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NO with NH3

Catalysis Today ◽

10.1016/j.cattod.2004.04.008 ◽

2004 ◽

Vol 90 (1-2) ◽

pp. 51-59 ◽

Cited By ~ 87

Author(s):

Grzegorz S. Szymański ◽

Teresa Grzybek ◽

Helmut Papp

Keyword(s):

Catalytic Activity ◽

Activated Carbon ◽

Low Temperature ◽

Scr Of No ◽

Low Temperature Scr

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Fe and Mn mixed oxide catalysts supported on Sn-modified TiO2 for the selective catalytic reduction of NO with NH3 at low temperature

New Journal of Chemistry ◽

10.1039/d1nj05290j ◽

2022 ◽

Author(s):

Zhitao Han ◽

Huan Du ◽

Duo Xu ◽

Yu Gao ◽

Shaolong Yang ◽

...

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Mixed Oxide ◽

Catalytic Reduction ◽

Oxide Catalysts ◽

Reduction Of No ◽

Sn Doping ◽

Mixed Oxide Catalysts ◽

Fe And Mn ◽

Low Temperature Scr

FeMn/SnxTiO2 catalysts were synthesized by introducing Sn as an additive to modify TiO2 supports, and the Sn doping could improve the SO2 tolerance and low-temperature SCR activity significantly.

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