scholarly journals A Review of Low Temperature NH3-SCR for Removal of NOx

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 349 ◽  
Author(s):  
Devaiah Damma ◽  
Padmanabha Ettireddy ◽  
Benjaram Reddy ◽  
Panagiotis Smirniotis
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Transition Metal Oxides ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Operating Conditions ◽  
Advanced Materials ◽  
Research Progress ◽  
Nh3 Scr ◽  
Mixed Transition

The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe pollution regulations being imposed around the world. Supported and mixed transition metal oxides have been widely investigated for LT-SCR technology. However, these catalytic materials have some drawbacks, especially in terms of catalyst poisoning by H2O or/and SO2. Hence, the development of catalysts for the LT-SCR process is still under active investigation throughout seeking better performance. Extensive research efforts have been made to develop new advanced materials for this technology. This article critically reviews the recent research progress on supported transition and mixed transition metal oxide catalysts for the LT-SCR reaction. The review covered the description of the influence of operating conditions and promoters on the LT-SCR performance. The reaction mechanism, reaction intermediates, and active sites are also discussed in detail using isotopic labelling and in situ FT-IR studies.

Facile fabrication of hollow tubular mixed oxides for selective catalytic reduction of NOx at low temperature: a combined experimental and theoretical study

2017 ◽  
Vol 53 (5) ◽  
pp. 967-970 ◽  
Author(s):  
Xiuyun Wang ◽  
Zhixin Lan ◽  
Yi Liu ◽  
Yongjin Luo ◽  
Jianjun Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Theoretical Study ◽  
Mixed Oxides ◽  
Catalytic Reduction ◽  
Heating Rates ◽  
Facile Fabrication ◽  
Reduction Of Nox

The 1D nanowire or hollow tubular structure of various transition metal oxides can be tuned by controlling heating rates.

Theoretical Design of Transition Metal-Doped TiO2 for the Selective Catalytic Reduction of NO with NH3 by DFT Calculations

2022 ◽  
Author(s):  
Huiling Zheng ◽  
Renjie Li ◽  
Chengming Zhong ◽  
Zhi Li ◽  
Yikun Kang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Selective Catalytic Reduction ◽  
Transition Metal Oxides ◽  
Catalytic Reduction ◽  
Trade Off ◽  
Reduction Of No ◽  
Theoretical Design ◽  
Scr Of No ◽  
Metal Doped

Many transition metal oxides supported on TiO2 have been studied for selective catalytic reduction (SCR) of NO with NH3. However, the trade-off exists between the low-temperature activity and N2 selectivity....

scholarly journals Effect of Transition Metal Additives on the Catalytic Performance of Cu–Mn/SAPO-34 for Selective Catalytic Reduction of NO with NH3 at Low Temperature

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 685
Author(s):  
Guofu Liu ◽  
Wenjie Zhang ◽  
Pengfei He ◽  
Dekui Shen ◽  
Chunfei Wu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Oxides ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Decomposition Temperature ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Before And After ◽  
So2 Resistance

The adsorption of NO, NH3, H2O, and SO2 gaseous molecules on different transition metal oxides was studied based on density function theory (DFT), and three better-performing transition metal elements (Fe, Co, and Ce) were selected. Cu–Mn/SAPO-34 catalysts were prepared by impregnation method and then modified by the selected transition metals (Fe, Co, and Ce); the SO2 resistance experiments and characterizations including Brunner−Emmet−Teller (BET), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), and thermal gravity analysis (TG)-differential thermal gravity (DTG) before and after SO2 poisoning were conducted. The results showed that the deactivation of the Cu–Mn/SAPO-34 catalyst is ascribed to the deposition of lots of ammonium sulfates on the surface, depositing on the active sites and inhibiting the adsorption of NH3. After the modification of Fe, Co, and Ce oxides, the SO2 resistance of the modified Cu–Mn/SAPO-34 catalyst was significantly enhanced due to the less formation of ammonium sulfates. Among all these modified Cu–Mn/SAPO-34 catalysts, the Cu–Mn–Ce/SAPO-34 exhibited the highest SO2 resistance owing to the decreased decomposition temperature and the trapper of ceria for capturing SO2 to form Ce(SO4)2, further inhibiting the deposition of ammonium sulfates.

scholarly journals Promoting Effect of Mn on In Situ Synthesized Cu-SSZ-13 for NH3-SCR

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1375
Author(s):  
Jinpeng Du ◽  
Jingyi Wang ◽  
Xiaoyan Shi ◽  
Yulong Shan ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Acid Sites ◽  
Promoting Effect ◽  
Nh3 Scr ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared ◽  
Redox Ability

The effect of Mn impregnation on the NH3-SCR (selective catalytic reduction of NOx by NH3) activity of in situ synthesized Cu-SSZ-13 was investigated in this work. It was found that Mn addition could efficiently improve the low-temperature activity of Cu-SSZ-13. The optimal amount of Mn was 5 wt.%, and NOx conversion was improved by more than 20% over a temperature range of 120 °C to 150 °C. SEM (scanning electron microscopy), XRD (X-ray diffraction), N2 adsorption-desorption, H2-TPR (temperature programmed reduction of H2), NH3-TPD (temperature programmed desorption of NH3) and in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) experiments were conducted to investigate the changes in the zeolite structure, active sites, acid sites and reaction mechanism. The impregnated MnOx species caused a decline in the crystallinity of Cu-SSZ-13 but markedly improved the redox ability. Nitrate and nitrite species were observed in the Mn-modified Cu-SSZ-13, and the formation of these species was thought to cause the observed increase in low-temperature NH3-SCR activity. The results show that the addition of Mn is a promising method for promoting the low-temperature catalytic activity of Cu-SSZ-13.

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