Ca Doping Effect on the Competition of NH3–SCR and NH3 Oxidation Reactions over Vanadium-Based Catalysts

2021 ◽  
Author(s):  
Yang Zheng ◽  
Yangyang Guo ◽  
Jian Wang ◽  
Lei Luo ◽  
Tingyu Zhu
Keyword(s):  
Doping Effect ◽  
Oxidation Reactions ◽  
Ca Doping ◽  
Nh3 Scr ◽  
Vanadium Based Catalysts ◽  
Nh3 Oxidation

scholarly journals Byproduct Analysis of SO2 Poisoning on NH3-SCR over MnFe/TiO2 Catalysts at Medium to Low Temperatures

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 265 ◽  
Author(s):  
Tsungyu Lee ◽  
Hsunling Bai
Keyword(s):  
Reaction Temperature ◽  
Catalytic Reduction ◽  
No Oxidation ◽  
Ammonium Salts ◽  
Oxidation Reactions ◽  
No Conversion ◽  
Nh3 Scr ◽  
So2 Poisoning ◽  
No Consumption ◽  
Nh3 Oxidation

The byproducts of ammonia-selective catalytic reduction (NH3-SCR) process over MnFe/TiO2 catalysts under the conditions of both with and without SO2 poisoning were analyzed. In addition to the NH3-SCR reaction, the NH3 oxidation and the NO oxidation reactions were also evaluated at temperatures of 100–300 °C to clarify the reactions occurred during the SCR process. The results indicated that major byproducts for the NH3 oxidation and NO oxidation tests were N2O and NO2, respectively, and their concentrations increased as the reaction temperature increased. For the NH3-SCR test without the presence of SO2, it revealed that N2O was majorly from the NH3-SCR reaction instead of from NH3 oxidation reaction. The byproducts of N2O and NO2 for the NH3-SCR reaction also increased after increasing the reaction temperature, which caused the decreasing of N2-selectivity and NO consumption. For the NH3-SCR test with SO2 at 150 °C, there were two decay stages during SO2 poisoning. The first decay was due to a certain amount of NH3 preferably reacted with SO2 instead of with NO or O2. Then the catalysts were accumulated with metal sulfates and ammonium salts, which caused the second decay of NO conversion. The effluent N2O increased as poisoning time increased, which was majorly from oxidation of unreacted NH3. On the other hand, for the NH3-SCR test with SO2 at 300 °C, the NO conversion was not decreased after increasing the poisoning time, but the N2O byproduct concentration was high. However, the SO2 led to the formation of metal sulfates, which might inhibit NO oxidation reactions and cause the concentration of N2O gradually decreased as well as the N2-selectivity increased.

Insights into the co-doping effect of Fe3+ and Zr4+ on the anti-K performance of CeTiOx catalyst for NH3-SCR reaction

2021 ◽  
pp. 125821
Author(s):  
Keke Kang ◽  
Xiaojiang Yao ◽  
Yike Huang ◽  
Jun Cao ◽  
Jing Rong ◽  
...  
Keyword(s):  
Doping Effect ◽  
Co Doping ◽  
Nh3 Scr

Doping effect of Sm on the TiO2/CeSmOx catalyst in the NH3-SCR reaction: structure–activity relationship, reaction mechanism and SO2 tolerance

2019 ◽  
Vol 9 (13) ◽  
pp. 3554-3567 ◽  
Author(s):  
Hao Liu ◽  
Chuanzhi Sun ◽  
Zhongxuan Fan ◽  
XuanXuan Jia ◽  
Jingfang Sun ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
High Activity ◽  
Surface Acidity ◽  
Redox Properties ◽  
Doping Effect ◽  
Activity Relationship ◽  
Good Balance ◽  
Nh3 Scr ◽  
Structure Activity ◽  
So2 Tolerance

A good balance between the redox properties and surface acidity induces the high activity of the Sm doped TiO2/CeO2 catalyst.

Design of a “high-efficiency” NH3-SCR reactor for stationary applications. A kinetic study of NH3 oxidation and NH3-SCR over V-based catalysts

2015 ◽  
Vol 179 ◽  
pp. 185-195 ◽  
Author(s):  
Nicola Usberti ◽  
Magdalena Jablonska ◽  
Miriam Di Blasi ◽  
Pio Forzatti ◽  
Luca Lietti ◽  
...  
Keyword(s):  
Kinetic Study ◽  
High Efficiency ◽  
Nh3 Scr ◽  
Nh3 Oxidation

Ca doping effect on superconductivity in (Yb1−xCax)(Ba0.8Sr0.2)2Cu3O6+z

1998 ◽  
Vol 54 (1-2) ◽  
pp. 108-111 ◽  
Author(s):  
K Fujinami ◽  
H Suematsu ◽  
M Karppinen ◽  
H Yamauchi
Keyword(s):  
Doping Effect ◽  
Ca Doping

scholarly journals Insight into Platinum Poisoning Effect on Cu-SSZ-13 in Selective Catalytic Reduction of NOx with NH3

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 796
Author(s):  
Huawang Zhao ◽  
Lei Han ◽  
Yujie Wang ◽  
Jiandong Zheng
Keyword(s):  
Catalytic Reduction ◽  
No Oxidation ◽  
Oxidation Reactions ◽  
Hydrothermal Aging ◽  
N2o Formation ◽  
Poisoning Effect ◽  
Nh3 Oxidation ◽  
Reduction Of Nox ◽  
Parallel Reactions ◽  
Insight Into

Platinum’s (Pt) poisoning effect on Cu-SSZ-13 and its regeneration were investigated. The Pt enhanced the parallel reactions, such as NH3 oxidation and NO oxidation reactions, which decreased the deNOx activities. In the temperature range below 330 °C, the deactivation of Cu-SSZ-13 by Pt poisoning was primarily caused by the overconsumption of NH3, due to the enhanced NH3-selective oxidation reaction, while the formation of NOx in NH3 oxidation and NO oxidation into NO2 further aggravated the degradation when the temperature was above 460 °C. The non-selective NH3 oxidation and non-selective NOx catalytic reduction reactions resulted in increased N2O formation over Pt-doped samples. The transformation of Pt0 into PtOx after hydrothermal aging recovered the deNOx activities of the Pt-poisoned samples.

scholarly journals Doping effect of cations (Zr4+, Al3+, and Si4+) on MnO /CeO2 nano-rod catalyst for NH3-SCR reaction at low temperature

2019 ◽  
Vol 40 (5) ◽  
pp. 733-743 ◽  
Author(s):  
Xiaojiang Yao ◽  
Jun Cao ◽  
Li Chen ◽  
Keke Kang ◽  
Yang Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Doping Effect ◽  
Nh3 Scr

scholarly journals Deactivation of Cu/SSZ-13 NH3-SCR Catalyst by Exposure to CO, H2, and C3H6

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 929 ◽  
Author(s):  
Auvray ◽  
Mihai ◽  
Lundberg ◽  
Olsson
Keyword(s):  
Flow Reactor ◽  
Catalytic Reduction ◽  
Plug Flow ◽  
Acid Sites ◽  
Drift Spectroscopy ◽  
Scr Catalyst ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
Nh3 Oxidation ◽  
Diffuse Reflectance Infrared

Lean nitric oxide (NOx)-trap (LNT) and selective catalytic reduction (SCR) are efficient systems for the abatement of NOx. The combination of LNT and SCR catalysts improves overall NOx removal, but there is a risk that the SCR catalyst will be exposed to high temperatures and rich exhaust during the LNTs sulfur regeneration. Therefore, the effect of exposure to various rich conditions and temperatures on the subsequent SCR activity of a Cu-exchanged chabazite catalyst was studied. CO, H2, C3H6, and the combination of CO + H2 were used to simulate rich conditions. Aging was performed at 800 °C, 700 °C, and, in the case of CO, 600 °C, in a plug-flow reactor. Investigation of the nature of Cu sites was performed with NH3-temperature-programed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of probe molecules (NH3 and NO). The combination of CO and H2 was especially detrimental to SCR activity and to NH3 oxidation. Rich aging with low reductant concentrations resulted in a significantly larger deactivation compared to lean conditions. Aging in CO at 800 °C caused SCR deactivation but promoted high-temperature NH3 oxidation. Rich conditions greatly enhanced the loss of Brønsted and Lewis acid sites at 800 °C, indicating dealumination and Cu migration. However, at 700 °C, mainly Brønsted sites disappeared during aging. DRIFT spectroscopy analysis revealed that CO aging modified the Cu2+/CuOH+ ratio in favor of the monovalent CuOH+ species, as opposed to lean aging. To summarize, we propose that the reason for the increased deactivation observed for mild rich conditions is the transformation of the Cu species from Z2Cu to ZCuOH, possibly in combination with the formation of Cu clusters.

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