Effect of doping Cr on NH3 adsorption and NO oxidation over the FexOy/AC surface: a DFT-D study

2021 ◽  
pp. 125798
Author(s):  
Chaoyue Xie ◽  
Baozhong Zhu ◽  
Yunlan Sun ◽  
Weiyi Song ◽  
Minggao Xu
Keyword(s):  
No Oxidation ◽  
Nh3 Adsorption ◽  
Effect Of Doping

scholarly journals Numerical Investigation on the Intraphase and Interphase Mass Transfer Limitations for NH3-SCR over Cu-ZSM-5

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1966
Author(s):  
Shiyong Yu ◽  
Jichao Zhang
Keyword(s):  
Pressure Drop ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Catalytic Performance ◽  
No Oxidation ◽  
Relative Pressure ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Nh3 Adsorption ◽  
Media Channels

A systematic modeling approach was scrutinized to develop a kinetic model and a novel monolith channel geometry was designed for NH3 selective catalytic reduction (NH3-SCR) over Cu-ZSM-5. The redox characteristic of Cu-based catalysts and the variations of NH3, NOx concentration, and NOx conversion along the axis in porous media channels were studied. The relative pressure drop in different channels, the variations of NH3 and NOx conversion efficiency were analyzed. The model mainly considers NH3 adsorption and desorption, NH3 oxidation, NO oxidation, and NOx reduction. The results showed that the model could accurately predict the NH3-SCR reaction. In addition, it was found that the Cu-based zeolite catalyst had poor low-temperature catalytic performance and good high-temperature activity. Moreover, the catalytic reaction of NH3-SCR was mainly concentrated in the upper part of the reactor. In addition, the hexagonal channel could effectively improve the diffusion rate of gas reactants to the catalyst wall, reduce the pressure drop and improve the catalytic conversion efficiencies of NH3 and NOx.

scholarly journals Sb-Containing Metal Oxide Catalysts for the Selective Catalytic Reduction of NOx with NH3

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1154
Author(s):  
Qian Xu ◽  
Dandan Liu ◽  
Chuchu Wang ◽  
Wangcheng Zhan ◽  
Yanglong Guo ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
Catalytic Reduction ◽  
No Oxidation ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Nh3 Scr ◽  
Brönsted Acid ◽  
Nh3 Adsorption

Sb-containing catalysts (SbZrOx (SbZr), SbCeOx (SbCe), SbCeZrOx (SbCeZr)) were prepared by citric acid method and investigated for the selective catalytic reduction (SCR) of NOx with NH3 (NH3-SCR). SbCeZr outperformed SbZr and SbCe and exhibited the highest activity with 80% NO conversion in the temperature window of 202–422 °C. Meanwhile, it also had good thermal stability and resistance against H2O and SO2. Various characterization methods, such as XRD, XPS, H2-TPR, NH3-TPD, and in situ diffuse reflectance infrared Fourier transform (DRIFT), were applied to understand their different behavior in NOx removal. The presence of Sb in the metal oxides led to the difference in acid distribution and redox property, which closely related with the NH3 adsorption and NO oxidation. Brønsted acid and Lewis acid were evenly distributed on SbCe, while Brønsted acid dominated on SbCeZr. Compared with Brønsted acid, Lewis acid was slightly active in NH3-SCR. The competition between NH3 adsorption and NO oxidation was dependent on SbOx and metal oxides, which were found on SbCe while not on SbCeZr.

scholarly journals Insight into the Promoting Role of Er Modification on SO2 Resistance for NH3-SCR at Low Temperature over FeMn/TiO2 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 618
Author(s):  
Huan Du ◽  
Zhitao Han ◽  
Xitian Wu ◽  
Chenglong Li ◽  
Yu Gao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Catalyst Surface ◽  
Impregnation Method ◽  
In Situ Drifts ◽  
Tio2 Catalyst ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
So2 Resistance ◽  
Fast Scr

Er-modified FeMn/TiO2 catalysts were prepared through the wet impregnation method, and their NH3-SCR activities were tested. The results showed that Er modification could obviously promote SO2 resistance of FeMn/TiO2 catalysts at a low temperature. The promoting effect and mechanism were explored in detail using various techniques, such as BET, XRD, H2-TPR, XPS, TG, and in-situ DRIFTS. The characterization results indicated that Er modification on FeMn/TiO2 catalysts could increase the Mn4+ concentration and surface chemisorbed labile oxygen ratio, which was favorable for NO oxidation to NO2, further accelerating low-temperature SCR activity through the “fast SCR” reaction. As fast SCR reaction could accelerate the consumption of adsorbed NH3 species, it would benefit to restrain the competitive adsorption of SO2 and limit the reaction between adsorbed SO2 and NH3 species. XPS results indicated that ammonium sulfates and Mn sulfates formed were found on Er-modified FeMn/TiO2 catalyst surface seemed much less than those on FeMn/TiO2 catalyst surface, suggested that Er modification was helpful for reducing the generation or deposition of sulfate salts on the catalyst surface. According to in-situ DRIFTS the results of, the presence of SO2 in feeding gas imposed a stronger impact on the NO adsorption than NH3 adsorption on Lewis acid sites of Er-modified FeMn/TiO2 catalysts, gradually making NH3-SCR reaction to proceed in E–R mechanism rather than L–H mechanism. DRIFTS.

scholarly journals Responses of Defect-Rich Zr-Based Metal–Organic Frameworks toward NH3 Adsorption

2021 ◽  
Vol 143 (8) ◽  
pp. 3205-3218
Author(s):  
Tatchamapan Yoskamtorn ◽  
Pu Zhao ◽  
Xin-Ping Wu ◽  
Kirsty Purchase ◽  
Fabio Orlandi ◽  
...  
Keyword(s):  
Metal Organic Frameworks ◽  
Nh3 Adsorption ◽  
Metal Organic

scholarly journals The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst

2019 ◽  
Vol 17 (1) ◽  
pp. 1459-1465
Author(s):  
Xuedong Feng ◽  
Jing Yi ◽  
Peng Luo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
No Oxidation ◽  
Test Results ◽  
X Ray Diffraction ◽  
Storage Performance ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Physical And Chemical ◽  
Al2o3 Catalyst

AbstractWith the purpose of studying the influence of NO/O2 on the NOx storage activity, a Pt-Ba-Ce/γ-Al2O3 catalyst was synthesized by an acid-aided sol-gel method. The physical and chemical properties of the catalyst were characterized by X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results showed that the composition of the catalyst was well-crystallized and the crystalline size of CeO2 (111) was about 5.7 nm. The mechanism of NO and NO2 storage and NOx temperature programmed desorption (NO-TPD) experiments were investigated to evaluate the NOx storage capacity of the catalyst. Pt-Ba-Ce/γ-Al2O3 catalyst presented the supreme NOx storage performance at 350℃, and the maximum value reached to 668.8 μmol / gcat. Compared with O2-free condition, NO oxidation to NO2 by O2 had a beneficial effect on the storage performance of NOx. NO-TPD test results showed that the NOx species stored on the catalyst surface still kept relatively stable even below 350℃.

EDMOS in ultrathin FDSOI: Effect of doping and layout of the drift region

2015 ◽  
Author(s):  
Antoine Litty ◽  
Sylvie Ortolland ◽  
Dominique Golanski ◽  
Christian Dutto ◽  
Sorin Cristoloveanu
Keyword(s):  
Drift Region ◽  
Effect Of Doping

Study of TiO2 anatase nano and microstructures with dominant {001} facets for NO oxidation

2012 ◽  
Vol 19 (9) ◽  
pp. 3719-3726 ◽  
Author(s):  
Maria-Veronica Sofianou ◽  
Christos Trapalis ◽  
Vassils Psycharis ◽  
Nikos Boukos ◽  
Tiverios Vaimakis ◽  
...  
Keyword(s):  
No Oxidation ◽  
Tio2 Anatase
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