Comparison of sulfur poisoning resistance of Ce/Mn doped γ-Fe2O3 (0 0 1) surface in NH3-SCR reaction with DFT method

2021 ◽  
pp. 149847
Author(s):  
Dongdong Ren ◽  
Keting Gui ◽  
Shaochen Gu
Keyword(s):  
Nh3 Scr ◽  
Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 797 ◽  
Author(s):  
Yan Wang ◽  
Zhaoqiang Li ◽  
Rongrong Fan ◽  
Xin Guo ◽  
Cheng Zhang ◽  
...  

Cu-SSZ-13 has been generally considered as the predominant commercial selective catalytic reduction (SCR) catalyst in the NH3-SCR reaction because of its superior activity and durability. However, in real applications, SCR catalysts readily undergo hydrothermal aging and sulfur poisoning. In this work, the deactivation and regeneration of a commercial Cu-SSZ-13 catalyst was investigated for SO2 exposures during hydrothermal aging and the effect of different regeneration temperatures was compared. By using XRD, SEM, H2-temperature programmed reduction (TPR), X–ray photoelectron spectra (XPS) and NH3-temperature programmed desorption (TPD) analysis, it was found that SO2 poisoning influenced the chabazite (CHA) structure even if regeneration cannot restore its original structure, the redox ability and ammonia storage performance also influenced by sulfation and the regeneration process. Moreover, the extent of a decrease in redox ability was more severe than acidity, suggesting that the amount of isolated Cu2+ and Cu+ reduction was responsible for irreversible deactivation over the Cu-SSZ-13 catalyst. Combined with the analysis of Ea values and pre-exponential factor of the SCR reaction, a more likely explanation for the irreversible deactivation was that active sites were lost mostly in sulfated and regenerated process sites.


Fuel ◽  
2022 ◽  
Vol 310 ◽  
pp. 122237
Author(s):  
Aidong Fan ◽  
Yue Jing ◽  
Jiaxiu Guo ◽  
Xueke Shi ◽  
Shandong Yuan ◽  
...  
Keyword(s):  
Nh3 Scr ◽  
Mn Doped ◽  

2017 ◽  
Vol 93 ◽  
pp. 33-36 ◽  
Author(s):  
Tengfei Xu ◽  
Xiaodong Wu ◽  
Yuxi Gao ◽  
Qiwei Lin ◽  
Jianfeng Hu ◽  
...  

2018 ◽  
Vol 32 (27) ◽  
pp. 1850304 ◽  
Author(s):  
Qingxiao Zhou ◽  
Yongliang Yong ◽  
Xiangying Su ◽  
Weiwei Ju ◽  
Zhibing Fu ◽  
...  

The influence of vacancy and dopants on the adsorption of O2 molecule on graphene was explored by using the density functional theory (DFT) method. The results indicated that the presence of vacancy-defect improved the sensitivity of graphene toward the O2 molecule. Furthermore, the two O atoms of O2 molecule separately formed chemical bonds with C atoms at the defect sites. After introducing the transition-metal (TM) dopants, the O–O bond length of O2 molecule was enlarged by the adsorption on the surface of graphene. Furthermore, the Mn-doped adsorption complexes became magnetic, which was mainly contributed by the O-2p and Mn-3d orbitals.


2013 ◽  
Vol 201 ◽  
pp. 139-144 ◽  
Author(s):  
Huazhen Chang ◽  
Junhua Li ◽  
Jian Yuan ◽  
Liang Chen ◽  
Yun Dai ◽  
...  
Keyword(s):  
Nh3 Scr ◽  
Mn Doped ◽  

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122108
Author(s):  
Heng Xie ◽  
Daobing Shu ◽  
Tianhu Chen ◽  
Haibo Liu ◽  
Xuehua Zou ◽  
...  

Author(s):  
Xavier Auvray ◽  
Maria Arvanitidou ◽  
Åsa Högström ◽  
Jonas Jansson ◽  
Sheedeh Fouladvand ◽  
...  

AbstractTwo copper-exchanged zeolites, Cu/SSZ-13 and Cu/BEA, were studied as catalysts for the selective reduction of NOx by NH3 (NH3-SCR). Their activities for standard SCR (NOx = NO) and fast SCR (NOx = 50% NO + 50% NO2) were measured before and after sulfur poisoning at 250 °C. The effect of 30 ppm SO2 and a mixture of 24 ppm SO3 + 6 ppm SO2 was evaluated. The repetition of subsequent activity measurements served as regeneration method in SCR conditions. SO2 deactivated Cu/SSZ-13 whereas Cu/BEA was only moderately affected. SO3 led to stronger deactivation of both catalysts than SO2. However, also for this case, the Cu/BEA was significantly less affected than Cu/SSZ-13, even though Cu/BEA contained larger amount of stored sulfur. One possible reason for this could be the large pores of Cu/BEA, where the sulfur species possibly resulted in less sterical hindrance than in the small pore SSZ-13 structure. NH3 temperature-programmed desorption (NH3-TPD) showed no loss of storage sites upon sulfur treatment and subsequent regeneration. Partial activity recovery was observed after a period in SCR conditions at 400 °C and 500 °C. Temperature at 300 °C was insufficient to regenerate the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of NO adsorption suggested that SO2 interacts with the ZCuOH sites on Cu/SSZ-13, causing the strong poisoning.


2019 ◽  
Author(s):  
Minho Kim ◽  
won june kim ◽  
Tim Gould ◽  
Eok Kyun Lee ◽  
Sébastien Lebègue ◽  
...  

<p>Materials design increasingly relies on first-principles calculations for screening important candidates and for understanding quantum mechanisms. Density functional theory (DFT) is by far the most popular first-principles approach due to its efficiency and accuracy. However, to accurately predict structures and thermodynamics, DFT must be paired with a van der Waals (vdW) dispersion correction. Therefore, such corrections have been the subject of intense scrutiny in recent years. Despite significant successes in organic molecules, no existing model can adequately cover the full range of common materials, from metals to ionic solids, hampering the applications of DFT for modern problems such as battery design. Here, we introduce a universally optimized vdW-corrected DFT method that demonstrates an unbiased reliability for predicting molecular, layered, ionic, metallic, and hybrid materials without incurring a large computational overhead. We use our method to accurately predict the intercalation potentials of layered electrode materials of a Li-ion battery system – a problem for which the existing state-of-the-art methods fail. Thus, we envisage broad use of our method in the design of chemo-physical processes of new materials.</p>


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