Revealing the Synergistic Deactivation Mechanism of Hydrothermal Aging and SO2 Poisoning on Cu/SSZ-13 under SCR Condition

2021 ◽  
Author(s):  
Yani Zhang ◽  
Hongchang Zhu ◽  
Tao Zhang ◽  
Jie Li ◽  
Jianjun Chen ◽  
...  
Keyword(s):  
Hydrothermal Aging ◽  
So2 Poisoning ◽  
Deactivation Mechanism

Impact of Hydrothermal Aging on SO2 Poisoning over Cu-SSZ-13 Diesel Exhaust SCR Catalysts

2019 ◽  
Vol 58 (10) ◽  
pp. 3949-3958 ◽  
Author(s):  
Lai Wei ◽  
Dongwei Yao ◽  
Feng Wu ◽  
Biao Liu ◽  
Xiaohan Hu ◽  
...  
Keyword(s):  
Diesel Exhaust ◽  
Hydrothermal Aging ◽  
So2 Poisoning ◽  
Scr Catalysts

scholarly journals Deactivation and Regeneration for the SO2-Poisoning of a Cu-SSZ-13 Catalyst in the NH3-SCR Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 797 ◽  
Author(s):  
Yan Wang ◽  
Zhaoqiang Li ◽  
Rongrong Fan ◽  
Xin Guo ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Sulfur Poisoning ◽  
Photoelectron Spectra ◽  
Hydrothermal Aging ◽  
Exponential Factor ◽  
Nh3 Scr ◽  
So2 Poisoning ◽  
Scr Catalysts ◽  
Temperature Programmed ◽  
Redox Ability

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.

Deactivation mechanism of Cu active sites in Cu/SSZ-13 — Phosphorus poisoning and the effect of hydrothermal aging

2020 ◽  
Vol 269 ◽  
pp. 118781 ◽  
Author(s):  
Aiyong Wang ◽  
Kunpeng Xie ◽  
Diana Bernin ◽  
Ashok Kumar ◽  
Krishna Kamasamudram ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrothermal Aging ◽  
Phosphorus Poisoning ◽  
Deactivation Mechanism

Environmental Factors and Deactivation Mechanism of Au/α-Fe2O3 Catalyst during Storage in Ambient Air

2011 ◽  
Vol 31 (12) ◽  
pp. 1489-1495 ◽  
Author(s):  
Jiying WEI ◽  
Guifang FAN ◽  
Feng JIANG ◽  
Zhenzhong ZHANG ◽  
Lan ZHANG
Keyword(s):  
Environmental Factors ◽  
Ambient Air ◽  
Deactivation Mechanism

scholarly journals The Hydrothermal Stability and the Properties of Non- and Strongly-Interacting Rh Species over Rh/γ, θ-Al2O3 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 99
Author(s):  
Guanghao Cheng ◽  
Gurong Shen ◽  
Jun Wang ◽  
Yunhao Wang ◽  
Weibo Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Aging Time ◽  
Reaction Path ◽  
Aging Treatment ◽  
Hydrothermal Stability ◽  
Hydrothermal Aging ◽  
Strongly Interacting

The present work reports the effects of γ-, θ-phase of alumina on the hydrothermal stability and the properties of non- and strongly-interacting Rh species of the Rh/Al2O3 catalysts. Comparing to γ-Al2O3, θ-Al2O3 can not only reduce the amount of occluded Rh but also better stabilize Rh during hydrothermal aging treatment. When the aging time was prolonged to 70 h, all the non-interacting Rh was transformed into strongly-interacting Rh and occluded Rh. The XPS results indicated that non- and strongly-interacting Rh might exist in the form of Rh/Rh3+ and Rh4+, respectively. CO-NO reaction was chosen as a probe reaction to research more information about non- and strongly-interacting Rh. The two Rh species had similar apparent activation energy (Eapp) of 170 kJ/mol, which indicated that non- and strongly-interacting Rh follow the same reaction path. The non-interacting Rh was removed from aged samples by the acid-treated method, and obtained results showed that only 2.5% and 4.0% non-interacting Rh was maintained in aged Rh/γ-Al2O3 and Rh/θ-Al2O3.

scholarly journals Deactivation mechanism and regeneration study of Zn/HZSM-5 catalyst in ethylene transformation

2021 ◽  
Vol 611 ◽  
pp. 117976
Author(s):  
Aurélien Bonnin ◽  
Yannick Pouilloux ◽  
Vincent Coupard ◽  
Denis Uzio ◽  
Ludovic Pinard
Keyword(s):  
Regeneration Study ◽  
Deactivation Mechanism

scholarly journals Phase evolution and mechanical performance of an ettringite-based binder during hydrothermal aging

2021 ◽  
Vol 143 ◽  
pp. 106403
Author(s):  
Hoang Nguyen ◽  
Valter Carvelli ◽  
Wolfgang Kunther ◽  
Mirja Illikainen ◽  
Paivo Kinnunen
Keyword(s):  
Mechanical Performance ◽  
Phase Evolution ◽  
Hydrothermal Aging

scholarly journals Effect of Accelerated Aging on Some Mechanical Properties and Wear of Different Commercial Dental Resin Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2769
Author(s):  
Jonne Oja ◽  
Lippo Lassila ◽  
Pekka K. Vallittu ◽  
Sufyan Garoushi
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Accelerated Aging ◽  
Wear Depth ◽  
Resin Composites ◽  
Expiration Date ◽  
Dental Resin ◽  
Hydrothermal Aging ◽  
Dental Resin Composites

The aim of current in vitro research was to determine the effect of hydrothermal accelerated aging on the mechanical properties and wear of different commercial dental resin composites (RCs). In addition, the effect of expiration date of the composite prior its use was also evaluated. Five commercially available RCs were studied: Conventional RCs (Filtek Supreme XTE, G-aenial Posterior, Denfil, and >3y expired Supreme XTE), bulk-fill RC (Filtek Bulk Fill), and short fiber-reinforced RC (everX Posterior). Three-point flexural test was used for determination of ultimate flexural strength (n = 8). A vickers indenter was used for testing surface microhardness. A wear test was conducted with 15,000 chewing cycles using a dual-axis chewing simulator. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Degree of C=C bond conversion of monomers was determined by FTIR-spectrometry. The specimens were either dry stored for 48 h (37 °C) or boiled (100 °C) for 16 h before testing. Scanning electron microscopy (SEM) was used to evaluate the microstructure of each material. Data were analyzed using ANOVA (p = 0.05). Hydrothermal aging had no significant effects on the surface wear and microhardness of tested RCs (p > 0.05). While flexural strength significantly decreased after aging (p < 0.05), except for G-aenial Posterior, which showed no differences. The lowest average wear depth was found for Filtek Bulk Fill (29 µm) (p < 0.05), while everX Posterior and Denfil showed the highest wear depth values (40, 39 µm) in both conditions. Passing the expiration date for 40 months did not affect the flexural strength and wear of tested RC. SEM demonstrated a significant number of small pits on Denfil’s surface after aging. It was concluded that the effect of accelerated aging may have caused certain weakening of the RC of some brands, whereas no effect was found with one brand of RC. Thus, the accelerated aging appeared to be more dependent on material and tested material property.

Theoretical insights on the excited-state-deactivation mechanisms of protonated thymine and cytosine

2021 ◽  
Vol 23 (14) ◽  
pp. 8916-8925
Author(s):  
Leila Shahrokh ◽  
Reza Omidyan ◽  
Gholamhassan Azimi
Keyword(s):  
Excited State ◽  
Ab Initio ◽  
Simulation Methods ◽  
Protonated Cytosine ◽  
Protonated Thymine ◽  
Ring Deformation ◽  
Deactivation Mechanism

Excited-state deactivation mechanism of protonated cytosine and thymine is investigated based on ab initio and NAMD simulation methods. The ring deformation from C6 region is suggested to play the most prominent role in deactivation mechanism.

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