scholarly journals Methane-to-methanol conversion over zeolite Cu-SSZ-13, and its comparison with the selective catalytic reduction of NOx with NH3

2018 ◽  
Vol 8 (4) ◽  
pp. 1028-1038 ◽  
Author(s):  
Ramon Oord ◽  
Joel E. Schmidt ◽  
Bert M. Weckhuysen
Keyword(s):  
Selective Catalytic Reduction ◽  
Active Site ◽  
Catalytic Reduction ◽  
Methanol Conversion ◽  
Nuclear Site ◽  
Ft Ir ◽  
Reduction Of Nox

Using in situ FT-IR and operando UV-vis-NIR DRS, performed on a series of different Cu–ion-exchanged SSZ-13 zeolites, both a mono-nuclear site or a dimeric copper active site are consistent for methane-to-methanol activation.

scholarly journals In Situ DRIFTS Studies of NH3-SCR Mechanism over V2O5-CeO2/TiO2-ZrO2 Catalysts for Selective Catalytic Reduction of NOx

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1307 ◽  
Author(s):  
Yaping Zhang ◽  
Xiupeng Yue ◽  
Tianjiao Huang ◽  
Kai Shen ◽  
Bin Lu
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxygen Storage ◽  
In Situ Drifts ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
Reduction Of Nox ◽  
Zro2 Catalyst

TiO2-ZrO2 (Ti-Zr) carrier was prepared by a co-precipitation method and 1 wt. % V2O5 and 0.2 CeO2 (the Mole ratio of Ce to Ti-Zr) was impregnated to obtain the V2O5-CeO2/TiO2-ZrO2 catalyst for the selective catalytic reduction of NOx by NH3. The transient activity tests and the in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analyses were employed to explore the NH3-SCR (selective catalytic reduction) mechanism systematically, and by designing various conditions of single or mixing feeding gas and pre-treatment ways, a possible pathway of NOx reduction was proposed. It was found that NH3 exhibited a competitive advantage over NO in its adsorption on the catalyst surface, and could form an active intermediate substance of -NH2. More acid sites and intermediate reaction species (-NH2), at lower temperatures, significantly promoted the SCR activity of the V2O5-0.2CeO2/TiO2-ZrO2 catalyst. The presence of O2 could promote the conversion of NO to NO2, while NO2 was easier to reduce. The co-existence of NH3 and O2 resulted in the NH3 adsorption strength being lower, as compared to tests without O2, since O2 could occupy a part of the active site. Due to CeO2’s excellent oxygen storage-release capacity, NH3 adsorption was weakened, in comparison to the 1 wt. % V2O5-0.2CeO2/TiO2-ZrO2 catalyst. If NOx were to be pre-adsorbed in the catalyst, the formation of nitrate and nitro species would be difficult to desorb, which would greatly hinder the SCR reaction. All the findings concluded that NH3-SCR worked mainly through the Eley-Rideal (E-R) mechanism.

FT-IR operando study on selective catalytic reduction of NOx species by ammonia: A comparison between zeolitic and GAPON compounds

2006 ◽  
Vol 113 (1-2) ◽  
pp. 87-93 ◽  
Author(s):  
F. Romero Sarria ◽  
O. Marie ◽  
P. Bazin ◽  
J. Saussey ◽  
J. Lesage ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Ft Ir ◽  
Reduction Of Nox

In situ design of Cu and Co nanoparticles encapsulated in N-doped graphene with core–shell structure-derived 8-hydroxyquinoline complexes for the selective catalytic reduction of NOx by NH3

2020 ◽  
Vol 44 (29) ◽  
pp. 12639-12645
Author(s):  
Zhifang Li ◽  
Jian Yang ◽  
Xiaoyu Ma ◽  
Jinxing Cui ◽  
Yuanyuan Ma ◽  
...  
Keyword(s):  
Active Site ◽  
Shell Structure ◽  
Catalytic Reduction ◽  
Core Shell ◽  
Excellent Activity ◽  
Doped Graphene ◽  
Reduction Of Nox ◽  
Core Shell Structure ◽  
Co Nanoparticles

The Cu and Co nanoparticles surrounding by N-doped graphene (labeled Cu@N-Gr and Co@N-Gr) catalysts exhibited excellent activity in the NH3-SCR, which is because the graphene shell can effectively prevent the agglomeration of active site.

Computational Insights into the Mechanism of the Selective Catalytic Reduction of NOx: Fe- Versus Cu-Doped Zeolite Catalysts

2019 ◽  
Author(s):  
Julian Rudolph ◽  
Christoph R. Jacob
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Zeolite Catalysts ◽  
Reaction Pathways ◽  
Half Cycle ◽  
Computational Results ◽  
Comprehensive Picture ◽  
Cu Catalysts ◽  
Reduction Of Nox

<div> <div> <div> <p>We computationally investigate the mechanism of the reduction half-cycle of the selective catalytic reduction (SCR) of nitrogen oxides with ammonia. We compare both Fe- and Cu-doped zeolite catalysts and aim at exploring all accessible reaction pathways. From our calculations, a comprehensive picture emerges that unifies sev- eral previous mechanistic proposals. We find that both for Fe and for Cu catalysts, different reaction pathways are feasible, but some of the possible reaction pathways differ in these two cases. Our computational results provide a basis for the inter- pretation of in situ spectroscopic investigations that can possibly distinguish the different mechanistic pathways. </p> </div> </div> </div>

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