Tailoring of the structure of Fe-cationic species in Fe-ZSM-5 by distribution of Al atoms in the framework for N2O decomposition and NH3-SCR-NOx

A series of iron functionalized hydroxyapatite (Fe/HAP) samples with different metal loading (2 < wt.% Fe < 13) was prepared by a flash ionic exchange procedure from iron(III) nitrate as precursor and tested in some environmental air-quality protection reactions such as the catalytic reduction of NOx by NH3 (NH3-SCR), catalytic oxidation of NH3 (NH3-SCO) and catalytic N2O decomposition. The catalytic performances of the Fe/HAP catalysts were determined under flow conditions as a function of temperature and using reactant concentrations typical of polluting gaseous emissions from industrial vents. Physico-chemical characterization with various techniques of study (UV-DR and Mössbauer spectroscopies, NH3 titration, N2-physisorption, and XRPD analyses) provided valuable information on Fe-speciation, acidity, morphology, and structure of the samples. In general, highly dispersed Fe3+ centers were the predominant species, irrespective of Fe-loading, while just low percentage (≤15%) of FexOy nanoclusters (2 < size/nm < 4) was detected on the samples. As expected, the differences in iron concentration produced a diversified effect of both catalyst properties and catalytic activity, comprising the conversion and selectivity profiles, different for each reaction considered. The obtained results indicate a good potentiality for the eco-friendly Fe-catalysts for some environmental reactions of air protection.

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Unique Dynamic Changes of Fe Cationic Species under NH3-SCR Conditions

The Journal of Physical Chemistry C ◽

10.1021/jp300349q ◽

2012 ◽

Vol 116 (9) ◽

pp. 5846-5856 ◽

Cited By ~ 19

Author(s):

Sarah M. Maier ◽

Andreas Jentys ◽

Markus Janousch ◽

Jeroen A. van Bokhoven ◽

Johannes A. Lercher

Keyword(s):

Dynamic Changes ◽

Cationic Species ◽

Nh3 Scr

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Maize Stalk as Natural Ion Exchanger for Hazardous Pollutants

Revista de Chimie ◽

10.37358/rc.17.8.5753 ◽

2017 ◽

Vol 68 (8) ◽

pp. 1726-1731

Author(s):

Nicoleta Mirela Marin ◽

Luoana Florentina Pascu ◽

Ioana Stanculescu ◽

Ovidiu Iordache ◽

Denisa Jianu ◽

...

Keyword(s):

Ion Exchange ◽

Kinetic Models ◽

High Selectivity ◽

Ion Exchanger ◽

Exchange Equilibrium ◽

Waste Waters ◽

Cationic Species ◽

Hazardous Pollutants ◽

Tailing Ponds

This paper recommends maize stalk as a cheap natural ion exchanger. Ion exchange equilibrium was studied using thermodynamic and kinetic models. The results showed a high selectivity towards cationic species of antimony (III), molybdenum (VI), lead (II) and arsenium (III). Waste waters and sediments from tailing ponds samples were analysed.

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The synergistic effects between Ce and Cu in CuyCe1−yW5Ox catalysts for enhanced NH3-SCR of NOx and SO2 tolerance

Catalysis Science & Technology ◽

10.1039/c8cy01949e ◽

2019 ◽

Vol 9 (3) ◽

pp. 718-730 ◽

Cited By ~ 17

Author(s):

Jian-Wen Shi ◽

Yao Wang ◽

Ruibin Duan ◽

Chen Gao ◽

Baorui Wang ◽

...

Keyword(s):

Metal Oxides ◽

Selective Catalytic Reduction ◽

Low Temperatures ◽

Catalytic Reduction ◽

Synergistic Effects ◽

Reduction Of No ◽

Nh3 Scr ◽

So2 Tolerance ◽

Scr Of Nox

Non-manganese-based metal oxides are promising catalysts for the NH3-SCR (selective catalytic reduction) of NOx at low temperatures.

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

Catalysts ◽

10.3390/catal11050618 ◽

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.

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