Mechanism of formation of framework Fe3+ in bimetallic Ag-Fe mordenites - Effective catalytic centers for deNOx reaction

Shelyapina, Marina G.; Gurgul, Jacek; Łątka, Kazimierz; Sánchez-López, Perla; Bogdanov, Dmitrii; Kotolevich, Yulia; Petranovskii, Vitalii; Fuentes, S.

doi:10.1016/j.micromeso.2019.109841

Cited by 18 publications

(13 citation statements)

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“…35.2° for Fe (200), (111) and (211) at 42°. Reflections were observed at 44.8° and attributed to zerovalent Pd [ 13 ]. The Pd (002) at 2Ɵ = 45.5° has also been previously reported as a combinatorial phase between Fe and Pd in the synthesis of bimetallic nanoparticles of such elemental compositions.…”

Section: Resultsmentioning

confidence: 99%

The Synthesis and Characterization of Novel Bi-/Trimetallic Nanoparticles and Their Nanocomposite Membranes for Envisaged Water Treatment

et al. 2020

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The impact of worldwide water scarcity, further exacerbated by environmental pollution, necessitates the development of effective water treatment membranes. Herein, we report the synthesis and characterization of nanocomposite membranes containing hyperbranched polyethyleneimine (HPEI) stabilized bi-and trimetallic nanoparticles. These membranes were prepared by blending a pre-grafted Polyethersulfone (PES) powder with the Pd@Fe@HPEI and Pd@FeAg@HPEI nanoparticles followed by phase inversion. The membranes, together with stabilized nanoparticles, were characterized by several analytical techniques, such as attenuated total reflectance–Fourier transform infra-red spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), optical contact angle (OCA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). These techniques revealed the elemental composition, zerovalent nature of the nanoparticles, and their small and even size distribution. Surface analysis showed chemical bonding between the polymeric functional groups and the supported nanoparticles. Furthermore, the nanocomposite membranes were found to be hydrophilic. Additionally, the membranes were investigated for swelling (water uptake), porosity, pore size, pure water permeation fluxes, and they indicated a decreased protein adhesion property. As such, the membranes fabricated in this work indicate the required properties for application in water treatment.

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Section: Resultsmentioning

confidence: 99%

The Synthesis and Characterization of Novel Bi-/Trimetallic Nanoparticles and Their Nanocomposite Membranes for Envisaged Water Treatment

et al. 2020

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“…According to the de-NO x , XANES, and EXAFS data, and our previous results [33], the de-NO x activity can be provided by two types of active centers: Fe 3+ compensating cation at the vacant negatively charged site of mordenite, or Fe 3+ in the mordenite framework instead of Al 3+ . Due to the complex correlation of activity with temperature, until now, it has not been possible to determine a reliable difference between them.…”

Section: Samplementioning

confidence: 52%

“…The AgMOR catalyst presents low-temperature activity (120-150 • C), which is associated with the Ag + , and two peaks at 260 and 377 • C. The latter has shown an increased conversion at temperatures in the range of 320-520 • C, which could be due to the reduction of Ag + →Ag 0 under the reaction conditions. According to the de-NOx, XANES, and EXAFS data, and our previous results [33], the de-NOx activity can be provided by two types of active centers: Fe 3+ compensating cation at the vacant negatively charged site of mordenite, or Fe 3+ in the mordenite framework instead of Al 3+ . Due to the complex correlation of activity with temperature, until now, it has not been possible to determine a Since all samples are subjected to preliminary oxidative treatment, the observed activity should be attributed to the oxidized states of the active components (Fe 3+ and Ag + ) present in the catalyst.…”

Section: Samplementioning

confidence: 52%

“…Therefore, based on the EXAFS data, we may conclude that Fe in FeAgMOR and AgFeMOR is partially included in the zeolite framework as Fe 3+ instead of Al 3+ . Previously, the mechanism of the isomorphous substitution of Al 3+ in the mordenite framework by tetrahedrally coordinated Fe 3+ , which is promoted by the presence of Ag + ions, has been proposed and confirmed by Mössbauer spectroscopy, and it has also been shown that the presence and concentration of the framework Fe 3+ ion in various samples correlate with their catalytic activity in de-NO x [33]. ).…”

Section: Samplementioning

confidence: 91%

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Properties of Iron-Modified-by-Silver Supported on Mordenite as Catalysts for NOx Reduction

et al. 2020

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A series of mono and bimetallic catalysts based on a Fe-Ag mixture deposited on mordenite was prepared by ion-exchange and evaluated in the catalytic activity test of the de-NOx reaction in the presence of CO/C3H6. The activity results showed that the most active samples were the Fe-containing ones, and at high temperatures, a co-promoter effect of Ag on the activity of Fe catalysts was also observed. The influence of the order of cation deposition on catalysts formation and their physicochemical properties was studied by FTIR (Fourier Transform Infrared Spectroscopy) of adsorbed NO, XANES (X-ray Absorption Near-Edge Structure), and EXAFS (Extended X-ray Absorption Fine Structure) and discussed in terms of the state of iron. Results of Fe K-edge XANES oscillations showed that, in FeMOR catalysts, iron was present in a disordered state as Fe3+ and Fe2+. In FeAgMOR, the prevailing species was Fe3+, while in the AgFeMOR catalyst, the state of iron was intermediate or mixed between FeMOR and FeAgMOR. The Fe K-edge EXAFS results were characteristic of a disordered phase, the first coordination sphere being asymmetric with two different Fe-O distances. In FeAgMOR and AgFeMOR, coordination of Fe-O was similar to Fe2O3 with a few amount of Fe2+ species. We may conclude that, in the bimetallic FeAgMOR and AgFeMOR samples, a certain amount of tetrahedral Al3+ ions in the mordenite framework is replaced by Fe3+ ions, confirming the previous reports that these species are active sites for the de-NOx reaction. Based on the thermodynamic analysis and experimental data, also, it was confirmed that the order of deposition of the components influenced the mechanism of active sites’ formation during the two steps ion-exchange synthesis.

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“…It is known that the unique physicochemical properties of zeolites, such as their controlled acidity, sorption capacity, ion exchange properties and thermal stability, as well as structural characteristics, including crystallographically ordered channels and cavities with a certain size and position, determine their effectiveness in catalytic processes [81,82]. In addition, zeolites are a very suitable substrate for the formation of clusters and nanoparticles either outside or inside the cavities, which are a good option as a carrier of active metals for SCR NO x [82][83][84]. Bimetallic or multimetallic catalysts appear due to the fact that they exhibit a synergistic effect between components present in some cases, such as higher catalytic activity, selectivity and stability during the NO x reduction reaction.…”

Section: Catalysis For No X Removalmentioning

confidence: 99%

Materials for CO2, SOx, and NOx Emission Reduction

Shelyapina

Rodrı́guez-Iznaga

Petranovskii

2020

Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications

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Industrial development and urbanization require effective constant monitoring and effective removal of major air pollutants. Three of them, the fight against which is discussed in this chapter, appear in the process of burning fuel, although their genesis is different. Sulfur oxide is formed as a result of the combustion of impurities either in hydrocarbons, and in this case, the fight against it should begin with a deep cleaning of the fuel, or by burning coal, and then you have to deal with the desulfurization of exhaust gases. Nitrogen oxide pollutants are formed at high temperatures from nitrogen present in the air, and purification, respectively, occurs in the exhaust gases of heat engines. Carbon dioxide is the main product of the combustion of any fuel and, accordingly, requires special methods for its removal. The environmental impact of these gases is also different. SO x and NO x are pollutants that form smog and acid rain. CO 2 is greenhouse gas, and its removal is becoming one of the main goals for climate stabilization. Given these differences, this review of existing materials and processes to eliminate the three main gaseous air pollutants has been made.

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Mechanism of formation of framework Fe3+ in bimetallic Ag-Fe mordenites - Effective catalytic centers for deNOx reaction

Cited by 18 publications

References 44 publications

The Synthesis and Characterization of Novel Bi-/Trimetallic Nanoparticles and Their Nanocomposite Membranes for Envisaged Water Treatment

The Synthesis and Characterization of Novel Bi-/Trimetallic Nanoparticles and Their Nanocomposite Membranes for Envisaged Water Treatment

Properties of Iron-Modified-by-Silver Supported on Mordenite as Catalysts for NOx Reduction

Materials for CO2, SOx, and NOx Emission Reduction

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