Theoretical Studies of DENOx SCR over Cu-, Fe- and Mn-FAU Catalysts

Kurzydym, Izabela; Czekaj, Izabela

doi:10.23939/chcht15.01.016

Cited by 4 publications

(3 citation statements)

References 62 publications

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“…As part of the publication, calculations using the DFT method were also performed. For this purpose, a cluster model of zeolites was developed and computational processes for adsorption were performed [21][22][23].…”

Section: Theoretical Modellingmentioning

confidence: 99%

Odors Adsorption in Zeolites Including Natural Clinoptilolite: Theoretical and Experimental Studies

Czekaj,

Sobuś

2024

Materials

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This publication presents the results of combined theoretical and experimental research for the potential use of natural clinoptilolite zeolite (CLI) as an odor-adsorbing material. In this study of adsorption capacity, CLI of various granulation was used and its modifications were made by ion exchange using Sn and Fe metals to check whether the presence of metals as potential active centers does not lead to catalytic processes and may lead to enhanced absorption of odorous substances through their adsorption on the created metallic forms. Additionally, in order to increase the specific surface area, modifications were made in the form of hierarchization in an acidic environment using hydrochloric acid to also create the hydrogen form of zeolite and thus also check how the material behaves as an adsorbent. To compare the effect of CLI as a sorption material, synthetic zeolite MFI was also used—as a sodium form and after the introduction of metals (Sn, Fe). The above materials were subjected to adsorption measurements using odorous substances (including acetaldehyde, dimethylamine, pentanoic acid and octanoic acid). Based on the measurements performed, the most advantageous material that traps odorants is a natural material—clinoptilolite. Depending on the faction, its ability varies for different compounds. In the case of acetaldehyde, an effective material is clinoptilolite with a grain size of up to 2 mm. In the case of carboxylic acids, it is material after hierarchization with a fraction of 3–4 mm. In the case of theoretical calculations, information was obtained to show that metallic centers are more stable above oxygen, which is associated with the skeletal aluminum in clinoptilolite.

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Section: Theoretical Modellingmentioning

confidence: 99%

Odors Adsorption in Zeolites Including Natural Clinoptilolite: Theoretical and Experimental Studies

Czekaj,

Sobuś

2024

Materials

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“…As mentioned earlier, a precise understanding of the reaction mechanism is required to fully explore the SCR process and optimise the conditions of the process [16]. Theoretical calculations allow different variants to be tested in a relatively quick and reasonably lowcost way, allowing a wider view of the entire catalytic system, as well as the investigation of, for example, important intermediates that decompose rapidly and are consequently more difficult to analyse in experimental studies [37]. Theoretical studies have also shown that systems in which metal deposition occurs in the form of an oxygen-bridged dimer between metal atoms (M 1 -O b -M 2 ) are especially important in the deNOx process [38].…”

Section: Introductionmentioning

confidence: 99%

Mechanisms for deNOx and deN2O Processes on FAU Zeolite with a Bimetallic Cu-Fe Dimer in the Presence of a Hydroxyl Group—DFT Theoretical Calculations

Kurzydym,

Czekaj

2024

Molecules

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In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry–this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect.

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“…In the search for more efficient catalysts for the deNOx process, it is also extremely important to understand the mechanism of intermediate reactions that result in the production of harmless nitrogen and water molecules [ 36 , 37 ]. In this aspect, theoretical studies prove to be indispensable, because they allow for a more comprehensive view of the catalytic system and make it possible to test many variants in a relatively short time [ 38 ]. The studies have shown that the systems representing metallic dimers with an oxygen atom in the bridge position (M–O–M) have proven to be particularly important [ 39 ].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies on the Mechanism of deNOx Process in Cu–Zn Bimetallic System—Comparison of FAU and MFI Zeolites

Kurzydym

Czekaj

2022

Molecules

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In the present study we propose a more promising catalyst for the deNOx process to eliminate harmful nitrogen oxides from the environment. The study was performed with a computer calculation using density functional theory (DFT) based on an ab initio method. Two zeolite catalysts, FAU and MFI, were selected with additional Cu–O–Zn bimetallic dimer adsorbed inside the pores of both zeolites. Based on the analysis of preliminary studies, the most probable way of co-adsorption of nitric oxide and ammonia was selected, which became the initial configuration for the reaction mechanism. Two types of mechanisms were proposed: with hydroxyl groups on a bridged position of the dimer or a hydroxyl group on one of the metal atoms of the dimer. Based on the results, it was determined that the FAU zeolite with a bimetallic dimer and an OH group on the zinc atom was the most efficient configuration with a relatively low energy barrier. The real advantage of the Cu–Zn system over FAU and MFI in hydrothermal conditions has been demonstrated in comparison to a conventional Cu–Cu catalyst.

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Theoretical Studies of DENOx SCR over Cu-, Fe- and Mn-FAU Catalysts

Cited by 4 publications

References 62 publications

Odors Adsorption in Zeolites Including Natural Clinoptilolite: Theoretical and Experimental Studies

Odors Adsorption in Zeolites Including Natural Clinoptilolite: Theoretical and Experimental Studies

Mechanisms for deNOx and deN2O Processes on FAU Zeolite with a Bimetallic Cu-Fe Dimer in the Presence of a Hydroxyl Group—DFT Theoretical Calculations

Theoretical Studies on the Mechanism of deNOx Process in Cu–Zn Bimetallic System—Comparison of FAU and MFI Zeolites

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