Edyta Tabor's research while affiliated with The Czech Academy of Sciences and other places

Publications (45)

Article
Framework AlFR Lewis sites represent a substantial portion of active sites in H-BEA zeolite catalysts activated at low temperatures. We studied their nature by 27Al WURST-QCPMG nuclear magnetic resonance (NMR) and proposed a plausible mechanism of their formation based on periodic density functional theory calculations constrained by 1H MAS, 27Al W...
Article
NH3 temperature‐programmed desorption (NH3‐TPD) is frequently used for probing the nature of the active sites in CuSSZ‐13 zeolite for selective catalytic reduction (SCR) of NOx. Herein, we propose interpretation of NH3‐TPD results, which takes into account the temperature‐induced dynamics of NH3 interaction with the active centers. It is based on a...
Article
Here we demonstrate for the first time the splitting of dioxygen at RT over distant binuclear transition metal (M = Ni, Mn, and Co) centers stabilized in ferrierite zeolite. Cleaved...
Article
Activation of dioxygen is of extreme importance due to its potential for transformation of methane to valuable products and applications in other selective oxidation reactions. Distant binuclear cationic Fe(II) centers in Fe-ferrierite were shown to split dioxygen at room temperature to form a pair of very active oxygen species (i.e., α-oxygens) an...
Article
Splitting dioxygen to yield highly active oxygen species attracts enormous attention due to its potential in direct oxidation reactions, mainly in transformation of methane into valuable products. Distant binuclear cationic Fe(II) centers in Fe‐ferrierite have recently been shown to be active in splitting dioxygen at room temperature to form very a...
Article
Two Al-rich mordenite samples were prepared by the same synthesis procedure except for the activation of the gel for which classical stirring and ultrasonic pretreatment was used. The organization of...
Article
Full-text available
Beta zeolites with Si/Al around 14 were prepared using three new alkali-free synthesis methods based on the application of amorphous aluminosilicate precursor and calcined in ammonia or air. All samples exhibit structural and textural properties of standard beta zeolite. Comprehensive study by 27Al and 29Si MAS NMR, together with FTIR adsorption of...
Article
Full-text available
Activation of dioxygen attracts enormous attention due to its potential for utilization of methane and applications in other selective oxidation reactions. We report a cleavage of dioxygen at room temperature over distant binuclear Fe(II) species stabilized in an aluminosilicate matrix. A pair of formed distant α-oxygen species [i.e., (Fe(IV)═O)2+]...
Article
Full-text available
The organization of aluminium atoms in zeolites affects their catalytic properties. Here we demonstrate that the aluminium distribution is a key parameter controlling the reaction pathway of acid catalysed reactions over ZSM-5 zeolites. We study ethanol transformation over two ZSM-5 samples with similar Si/Al ratios of ~15, and with aluminium atoms...
Article
Cu- and Fe-zeolites can activate oxygen for oxidative reactions of methane and stable hydrocarbon molecules. Here, we analysed the activity of Cu- and Fe- sites with various nuclearities and coordination in *BEA zeolites towards complete oxidation of methane, toluene and ethanol by molecular oxygen. Spectral analysis of the interaction of methane w...
Article
The enhanced effect of proximate strongly acidic protons (distance 5.0–5.5 Å) in ZSM-5 is presented on a complex propene oligomerization up to its aromatization and development of individual carbenium ion intermediates in the zeolite pores. H-ZSM-5 were hydrothermally synthesized to possess intentionally similar content of framework Al (Si/Al 23.8...
Article
Full-text available
Highly active oxygen capable to selectively oxidize methane to methanol at low temperature can be prepared in transition-metal cation exchanged zeolites. Here we show that the α-oxygen stabilized by the negative charges of two framework aluminum atoms can be prepared by the dissociation of nitrous oxide over distant binuclear cation structures (M(I...
Article
Full-text available
Speciation and location of Co ²⁺ , Mn ²⁺ and Ni ²⁺ in the extraframework positions of the dehydrated zeolite matrix of ferrierite structure were studied in detail using FTIR spectroscopy of antisymmetric T–O–T vibrations of the zeolite framework. Me ²⁺ –ferrierites were prepared by the ion exchange of the NH 4 – and Na–zeolite forms and by impregna...
Article
Full-text available
We investigated the use of a supported silicalite-1 film (SF) as a promising coating for metallic materials used in the fabrication of prostheses. The role of carbonaceous residua present on high-temperature calcined-SF in generating singlet oxygen for future use as a sterilization method has also been addressed, and the potential genotoxicity of t...
Article
The Cover Feature shows the effects of various Al distributions in Si‐rich zeolites on the catalytic performance. More information can be found in the Review by Dědeček et al.
Article
Ferrierite based catalyst is expected to be used for high-temperature decomposition of N 2 O. The stability of the ferrierite structure and divalent cations in ferrierite in this process were analysed using XRD, SEM, FTIR, ²⁷ Al and ²⁹ Si MAS NMR. This study provides detailed information regarding to Al removal from zeolite that is either involved...
Article
Full-text available
The organization of Al atoms in the framework of Si‐rich zeolites is very important and includes two classes: (i) the Al siting that determines which individual, crystallographically distinguishable framework T sites are occupied by Al atoms and (ii) the Al distribution, which describes the relation of two or more Al atoms in the framework, their d...
Article
Three generations of cobalt porphyrins were synthesized, physicochemically characterized by FTIR and UV‐Vis spectroscopy as well as cyclic voltammetry and applied as catalysts in oxidation of cycloalkanes with molecular oxygen as air under mild conditions. It was found that all the examined catalysts were active in the tested reaction and their cat...
Article
The SSZ-13 zeolite of the CHA topology is one of the most important Si-rich small pore zeolites. The SSZ-13 matrix represents a highly promising material for both acid and redox catalytic reactions. We present a new significantly improved approach to determine the Al distribution and analyze the arrangements of Al-O-(Si-O)2-Al and Al-O-(Si-O)3-Al s...
Article
The role of NO in the N2O decomposition under conditions relevant to its formation by NH3 oxidation during nitric acid production over iron-containing ferrierite (Fe-FER) catalyst was investigated. In particular, the relative productions of O2 and NO2 during the high-temperature decomposition of N2O over Fe-FER as the result of the direct recombina...
Article
The catalytic activity of a series of FeOx/Al2O3 prepared under various conditions was evaluated for high temperature decomposition of N2O (HT-deN2O) in the complex gas mixture produced by oxidation of ammonia. Thus the relevant step in the industrial nitric acid production process was simulated. The catalyst stability during a long exposure (12 da...
Article
The long-term stabilities of a group of iron zeolites with MFI, *BEA, and FER structures and similar Fe/Al ratios were evaluated to assess their performance as catalysts for N2O decomposition. Conditions relevant for the application of the catalyst at the secondary level for N2O elimination, i.e., directly after the NH3 oxidation step of the proces...
Article
This paper describes a study of the nature and the accessibility of the acid sites in micro-mesoporous mordenite zeolites obtained by desilication and dealumination and analysis of their activity and selectivity in the hydroisomerization of n-hexane. The alkaline-acid, acid-alkaline-acid, and fluorination-alkaline-acid postsynthesis treatments were...
Article
The TNU-9 zeolite of the TUN framework is one of the most complex zeolites known. Here, a newly developed approach, which includes ²⁹Si and ²⁷Al (3Q) MAS NMR spectroscopy, CoII cations as probes monitored by UV/Vis and FTIR spectroscopies, and extensive periodic DFT calculations including molecular dynamics, is presented for the investigation of th...
Article
The TNU-9 zeolite (TUN framework) is one of the most complex zeolites known. It represents a highly promising matrix for both acid and redox catalytic reactions. We present a newly developed approach which includes 29Si and 27Al (3Q) MAS NMR spectroscopy, Co(II) cations as probes monitored by UV-vis and FTIR spectroscopies, and extensive periodic D...
Article
Skeletal isomerization of linear alkanes, an essential reaction for the production of gasoline, relies on environmentally questionable chlorinated catalysts, whose activity exceeds that of alternative zeolite catalysts. This work describes an attempt to understand relations between the local arrangement of active sites and skeletal isomerization of...
Article
The proximity of protons (∼5 Å) derived from the distribution of Al atoms in the H-ZSM-5 framework has been shown to substantially affect the rate of propene oligomerization. Two sets of H-ZSM-5 zeolites (Si/Al 13–30) greatly differing in the occurrence of Al pairs (AlSiSiAl sequences in 6MRs) or distant Al atoms in the framework (both located prev...
Article
The scope of the study was to identify the performance and long-term stability of Fe-FER for N2O decomposition under conditions relevant for use as a secondary-level catalyst for N2O decomposition in the production of HNO3, i.e., in a complex gas phase mixture produced by NH3 oxidation and at temperatures between 750 and 850 °C. The 12 days aging d...
Article
The aim of this work was to study the effect of substituents on the catalytic activity of iron μ -oxo porphyrins in oxidation of cycloalkanes. Electron donating or electron-withdrawing substituents were introduced in meso-aryl groups of iron m-oxo porphyrins. An important part of the work was the characterization of the catalysts, in particular the...
Article
Al-rich BEA∗ zeolites with Si/Al 4.5 and 5.1, prepared by a template-free synthesis, were compared to a conventional (Si-rich) BEA∗ (Si/Al 11.3) regarding (i) the distribution of Al atoms in the framework, (ii) the behavior of the H-BEA∗ samples at high temperature, and (iii) the nature of charge balancing counter metal-ion species. 27Al and 29Si (...
Article
Zeolites are highly important heterogeneous catalysts. Besides Brønsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H-forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity in acid-catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and th...
Article
The heterogeneity and redox behavior of Fe-cationic species in Fe-ZSM-5 catalysts for N2O decomposition and NH3-SCR-NOx were analyzed by Mossbauer and UV-Vis spectroscopy, TPR-H-2, and reaction kinetic measurements. Iron was introduced into ZSM-5 zeolites of similar Si/AI but with different populations of close (AI-Si-Si-Al sequences in one ring -...
Article
The oxidation of cycloalkanes with molecular oxygen, catalyzed by two groups of metallosalen complexes, was studied. The first group consisted of salen complexes with different metals such as Mn, Fe, Co, Ni, Cu, Zn, while the second group was composed of manganese salen complexes with different substituents (t-butyl electron-donating substituents a...
Article
The structure and population of ion-exchanged Fe ions, Fe-oxo species, and Fe-oxo oligomers and Fe2O3 oxide particles and the concentration of acid sites in non-steamed and steamed Fe-ZSM-5 were elucidated using semi-quantitative Mössbauer and FTIR analysis supplemented by UV–Vis and H2-TPR. Differences in the concentration of the individual Fe spe...
Article
Presence of metallic Pt clusters highly enhances catalytic activity of iron ferrierite in N2O decomposition, even at low Pt loading (Pt/Al > 0.003). Platinum (II) cations in ferrierite are inactive; only some low activity appears with pre-reduced samples. The behavior of bimetallic Pt,Fe-ferrierites samples is strongly dependent on the sequence of...
Article
Direct evidence for the formation of surface Fe–NOx species over iron ferrierites during decomposition of N2O was found with a combination of temperature-programmed desorption of adsorbed surface species and infrared and Mössbauer spectroscopies. Surface NOx species were produced via the conversion of a transiently formed Fe(III)–O by exposing iron...
Article
Two parent ferrierites with similar Si/Al ratio (8.5 and 10.5), a commercial and a laboratory specimen with different distribution of Al atoms in the framework, were used for the preparation of model Fe-ferrierite catalysts for N2O decomposition. As proven by UV–Vis analysis of the fully exchanged Co(II)-ferrierites, the two ferrierites differ in t...
Article
Iron ferrierites with low iron content (Fe/Al between 0.018 and 0.072) were used as model catalysts to evaluate the participation of individual iron species, with special interest in the role of iron in β cationic sites, for formation of active sites for N2O decomposition. Despite low iron content, the catalysts with prevailing iron located in β si...
Article
Iron ferrierites with low iron content and well-defined cation occupation supported by FTIR, UV–vis and EPR analysis, were utilized in order to settle the Mössbauer parameters of individual iron cationic species. These samples thus could serve as standard for establishing parameters for the Mössbauer spectroscopy analysis. In accordance with the an...
Article
Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of CexZr1−xO2 solid solutions (x = 0.10–0.85), interacting with NO and NO2 in the absence and presence of oxygen. Strong influence of ceria loading on the adsorption modes of...
Article
Physicochemical properties of metallosalen complexes entrapped within NaX zeolite and their catalytic activities in the oxidation of cyclooctane with dioxygen in the absence of a reducing agent were studied, and compared with free metallocomplexes.Broadening of the zeolite structure-sensitive vibrations observed after the encapsulation gives the ev...
Article
Electron-donating or electron-withdrawing substituents at the porphyrin rings considerably increase the catalytic activity of the manganese monomeric and μ-oxo porphyrins in the oxidation of cyclooctane with molecular oxygen without the use of sacrificial co-reductant. The change in the catalytic activity is due to the nature and number of the subs...

Citations

... An analysis of the broader literature on NH 3 adsorption on metal oxides and oxidic supports like SiO 2 , Al 2 O 3 , and alumino-silicate zeolites, which contain LABP sites discussed in the introduction section, suggests that the IR band at ∼3520-3530 cm −1 can be attributed to ν(N-H) from surfacebound amine species (-NH 2 ), 6,7 formed via dissociation of NH 3 species. Such -NH 2 groups have been reported to form on SiO 2 , 6,27 Al 2 O 3 , 4,27 Cu-SSZ-13, 3,7,13,28,29 MgO, 4,27 etc. Likewise, reviewing the broader literature also suggests that a Fig. 5 (a) Theoretical time to achieve θ ∼ 0.12 in the DRIFTS cell, highlighting that if the bed is assumed to be 1-2 mm thick, it would take ∼150-300 s to reach that target fractional coverage. ...
... It is known that three different cationic positions exist, i.e. α-, β-, and γ-sites, in the FER framework as described in Fig. S1 [30,31]. The perturbed band with various divalent cations in α-site has been observed at 935-950 cm -1 , in β-site is 913-928 cm -1 , and in γ-site at 879-905 cm -1 [51]. It is obvious that high-temperature calcination causes Pd 2+ ions to be located near the β-site according to the difference electron density map plotted from Rietveld J o u r n a l P r e -p r o o f refinement in Fig. 2e-f. ...
... The tetrahedral 3D network of zeolites has a lot of voids and spaces in them [5], and these voids supplement the characteristics to the zeolites, for instance, the adsorption of molecules in the huge internal channels [6,7]. Zeolites can be readily dehydrated and rehydrated [8] and are used as cation exchangers [9], soil decontamination [9,10], and molecular sieves [11]. The unique and remarkable properties of zeolites viz. ...
... However, the activation of methane at ambient conditions is a long-term challenge due to the high stability of the C−H bonds (435 kJ mol −1 ). Enzymes like the methane monooxygenase, 1 mass-selected gaseous [MgO] + ions, 2 some iron-and zinc-modified zeolites, 3,4 and specified metal/metal oxide or metal oxide/metal oxide interfaces 5−7 can activate C−H bonds near room temperature. Except for [MgO] + ions, they all contain a limited number of transition-metal atoms with a unique coordination environment/complex structure that are different from their oxide analogues; 5 the origin of their low-temperature methane activation property is thus still an open question. ...
... In the dimeric intermediate, the proton is placed between alcohol and oxygen atoms and subsequently, the protonated dimers are rearranged and decomposed into water causing an adsorbed diethyl ether that desorbs to regenerate the proton site (see Fig. 4 (c)). The occurrence of protonated ethanol dimers through ethanol dehydration on zeolitic catalysts was confirmed in previous reports [47][48][49]. ...
... Methane monooxygenases (MMOs), as a type of methanotrophic bacteria, can readily transform CH 4 into CH 3 OH at room temperature, the active site of which consists of iron or copper [5]. To mimic its catalytic behavior, the Fe-and Cu-exchanged zeolites have been extensively investigated for the DMTM [6][7][8][9][10][11][12][13][14][15][16], wherein the specific active site motifs significantly affect the DMTM activity. For example, Jeong et al. [7] recently reported a continuous DMTM by passing O 2 over Cu-MOR, finding that the binuclear [Cu-O-Cu] 2+ site possessed much higher activity than that of the mononuclear [Cu] + site. ...
... However, the monomolecular mechanism predominantly occurs at high temperatures, while the bimolecular mechanism usually occurs at a mild temperature (<350 • C). Aromatization can proceed through polymerization reactions to form dienes [132], which is then followed by cyclization in zeolite channels and multi-step Htransfer with olefin, yielding aromatics and paraffin [133]. Subsequently, inter-conversion reactions such as isomerization, disproportionation, and alkylation/dealkylation take place. ...
... These vibrations were observed at the band of about 790 cm −1 and 560 cm −1 . Additionally, for the 668 cm −1 band, the Si-O-M bond can be attributed, where M is the exchangeable Na + present in the BEA zeolite [27,28]. Figure 4 shows the ATR-FTIR spectrum for the Na-BEA sample. ...
... 38,44 Then, part of the obtained NH 4 -FER was exchanged with 1 M of NaNO 3 (3 × 24 h at RT, 100 mL of a solution per 1 g of the zeolite) to prepare Na-FER (K + ions can be effectively replaced exclusively by NH 4 + ones). 38,41 Distribution of the Al atoms in the studied parent FER was established previously using a well-proven method based on the analysis of the visible light spectra of Co exchanged zeolites, 37 zeolites established using X-ray fluorescence spectroscopy (XRF) are gathered in Table 1. Infrared spectra were recorded using an FTIR spectrometer (Nicolet 6700) equipped with a liquid-nitrogen-cooled MCT-B detector. ...
... The intensity of overtone band 6 of SF-500 at ~1642 cm −1 was slightly increased due to an overlap with another band of aromatic species. The shoulder 7 at ~1617 cm −1 of SF-500 belongs to physisorbed water 33 . ...