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January 2014 - January 2017
Publications
Publications (44)
Ceria nanoparticles supported on alumina are widely used in various catalytic reactions, particularly in conjunction with platinum group metals (PGMs)1, 2, 3, 4, 5, 6, 7, 8–9. Here we found that treating these catalysts at temperatures between 750 and about 1,000 °C in the presence of CO and NO in steam (reactive treatment under reducing atmosphere...
Herein, we present an elegant and simple method for significant improvement of eugenol water solubility using the polymers Soluplus® and Lutrol F 127 as carriers and spray drying as an encapsulation method. The formulations were optimized by adding myo-inositol—a sweetening agent—and Aerosil® 200 (colloidal, fumed silica)—an anticaking agent. The h...
A new heterocyclic compound, 2-(2,6-diisopropylphenyl)-1-methylimidazo[1,5-a]quinolin-2-ium tetrafluoroborate 1 was obtained from its precursor, N-(2,6-diisopropylphenyl)-N-(quinolin-2-ylmethyl)acetamide 2, by POCl3-mediated cyclization. For the first time, tertiary acetamide 2, the precursor of 1, was synthesized by using commercially available st...
A new heterocyclic compound, 2-(2,6-diisopropylphenyl)-1-methylimidazo[1,5-a]quinolin-2-ium tetrafluoroborate 1 was obtained from its precursor, N-(2,6-diisopropylphenyl)-N-(quinolin-2-ylmethyl)acetamide 2, by POCl3-mediated cyclization. For the first time – the tertiary acetamide 2, precursor of 1, was synthesized by using commercially available s...
Ceria and ceria-based catalysts are very important in redox and acid-base catalysis. Nanoceria have also been found to be important in biomedical applications. To design efficient materials, it is necessary to thoroughly understand the surface chemistry of ceria, and one of the techniques that provides such information about the surface is the vibr...
Ceria nanoparticles supported on alumina have found wide applications for various catalytic reactions, especially in contact with precious metals. We discovered that treatment of these catalysts at temperatures between 750 and ~1,000 ºC under the flow of CO and NO in the presence of steam (reactive aging in reducing atmosphere) leads to dispersion...
Ultra small Pd4 clusters form inside FER zeolite during low temperature treatment (100 °C) in the presence of humid CO gas. They effectively catalyze CO oxidation below 100°C, whereas Pd nanoparticles are not active as they are poisoned by CO. Using catalytic measurements, infrared (IR) spectroscopy, X-ray absorption spectroscopy (EXAFS), microscop...
Pd-based catalysts are widely used in the oxidation of CH4 and have a significant impact on global warming. However, understanding their active sites remains controversial, because interconversion between Pd and PdO occurs consecutively during the reaction. Understanding the intrinsic active sites under reaction conditions is critical for developin...
Quantum-chemical calculations on the spectral properties of some aryl substituted 3-phosphonocoumarins were performed, and the effect of the substituents in the aryl moiety was evaluated. The structures possessing promising fluorescent properties were successfully synthesized via Suzuki and Sonogashira cross-coupling. The synthetic protocol was als...
Cu/zeolites efficiently catalyze selective reduction of environmentally harmful nitric oxide with ammonia. Despite over a decade of research, the exact NO reduction steps remain unknown. Herein, using a combined spectroscopic, catalytic and DFT approach, we show that nitrosyl ions (NO+) in zeolitic micropores are the key intermediates for NO reduct...
Carbon interaction with transition metal (TM) surfaces is a relevant topic in heterogeneous catalysis, either for its poisoning capability, for the recently attributed promoter role when incorporated in the subsurface, or for the formation of early TM carbides, which are increasingly used in catalysis. Herein, we present a high-throughput systemati...
Pd‐based catalysts are the most widely used for CO oxidation because of their outstanding catalytic activity and thermal stability. However, fundamental understanding of the detailed catalytic processes occurring on Pd‐based catalysts under realistic conditions is still lacking. In this study, we investigated CO oxidation on metallic Pd clusters su...
Cu/Zeolites efficiently catalyze selective reduction of environmentally harmful nitric oxide with ammonia. Despite over a decade of research, the exact NO reduction steps remain unknown. Herein, using combined spectroscopic, catalytic and DFT approach we show that nitrosyl ions (NO+) in the zeolitic micropores are the key intermediates for NO reduc...
Ceria nanoparticles supported on alumina have low activity for industrially relevant NO reduction by CO. We discovered that treatment of these catalysts at temperatures between 750 and ~1,000 ºC under the flow of CO and NO in the presence of steam, which typically leads to catalyst deterioration and sintering, in fact, leads to dispersion of ceria...
Cucurbiturils (CBs), the pumpkin-shaped macrocycles, are suitable hosts for an array of neutral and cationic species. A plethora of host-guest complexes between CBs and a variety of guest molecules has been studied. However, much remains unknown, even in the complexation of very simple guests such as metal cations. In the computational study herein...
We used computational modeling, based on Density Functional Theory, to help understand the preference for the formation of silanol nests and the substitution of Si by Ti or Al in different crystallographic positions of the MSE-type framework. All these processes were found to be energetically favorable by more than 100 kJ/mol. We suggested an appro...
Silica nanoparticles incorporating magnetic iron oxides (MS) with sizes around 20 nm were developed. The MS material was modified with NH2-groups and then grafted by PEG chains. The anticancer drug miltefosine was loaded into the NH2-modified and PEGylated MS nanoparticles by impregnation procedure resulting in 11–28% of drug content. PEG chains we...
Structural properties and reducibility of zirconium-doped cerium dioxide systems were studied using periodic plane-wave calculations based on density functional theory. A systematic analysis of the results for nanoparticles of two sizes, Ce40−nZrnO80 ∼ 1.5 nm large and Ce140−nZrnO280 ∼ 2.4 nm large, in comparison with slab model data for Ce1−xZrxO2...
Magnetic iron oxide containing MCM-41 silica (MM) with ~300 nm particle size was developed. The MM material before or after template removal was modified with NH2- or COOH-groups and then grafted with PEG chains. The anticancer drug tamoxifen was loaded into the organic groups’ modified and PEGylated nanoparticles by an incipient wetness impregnati...
Supramolecular complexes based on classical synthetic macrocyclic host molecules such as cyclodextrins and calixarenes have received much attention recently due to their broad applications as biological and chemical sensors, bioimaging agents, drug delivery carriers, light-emitting materials, etc. Cucurbit[n]urils comprise another group of cavitand...
We provide the first observation of super-electrophilic metal cations on a solid support. For Pd/SSZ-13 the results of our combined experimental (FTIR, XPS, HAADF-STEM) and density functional theory study reveal that Pd ions in zeolites, previously identified as Pd+3 and Pd+4, are in fact present as super electrophilic Pd+2 species (charge-transfer...
Iron-containing HZSM-5 zeolites are materials with important industrial applications as catalysts. Their characterization is difficult due to the various possible Fe-containing species which can exist in the pores of HZSM-5 zeolites and their dependence on the preparation technique. Three Fe–HZSM-5 samples were prepared by ion-exchange technique us...
Using periodic density functional calculations we clarified the variations of the electronic structure of platinum clusters and nanowires upon their deposition on reducible and on non-reducible oxide as well as upon adsorption of carbon monoxide. Three models of platinum clusters and nanowires deposited on ceria surface and one on gamma-alumina sur...
NaY samples in the crystalline form with Si/Al ratios from 2.15 to 2.40 were synthesized as adsorbents for paraquat. Their surface areas, particle size, concentration of basic sites decreased with an increase of Al content in the synthesis gel. The interaction between paraquat molecule and NaY zeolite was investigated by periodic DFT calculations t...
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The results of our combined experimental (FTIR, XPS, HAADF-STEM, EXAFS) and density functional theory study reveal that Pd ions in zeolites, previously identified as Pd<sup>+3</sup> and Pd<sup>+4</sup>, are in fact present as super electrophilic Pd<sup>+2</sup> species (ion pairs with the negatively charged framework oxygens). In this contrib...
Carbon moieties on late transition metals are regarded as poisoning agents in heterogeneous catalysis. Recent studies show the promoting catalytic role of subsurface C atoms in Pd surfaces and their existence in Ni and Pt surfaces. Here energetic and kinetic evidence obtained by accurate simulations on surface and nanoparticle models shows that suc...
Carbon Cn moieties on late transition metals are historically regarded as poisoning agents for their use in heterogeneous catalysis. Recent experimental studies combining ab initio simulations showed the promoting catalytic role of subsurface C atoms in Pd surfaces, plus their existence was well established in Ni and Pt surfaces. Here we show, adjo...
The synthesis of mesoporous KIL-2 and KIT-6 nanoparticles (40 and 60 nm, respectively) was performed. Post synthesis procedure was applied for the modification of the initial mesoporous silicas with amino groups. Incipient wetness impregnation or solid state reaction were used for curcumin loading in the parent and amino-modified nanoporous support...
Atomically dispersed palladium in small‐pore zeolites is highly effective for simultaneous low temperature NO and CO abatement. In their Communication (DOI: 10.1002/anie.201809343) J. Szanyi and co‐workers develop a modified incipient wetness impregnation method for the synthesis of transition‐metal‐ion loaded small‐pore zeolites. Pd/SSZ‐13 with at...
Palladiumatome in kleinen Zeolithporen binden NO und CO effektiv bei niedrigen Temperaturen. In ihrer Zuschrift (DOI: 10.1002/ange.201809343) stellen J. Szanyi und Mitarbeiter eine benetzungsbasierte Synthesemethode vor, um kleinporige Zeolithe mit Übergangsmetallionen zu beladen. Pd/SSZ‐13 mit dispergierten Metallatomen speichert NOx und CO bei ni...
The majority of harmful atmospheric CO and NOx emissions comes from vehicles’ exhaust. Although there has been success addressing NOx emissions at temperatures above 250 ºC with the aid of selective catalytic reduction technology that relies on the Cu/SSZ‐13 material and sacrificial urea source, emissions during vehicle cold start (when the tempera...
The majority of harmful atmospheric CO and NOx emissions comes from vehicles’ exhaust. Although there has been success addressing NOx emissions at temperatures above 250 ºC with the aid of selective catalytic reduction technology that relies on the Cu/SSZ‐13 material and sacrificial urea source, emissions during vehicle cold start (when the tempera...
Using periodic density functional calculations, we studied the local structure and preferred locations of yttrium cations and oxygen vacancies in Y-doped cerium dioxide. We employed three kinds of models – a slab of the CeO2(111) surface and two ceria nanoparticles of different sizes and shapes. In the slab models, which represent the (111) surface...
Since the catalytic behavior of supported platinum species strongly depends on their nuclearity under the reaction conditions, in this study we addressed the stability of platinum species in the presence of CO. We applied density functional modeling to clarify the effect of the CO coverage on the structure and stability of small platinum clusters d...
We report the structure and stability of ceria units deposited on the surface of γ-Al2O3 respectively incorporated in its cavities, as determined by periodic density functional calculations. Ceria species are modeled as CeO2 or Ce2O4 moieties or as a small nanoparticle, Ce13O26, on the (100) and (001) surfaces of a γ-Al2O3 slab. Among the studied s...
The efficiency of zeolite X nanocrystals (FAU-type framework structure) containing different extra-framework cations (Li+, Na+, K+ and Ca2+) in slowing down the thermal oxidation of palm oil is reported. The oxidation study of palm oil is conducted in the presence of zeolite nanocrystals (0.5 wt.%) at 180 °C. Several characterization techniques suc...
Thin films of ferrites of the type MIIFe2O4 (M = Cu, Mg, Zn) are prepared by spray-pyrolysis using ethylene glycol solutions of mixed-metal citric complexes of the respective metals at substrate temperature between 350 °C and 450 °C and post-deposition annealing at 480–750 °C in air. Phase composition, crystal structure, morphology and adhesion of...