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163 results on '"Koštejn, Martin"'

13. Functionalization of Titanium Surfaces Using Laser Ablation in Vacuum and Liquid by Hydrolytically Instable Casi2 Affects Behavior of Bone Healing-Related Cell Types

Author

Křenek, Tomáš, primary, Pola, Josef, additional, Stich, Theresia, additional, Pattappa, Girish, additional, Docheva, Denitsa, additional, Koštejn, Martin, additional, Medlín, Rostislav, additional, Mikysek, Petr, additional, Jandová, Věra, additional, Pola, Michal, additional, Kovářík, Tomáš, additional, Cassel, Júlia, additional, Holzman, Martin, additional, and Moskal, Denys, additional

Published
2024
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20. The Effect of Lithium on NiMo/Al2O3 Hydrotreating Catalysts Prepared from Heteropolycompounds.

Author

Kaluža, Luděk, Jirátová, Květa, Spojakina, Alla A., Balabánová, Jana, Gulková, Dana, Koštejn, Martin, Palcheva, Radostina, Tyuliev, Georgi, and Fajgar, Radek

Subjects
HYDROTREATING catalysts, OCTANOIC acid, CATALYST testing, STEAM reforming, MOLYBDENUM, DESULFURIZATION, MOLYBDENUM compounds
Abstract

Recently, simultaneous hydrotreatment of various petroleum fractions and plant feedstocks has been in demand. NiMo catalysts can be active in these processes. Therefore, supported NiMo oxide catalysts were prepared by impregnating an alumina support with Anderson's molybdenum salt (ammonium salt of nickel heteropolymolybdate (NH4)4NiMo6O24H6) and lithium carbonate. The prepared catalysts were tested in hydrodesulfurization (HDS) of thiophene and parallel HDS/HDO (hydrodeoxygenation) of 1-benzothiophene and octanoic acid. Experimental data showed a positive effect of lithium on the parallel HDS/HDO reactions and a negative effect on the HDS of thiophene. A significant effect of lithium on the acidity and reducibility of the NiMo/Al2O3 catalyst as well as the contribution of an Anderson-type heteropolycompound was demonstrated. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Nickel-Copper Oxide Catalysts Deposited on Stainless Steel Meshes by Plasma Jet Sputtering: Comparison with Granular Analogues and Synergistic Effect in VOC Oxidation

Author

Jirátová, Květa, primary, Soukal, Petr, additional, Kapran, Anna, additional, Babii, Timur, additional, Balabánová, Jana, additional, Koštejn, Martin, additional, Čada, Martin, additional, Maixner, Jaroslav, additional, Topka, Pavel, additional, Hubička, Zdeněk, additional, and Kovanda, František, additional

Published
2023
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27. Plasma Jet Sputtering as an Efficient Method for the Deposition of Nickel and Cobalt Mixed Oxides on Stainless-Steel Meshes: Application to VOC Oxidation

Author

Jirátová, Květa, primary, Čada, Martin, additional, Naiko, Iryna, additional, Ostapenko, Alina, additional, Balabánová, Jana, additional, Koštejn, Martin, additional, Maixner, Jaroslav, additional, Babii, Timur, additional, Topka, Pavel, additional, Soukup, Karel, additional, Hubička, Zdeněk, additional, and Kovanda, František, additional

Published
2022
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33. Surface Potassium Promotion of Co4MnAlOxin Direct NO Decomposition Generates the Same Type of Active Sites as Bulk Promotion

Author

Bílková, Tereza, Pacultová, Kateřina, Karásková, Kateřina, Fridrichová, Dagmar, Jirátová, Květuše, Koštejn, Martin, Slowik, Grzegorz, Ritz, Michal, Haneda, Masaaki, and Obalová, Lucie

Abstract

K/Co4MnAlOxmixed oxides are active in direct NO decomposition. This work investigates the effect of the preparation method and K precursor type. Using the incipient wetness impregnation method, the modification by the required amount of K was ensured. Regardless of the K precursor type, similar NO conversions were reached for samples modified by 4 wt % K. The optimal amount of K from the KNO3precursor was evaluated as 2–6 wt %. The physicochemical properties were carefully explored using atomic absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform IR spectroscopy, N2physisorption, H2temperature-programmed reduction, CO2and NO temperature-programmed desorption, scanning electron microscopy, and transmission electron microscopy, correlated with catalytic properties in transient and steady state and compared with the results obtained in our previous study using bulk modified samples. The present study underlines the effect of the preparation method on the Brunauer–Emmett–Teller surface area (SBET) of prepared catalysts and thus the amount of active sites available for catalytic reaction. Moreover, the results emphasize the importance of catalyst basicity, which affects the amount of adsorbed NO2–species, the key intermediates in the direct NO catalytic reaction.

Published
2023
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34. A novel route of colloidal chemistry: room temperature reactive interactions between titanium monoxide and silicon monoxide sols produced by laser ablation in liquid resulting in the formation of titanium disilicide

Author

Křenek, Tomáš, primary, Vála, Lukáš, additional, Medlín, Rostislav, additional, Pola, Josef, additional, Jandová, Věra, additional, Vavruňková, Veronika, additional, Mikysek, Petr, additional, Bělský, Petr, additional, and Koštejn, Martin, additional

Published
2022
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36. Plasma Jet Sputtering as an Efficient Method for the Deposition of Nickel and Cobalt Mixed Oxides on Stainless-Steel Meshes: Application to VOC Oxidation.

Author

Jirátová, Květa, Čada, Martin, Naiko, Iryna, Ostapenko, Alina, Balabánová, Jana, Koštejn, Martin, Maixner, Jaroslav, Babii, Timur, Topka, Pavel, Soukup, Karel, Hubička, Zdeněk, and Kovanda, František

Subjects
PLASMA jets, COBALT oxides, CATHODES, TEMPERATURE-programmed reduction, OXIDE coating, MAGNETRON sputtering
Abstract

Hollow cathode plasma sputtering is an advantageous method of preparing catalysts in the form of thin oxide films on supports. Such catalysts are particularly suitable for processes such as catalytic total oxidation of volatile organic compounds (VOCs), representing an economically feasible and environmentally friendly method of VOC abatement. Catalysts with Ni:Co molar ratios of 1:4, 1:1, and 4:1 were prepared on stainless-steel meshes and compared with single-component Ni and Co oxide catalysts. The properties of the catalysts were characterized by EDX, SEM, powder XRD, temperature-programmed reduction (H2-TPR), Raman spectroscopy, and XPS. Powder XRD revealed the formation of various crystalline phases that were dependent on molar the Ni:Co ratio. NiO and Co3O4 were identified in the single-component Ni and Co oxide catalysts, whereas Ni-Co mixed oxides with a spinel structure, together with NiO, were found in the catalysts containing both Ni and Co. Raman spectra of the catalysts prepared at high working pressures showed a slightly lower intensity of bands, indicating the presence of smaller oxide particles. The TPR profiles confirmed the improved reducibility of the Ni-Co oxide catalysts compared to the single-component Ni and Co catalysts. Catalytic activity was investigated in the deep oxidation of ethanol and toluene, which were used as model volatile organic compounds. In ethanol oxidation, the activity of sputtered catalysts was up to 16 times higher than that of the commercial Cu-Mn oxide catalyst EnviCat® VOC-1544. The main benefits of the sputtered catalysts are the much lower content of Ni and Co oxides and a negligible effect of internal diffusion. Moreover, the process of plasma jet sputtering can be easily implemented on a large scale. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Effect of Zinc on the Structure and Activity of the Cobalt Oxide Catalysts for NO Decomposition.

Author

Karásková, Kateřina, Pacultová, Kateřina, Bílková, Tereza, Fridrichová, Dagmar, Koštejn, Martin, Peikertová, Pavlína, Stelmachowski, Paweł, Kukula, Pavel, and Obalová, Lucie

Subjects
COBALT catalysts, COBALT oxides, ATOMIC absorption spectroscopy, METHANATION, X-ray photoelectron spectroscopy, TEMPERATURE-programmed reduction, POTASSIUM, FISCHER-Tropsch process
Abstract

Co4−iZniMnAlOx mixed oxides (i = 0, 0.5 and 1) were prepared by coprecipitation, subsequently modified with potassium (2 or 4 wt.% K), and investigated for direct catalytic NO decomposition, one of the most attractive and challenging NOx abatement processes. The catalysts were characterised by atomic absorption spectroscopy, powder X-ray diffraction, Raman and infrared spectroscopy, temperature-programmed reduction by hydrogen, the temperature-programmed desorption of CO2 and NO, X-ray photoelectron spectroscopy, scanning electron microscopy, the work function, and N2 physisorption. The partial substitution of cobalt increased the specific surface area, decreased the pore sizes, influenced the surface composition, and obtained acid-base properties as a result of the higher availability of medium and strong basic sites. No visible changes in the morphology, crystallite size, and work function were observed upon the cobalt substitution. The conversion of NO increased after the Co substitution, however, the increase in the amount of zinc did not affect the catalytic activity, whereas a higher amount of potassium caused a decrease in the NO conversion. The results obtained, which were predominantly the acid-base characteristics of the catalyst, are in direct correlation with the proposed NO decomposition reaction mechanisms with NOx− as the main reaction intermediates. [ABSTRACT FROM AUTHOR]

Published
2023
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38. On Stability of High-Surface-Area Al 2 O 3 , TiO 2 , SiO 2 -Al 2 O 3 , and Activated Carbon Supports during Preparation of NiMo Sulfide Catalysts for Parallel Deoxygenation of Octanoic Acid and Hydrodesulfurization of 1-Benzothiophene.

Author

Kaluža, Luděk, Soukup, Karel, Koštejn, Martin, Karban, Jindřich, Palcheva, Radostina, Laube, Marek, and Gulková, Daniela

Subjects
ALUMINUM oxide, OCTANOIC acid, ACTIVATED carbon, DEOXYGENATION, TITANIUM dioxide
Abstract

NiMo sulfide catalysts were prepared by the impregnation of high surface area supports with an aqueous solution made of NiCO3·2Ni(OH)2, MoO3 and citric acid, followed by freeze drying and sulfidation in H2S/H2 mixture. N2 physisorption and X-ray diffraction were selected to investigate the amphoteric oxides Al2O3 and TiO2, acidic SiO2-Al2O3 and activated carbon supports, fresh prepared sulfide NiMo catalysts and spent catalysts after model parallel reaction of octanoic acid deoxygenation and 1-benzothiophene hydrodesulfurization. The studied mesoporous amphoteric oxides Al2O3 and TiO2 did not lead to highly active NiMo catalysts due to the low hydrothermal stability of these supports during the preparation of the active sulfide phase and deoxygenation reaction. The most active catalyst based on oxidic support was the NiMo sulfide supported on acidic mesoporous SiO2-Al2O3, which was explained by the increased stability of this support to the water and CO/CO2 mixture during the activation of the sulfidic phase and deoxygenation reaction. The extraordinarily high stability of the activated carbon support led to outstanding activities of the sulfidic NiMo/C catalyst. [ABSTRACT FROM AUTHOR]

Published
2022
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39. Modification of Cobalt Oxide Electrochemically Deposited on Stainless Steel Meshes with Co-Mn Thin Films Prepared by Magnetron Sputtering: Effect of Preparation Method and Application to Ethanol Oxidation

Author

Jirátová, Květa, primary, Perekrestov, Roman, additional, Dvořáková, Michaela, additional, Balabánová, Jana, additional, Koštejn, Martin, additional, Veselý, Martin, additional, Čada, Martin, additional, Topka, Pavel, additional, Pokorná, Dana, additional, Hubička, Zdeněk, additional, and Kovanda, František, additional

Published
2021
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45. Multivalent Bifunctional Carbosilane Dendrimer-Supported Ammonium and Phosphonium Organocatalysts for the Coupling of CO2 and Epoxides

Author

Červenková Št’astná, Lucie, primary, Krupková, Alena, additional, Petrickovic, Roman, additional, Müllerová, Monika, additional, Matoušek, Jindřich, additional, Koštejn, Martin, additional, Cuřínová, Petra, additional, Jandová, Věra, additional, Šabata, Stanislav, additional, and Strašák, Tomáš, additional

Published
2020
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48. Novel perspectives of laser ablation in liquids: the formation of a high-pressure orthorhombic FeS phase and absorption of FeS-derived colloids on a porous surface for solar-light photocatalytic wastewater cleaning

Author

Křenek, Tomáš, primary, Vála, Lukáš, additional, Kovářík, Tomáš, additional, Medlín, Rostislav, additional, Fajgar, Radek, additional, Pola, Josef, additional, Jandová, Věra, additional, Vavruňková, Veronika, additional, Pola, Michal, additional, and Koštejn, Martin, additional

Published
2020
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49. MALES-FEMALES DIFFERENCES IN THE SPECTRUM OF CHROMOSOMAL ABERRATIONS IN THE GROUP OF NANOCOMPOSITES PRODUCTION WORKERS

Author

RÖSSNEROVÁ, Andrea, primary, PELCLOVÁ, Daniela, additional, ŽDÍMAL, Vladimír, additional, ELZEINOVÁ, Fatima, additional, MARGARYAN, Hasmik, additional, CHVOJKOVÁ, Irena, additional, TOPINKA, Jan, additional, SCHWARZ, Jaroslav, additional, ONDRÁČEK, Jakub, additional, KOŠTEJN, Martin, additional, KOMARC, Martin, additional, VLČKOVÁ, Štěpánka, additional, FENCLOVÁ, Zdeňka, additional, LISCHKOVÁ, Lucie, additional, DVOŘÁČKOVÁ, Štěpánka, additional, and RÖSSNER, Pavel Jr., additional

Published
2020
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