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11.
Optimizacija poroznih materialov za zajemanje CO2
Lara Valentić, 2015, undergraduate thesis

Abstract: V diplomskem delu sem želela raziskati razlike v sposobnostih za vezavo ogljikovega dioksida v kovinsko-organskih poroznih (MOF) materialih, sintetiziranih z okoljsko manj obremenjujočimi reaktanti, kot so trenutno v uporabi, in oceniti primernost materialov za zajem ogljikovega dioksida iz dimnih plinov v že obstoječih tehnoloških procesih. Pri sintezah sem spreminjala vir Mg in Al ionov, vrsto organskih ligandov in topil, temperaturo in čas sinteze. Večina produktov je bila narejena s solvotermalno sintezo, dva produkta sem poskusila optimizirati z mikrovalovno sintezo. Sintetiziranim produktom sem določala strukturo in/ali poroznost z uporabo rentgenske difrakcije (XRD), elektronske mikroskopije z uporabo elementne analize (SEM in EDX) ter s fizisorpcijo dušika. Najprimernejše produkte sem nato testirala za zajem ogljikovega dioksida. Najboljši produkt za zajemanje ogljikovega dioksida je Al-BPDC, aromatski kovinsko-organski porozni material z BET-specifično površino 1712 m2/g. Alifatski produkti z aluminijem in magnezijem (sukcionat, glutarat in pimelat) imajo opazno stopnjo adsorpcije šele pri visokih tlakih, zato niso primerni za adsorpcijo in zajem ogljikovega dioksida iz dimnih plinov.
Found in: osebi
Keywords: kovinsko-organski porozni materiali, zajem CO2, strukturna karakterizacija, alifatski karboksilati, aromatski karboksilati
Published: 01.09.2015; Views: 3997; Downloads: 210
.pdf Fulltext (3,63 MB)

12.
New Insights into Manganese Local Environment in MnS-1Nanocrystals
Alenka Ristić, Matjaž Mazaj, Iztok Arčon, Nina Daneu, Nataša Zabukovec Logar, Roger Glaser, Nataša Novak Tušar, 2019, original scientific article

Abstract: Manganese plays an important role in redox catalysis using zeolites as inorganic support materials, but the formation of the preferred redox manganese species (framework or extraframework) is still not well understood. Herein, the influence of the amount of manganese together with conventional and microwave-assisted hydrothermal synthesis paths on the formation of manganese species within the zeolite silicalite-1 (S-1) with MFI structure was investigated. It was found out that both synthesis procedures led to the formation of framework and extraframework manganese species, but in different molar ratios. However, the conventional synthesis procedure with all Mn/Si molar ratios generates more framework Mn in comparison to the microwave procedure. Additionally, the diminution of the zeolite crystals to nanoscale from 100 to 200 nm was achieved via the conventional procedure for the first time. UV–vis, Raman, and X-ray absorption spectroscopic analyses revealed different local environments of manganese: Mn3+ incorporated into the silicalite-1 framework as “framework manganese” and Mn2+/3+ present as “extraframework manganese” (Mn2O3, Mn3O4). TEM reveals the presence of Mn3O4 nanorods. Both framework manganese and extraframework manganese exhibit good catalytic activity for styrene epoxidation. Catalytic results suggest that, in oxidation reactions of hydrocarbons, framework manganese is more active at lower Mn contents (Mn/Si < 0.015), whereas extraframework manganese is more active at higher loadings (Mn/Si > 0.015).
Found in: osebi
Keywords: MnS-1 Nanocrystals, Mn XANES, EXAFS, zeolites, microwave-assisted hydrothermal synthesis
Published: 06.05.2019; Views: 1606; Downloads: 0
.pdf Fulltext (9,33 MB)

13.
Study of water adsorption on EDTA dealuminated zeolite Y
O. L. Pliekhov, Olena Pliekhova, Iztok Arčon, Federica Bondino, Elena Magnano, Gregor Mali, Nataša Zabukovec Logar, 2020, original scientific article

Abstract: Zeolite Y was synthesized and modified with EDTA dealumination procedure. The modified zeolites were analyzed by X-ray diffraction, X-ray absorption spectroscopy, chemical analysis and water adsorption measurements. We demonstrated that dealumination with bulk organic acid such as EDTA is able to reduce the original intense water affinity. Furthermore, it was found that dealumination with EDTA, in contrast with steaming and HCl dealumination, provides fully controllable, predictable and secure process of Al removal from the zeolites’ frameworks. The shift of the adsorption isotherm in the low partial pressure range represents an interesting result for adsorption-based applications.
Found in: osebi
Keywords: Zeolite Y Water sorption Dealumination Al XANES EDTA treatment
Published: 05.06.2020; Views: 1212; Downloads: 0
.pdf Fulltext (667,27 KB)

14.
Removal of copper from aqueous solutions with zeolites and possible treatment of exhaust materials
Iztok Arčon, Janez Kovač, Margarita Popova, Nataša Zabukovec Logar, 2021, original scientific article

Abstract: The mechanism of Cu2+ loading into commercially available natural HEU-type and synthetic LTA-type zeolites for their possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis, SEM/EDXS, XRD, XAS and XPS analyses revealed 4-fold coordination of Cu2+ cations with oxygen atoms in the pores, a predominant location of copper atoms on the surface of crystallites and retained crystallinity of zeolites throughout the processes. The post-treatment of Cu2+-loaded samples with HCl and/or NaCl solutions confirmed the predominantly reversible sorption of copper on zeolites from aqueous solutions by ion-exchange mechanism and, therefore, excellent regeneration possibilities for both types of zeolites. Furthermore, with the calcination of exhaust metal-loaded zeolites, catalysts for total toluene oxidation reaction, as a model VOC pollutant, were obtained.
Found in: osebi
Keywords: Cu2+ ion exchange, Total toluene oxidation, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, Zeolite
Published: 03.06.2021; Views: 287; Downloads: 12
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