Ana Palčić

Ana Palčić
Rudjer Boskovic Institute | RBI

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44
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Publications

Publications (44)
Article
Full-text available
A series of ZSM-5 zeolite materials were synthesized from organic structure-directing agent (OSDA)-free seeded systems, including nanosized silicalite-1 (12 wt % water suspension or in powder form) or nanosized ZSM-5 (powder form of ZSM-5 prepared at 100 or 170 °C). The physicochemical characterization revealed aggregated species in the samples bas...
Article
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The aim of this work was to develop hybrid TiO2/ZIF-8 photocatalysts and test their activity for the removal of agricultural pollutants in water. The hybrid photocatalysts were prepared by an innovative method involving hydrothermal synthesis at 150 °C using a mechanochemically synthesized zeolitic imidazolate framework (ZIF-8) and titanium tetrais...
Article
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Two series of zeolite Y were prepared with varying particle size (estimated 100 or 400 nm) by applying different synthesis gel composition ratios as well as different ageing and hydrothermal...
Article
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Catalyzed reactions of organic substrates that operate continuously by extrusion techniques are rare. In this study, we developed a mechanochemical bromination of unactivated naphthalene (1) with 1,3‐dibromo‐5,5‐dimethylhydantoin (DBDMH), catalyzed by zeolites in a ball mill. The use of DBDMH enabled the atom economy of the reaction to be superior...
Article
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Nanosized Cu‐containing ZSM‐5 catalysts with different n(Si)/n(Al) ratio of 18.9–50.5 were prepared by ion‐exchange. The physico‐chemical characterization clearly shows that the molar ratio of framework T atoms influences the nature and distribution of copper species. According to DR UV‐Vis, TPR‐H2, EPR, or FT‐IR spectroscopy analyses, the amount o...
Article
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This paper deals with the synthesis conditions–defect formation relationship in zeolites. Silicalite‐1 (MFI‐type) is used as a model material. Samples synthesized from a system with high basicity (at 100 °C), a system with moderate basicity (at 150 °C), and a fluoride‐containing system in neutral medium (at 170 °C) are compared. Well‐crystallized m...
Article
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YNU-5 zeolite has the YFI-type framework with a 12-12-8-ring system (2-dimensional 12-oxygen membered ring pores 3-dimensionally connected by twin 8-ring channels), and isolated 8-ring channels separated from the system by a thin (mono-atomic silicate) wall. In this study, the acidic property of YNU-5 zeolite was analyzed mainly by means of the amm...
Article
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Zeolite crystal growth mechanisms are not fully elucidated owing to their complexity wherein the formation of a particular zeolite can occur by more than one crystallization pathway. Here, we have conducted time-resolved dissolution experiments of MFI-type zeolite crystals in ammonium fluoride medium where detailed structural analysis allowed us to...
Article
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Embryonic X-ray amorphous semi-formed MFI-type zeolite units mixed with the Cu–Zn–Al catalyst have been used for the direct synthesis of dimethyl ether (DME) from syngas. The hybrid catalyst with embryonic zeolite (EZ) with the particle size of 5 nm has demonstrated superior performance in terms of activity, selectivity, and stability compared to t...
Article
The effective conversion of methanol toward high-added value molecules, such as dimethyl ether (methanol-to-dimethyl ether process, MTD), olefins (methanol-to-olefins process, MTO), or gasoline-cut hydrocarbons (methanol-to-gasoline process, MTG), is of paramount importance for the transition toward a methanol-based economy. In these processes, zeo...
Chapter
The article is devoted to the synthesis of zeolite materials in an accent on the nano zeolites. After a general introduction of zeolite materials, the factors controlling zeolite nucleation and growth are addressed. This information is further used to discuss the key issues related to the synthesis of nano zeolites. A comprehensive analysis of the...
Article
The exceptional catalytic performance of zeolites is due to the presence of active sites in a shape-selective environment, i.e., in micropores with molecular dimensions. The present review provides a comprehensive analysis of active sites in zeolite frameworks. It is focused on the active sites generated by the Al incorporation in the framework. Th...
Article
Full-text available
Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with copper ions (Cu...
Article
Zeolites are materials widely used in many fields of human activities. Furthermore, new potential applications constantly emerge, so understanding their possible impact on the environment is necessary. Within this study, the potential toxicity of nanosized particles (140 and 600 nm) of a widely used zeolite beta was evaluated using zebrafish Danio...
Article
Typical zeolite synthesis reaction mixture involves framework atom source, solvent, mineraliser, and structure directing agent. However, these components often have a dual function, and their impact on the nucleation/crystallization process is difficult to be established straightforwardly. The present study deals with the structure directing effect...
Article
Investigation (DLS, AFM, pH measurements, ²⁹Si-NMR and ²³Na-NMR) of the influence of small inorganic cations (Na⁺ ions in this case) on the core@shell silica nanoparticles, formed by room temperature hydrolysis of TEOS in aqueous TPAOH (subsequent addition of NaOH – SA) and NaOH/TPAOH (direct addition of NaOH - DA) solutions showed that the smaller...
Article
Dimethyl ether is one of the most promising environmentally optimized alternatives to the conventional fossil fuels and an important platform molecule for chemical industry. Catalyst deactivation is one of the most important challenges of the single-step dimethyl ether synthesis from syngas. Because of the lack of direct characterization techniques...
Article
Boosting propylene selectivity is an important issue in the methanol‐to‐olefin (MTO) production. The present study reports the impact of the synthesis temperature on the propylene selectivity of the ZSM‐5 catalyst. The use of a low crystallization temperature results in zeolites with very small particle size, large number of structural defects and...
Article
Series of nanosized ZSM‐5 samples is synthesized at 170 °C, 150 °C, 120 °C and 100 °C. Experimental data show that the decrease of crystallization temperature leads to significant changes in zeolite properties. Crystals synthesized at 100 °C exhibit many framework defects with lower acid sites density, strength and larger external surface area. The...
Article
Following the assumption that the crucial processes governing the formation, properties and evolution of the core(amorphous silica)@shell(organocations) nanoparticles take place during short-time, room-temperature (rt) stirring/aging of the homogeneous reaction mixtures (HmRMs) formed by hydrolysis of TEOS (tetraethyl orthosilicate) in solutions of...
Article
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Two new coordination polymers, Zn(Gly-L-Phe)2 and Cd(Gly-L-Phe)2 (Gly-L-Phe=glycyl-L-phenylalanine), have been synthesized by reaction of Zn(NO3)2×6H2O or Cd(NO3)2×6H2O, NaOH and glycyl-L-phenylalanine. The obtained materials were characterized by infrared spectroscopy, thermal analysis, atomic absorption spectropscopy, while crystal structures wer...
Article
The principle aspects and constraints of the dynamics and kinetics of zeolite nucleation in hydrogel systems are analyzed on the basis of a model Na-rich aluminosilicate system. A detailed time-series EMT-type zeo-lite crystallization study in the model hydrogel system was performed to elucidate the topological and temporal aspects of zeolite nucle...
Article
The crystallization process of RUB-17 (RSN-type), a zeolite-type zincosilicate, was studied in order to shed light on the zeolite crystallization mechanism. The sequence of crystallization events from the formation of the initial gel to the complete transformation into a zeolite-type material was investigated. Complementary methods, including XRD,...
Article
The potential use of L-3,4-dihydroxyphenylalanine (L-DOPA) amino acid in the treatment of Parkinson's disease is hindered by an oxidative polymerization under air that might be at least partially circumvented by the immobilization on an inorganic matrix. This study reports on the preparation of dihydroxyphenylalanine (DOPA) - zeolite Beta composite...
Article
Organic additives were used to control the formation of EMT type zeolite in a sodium-rich initial system. Triethanolamine was employed as a nucleation suppression agent able to complex the aluminum during the synthesis of the EMT type zeolite. The commonly used tetramethylammonium (TMA) chloride and tetraethylammonium (TEA) chloride as structure di...
Article
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The microstructure of the starting hydrogel has extremely important role in the synthesis of the microporous materials. Due to the fact that very limited number of experimental methods (techniques) can be used for gel analysis, there are still a lot of missing informations about the processes on molecular level, which occur before and during the nu...
Article
The crystal structure of copper(II) citrate monohydrate (C6H4O7Cu2.H2O) has been solved from a mixture powder diffraction pattern. Approach to indexing, structure solution and Rietveld refinement of multiphase diffraction patterns is discussed. Rietveld refinement is carried out employing free-atom refinement and rigid body refinement. (c) 2013 Int...
Article
Various factors affect the process of zeolite formation and thus the characteristics of the ultimate material. The present study is devoted to the influence of the density of the starting aluminosilicate hydrogels, i.e. the amount of the solid phase in the system, on the characteristics of the final product. Different density (viscosity) of the fiv...
Article
Full-text available
Zeolites are crystalline, microporous, alumo-silicate materials (around 400 types) which are used in many applications. Each field of usage (catalysis, ion exchange, sorption, molecular sieving, etc.) has demands regarding crystals' structural and particulate properties. Detailed understanding of the mechanisms of crystals' formation and growth ena...
Article
The performance of zeolite crystals in different industrial processes often depends on their size and shape. Several physico-chemical parameters can have significant impact on their particulate properties (especially morphology). Amongst the chemical parameters the Si/Al ratio is one of most important variable together with the Na+ ions (alkalinity...
Article
The course of hydrothermal crystallisation of aluminosilicates (zeolites) as well as their particulate properties can be affected by many factors, which influence processes at molecular level, especially nucleation events. Using kinetic data (rate of crystallisation, rate of crystal growth) and crystal size distributions of zeolite A at the end of...
Article
Full-text available
Many transition metal cations (e.g., Cu, Fe, Co, Ni, etc.) are widely used as catalysts for different reactions. Often they are placed within zeolites (as inert carrier) and many preparation pathways have been tested in order to obtain stable catalyst and to prevent metal leaching from the catalyst. The fixation of the metal cations, during hydroth...

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