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Mordenite belongs to the so-called “big five” zeolites, which are extensively applied in the industry as catalysts.1 Important issue in catalysis efficiency is the number of active sites (i.e. Lewis and Brønsted acid sites). Numerous studies have shown that the catalytic properties of metal exchanged zeolites are determined by the location and valence state of metal cation and coordination in the zeolite lattice, as well as by the metal content. Mono- and bimetallic systems of Ag, Fe, and Ag–Fe were prepared by the wet impregnation of the H- form of mordenite (Si/Al=11) and consecutive thermal treatment. PXRD patterns show that after all post-synthesis treatments there is no significant influence on the crystallinity of the samples and the only detected phase was mordenite. The results from catalyst characterization by SEM/EDS have shown preserved morphology after wet impregnation and that a certain amount of metals was incorporated into mordenite crystals. The more precise composition of the samples was determined by FAAS, but the technique is not able to detect the position and coordination of the metal cation in the framework. UV–Vis spectroscopy was applied to identify the silver and iron complex species, due to their specific behavior under the light. Also, their photostability was tested by exposing the samples to radiation in the wavelength range of 200 to 1000 nm.

In this work zeolites samples with different amount of boron were prepared. Obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). Results of characterization showed that presence of boron in the reaction mixture influences size and morphology of synthesized zeolite crystals. Furthermore, the amount of boron in the reaction mixture, as well as presence of aluminum, influence extent of boron loss during calcination of the final zeolite product.

Two methods were investigated to synthesize mesoporous mordenite. PXRD showed that the samples made by both methods are crystalline mesoporous material with MOR framework. The transition metal cations Ag and Fe were introduced by the ion exchange method. The introduction was confirmed with EDS and AAS analysis. UV–Vis spectroscopy was applied to identify the silver and iron species in samples.

Introduction Due to its’ 12-member ring cage faujasite type zeolite is one of the best catalysts for fluid catalytic cracking (FCC) and is often used as support for platinum or palladium in a hydrocracking process. Depending on the Si/Al ratio synthetic FAU is classified as X, if ratio is between 2 and 3, or Y if ratio is 3 or higher. High aluminum content in X type zeolite results in large number of Brønsted’s acid sites which often leads to unwanted cyclic byproducts and formation of coke. In order to avoid this problem postsynthetic modifications to the zeolite structure are needed. One of the most promising methods to do this is wet impregnation with metal cations that increase the number of Lewis’ and reduce the number of Brønsted’s acid sites [1] in order to create more controlled catalytic conditions. Experimental The zeolite for post synthetic treatment (HF-AS) was isolated from a gel with following composition 8Na2O:0.7Al2O3:10SiO2:160H2O adopted from Awala and co-workers [2]. Previously prepared HF-AS was added in the water solution of nickel(II) chloride (1:50, 0.5 mol dm-3) and stirred. After 45 minutes the crystals were separated from solution and the process was repeated once more. The prepared product HF-Ni1 was then washed two times with 40 cm3 of redistilled water and then calcined at 550°C for 6 hours. Thus prepared product (HF-Ni1iz) was then ion exchanged with 0.8 mol dm-3 water solution of ammonium nitrate (1:10) for 3 hours after which it was again calcined at 450°C for 5 hours. The same procedure as described above was also used for the synthesis of HF-Ni2, HF-Ni3 and HF- Ni4 with the exception that before washing the products with redistilled water they were hydrothermally treated at 100°C for 24, 1.5 and 3 hours respectively. Results and discussion It was observed that calcination following wet impregnation with nickel(II) ions leads to increase of intensity of (111) peak and disappearance of peaks at 10.3° and 11.7° which may indicate the migration of nickel cations from double-6 rings to supercage. The shift in the peak positions from 0.2° to 0.4° varying on sample was also observed (Fig.1.). The diffraction peaks of the nickel(II) oxide were not observed in any of the samples (Fig.2.). The samples were also analyzed using atomic absorption spectroscopy and vacuum FTIR.

Zeolites of faujasite type (FAU) are one of most widely used ones in the fuel industry. The tridimensional 12-member ring cages make them suitable as catalysts for fluid catalytic cracking (FCC) and support for platinum or palladium in a hydrocracking process. There are two subtypes of synthetics FAU type zeolites depending on their Si/Al ratio: the X type when the ratio is between 2 and 3 and Y type if ratio is 3 or higher. The high amount of aluminum in X type zeolite results in number of Brønsted’s acid sites much higher than in the Y type. While high number of active sites can speed up catalytic process significantly it can also lead to unwanted byproducts and formation of coke. These problems can be avoided with post synthetic modifications by wet impregnation with metal salts to tune in acidity of active sites. The synthesis gel of composition 4Na2O:Al2O3:10SiO2:158H2O was used for the preparation of FAU type zeolite. The reaction was conducted in teflon lined autoclaves for 48 h at 100°C.[1] One part of synthesized zeolite was modified during synthesis using cetrimonium bromide (CTAB) while the other part was post synthetically treated with aqueous solution of sodium hydroxide. This was done in order to create mesopores (Figure 1.) which can facilitate diffusion through crystal during catalysis.[2] The prepared parent materials were then wet impregnated using metal salts of magnesium(II), cobalt(II), nickel(II), or zinc(II).

The unique physicochemical properties of the zeolites, such as their controlled acidity, adsorption capacity, ion exchange properties, and thermal stability, as well as uniform channels and cavities crystallographically ordered in size and position, determine their effectiveness in catalytic processes. Mordenite is widely used in catalysis, separation and purification because of its uniform, small pore size and high internal surface area. Despite the microporous structure, there are limitations that decrease the efficiency of the zeolite as catalysts. Such limitations can be avoided by creating mesoporous voids. Another important issue in catalysis efficiency is the number of active sites (i.e. Lewis and Brønsted acid sites). Its number can be increased with a number of hetero T-atoms within the framework by post-synthesis treatment such as ion exchange. Parent material was prepared by the hydrothermal synthesis in Teflon-lined autoclaves as one-pot synthesis and resulted in sodium mordenite zeolite. Mono- and bimetallic systems of Ag, Fe, and Ag–Fe were prepared by the ion exchange method in H-form mordenite. PXRD pattern shows that the structure corresponds to the structure of mordenite. All post-synthesis treatments did not have a significant influence on the crystallinity of the samples. Preliminary results (FE-SEM with EDS) have shown a certain amount of metals incorporated in mordenite and preserved structure after wet impregnation. AAS gives the exact concentration of metals in mordenite structure and was used to confirm impregnation of metals, but can't say anything about metal species. UV–Vis spectroscopy was applied to identify the silver and iron species. Due to the usually specific behavior of the Ag and Fe cations under the light, photostability was confirmed by exposing the samples to the radiation in the wavelength range of 200 to 1000 nm.

Faujasite type zeolite isolated from the gel with a composition of 4Na2O:Al2O3:10SiO2:158H2O after 48 h at 100°C was modified during synthesis using cetrimonium bromide (CTAB), or post-synthetically treated with sodium hydroxide aqueous solution in order to create mesopores. This way prepared material was then wet impregnated using metal salts of magnesium(II), cobalt(II), nickel(II), or zinc(II). The effect of exchanged metal cation on Brønsted and Lewis acid sites was observed using adsorption of deuterated acetonitrile in vacuum IR.

Introduction Many organic reactions (Friedl-Crafts type, ring transformation, halogenation, condensation, isomerization, etc.) can be catalysed by solid acid catalyst. Among them, zeolites have been often used, due to the known nature of the active (acid) sites. It makes them unique catalysts in comparison with others such as metals, metal oxides, and sulphides. Conventional solid acids, (zeolites such as ZSM-5, USY, beta) of micrometer sized crystal, are model system for research of the relationship among their selectivity, activity, and deactivation in the polyolefins cracking, MTO conversion, methane dehydroaromatization, etc. At the same time, it shows importance of the accessibility of active sites to the larger molecules, due to steric and diffusion limitations. Experimental The ZSM-5 (MFI) was prepared using simple, classical hydrothermal synthesis. starting from the synthesis gel with molar composition: 0.10 Na2O – 0.08 TPABr – 1.00 SiO2 – 0.02 Al2O3 – 20.00 H2O. First, NaOH was dissolved in of distilled water, then Al(OH)3 and TPABr were added to the basic solution. Than precipitated SiO2 was added. Resulting gel was stirred for 1 hour at room temperature and kept in oven at 175 °C for 5 days in teflon-lined stainless steel autoclaves, under static conditions. After synthesis, product was washed, dried at 105°C and calcined in air at 550°C - to eliminate SDA. The H-form was obtained after two cycles of ion exchange with 1M NH4Cl (1 h each) followed by a calcination at 550°C. Desilication of the HZSM-5 was made using 0.2 M NaOH solution for 45 min at 65 °C, with stirring, and again transformed to H-form as described above. Results and discussion PXRD patterns show that all postsynthesis treatments (first desilication with NaOH solution, then wet impregnation (with Ag+, Mg2+, and Fe3+), than reassembly in reactor, and finally calcination) have not significant influence on crystallinity of the samples. At the same time, mesoporosity after dealumina tion increases about 4 times (Fig. 1). In comparison to starting material (HZSM-5) total amount of acid places decrease after desilication from 565.56 μmol/g to 523.83 μmol/g, to 509.77 μmol/g in Mg- ZSM-5, 485.21 μmol/g in Fe-ZSM-5, and surprisnigly increase to 590.64 μmol/g in Ag-ZSM- 5. The ratio between the number of strong NH3 desorption around 400 °C) and weak acid sites (NH3 desorption around 230 °C) significantly decrease in following order: HZSM-5 > desilicated HZSM-5 > Mg-ZSM-5 >. Fe-ZSM-5 > Ag-ZSM-5 (Fig 2), what is also confirmed by vacuum FTIR spectroscopy. The distribution of pores measured by nitrogen adsorption/desorption (BJH) of ZSM-5 crystals before (H-ZSM-5) and after postsynthesis treatment – desilication (parent), wet impregnation (Ag, Fe, Mg) and consecutive thermal treatment of samples were shown in Fig. 1., while NH3-TPD profiles of ZSM-5 samples before and after postsynthesis were shown in Fig. 2. Conclusions Introduction of the various metal cations into hierarchical ZSM-5 does not have influence on samples crystallinity, but significantly affects the ratio between weak and strong acid sites, mainly decreasing the number of strong acid sites, what was measured by NH4-TPD, and confirmed by vacuum FTIR spectroscopy. Acknowledgement: This work was supported by Croatian National Science Fundation, Project no. IP2016-06-2214

Zeolites are used in many fields of human activities [1]. Besides, new potential applications constantly emerge so understanding their possible impact on the environment is necessary [2]. In the frame of this study, zeolite beta nanoparticles were synthesized and characterized by a complimentary set of experimental techniques. Their potential negative impact towards environment was evaluated using zebrafish Danio rerio embryos embryotoxicity test [3]. Such a comprehensive study pinpointed zeolite nanoparticles as safe materials and opened the door for their application, but also emphasized the need to reduce the presence of organic structure directing agents in nanosized zeolite synthesis reaction mixtures.

Synthesis of hierarchical zeolite (Mordenite) by addition of mesoporous template (CTAB) and by desilication/dealumination of regular crystals. Increase of the number of weak acid sites was observed after postsynthesis treatment by wet impregnation with Al3+ and Sn4+ ions.

Beta zeolite is microporous, aluminosilicate characterized by big 12-ring channel systems. It is commonly used as commercial adsorbents and catalysts. Although the pores are exceptionally large there are limitations which decrease efficiency of the catalysts. Such limitations should be avoided by creating mesoporous voids (channels and holes) during catalyst synthesis or by postsynthesis treatment of classically prepared microcrystals. Another important issue in catalysis efficiency is the number of active sites (i.e. Lewis and Brønsted acid sites). It´s number can be increased with number of hetero T-atoms within framework by postsynthesis treatment.

One of the most important factors in zeolite catalyst for methanol-to-olefine conversion (MTO) is the number and accessability of “acid places”. The number of the acid places (Brönstedt or Lewis) largely depends on the way of the catalyst preparation. Generaly, catalyst with more Al content within the framework, have more acid places. On the other hand, their accessability towards MTO reaction can be limited to the thin subsurface layer within crystals, due to the difficulties of the intracrystalline diffusion of the reactants and products. In this paper we have prepared hierarchical ZSM-5 crystals using several methods for synthesis: classical hydrothermal synthesis followed by etching (TPAOH/NaOH), synthesis with microporous (TPAOH) and mesoporous template (CTAB), postsynthesis treatment by wet impregnation, in order to increase the number of heteroatoms (Al, Sn) in the zeolites framework. Results shows substantial increase in the number of acid places after wet impregnation process.

Faujasite type zeolite has potential as catalyst for methanol-to-olefin (MTO) conversion. In order to enhance its catalytic properties by reducing the intercrystal diffusion path for both reactants and product, a nanosized crystals were used and the prepared material was further functionalized by a wet impregnation with zinc ions. The wet impregnation was conducted at room temperature but also under hydrothermal conditions.

In a quest for optimal synthesis procedure of hierarchically porous zeolite by dual template method, a series of materials was prepared starting from zeolite yielding precursor with an addition of surfactant as a mesoporogen. Characterization of the obtained materials showed that all samples possess micro and mesoporous structures, which ratio depends on the amount of surfactant present in the reaction mixture. However, in the most of the samples separation of phases occurred, and crystalline zeolite phase along amorphous MCM-41 like phase were detected, except for the sample obtained from the modified precursor, where only crystalline zeolite phase was obtained, with a specific and unusual morphology. Adsorption isotherm of that sample resembles the isotherms obtained for post synthesis modified samples.

Faujasite type zeolites (FAU) showcase properties that make them great potential catalysts for methanol-to-olefins (MTO) conversion.1 Their catalytic properties can be further enhanced by creating mesopores using surfactants, such as cetrimoium bromide (CTAB) or etching the crystals with NH4F in order to facilitate intercrystal diffusion.2 Thus prepared materials are then further modified by wet impregnation with various zinc(II), iron(II) and iron(III) salts.3 Incorporation of the transition metal ions in the zeolite framework creates larger number of Brønsted’s and Lewis’s acid sites that are catalytic canters for MTO conversion.

Since the intracrystalline diffusion of the reactants and products within zeolite catalyst (microporous crystals of micrometer size) is slow, the limitations of their efficiency should be avoided adding mesoporous voids (channels, holes). Introduction of mesoporous voids (hierarchical structure of the crystals) can be obtained using additional mesoporous template (e.g. CTAB) during catalyst synthesis, or by postsynthesis treatment of classically synthesized microcrystals (dealumination and desilication using e.g. NH4F or NaOH solutions). Another important issue in catalysis efficiency (we study methanol-to- olefine conversion – MTO) is number of active places (i.e. Lewis and Brönsteadt acid places). Its number can be increased with number of hetero T-atoms within framework. Beside direct synthesis of catalyst (zeolite Beta) of larger Al content, postsynthesis treatment (wet impregnation) can be used. After treatment, results show significant increase of number of both types of acid sites.

Two-dimensional coordination polymers [Zn(Gly-L-Phe)2]n (1) and [Cd(Gly-L-Phe)2]n (2) (Gly-L-Phe=glycyl-L-phenylalanine) were mechanochemically synthesized using ball mill. Effects of starting metal salts and presence of added liquid on the reactions were investigated and products were analyzed by infrared spectroscopy and powder diffraction. We have found that reactions proceed surprisingly easily with ZnO and CdO, giving polymers 1 and 2, respectively. Reactions with hydrated acetates are also facile.

Following the assumption that the crucial processes governing the formation, properties, and evolution of the core (amorphous silica)@shell (organocations) nanoparticles (NPs) take place during short-time, room-temperature (rt) stirring/aging of the homogeneous reaction mixtures (HmRMs) formed by hydrolysis of tetraethyl orthosilicate (TEOS) in solutions of Org(OH)n, we investigated these processes by various experimental methods (pH, ionic conductivity, 29Si NMR, dynamic light scattering, and atomic force microscopy). The analysis of the data obtained by detailed and careful investigation of the “model” HmRMs having the starting chemical composition, xTEOS/0.25TPAOH/20H2O (TPAOH = tetrapropylammonium hydroxide ; x = 0.05−1), offer some new elements for the understanding of the mechanisms of the formation and rt evolution of the core@shell silica NPs: (1) There is a resolute evidence of the formation of the stable, about 1.2 nm-sized core (amorphous SiO2)@shell (TPA+ ions) NPs below the critical aggregation concentration. (2) Because of the intensive particulate processes (growth, aggregation, disaggregation, and dissolution) which take place during the rt aging of the investigated HmRMs, the equilibrated core@shell silica NPs do not exist as individual primary ones but as the aggregates (about 2 to about 20 nm), composed of 1−2 nm-sized “primary” NPs. (3) In spite of the most frequent meaning that the NP shell is composed of the “free” TPA+ ions adsorbed on the surface of the NP core, the results of this study show that the NP shell can be formed mainly by the attachment of the polysilicate anions (silicate oligomers), associated with TPA+ ions, on the surfaces of the NP cores.

By definition, zeolites and zeotypes are crystalline materials with well-defined system of channels and cages having size lower than 2 nm. They are built of tetrahedra of oxygen atoms bonded to central T atom (T = Si, Al, Zn, Ge, P, Ga, …) and connected via vertices thus forming porous framework. Taking into account possible bonding angles and energy restrictions, there are over two millions hypothetical zeolite structures. Herein we report the study of zincosilicte zeotype RUB-17, a representative of three-membered ring containing framework type RSN [1]. The methods employed to study the precursors and final products are XRD, TG, Raman, IR, UV/VIS and NMR spectroscopy. To get better insight into RSN formation several different zinc sources are used in the material synthesis. The collected results provide more opportunities for zeolite crystal engineering and rational design in similar systems.

Zeolite su industrijski najvažniji katalizatori u heterogenim procesima te je stoga ispitivanje njihovog utjecaja na okoliš nužno. Ovdje su predstavljeni rezultati istraživanja djelovanja nanočestica zeolita beta na embrije ribe zebrice.

Zeolites are widely used in various fields of human activities [1] and as such there are many particular cases when large amounts of zeolite powder can be released to certain area and have a potentially harmful effect on specific ecosystem. Therefore, the goal of this research is to prepare nanosized zeolite beta particles and evaluate their toxicity towards chosen representatives of vertebrates. For this reason zebrafish embryotoxicity test was performed [2] on two zeolite beta samples having different size. Zeolite beta samples have been prepared by hydrothermal treatment of alumosilicate precursors of molar oxide composition 0.35Na2O : 0.5Al2O3 : 25SiO2 : 9TEAOH : 295H2O at 100 °C 7 days and 1.23K2O : 1.23Na2O : 1Al2O3 : 50SiO2 : 25TEAOH : 745H2O at 140 °C for 30 h. The average size of synthesized zeolite Beta crystals was 140 nm and 640 nm, respectively. The washed samples have been freeze- dried and calcined at 550 °C. The solid product was characterized by XRD, DLS, TEM and TG. Prior testing, both merely dried and calcined powder have been dispersed in artificial water in three different concentrations. In addition, tetraethylammonium hydroxide solutions of corresponding concentrations have been prepared for the test. Standardized zebrafish Danio rerio embryotoxicity test has been conducted as follows: embryos have been exposed to zeolite beta suspensions up to 72 hours post fertilization (hpf), followed by determination of lethal (coagulation of the embryo, non- detachment of the tail, lack of heart beat and no somite formation) and sublethal effects (developmental retardation, deformations, formation of edems, blood accumulation, etc) of tested nanosized zeolites. In addition, at 48 and 72 hpf heart beat and hatching rate were evaluated, as well as pigmentation formation. All experiments have been performed on the non- protected embryonal stages, which do not require permission by animal welfare commissions. The collected data have been statistically analyzed. Results indicate the zeolites do exhibit a certain effect on the development of the Danio rerio embryos, but they are not lethal. The obtained results have showed that selected model organisms could improve our ability to understand the mechanism of the toxicity of alumosilicates, and should be incorporated in nanoparticles toxicity monitoring and risk assessment studies. Additionally, this research focuses on the importance of an early and accurate determination of the toxic potential of the nanoparticles to assess its further use.

Calcium carbonate is a common mineral that appears in a form of several hydrated phases and three polymorphs: calcite, vaterite and aragonite. Because of its stability, availability and biocompatibility, it is one of the most important filler used for paper, plastics, rubber or paints production. CaCO3 can be readily prepared via the solution (liquid + liquid ® solid) or the carbonation (gas + liquid ® solid) route. However, mechanochemical processing has been recently proposed as an alternative method of CaCO3 preparation, which contributes to homogeneous distribution of phases, control of particle size distribution and prevention of agglomeration. The aim of this study is to identify the factors that favor the formation of calcium carbonate polymorphs by mechanochemical treatment of different reactants in ball mill. The obtained samples of calcium carbonate were characterized by FTIR–ATR spectroscopy, PXRD and SEM microscopy and it was found that vaterite, calcite or aragonite could be prepared by selecting the appropriate source of calcium ions. The properties of thus obtained samples were compared with CaCO3, which has been prepared by conventional, solution mediated, synthetic routes.

By classical definition, zeolites are crystalline alumosilicate materials with well-defined system of channels and cages having size lower than 2 nm. This definition was further extended to all materials possessing structure features typical for zeolites, so called zeotypes. Zeotypes are built of tetrahedra of oxygen atoms bonded to central T atom (T = Si, Al, Zn, Ge, P, Ga, …) and connected via vertices thus forming porous framework. Taking into account possible bonding angles and energy restrictions, there are over two millions hypothetical zeolite structures. Zeolites are widely used materials, ranging from ion-exchange and molecular sieving to catalysis in oil refinement and drug delivery in medicine. For this reason engineering of their structure and properties in line with the requirements of a particular application would be beneficial for improving their performance. In spite of numerous studies performed in this field, still many of the results are based on empirical experience, rather than on profound comprehension of the basic processes of zeolite formation. It was perceived that some zeolite building units are more often formed in the presence of a certain T-atom than when others are used (1). Besides, depending on the synthesis conditions applied, different final products can be formed from the same initial reaction system (2). Herein we report the study of zincosilicte RUB-17 – three-membered ring containing framework type RSN (3). The methods employed to study the precursors and final products are XRD, GISAXS, TG, Raman, IR, UV/VIS and NMR spectroscopy. The effect of type of the potential framework T-atoms which were found to form three- membered rings in zeolite frameworks (Al, B, Ge, Li and Mg) is investigated. The collected data indicate that under studied conditions the RSN framework is formed exclusively in zinc containing systems. In order to get more insight into RSN formation several different zinc sources are used. Besides the synthesis conditions the necessity of the presence of structure directing agent in the RUB-17 reaction mixture is going to be discussed. The obtain data can be used for control of zeolite formation in similar systems. In addition, the potential of the prepared material to be used as semiconductor is investigated.

CHA-type zeolite is one of the most important zeolites that found application in important industrial processes and exhaust gas treatment. The simplest way to obtain aluminosilicate CHA is to transform zeolite Y under hydrothermal conditions. However, the mechanism of hydrothermal transformation of one zeolite framework type into another is not yet well understood. Herein, we report on the conversion of commercial zeolite Y (FAU) into chabazite, in KOH solution at 100 °C. The reaction course was followed using powder X-ray diffraction, Raman and NMR spectroscopy, scanning and transmission electron microscopy as well as dynamic light scattering technique. The set of experimental data pointed out that the zeolite transformation is a solution mediated process and an amorphous phase is the intermediate between FAU-type and CHA-type zeolite. The results obtained in this study shed a new light in the mechanism of the CHA formation and contribute in the understanding of the processes taking place during zeolite-zeolite conversion.

The solvothermal reaction between Zn2+ and glycl-L-phenylalanine was finished giving the crystalline Zn(GlyPhe)2 A part of the structural as well as thermal properties of the obtained crystals were examined. The characterization was performed using various methods: X-ray powder diffraction, infrared spectroscopy, thermal analysis (TG and DTG), and atomic absorption spectroscopy. Unit cell and its parameters of Zn(GlyPhe)2 have been determined and reported here.