Synthesis Of Zeolite Research Articles

Capturing Different Intermediate Phases during Zeolite Synthesis.

Despite extensive efforts over the past several decades, the current mechanistic understanding of zeolite crystallization is still far from satisfactory, thus precluding the synthesis of designer zeolites. Here we show that the nucleation and in situ transformation pathways during the synthesis of medium-pore zeolite TNU-9 can be altered by controlling the extent of cooperative structure direction between Na+ and Cs+ ions in the presence of 1,4-bis(N-methylpyrrolidinium)butane cations as an organic structure-directing agent. The intermediate phase selectivity was found to change from bikitaite to analcime to layered MCM-22 precursor when the gel Na/Cs ratio was adjusted to 7, 15, and 20, respectively. We also show that the transformation of bikitaite into TNU-9 begins at the surface of intermediate crystals, unlike that of analcime and MCM-22 precursor by a dissolution-recrystallization process. The force field simulation results suggest that the nucleation of different intermediate phases is not thermodynamically but kinetically controlled. This study provides a new basis for advancing the fundamental understanding of zeolite crystallization pathways.

Solvent-free synthesis of hierarchical tungsten-doped MFI zeolite for cyclohexene epoxidation reaction

Solvent-free synthesis method in zeolite preparation can largely decrease the generation of wastewater and improve the zeolite yield by simply grinding and hydrothermal treatment for the solid raw materials, and accordingly is considered as one of the most promisingly green and sustainable synthesis strategy for the metal-doped zeolite materials. However, there are scarcely any reports on the solvent-free synthesis and catalytic application of tungsten-doped zeolite materials. In this work, tungsten-doped MFI zeolites were prepared with solvent-free synthesis method and used as heterogeneous catalyst for cyclohexene epoxidation reaction. The synthesized tungsten-doped MFI zeolites displayed a monoclinic (P21/n) space group attributed to the successful incorporation of tungsten atom into MFI framework and meanwhile possessed an enormous number of irregular mesopores ranging from 2 nm to 50 nm. The influence of TPAOH addition amount on the mesopore structure and properties of tungsten-doped MFI zeolite was further investigated. In addition, the crystallization process of tungsten-doped MFI zeolite sample was tracked and analyzed with SEM, XRD and BET characterizations, and accordingly possible formation process for hierarchical zeolite was proposed. Furthermore, the prepared hierarchical tungsten-doped MFI zeolite displayed eminent cyclohexene epoxidation performance and re-usability for more than five times. This work provides some guidance for the solvent-free synthesis of metallosilicate zeolites, decreasing the generation of wastewater and improving the zeolite yield.

Study on the synthesis of nanosheets petal-shaped ZSM-5 Zeolites

In this work, a novel strategy for hydrothermal synthesis of nanosheets petal-shaped ZSM-5 zeolites was introduced. The experimental results indicated that the nanosheets petal-shaped ZSM-5 zeolites exhibited a higher specific surface area and more abundant acid sites. Under the synergistic crystallization effect of ethanol and seeds, the addition of CTAB promoted the growth of the layered structure, and the introduction of trace amounts of seeds effectively inhibited the growth of mordenite in a high alkalinity environment, reducing the crystallization time to 48 hours. More importantly, the petal-shaped ZSM-5 zeolites exhibited excellent MTP (Methanol-to-Propylene) catalytic performance, with methanol conversion maintained above 97.8 % for 80 hours and a maximum propylene selectivity of 49.1 %. This paper proposes an Ethanol-Seed-CTAB synthesis method for producing petal-shaped ZSM-5 zeolite with a unique morphology. This approach does not require the use of complex gemini quaternary ammonium surfactants in the synthesis process, greatly promoting the application and dissemination of nanosheets zeolites.

Synthesis of Nanoscale ZSM-5 Zeolites for the Catalytic Cracking of Oleic Acid into Light Olefins and Aromatics

Synthesis of Nanoscale ZSM-5 Zeolites for the Catalytic Cracking of Oleic Acid into Light Olefins and Aromatics

Rational Design of Organic Structure-Directing Agents for AFX Zeolite Synthesis from Molecular Mechanics and Molecular Dynamics

Rational Design of Organic Structure-Directing Agents for AFX Zeolite Synthesis from Molecular Mechanics and Molecular Dynamics

Effect of microwave irradiation on the synthesis of zeolite with ferrierite structure: Study of acid and catalytic properties

Ferrierite zeolite (FER) was synthesized under microwave conditions while varying the microwave exposure time from 6 to 12 h. For comparison, commercial FER and a FER zeolite synthesized by the conventional hydrothermal synthesis (72 h) were studied. The structure, texture, and acidic properties of the samples were investigated by XRD, low-temperature N2 adsorption, ICP-AES, SEM, and DRIFT spectroscopy using adsorption of CO, CD3CN and pyridine as probe molecules. The catalytic characteristics of the obtained zeolites were studied in the cyclocondensation reaction of 1,2-phenylenediamine and acetone to produce 1,5-benzodiazepine. The activity of the zeolites in this reaction was found to increase with increasing microwave exposure time. The FER-MW sample synthesized in 12 h showed the best results.

Rice Husk as Raw Material in Synthesis of NaA (LTA) Zeolite.

The present work deals with the hydrothermal synthesis of a Na-A (LTA) zeolite using rice husk as a starting material. The focus was on defining the most favorable conditions for the synthesis of zeolite Na-A from rice husk in order to economize on both energy (i.e., synthesis temperatures) and reaction time and to enlarge the field of the pure and isolated synthesized phase. Four sets of experiments were carried out at environmental pressure temperatures varying from 40 °C to 85 °C with a SiO2/Al2O3 ratio from 1.75 to 3.5. Optimal conditions for crystallization of the Na-A zeolite from rice husk were reached at 60 °C with a SiO2/Al2O3 ratio of 1.75. Sixty degrees Celsius represents the minimum known temperature used for the synthesis of NaA zeolite from rice husk. The products of synthesis were characterized by X-ray diffraction, scanning electron microscopy, infrared and Raman spectroscopy. The purity of the synthesized zeolite is verified here for the first time through quantitative phase analysis using the combined Rietveld and reference intensity ratio methods.

Decoding the zeolite cage effect in one-step ethylene purification from CO2/C2H2/C2H4 mixtures

Utilizing physical adsorption for ethylene purification from complex mixtures can significantly reduce the energy cost for production. The purification of multi-component systems through a single adsorption process presents a considerable challenge, largely stemming from the absence of customized strategies and thorough investigations into adsorption behaviours. We aim to understand adsorbents through a unique cage recognition approach and leverage these insights to develop an effective purification adsorbent, with the successful synthesis of SSZ-16 zeolite meeting requirements for multi-component purification. This zeolite, featuring a long aft supercage and a narrow gme cage construct two adsorption cages. The dense π-electron cloud of C2H2 enables a stronger interaction in aft cage, while CO2 is selectively captured within the environmentally compatible gme cage, demonstrating significantly higher C2H2 and CO2 adsorption capacity. The separation experiments reveal that SSZ-16 exhibits exceptional performance, with an unprecedented polymer-grade C2H4 productivity of 2099.16 L/kg from the CO2/C2H2/C2H4 mixture.

Sintesis Zeolit dari Abu Sekam Padi (OryzaSativa L.) Serta Uji Efektifitasnya Sebagai Material Antiseptik

Rice husks are obtained from 20% rice milling and have a silica content of 94-99% of ashed rice husks. Zeolite is a silica-based material and is known as an aluminosilicate compound, because it is formed from two main components, namely tetrahedral AlO4- and SiO4¬-. Synthetic zeolite is obtained by reacting Sodium Silicate (A) with Sodium Aluminate (B) which is then aged at 100oC for 24 hours to produce white synthetic Zeolite powder. Zeolite synthesis will be made with three variations of mixture ratios, namely 30A:70B, 50A:50B, 70A:30B and the characteristics of each will be evaluated. To test the success of this synthetic zeolite as an antiseptic material, its ability to reduce the infectious value of Bacteriuria and Candiduria will be tested, which will be represented by Escherecia coli and Candida albicans. The results obtained from the three variations of synthetic zeolite that were made had the same characteristics and had a ratio of less than two or type A. Synthetic zeolite made at a dose of 600 mg had the ability to act as an antiseptic material against Escherichia coli 104 by reducing the number of colonies to 72-79 %, as well as Candida albicans 103 was able to reduce the number of C. albicans colonies by 74-80%, this value is lower than Attapulgite 600mg in reducing the same number of colonies, namely 90% for bacteriuria and 94.90% for candiduria. To equalize its capabilities with Attapulgite 600 mg, the dosage of the synthetic zeolite obtained in the research was increased to 700 mg

Electrolytic manganese residue and red mud co-treatment: Synthesizing zeolite X and adsorbing leaching solution from electrolytic manganese residue

Electrolytic manganese residue (EMR) and red mud (RM) are solid wastes from electrolytic metallic manganese and alumina production. These wastes continue to accumulate, causing significant environmental damage and resource waste. To solve these problems, porous zeolite X (ERZ) was synthesized with EMR and RM as the main raw materials. ERZ was then employed to adsorb the leaching solution generated during EMR purification. Also, an investigation was carried out to ascertain the most favorable parameters for the synthesis of zeolite, and the resulting ERZ was characterized. The results indicated that the synthesized ERZ exhibits excellent crystallinity, high thermal stability, and a large specific surface area. Next, solid-state NMR (SSNMR), XRD, and Raman spectroscopy were used to characterize the ERZ synthesis process: the structural units of X zeolite are β cages and 4Rs. Additionally, the study examined the adsorption impact of ERZ on impurity ions in the leaching solution, revealing that the adsorption mechanism is chemisorption. Furthermore, the effective regeneration of ERZ demonstrated its significant practical utility. To summarize, this study presents a new feasible way for effectively utilizing EMR and BA.

Study on the catalytic performance of Fe in-situ modified small crystallite Silicalite-1 zeolite in Chichibabin condensation reaction

Pyridine and its derivatives, collectively referred to as pyridine bases, are widely used in industries such as pesticides and pharmaceuticals, serving as crucial intermediates in the chemical industry. In recent years, with the development of the pesticide and pharmaceutical industries, the demand for pyridine bases has rapidly increased. The Chichibabin condensation reaction is the most commonly route for industrial production of pyridine bases. Currently, the most used ZSM-5 zeolite catalyst is limited by the instability of its silicon-aluminum framework structure, resulting in a short active reaction cycle (5 h). To address this limitation, this study selected the thermally stable and hydrothermally stable Silicalite-1 zeolite. Polyvinylpyrrolidone (PVP) was employed as a colloidal dispersant and Fe was introduced into the MFI framework through in-situ modification during the hydrothermal synthesis of zeolite. The influence of PVP dosage, template agent dosage, and other crystallization conditions on the crystallinity, pore structure, and acidity of Silicalite-1 zeolite products was investigated using XRD, SEM, TG, and N2 adsorption-desorption measurement. The acidity of Fe-modified Silicalite-1 zeolites was characterized using NH3-TPD, Py-FTIR, FT-IR, and XPS. These results indicated that the introduction of seed crystals effectively reduced the particle size of the zeolite to about 200 nm. Fe-modified Silicalite-1 displayed a disk-like morphology with excellent crystal dispersion. The highest relative crystallinity of the zeolite reached 103% with 15% seed crystal input and 3.75% PVP addition. The Fe-modified Silicalite-1 possessed a significantly enhanced abundance of both Lewis (L) and Brønsted (B) acid sites, resulting in an increase in the initial activity from 66% to 85% for the pyridine bases synthesis through the Chichibabin condensation. Compared to ZSM-5, Fe-modified Silicalite-1 exhibited superior catalytic stability, maintaining the total carbon conversion and pyridine bases yield above 66% and 40%, respectively, over a 15 h reaction period. Furthermore, the strategy proposed in this study, employing polyvinylpyrrolidone as a colloidal stabilizer to modify Silicalite-1 zeolite, could significantly broadened the application prospects of weakly acidic pure silica zeolites in the field of acid catalysis. This approach has demonstrated significant scientific value and industrial potential.

Sintesis dan Karakterisasi Zeolit X dari Fly Ash Batu Bara Menggunakan Metode Sintesis pada Suhu Rendah

Many industries in Indonesia have switched to using coal fuel. The use of coal at PT PLTU Paiton has reached 250 tons per hour and produces 4% of waste by-products of combustion contained from bottom ash by 25% and fly ash by 75%. Fly ash waste will harm the environment and health. Fly ash contains many components, including SiO2 52%, Al2O3 31.86%, Fe2O2 4.89%, CaO 2.68%, and MgO 4.66%. This research aims to synthesize and characterize zeolite X from PT Paiton fly ash using a low-temperature synthesis method. Zeolite X synthesis in this study has 3 steps: The pretreatment process, silica synthesis process, and zeolite synthesis process. The results of silica synthesis obtained SiO2 55.54%. The resulting zeolite product has a typical peak at 2ϴ 28.72. Zeolite x has a wavelength of 430, 570, 695,7, and 965,7, which respectively indicates Si-O-Si and Si-O-Al bonds, double ring bonds, T-O ring symmetric strain (internal), and asymmetric (internal). The results of zeolite X crystal synthesis in this study could not be formed in the variable of adding time of 3-5 hours with a variation of moles of Al2O3 0,5-1,5 moles.

Solvent-free synthesis of micron-sized silicalite-1 zeolite: Optimization, characterization and mechanism

The solvent-free method fabrication of zeolites represents an eco-friendly approach, which a highly attractive field of scientific research. A novel method for synthesis of micron-sized silicalite-1 zeolite under fluoride-free and solvent-free conditions has been developed. Characterization of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunner-Emmett-Teller (BET) surface area were used to analyze the properties and structure of the silicalite-1 zeolite. The effects of mineralizers, organic structuring direct agents, catalyst, and crystallization time on the synthesized silicalite-1 zeolite are investigated. Silicalite-1 zeolite has microporous and mesoporous structures with a BET surface area of 350.4 m2/g. The synthesis mechanism of micron-sized silicalite-1 zeolite has been proposed, revealing that the intermediate sodium silicate dry gel is crucial for the formation of zeolite.

Synthesis of magnetic 4A zeolite and its performance on ammonia nitrogen adsorption in water

Synthesis of magnetic 4A zeolite and its performance on ammonia nitrogen adsorption in water

Realizing the Direct Synthesis of High Silica IWS Zeolite with Improved Hydrothermal Stability.

Direct synthesis of germanosilicate zeolites with low Ge content and improved hydrothermal stability is a great challenge. Herein, we successfully achieve the direct synthesis of IWS zeolite with a Si/Ge ratio higher than 4 for the first time. High silica IWS zeolites can be prepared in a wide range of Si/Ge ratios (4-16) by utilizing bulky 1,3-bis(1-adamantyl)-imidazolium (BAdaI+) as an efficient organic structure-directing agent from the concentrated synthesis gel under fluoride conditions. It is proven by a series of characterizations that Ge atoms preferentially occupy the double-four-ring (D4R) units. Theoretical calculations reveal the preferential interactions of guest organic structure-directing agents (OSDAs) and host IWS zeolites with different Si/Ge ratios. The introduction of more Ge atoms cannot improve the host-guest interaction when the BAdaI+ molecule is accommodated within the nanopores of IWS zeolite compared to other OSDAs. The obtained IWS zeolite shows an extremely high specific surface area (905 m2/g) and pore volume (1.31 cm3/g). Due to the low Ge content, IWS zeolite exhibits outstanding hydrothermal stability and experiences high temperature steam heating with no loss of crystallinity and only a slight loss of microporosity.

Selective conversion of spent cracking catalyst to faujasite-structured zeolites

Current recycling strategies for spent catalyst in Fluid Catalytic Cracking (FCC) focus on valuable rare-earth elements (REE) and sometimes include a reuse of spent materials by down-cycling, which hinders a circular economy. Herein, a new procedure for the selective conversion of spent FCC catalysts to FAU-type zeolite without secondary crystalline phases such as sodalite, zeolite P or zeolite A is reported. The steps include a leaching process of REE, followed by thermal activation with sodium hydroxide and acid treatment to get an aluminum-rich feed. The synthesis of FAU-type zeolites with varying Si/Al ratios uses the aluminum-rich catalyst feed and commercial water glass. The experiments show that incorporation of silicate from water glass into the zeolite structure is limited to zeolite products with Si/Al ratio ≤ 2.0. It indicates a flocculation of silicates in higher concentration in competition to the crystallization process of FAU-type zeolites. This is reinforced by the resulting crystals, covered and surrounded with small particles with morphology of silica. Moreover, a clear differentiation between zeolite Y and zeolite X is possible from materials properties with the definite evidence of a mixed phase. The kinetics of feed dissolution and incorporation of impurities, alumina and silica are controlled by the pre-treatment temperature, duration and silicon source. This enables flexible adjustment of the aluminum re-use from spent FCC catalyst, the amount of foreign elements (Fe, Ni, V), phase purity, Si/Al ratio, specific surface area and thermal stability of the final zeolite product. Structural and textural data of the resulting zeolites reveals high crystallinity > 80 %, Si/Al ratios of 1.6–2.0, and specific surface areas up to 780 m2/g.

Organic template-free synthesis of CHA zeolite by hydrothermal conversion of magadiite with the assistance of seeds and an investigation of crystallization mechanism

This study aims to explore the process of pure CHA zeolite production by a hydrothermal magadiite transformation method, with the chemical formulation of 36 NaOH: 40 SiO2: Al2O3: 400H2O, running for 7 h at 80 °C with 12 wt% seeds. Considering various synthesis factors such as NaOH/SiO2, temperature, and seeds dosage etc., XRD, SEM, FT-IR, Solid-state MAS NMR and ESI-MS were applied to investigated to discuss the transformation behavior and mechanism in both solid and liquid phase. The results indicated that the changes of secondary building units had a formation sequence progresses from 6 R s to D6Rs, and oligomers in liquid phases would take part in the formation of CHA framework. In conclusion, the study demonstrates a novel pathway for the highly efficient and green synthesis of CHA zeolite via seed-assisted hydrothermal conversion of magadiite.

Catalytic pyrolysis of polystyrene over rice husk silica-derived traditional and hierarchical green MWW zeolites

This work aimed at the green synthesis of MWW zeolites using rice husk silica as an alternative raw material. It was also performed a post-synthesis desilication procedure with NaOH and CTABr aiming to obtain MWW zeolites with improved accessibility. The set of characterization techniques (XRD, 27Al MAS NMR, N2 physisorption, SEM, TEM, and Pyridine-FTIR) revealed the phase purity and combined structure of micro-mesopores after desilication. The zeolites were evaluated as catalysts for polystyrene pyrolysis, producing benzene, toluene and ethylbenzene, besides styrene monomers, and dimers. Without any catalyst, polystyrene produces only styrene monomers, dimers and trimers. The desilication increases the amount of Brønsted and Lewis sites and the external area, catalyzing the production of polyaromatics and naphthalene derivatives. The activation energy decreased for the catalyzed reactions, reflecting other reaction pathways.

Thermal behavior of synthesized zeolites by hydrothermal treatment

Due to the increase in new production processes that are more efficient and environmentally friendly, the study of zeolites has been encouraged, with applications in areas such as oil refining, construction, wastewater, and gas treatment. In this study, the synthesis of zeolites was carried out by hydrothermal treatment at 100 ºC for 4 and 24 hours, in which two different routes to synthesize NaY zeolite and A zeolite were implemented. Thermal stability was analyzed by differential scanning calorimetry (DSC), defining calcination temperatures of 200, 400, and 600 ºC. Phase formation was characterized by X-ray diffraction (XRD). XRD analysis identified the crystalline phases NaY, P2, A, NaX, sodalite, and ZK-14. Additionally, calcination was able to promote the rearrangement of the structures, increasing crystallinity and promoting the formation of new phases. DSC analysis indicated three regions: one at 200 ºC, representing the loss of water and volatile substances, and two other regions at 400 and 600 ºC, indicating structural collapse due to high temperatures.

Characterization of Natural Zeolite Synthesized by Dealumination and Desilication Method

Delamination and desilication are two methods used in the hierarchical synthesis of zeolites. This process is important for industrial applications, particularly in synthesizing natural zeolites due to their abundance. For instance, Lampung, Indonesia, has abundant natural zeolites. The synthesis process of natural zeolite can be simplified using the solvent swelling mechanism. The swelling solvent mechanism combines the dealumination and desilication methods into one process, making it advantageous to use natural zeolites as raw materials for manufacturing hierarchical zeolites on an industrial scale. The sample used in this study was Natural Zeolite Lampung (NZL), and the resulting product was characterized as NZL Swelling. In this study, only two characterization analyses were selected to test the reliability of the dealumination and desilication methods simultaneously in one process, namely XRD and BET.