Synthesis and characterization of mordenite-type zeolites via hydrothermal method using silica gel and sodium aluminate as Si and Al sources at varying temperature (original) (raw)
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Synthesis and morphological studies of nanocrystalline MOR type zeolite material
Journal of Colloid and Interface Science, 2008
A number of nanosize mordenite (MOR) analogues with particle size ranging from 5 to 50 nm were synthesized by the hydrothermal method. The effect of various growth parameters like: alkalinity of the medium, type of silica source, etc. on crystal morphology and the crystal size of MOR type of zeolites was investigated. Specific surface and micropore volume were investigated by the Brunauer-Emmett-Teller (BET) method. XRD, SEM, TEM studies indicate nanosize growth of the MOR type crystals. Electron diffraction patterns confirm the crystalline nature of the nanoparticles and the results of their indexing prove that the material is MOR. These synthesized materials show microporous as well mesoporous character. In the case of MOR material synthesized using sodium silicate, it was found that an increase in the alkalinity of the medium led to changes in the morphology and crystal size of the material. For low concentrations of NaOH, the crystallites were spherical in shape whereas at high concentrations, they were in the shape of nanorods of diameter 25 to 50 nm. The morphology of the MOR material synthesized using tetraethyl orthosilicate (TEOS), on the other hand, did not change when the NaOH concentration was increased beyond 2.0 molar. (P. Sharma). and morphology of zeolite L. Their investigation provides a detailed picture of the effects and interdependence of different variables influencing zeolite crystallization.
Synthesis of Mesoporous Mordenite Zeolite by Different Natural Raw Materials
Mordenite (Si/Al = 12.26) was hydrothermally synthesized from locally available low-cost materials using (Sunflower husk, Seed husk, Popcorn waste and chert rock) as a source of extracted Silica (SiO2) without the addition of a templating agent, seed powder, structure-directing agent, and additives. Chert rock is the best-extracted silica source that can be used in synthesizing mesoporous Mordenite Zeolite by this method, since (Sunflower husk, Seed husk and Popcorn waste) were not obtained a significant amount of silica. The starting material in the reaction temperature 25 ± 2 ° C for 72 h. The synthesized zeolites were characterized by Fourier Transform Infrared (FTIR) spectroscopy. The results obtained using X-ray diffraction (XRD) show moderate average crystal size of 26.65nm and confirm the formation of mordenite zeolite. X-ray Fluorescence (XRF) used to determine the Si/Al ratio and the result also confirmed the formation of mordenite zeolite. Field Emission Scanning Electron Microscopy (FE-SEM) was exploited to find out the morphology of the zeolite product and the result displayed a mixture of multi-faced spherules crystal with an ice hockey shape with different particle diameter along with round amorphous particles. The average pore size, pore volume and surface area were determined by Brunauer-Emmett and Teller (BET) method with values of 26.30 nm, 0.28 mL.g-1 and 254.38m 2 .g-1 respectively. Finally, Transmission Electron Microscopy (TEM) was used to find the average crystal size and shape of zeolite, showing 37.82 nm of its average crystal size. The results verified that mordenite zeolites obtained from the hydrothermal condition, present a good zeolitic property and then can be suitable for using in adsorption ion exchange and catalysis experiments. The properties of zeolite materials formed are strongly depended upon the composition and the type of raw materials used.
Hydrothermal Synthesis of Mordenite Type Zeolite
International Journal of Computational and Experimental Science and Engineering
Zeolite is a crystalline alumino-silicate microporous material, which has been widely used as ion-exchangers, adsorbent and catalyst. Recently, several researches highlights the progress of zeolite-based catalysts in the CO2 conversion to valuable products. In the present work, hydrothermal synthesis of mordenite zeolite crystals, with composition of the chemical products Al2O3, 12.5 SiO2,2.4 NaOH, 110 H2O at 160°C for 96 hours (4 days) at Ph 11 is described. Results of characterization of the mordenite zeolite by XRD, FTIR, EDAX, SEM, TGA, are presented and discussed. In the present work, hydrothermal synthesis and characterization of mordenite zeolite crystals is described.
2001
High-energy ball milling of zeolites A, X and synthetic mordenite for an appropriate time results in the formation of true amorphous aluminosilicate phases having the same chemical composition as the starting (unmilled) crystalline materials (zeolites). Since the solubility of thus prepared amorphous solids in hot alkaline solutions is considerably higher than the solubility of the starting zeolites under the same conditions, it can be expected that hydrothermal treatment of the amorphous solids would result in their transformation to more stable phases by solution-mediated processes. To evaluate this thesis, the X-ray amorphous solid phases obtained by high-energy ball milling of zeolites A, X and synthetic mordenite were hydrothermally treated at 80 degreesC by 2 M and 4 M NaOH solution, respectively, for 4 h. The products obtained (zeolites A, P and hydroxysodalite) were characterized by X-ray powder diffraction and particle size distribution measurements. It was concluded that t...
Ultrasonic Pretreatment as a Tool for the Preparation of Low-Defect Zeolite Mordenite
ACS Omega
The effects of the ultrasonic (US) pretreatment of synthesis gel for the preparation of mordenite zeolite were studied in comparison with the classical stirring method. Even though the US pretreatment was performed before the hydrothermal crystallization, it significantly affected the properties of the obtained mordenite crystals. The US-assisted procedure resulted in a material with improved textural characteristics, in particular, the micropore volume accessible for nitrogen molecules in the as-made form. On the other hand, mordenite prepared with the classical stirring method demonstrated comparable sorption properties only after a postsynthetic treatment. Moreover, in the case of US-pretreated mordenite, altered crystal shape and more homogeneous morphology were observed. 29 Si magic-angle spinning nuclear magnetic resonance (MAS NMR) demonstrated that the US pretreatment introduced structural changes on the atomic level, resulting in fewer defects (reflected in the number of silanol groups) and less pore blockage (affected by Na + cations) for the as-made sample.
Chemical Papers, 2020
Mordenite zeolite is considered a molecular sieve because of its adsorbent material characteristics used in the industry as a gas separator. High Si/Al ratios of this zeolitic material in its crystal lattice provide high thermal stability in the structure. To minimize the production costs, this work synthesized the mordenite zeolite in absence organic template (high costs of production). For this purpose, rice husk ash (silicon source) was used from a thermoelectric plant that uses biomass for power generation under the "Moving Grade Reactor" method and metakaolin (aluminium source) derived from the construction. To obtain the zeolitic material, an alkaline treatment with sodium hydroxide and deionized water was required. Different Si/ Al ratios (5, 10, 15, and 20) were used to evaluate the highest efficiency in adsorption capacity. The textural properties of mordenite as a function of specific surface area ranged from 314 to 347 m 2 /g, with micropore volume 0.198-0.279 cm 3 /g with average pore diameter ranging from 5.9 to 6.2 Å. N 2 adsorption/desorption isotherms obtained for mordenite presented type IV hysteresis, characteristic of microporous materials. X-ray diffraction showed crystalline phases of mordenite zeolite, mostly. The FTIR reinforces the success of mordenite synthesis by the vibration bands corresponding to the zeolitic material. TGA revealed water desorption and absence of an organic director. The mean cation-exchange capacity values ranged from 1.10 to 1.78 meq/g indicating a 62% increase of 20-mordenite zeolite compared to 5-mordenite in the zeolitization process. This result is satisfactory and promising for the use of mordenite as adsorbent material.
Microporous and Mesoporous Materials, 2007
The amorphous aluminosilicates formed at the beginning of the hydrothermal synthesis of mordenite present a zeolite-like microporosity. The disorder of the aluminosilicate framework is witnessed by the absence of structural bands in IR spectra, the width of the 29 Si MAS-NMR signals and the broad X-ray diffraction patterns. The microporosity of the hydrothermal gels can be easily overlooked as it completely collapses under evaporative drying. Aerogels formed by CO 2 supercritical drying retains the structure of the parent gel and allows the microporosity to be detected and characterised.
Croatica Chemica Acta, 2002
Thermal treatment of (NH4, Na)-exchanged zeolites 4A and 13X results in the formation of an amorphous phase (T < 1000 degreesC) and a crystalline phase of mullite at temperatures above 1000 degreesC. No structural changes have been noticed for the (NH4, Na)-exchanged synthetic mordenite treated under the same conditions. Scanning electron microscopy (SEM), X-ray powder diffraction, Fourier transform infrared (FT-IR) spectroscopy and particle size analysis were used to characterize the initial materials and the obtained products.
Microwave-assisted hydrothermal synthesis of mordenite zeolite: Optimization of synthesis parameters
Microporous and Mesoporous Materials, 2016
Sustainable industrial processes demand rapid and cost-effective synthesis procedures of zeolites. Herein, we report the synthesis zone of pure mordenite (MOR) zeolite under microwave irradiations. Phase purity, crystallinity, and morphology were carefully studied through optimization of synthesis parameters such as crystallization time, aging time and Si/Al ratio. Without the seeds, the organicstructure directing agent (OSDA)-free synthesis of pure MOR crystals was achieved in the shortest time of 12 h. Moreover, the addition of two different OSDAs, namely o-phenylenediamine (OPDA) and tetramethylammonium hydroxide (TEAOH), decreases the crystallization time up to 6 h with the same gel composition. Whereas, minimum crystallization time through conventional heating was 24 h with an OSDA and 48 h without the template. Rectangular and spherical shaped crystals with low aspect ratio were formed under this condition. The same optimized condition was used with different gel compositions (i.e. Si/Al of 15, 25, 50) to crystallize pure MOR. Also, effect of alkalinity was investigated at different Si/Al ratios.