Synthesis of lta type zeolites from georgian clinoptilolite (original) (raw)
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Journal of Colloid and Interface Science, 2012
Slow crystallization and growth rate at room temperature in the presence of surfactant micelles is a new strategy used to synthesize hierarchical Na-A zeolites. The observed structure of the hierarchical materials was consistent with a two stage growth mechanism. During the early stage of the gel evolution, miniature zeolite gel particles were formed and assembled around surfactant (cetyltrimethylammonium bromide -CTAB) micelles. In a second stage, the slow mass transformation into crystalline phase and the low growth rate of the formed crystallites retained the CTAB micelles within the crystallization domain. After the removal of CTAB templates, the products showed large mesopores which were attributed to the interstitial voids between the aggregated zeolite nanocrystallites. The size of the mesopores can be further expanded by using linear hydrocarbons as swelling agents. The influences of the added amount of the hydrocarbons and the length of the hydrocarbon chains on the mesopore size were examined. The effects of the aging period and CTAB concentration in the synthesis mixture on the pore size distribution were also investigated. The colloidal suspension of the synthesized zeolite showed negative zeta potential throughout the entire range of pH. The mesoporous Na-A zeolite synthesized in this work showed higher ethylene adsorption capacity as compared to the conventional microporous Na-A zeolite. XRD, DLS, SEM, N 2 adsorption-desorption at 77 K, TEM, 29 Si NMR and FTIR techniques were used to characterize the hierarchical Na-A zeolite.
Morphology-Controlled Synthesis of Zeolite and Physicochemical Properties
Engineering Journal, 2012
Zeolite L is a crystalline aluminosilicate compound and a typical chemical composition of K9Al9Si27O72•nH2O (n = 0-36). The structure and chemical properties, as well as their sizes and morphologies of zeolite L has led to various applications in different fields. The aim of this study is to investigate the effects of chemical compositions of the starting gel on the synthesis, size and morphology of zeolite L crystals. Zeolite L had been synthesized hydrothermally at 180 ˚C for 2 days, from gels with the molar compositions of 2.62-3.78 K2O: 0.8-1.4 Al2O3: 8-12 SiO2: 80-200 H2O. The variation of chemical compositions led to the differences in morphologies and crystal sizes. Their morphologies varied from ice hockey to cylindrical shapes and their crystal sizes varying from 1.50-7.53 µm. With an increase in H2O and SiO2, the crystal size was also increased but decreased with an increase in K2O. In varying Al2O3, there was no effect on their shapes which were still cylindrical but with different crystal sizes. Moreover, the adsorption of ethylene on zeolite L samples depended significantly on crystal shapes and sizes.
1985
The synthesis, crystallization and structure o f heteroatom containing ZSM-5 type zeolite (M-ZSM-5) (Xu Ruren and Pang Wenqin (Plenary lecture) 27 Synthesis of ZSM-5 type zeolites i n the system (Na, K) 2 0-A1 2 0 3-Si0 2-H 2 0 without and with ΤPA Br (A. Nastro, C. Colella and R. Aiello) 39 Crystallization of ZSM-5 type zeolites from reaction mixtures free o f organic cations (Ü.M. Berak and R. Mostowicz) 47 Nature and structure o f high silica zeolites synthesized i n presence of (poly) alkyl mono-and diamines (Z. Gabelica, M. Cavez-Bierman, P. Bodart, A. Gourgue, and J.B. Nagy) 55 Factors influencing the crystal morphology o f ZSM-5 type zeolites (R. Mostowicz and J.M. Berak) 65 The influence of alkali metal cations on the formation o f silicalite in NH^OH-TBAOH systems (Tu Kungang and Xu Ruren) 73 Template variation i n the synthesis o f zeolite ZSM-5 (F.J. van der Gaag, J.C. Jansen and H.van Bekkum) 81 The synthesis o f high silica zeolites i n the absence of sodium ion
A Short Review on Synthesis, Characterization, and Applications of Zeolites
Advances in Materials Science and Engineering
The review emphasizes on synthesis, characterization, and application of zeolite. Zeolite is a hydrated aluminosilicate having a tetrahedral structural framework; it contains channels and cages which are occupied by exchangeable active metal ions and water molecules. Zeolite was synthesized through different synthesis methods, particularly, hydrothermal and green synthesis methods. The review also has tried to address the structure of zeolite such as morphology, functional group, and particle size using different characterization methods as reported via different authors. The characterization results verify that zeolite shows many unique properties such as uniform pore size, acidic properties, thermal stability, mobile extra cation, hydrophilicity, and hydrophobicity. These lead to a number of applications in catalysis, water purification, adsorption, and agriculture.
Powder Technology, 2011
Hydrothermal synthesis of zeolite T in aqueous alkaline solutions without using templates was investigated. Zeolite T crystals were prepared via hydrothermal synthesis using milk-like aluminosilicate gel with a composition of aSiO 2 :bAl 2 O 3 :cNa 2 O:dK 2 O:xH 2 O. The effects of molar compositions including silicon module (n RM = a/b) and relative alkalinity (α = OH/SiO 2), and crystallization conditions including crystallization temperature (T) and time (t) on the yield of T-type crystals were investigated. This research work examines changes in the yield of crystalline zeolite phases by varying the gel composition parameters (n RM =20-25, and α = 0.71-0.82) and crystallization process temperature and time (T = 100°−140°C, t = 120-216 h), while keeping constant the parameters [OH] = 2.77 m, U RM (Na/Na + K) = 0.75, stirring time = 24 h , stirring temperature = 30°C, and drying temperature = 100°C. The crystal species of zeolite T were characterized by XRD (X-ray diffraction) and SEM (Scanning Electron Microscope).
Hydrothermal Synthesis of Nanocrystalline Zeolite using Clear Solution
Sriwijaya International Seminar on Energy Environmental Science and Technology, 2014
Nano size particles such as nanocrystalline zeolites have unique properties relative to conventional micrometer sized zeolite crystals. The reduction of particle size to the nanometer scale leads to substantial changes in properties of zeolite which make them as promising materials for many applications. Nanocrystalline zeolite A, silicate successfully synthesiszed at temperature of of 1.46, 3.06, 4.59 and 6.79 are effective Si/Al ratio to synthesis LTA zeolite. Further, high Si/Al ratio of 30, 40 and 60 were used for ZSM-5 synthesis. The product could be obtai (aluminum free) could be obtained at 5 time, Si/Al ratio and organic template. Moreover found to influence the particle size. TEOS makes the zeolite particle smaller than Ludox LS. Two stage synthesis conducted on silicate-1 crystallization could decrease time and increase yield. However it is found that t particle size was slightly higher than that in one Key words: Nanocrystalline zeolite, clear solution, organic template, one 1. INTRODUCTION Nanozeolites are crystalline aluminosilicates with molecular dimension in the range of 10 particle size (Mintova, 2003). Nanozeoilites have higher external surface area and reduced diffusion path lengths due to smaller particle size. The red particle size to the nanometer scale leads to substantial changes in properties of zeolite which make them as promising materials for many applications. Zeolite nanocrystals are usually synthesized under hyhrothermal condition using clear alumin solution, usually in the presence of organic compounds as templates such as tetramethylammonium (TMA) and tetrapropylammonium (TPA) (Zhan, et al. 2001). Further, Cundy and Cox (2004) reported aluminosilicate zeolites synthesized under hydrothermal condition from reactive gels in alkaline media at temperature of about 80 0 C and 200 most high Si/Al ratio of zeolites (>10) are synthesized using organic templates, which have to be removed from the zeolites structure by calcinations. Mintova (2003) reported the synthesis of nano size zeolites including nanozeolite A (LTA), nanozeolite Y (FAU), nanozeolite silicate-1 (MFI) and nanozeolite beta (BEA) at temperatures lower than 100 0 C with synthesis time up to 400 hours. The successful synthesis of nanozeolite A was also reported by Rakoczy and Traa
LTA and FAU zeolites were successfully synthesized from a Venezuelan sodium silicate solution, by hydrothermal crystallization under autogenous pressure at 100 °C, with 2 – 24 h crystallization times. The synthesized materials were characterized by XRD, BET specific surface area and SEM. A series of synthesis tests were performed to study the influence of the molar composition of the starting mixture over zeolites crystallization. The effect of crystallization time for a particular synthesis mixture composition was studied for both zeolites types. The reuse as alkaline medium of the mother liquor separated during filtration, and the effect of the aging before crystallization were additionally studied. The experimental results are in agreement with the crystallization mechanism proposed for zeolites synthesis in liquid phase. The use of a 2SiO 2 :Al 2 O 3 :6.Na 2 O:240H 2 O synthesis mixture composition allows obtaining LTA zeolite within 2 h of crystallization. For FAU zeolite, no aging period was needed when starting with a 4SiO 2 :Al 2 O 3 :6.6Na 2 O:264H 2 O composition. It was possible to synthesize both zeolites with high purity and crystallinity and with adequate water adsorption properties.
Nanocrystalline Zeolite Y: Synthesis and Characterization
IOP Conference Series: Materials Science and Engineering, 2011
Preparation of zeolite from incinerator ash and its application for the remediation of selected inorganic pollutants: A greener approach J Iqra, M Faryal, R Uzaira et al. APPLICATION OF SYNTHETIC ZEOLITES(MOLECULAR SIEVES) TO CATALYSIS Khabib M Minachev, V I Garanin and Ya I Isakov Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction N N Binitha, P P Silija, V Suraj et al.
Synthesis of nano-crystalline zeolite β: Effects of crystallization parameters
Crystal Research and Technology, 2009
The effects of variation in Si/Al ratio (25 and 100) and crystallization temperature (80 °C to 180 °C, at an interval of 20 K) on crystal size of zeolite beta were studied. Products obtained at different synthesis parameters were characterized by powder X-ray diffraction, IR spectroscopy, thermal analysis, scanning electron microscopy and nitrogen adsorption. Increase in crystal size with crystallization temperature and Si/Al molar ratio was observed. Crystal morphology at 140 °C was spherical whereas at 180 °C it was of irregular shape.