Organic-free synthesis of ZSM-5 with narrow crystal size distribution using two-step temperature process

Kim, Shin Dong; Noh, Si Hyun; Park, Jun Woo; Kim, Wha Jung

doi:10.1016/j.micromeso.2006.01.009

Cited by 105 publications

(49 citation statements)

References 12 publications

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“…The significant increase in crystallinity of the produced NaP when the Na 2 O/SiO 2 molar ratio is 1.10 could be discussed in terms of the role of OH − groups in increasing the nucleation rate of NaP zeolite, which properly accounts for the dissolution of the amorphous gel and the formation and release of NaP zeolite heteronuclei at the gel-solution interface. This may lead to an effective acceleration of the crystal growth and shorten the induction period for the crystal growth of NaP zeolite [17][18][19][20]. Moreover, it was found that increasing the Na 2 O/SiO 2 ratio to 1.13 in the synthesis gel resulted in the preservation of the NaP zeolite matrix, whose degree of crystallinity decreased slightly.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Controllable synthesis of NaP zeolite and its application in calcium adsorption

et al. 2015

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functional performance of the different kinds of zeolites, many studies have been devoted to improving synthetic approaches to control crystal size, the size of the intracrystalline pore/channel system and morphology of zeolites [5,6].Among various types of zeolites, NaP (Na 6 [(AlO 2 ) 6 (SiO 2 ) 10 ]⋅15H 2 O) is one of the most interesting structured zeolite with two sets of intersecting channels: 0.31 nm × 0.44 nm and 0.26 nm × 0.49 nm. According to International Zeolite Association (IZA), this structure is called "Gismondine" (GIS) framework topology [7,8]. NaP zeolite offers the greatest promise for gas separation applications due to its small pore size [9,10], and is also useful for removal of toxic and radioactive waste species like Cs, Sr, Ba, Pb, U, heavy metals, and ammonium from wastewater, seawater potassium extraction and formation of environmental friendly detergent [11,12]. NaP zeolite can be synthesized from various precursor materials and various methods. It can be synthesized from: (i) clay at a crystallization temperature of 85ºC [13], (ii) sodium silicate solution [14], and (iii) high silicon fly ash of coal combustion at 120ºC for 4 h [15]. Among them the most common methods used for the synthesis of NaP zeolite are the sol-gel technique, hydrothermal synthesis and microwave heating synthesis [1]. The NaP zeolite with different morphologies can offer many intriguing properties: places to store the guest molecules and to perform chemical reactions with selected-sized molecules. Thus, the NaP zeolite morphology and its important correlation with properties is the need of the recent research.In this work, we attempted the template free hydrothermal synthesis of NaP under controlled conditions. Based on multiple paths that can be involved in the hydrothermal synthesis of NaP, optimization of crystallization conditions was adapted through variation of the following parameters: Na 2 O/SiO 2 and SiO 2 /Al 2 O 3 molar ratios, aging time and aging temperature. The characteristics of the synthesized gels NaP zeolite particles were prepared through a template-free hydrothermal condition at 100ºC. Parameters like Na2O/SiO2 and SiO2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulating the crystallization of the final product. The samples at different synthesis stages were characterized with N2 adsorption at −196ºC, field emission scanning electron microscopy (FE-SEM), temperature programmed desorption of ammonia adsorption, X-ray diffraction, thermogravimetric and differential scanning calorimetry analysis and Fourier transform infrared spectroscopy. The experimental results evidenced that a high ordering crystallinity of NaP zeolite was obtained at Na2O/SiO2 and SiO2/Al2O3 molar ratios of 1.10 and 1.40, respectively, and a temperature of 100°C for 4 days of aging. FE-SEM image exhibited polycrystalline aggregates of NaP zeolite with crystallite sizes ranging up to 5.04 μm with cactus/cabbage like structures. The quantitative analysis of the total number of acid sites...

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Section: Experimental Techniquesmentioning

confidence: 99%

Controllable synthesis of NaP zeolite and its application in calcium adsorption

et al. 2015

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“…13 and 14) indicate that the crystallization process generally takes place by a chain of processes: (i) formation of a small proportion of amorphous aluminosilicate at the very start of the crystallization process [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] (see also Fig. 1), (ii) formation of nuclei in the matrix of the amorphous aluminosilicate [13,[19][20][21][22]25,29,[40][41][42][43][44], (iii) release of nuclei from the matrix of amorphous aluminosilicate dissolved during the early stage of crystallization (autocatalytic nucleation [48,50,53,62,63,65,[70][71][72]), by the dynamics shown in Figs.…”

Section: Article In Pressmentioning

confidence: 99%

“…Hence, for a long time, a general meaning was that crystallization of zeolites from clear (alumino)silicate solutions takes place in a direct way, i.e., by nucleation and growth of zeolite crystals in/from the liquid phase [11,16,17], and thus without the formation of an intermediate amorphous (alumino)silicate. On the other hand, many recent studies of crystallization of different types of zeolites from clear (alumino)silicate solutions demonstrated the presence of (nano-scale) amorphous (alumino)silicate agglomerates formed during the room-temperature ageing [13,[18][19][20][21][22][23][24] or at the early stages of hydrothermal treatment of the synthesis solutions [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Formation and evolution of structurally ordered phase (potential nuclei) in the amorphous solids precipitated from initially clear (alumino)silicate solutions was evidenced by various experimental methods such as electron diffraction [13,40,41], highresolution transmission electron-microscopy [20][21][22]27], infrared spectroscopy [19][20][21][22], optical/electron-microscopy [42], small-angle X-ray scattering [25,29,…”

Section: Introductionmentioning

confidence: 99%

“…Formation and evolution of structurally ordered phase (potential nuclei) in the amorphous solids precipitated from initially clear (alumino)silicate solutions was evidenced by various experimental methods such as electron diffraction [13,40,41], highresolution transmission electron-microscopy [20][21][22]27], infrared spectroscopy [19][20][21][22], optical/electron-microscopy [42], small-angle X-ray scattering [25,29,43,44], wide-angle X-ray scattering [25,29] and small-angle neutron scattering [43]. However, although the formation of (nano-scale) amorphous aluminosilicate agglomerates in the starting clear (alumino)silicate synthesis solutions [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and the formation of nuclei in the gel matrix are intensively researched and well documented in the appropriate publications [13,[19][20][21][22]25,29,[40][41][42]…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of crystallization of zeolite A microcrystals from initially clear aluminosilicate solution: A population balance analysis

Bronić

Mužic

Jelić

et al. 2008

Journal of Crystal Growth

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“…With its adjustable framework Al content (from 0 to about 8Al per unit cell), two dimensional micropore channels (0.55 nm × 0.54 nm; Fig. 1a), sinusoidal pore geometry along c axis (Fig.1b) and easy insertion of hetero-T atoms, this material plays an important role in many of crucial catalytic processes such as hydro-cracking, de-waxing, alkylation, etc., [2][3][4][5] as well as in separation of organic compounds with different sizes and shapes [6]. In the case when zeolite ZSM-5 was used as catalyst, most of reactions are 'diffusioncontrolled' [7].…”

Section: Introductionmentioning

confidence: 99%