Template free crystallization of zeolite Rho via Hydrothermal synthesis: Effects of synthesis time, synthesis temperature, water content and alkalinity

Mousavi, Seyed Foad; Jafari, Mostafa; Kazemimoghadam, Mansoor; Mohammadi, Toraj

doi:10.1016/j.ceramint.2013.02.058

Cited by 42 publications

(30 citation statements)

References 46 publications

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“…Zeolites are crystalline aluminosilicate materials formed by the sharing of oxygen atoms in the aluminum and silicate tetrahedral framework [1,2]. Zeolites possess regular, microscopic interconnected pores and windows that can selectively adsorb molecules like sieves [3,4]. Among zeolites, 4A zeolite, Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ]•27H 2 O, possesses an α-cavity with a 0.41 nm diameter comprised of eight β-cages linked by 12 4-rings, which create its adsorption, screening, and ion exchange performance [5,6].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

2018

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As a solid waste, kaolinite-type pyrite flotation tailings (KPFT) are a type of low-quality kaolin that contain impurities, such as iron and titanium. In this study, KPFT were calcined at 800 °C for two hours. The calcined production (CKPFT), which is mainly metakaolin, was used as the silicon and aluminum source to synthesize 4A zeolite (Na12[(AlO2)12(SiO2)12]·27H2O) via hydrothermal synthesis. The optimal hydrothermal synthesis conditions were determined from X-ray diffraction phase analysis, relative crystallinity (RC), and cation ion exchange capacity (CEC). The optimal hydrothermal synthesis conditions were determined to be a ratio of 5 g CKPFT, 6.5 g NaOH, 65 mL H2O, crystallization temperature 110 °C, and crystallization time of three hours. Under the optimal hydrothermal synthesis conditions, the RC and CEC of the synthesized 4A zeolite were 40.77% and 210.32 mg CaCO3·g−1, respectively. Further characterizations including pore size distribution, scanning electron microscopy, energy dispersive X-ray, thermogravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy were performed. The results revealed that impurities in KPFT do not affect the synthesis of 4A zeolite. The surface morphology of the synthesized 4A zeolite was composed of chamfered-edged cubes with a particle size of one to three μm that was thermally stable up to approximately 890 °C.

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Section: Introductionmentioning

confidence: 99%

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

2018

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“…It is commonly seen that the presence of larger structure breaking cations retards the crystallisation process. [11][12][13][14][15][16][17] Zeolite RHO is a synthetic zeolite. However, work by Burkett et al, showed that alongside sodium, addition of larger secondary cations favoured the formation of different zeolite frameworks such as CHA and OFF, rather than impeding crystallisation as a process altogether.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16][17] The exact mechanism by which the cation promotes the formation of the framework has not been directly explained, however it is believed that it is the cation's size which directs the formation of a more open structure. [11][12][13][14][15][16][17] The exact mechanism by which the cation promotes the formation of the framework has not been directly explained, however it is believed that it is the cation's size which directs the formation of a more open structure.…”

Section: Introductionmentioning

confidence: 99%

Influence of alkali metal cations on the formation of zeolites under hydrothermal conditions with no organic structure directing agents

Nearchou

Sartbaeva

2015

CrystEngComm

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Alkali metal cations play an important role in directing formation of zeolite frameworks in the absence of organic structure directing agents. The interplay between Na and Cs cations in directing formation of zeolite RHO is the main focus of this study. Depending on the ratio of Na and Cs in the precursor gel, with no organic structure directing agents, several different zeolites form during synthesis. This indicates that pure zeolite RHO can only be obtained at a very specific Cs to Na ratio. More generally, this may shed light on the bigger question of how zeolite pores form in the absence of organic structure directing agents. Fig. 1 Zeolite RHO, Si and Al tetrahedral units are represented by blue and light blue tetrahedra, Cs atoms are in pink and Na atoms are yellow. LTA and D8R secondary building units are labelled. In this representation, there are 8 LTA cages in each corner and one in the middle, and 8 D8R units connecting the corner LTA units.

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“…Dodecahedron-shape crystals with 0.8 µm (size were formed after the synthesis as shown in Fig. 2 (a)), which is a typical morphology of Rho zeolite prepared from an OSDA-free synthesis reported in literatures 10,15) .…”

Section: Characterizationmentioning

confidence: 98%

“…1 Al2O3 : 3 Na2O : 0.4 Cs2O : 110 H2O 10) . At first, sodium hydroxide (Wako Pure Chemical Industries, Ltd) was added to deionized water and the mixture was stirred for about 10 minutes to dissolve chemicals completely.…”

Section: Synthesis Of Rho Zeolite Seedsmentioning

confidence: 99%

【Original Contribution】 Preparation of Rho Zeolite Membranes on Tubular Supports

et al. 2016

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Zeolite membranes have been investigated in various applications, including gas separations, such as CO 2 /CH 4 and hydrogen recovery, and liquid separations such as dehydration. MFI type zeolite is the most studied type of zeolite membranes for gas separations, while various other types, such as A(LTA) 1) , Y (FAU) 2) , MFI 3) , T 4) , DDR 5) and CHA 6, 7) membranes have also been reported for their unique CO 2 -selective permeations.Rho zeolite is an aluminosilicate zeolite firstly reported by H.E Robson et al. 8) . Rho zeolite is consisted of -cages connected with double eight-rings (D8Rs) 9) . Rho zeolite has a small pores (0.36 0.36 nm), a relative low Si/Al ratio (2.5 5) and a very high pore volume (0.26 cm 3 g -1 , the pore volumes of 0.36 cm 3 g -1 if cation size is negligible) 10 12) .A remarkably high CO 2 /CH 4 adsorption selectivity of Rho zeolite, 75.2 at approx. 100 kP and at ambient temperature, is reported 13) , which is originated from the smaller zeolitic pore size than the size of CH4 molecule (0.38 nm), strong affinity to CO2 and the high pore Rho zeolite crystals of 0.8 µm and Rho zeolite membranes were hydrothermally synthesized without using organic structure-directing agents (OSDAs). Rho zeolite membranes with thickness of 1 2 µm were formed on the outer surface of porous -Al 2 O 3 tubes via secondary growth method. Membrane showed CO 2 /CH 4 and CO 2 /N 2 ideal selectivities of ca. 6.8 and 2.8, respectively, which are smaller than the reported adsorption selectivities. Rho zeolite membranes showed dehydration performance when water/ethanol and water/isopropanol mixtures were applied.The highest separation factor obtained for water/isopropanol was 1390 with a total flux of 0.77 kg m -2 h -1 when 95wt%isopropanol feed was applied at 348K.

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Template free crystallization of zeolite Rho via Hydrothermal synthesis: Effects of synthesis time, synthesis temperature, water content and alkalinity

Cited by 42 publications

References 46 publications

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

Influence of alkali metal cations on the formation of zeolites under hydrothermal conditions with no organic structure directing agents

【Original Contribution】 Preparation of Rho Zeolite Membranes on Tubular Supports

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