Transformation of zeolite A into hydroxysodalite

Subotić, Boris; Škrtić, Drago; Šmit, Ivan; Sekovanić, Lavoslav

doi:10.1016/0022-0248(80)90099-8

Cited by 120 publications

(60 citation statements)

References 12 publications

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“…Sodalite has been shown to crystallize without the prior formation of NaA in previously published studies. [9,34,35] When NaA www.chemphyschem.org did form prior to sodalite, it was shown that NaA dissolves completely before sodalite is produced. [34,35] The formation of zeolites was also observed using continuous microwave heating and a NaA synthesis composition of 44 SiO 2 : Al 2 O 3 : 5 Na 2 O: 800 H 2 O reacted at 80 8C (Figure 12).…”

Section: Naa Zeolitementioning

confidence: 99%

“…[9,34,35] When NaA www.chemphyschem.org did form prior to sodalite, it was shown that NaA dissolves completely before sodalite is produced. [34,35] The formation of zeolites was also observed using continuous microwave heating and a NaA synthesis composition of 44 SiO 2 : Al 2 O 3 : 5 Na 2 O: 800 H 2 O reacted at 80 8C (Figure 12). No characteristic peaks were observed in the SAXS spectra of the NaA precursor solutions, therefore the primary particles are most likely larger than the 2q range available here.…”

Section: Naa Zeolitementioning

confidence: 99%

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In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

et al. 2007

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A custom waveguide apparatus is constructed to study the microwave synthesis of zeolites by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WR-284 waveguide is used to heat precursor solutions using microwaves at a frequency of 2.45 GHz. The reaction vessels are designed to include sections of thin-walled glass, which permit X-rays to pass through the precursor solutions with minimal attenuation. Slots were machined into the waveguide to provide windows for X-ray energy to enter and scatter from solutions during microwave heating. The synthesis of zeolites with conventional heating is also studied using X-ray scattering in the same reactor. SAXS studies show that the crystallization of beta zeolite and NaY zeolite is preceded by a reorganization of nanosized particles in their precursor solutions or gels. The evolution of these particles during the nucleation and crystallization stages of zeolite formation depends on the properties of the precursor solution. The synthesis of NaA and NaX zeolites and sodalite from a single zeolite precursor is studied by microwave and conventional heating. Microwave heating shifts the selectivity of this synthesis in favor of NaA and NaX over sodalite; conventional heating leads to the formation of sodalite for synthesis from the same precursor. The use of microwave heating also led to a more rapid onset of NaA zeolite product crystallization compared to conventional heating. Pulsed and continuous microwave heating are compared for zeolite synthesis. The resulting rates of formation of the zeolite products, and the relative amounts of the products determined from the WAXS spectra, are similar when either pulsed or continuous microwave heating is applied in the reactor while maintaining the same synthesis temperature. The consequences of these results in terms of zeolite synthesis are discussed.

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Section: Naa Zeolitementioning

confidence: 99%

Section: Naa Zeolitementioning

confidence: 99%

In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

et al. 2007

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“…6) Many researchers have investigated the transformation of zeolite A to sodalite. Subotic et al 16) reported that zeolite A transformed to zeolite P in 1 mol/L NaOH solution and to hydroxysodalite under high concentrations of NaOH. Walton et al 17) reported that higher temperatures and concentrations of NaOH resulted in the transformation of zeolite A to hydroxysodalite in a shorter period of time.…”

Section: Transformation Of Zeolite a To A Stable Phasementioning

confidence: 99%

Alkali Hydrothermal Synthesis of Zeolite A Using Oxide By-products

et al. 2011

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The alkali hydrothermal synthesis of zeolite A using oxide by-products such as blast furnace (BF) slag and aluminum dross was investigated. Na-P1 (Na 6 Al 6 Si 6 O 32 · 12H 2 O) was synthesized directly in NaOH aqueous solution for 86.4 ks at 373 K using BF slag, Al 2 O 3 , and SiO 2 . On the other hand, zeolite A was successfully synthesized by a two-step method including an elution treatment of Al 2 O 3 . Under optimal conditions, the formation ratio of zeolite A in various compounds contained in the product was 56 %. The utilization of dross residue squeezed out from the aluminum dross as a raw material to synthesis of zeolite A let this ratio increase to 60 %. The heat of water adsorption of the product synthesized by the two-step method using BF slag, SiO 2 , and aluminum dross residue was measured, and it was 184 J/g, being higher than that of commercial zeolite A.

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“…[14][15][16] Zones and co-workers also reported serial works on the phase transformation of many zeolites. 17,18 Direct synthesis of Al-SSZ-24 was unsuccessful by a common hydrothermal method and could only be prepared with Al-BEA as the precursor through the phase transition method.…”

Section: Introductionmentioning

confidence: 99%

Phase-Transformation Synthesis of SAPO-34 and a Novel SAPO Molecular Sieve with RHO Framework Type from a SAPO-5 Precursor

Tian

Wang

et al. 2011

Chem. Mater.

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SAPO-34 and a novel SAPO molecular sieve with the RHO framework (designated as DNL-6) were synthesized using SAPO-5 (the denser phase) as the precursor and diethylamine (DEA) as the template. The entire transition process had been investigated by XRD, SEM, XRF, and NMR spectroscopy, which clearly revealed a solution-mediated transport mechanism attributed to the transformation from SAPO-5 precursor to SAPO-34 via oscillating phases [SAPO-5 (FD = 16.9 T/nm 3 ) => SAPO-34 (15.1) þ DNL-6 (14.5) f DNL-6 f SAPO-34]. The initially formed SAPO-34 was different from the final one in this transformation due to very different percentages of organic inclusions, indicating that the host-guest interactions played important roles for the phase selectivity during the synthesis. DNL-6, obtained as an intermediate of the transformation process, possessed good thermal stability, large microporous surface area (724 m 2 /g), and high micropore volume (0.36 cm 3 /g). Rietveld refinement showed that the framework of calcined DNL-6 had typical features of the RHO structure with a high symmetry [I23, a = 15.08429(9) Å], composed of a body-centered cubic arrangement of R cages linked via double 8-rings.

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Transformation of zeolite A into hydroxysodalite

Cited by 120 publications

References 12 publications

In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

Alkali Hydrothermal Synthesis of Zeolite A Using Oxide By-products

Phase-Transformation Synthesis of SAPO-34 and a Novel SAPO Molecular Sieve with RHO Framework Type from a SAPO-5 Precursor

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