Key parameters in hydrothermal synthesis and characterization of low silicon content SAPO-34 molecular sieve

Izadbakhsh, Ali; Farhadi, Fatola; Khorasheh, Farhad; Sahebdelfar, Saeed; Asadi, Mousa; Zhang, Yan

doi:10.1016/j.micromeso.2008.12.009

Cited by 65 publications

(21 citation statements)

References 25 publications

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“…As shown in Table 1, the syntheses carried out without silicon in the gel only rendered amorphous solids when the hydrothermal treatment was prolonged up to 5 days using the lowest amount of SDA (y = 1). However, when the amount of TEAOH in the synthesis gel was increased up to y = 1.5, materials having pure chabazite phase were obtained for crystallization times from 1 up to 13 days [35]. XRD patterns of these samples are presented in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

Effect of silicon content on the catalytic behavior of chabazite type silicoaluminophosphate in the transformation of methanol to short chain olefins

2013

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AlPO-34 and SAPO-34 molecular sieves with different silicon content have been synthesized using a hydrothermal system in presence of tetraethylammonium hydroxide (TEAOH) and evaluated as catalysts for the transformation of methanol to short chain olefins. The results showed that SAPO-34 materials prepared with medium-high silicon concentration in the framework present quite similar silicon environment distributions 2 and, when it is so, the key factor to obtain materials with improved catalytic performance is the crystallite size.

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Section: Resultsmentioning

confidence: 99%

Effect of silicon content on the catalytic behavior of chabazite type silicoaluminophosphate in the transformation of methanol to short chain olefins

2013

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“…It has been recognized that the Si amount in SAPO-34 is the unique factor for controlling the catalyst acidity, relatively important for improving the catalyst lifetime and the selectivity of light olefins in the MTO reaction, for which SAPO-34 with a low Si content is required [17,18]. However, our previous results showed that the crystallization yield of SAPO-34 dropped with decreasing Si content in the synthesis gel, especially in the range of low Si content.…”

Section: Introductionmentioning

confidence: 80%

An effective route to improve the catalytic performance of SAPO-34 in the methanol-to-olefin reaction

Liu¹,

Tian²,

Xia³

et al. 2012

Journal of Natural Gas Chemistry

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“…Accordingly, many efforts have been focused on improving its catalytic performance by various physicochemical modifications 10–12. The adjustment of acidity as well as shape selectivity are two key properties to modify the reactive performance of such acidic crystalline material 13. Although the catalytic process and the role of the catalyst in the process are fairly well studied, several parameters remain to be evaluated in detail.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and catalytic performance of SAPO‐34 molecular sieves for methanol‐to‐olefin (MTO) reaction

Wang

et al. 2011

Asia-Pacific J Chem Eng

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The methanol-to-olefin (MTO) process is important because it offers an alternative to the conventional oil route for the conversion of natural gas or coal to light olefins. The most promising catalysts for the MTO reaction are solid acids with a zeolite structure, where reactants and products such as ethylene and propylene may freely diffuse through active catalysts, but products with larger kinetic diameters are trapped within the cages. In this work, SAPO-34 molecular sieves were synthesized by hydrothermal crystallization, using triethylamine (TEA) as the template. These samples were characterized by X-ray diffraction, scanning electron microscopy, thermo-gravimetric analysis-differential scanning calorimetry, energy dispersive spectroscopy, Fourier transform-infrared (FT-IR) and N 2 adsorption-desorption. The effects of template concentration and crystallization time on the physicochemical properties and catalytic performance were investigated. The crystallinity and morphology of SAPO-34 were influenced by the concentration of the template. Pure SAPO-34 was obtained when the TEA/Al 2 O 3 molar ratio was higher than 2.0. With increased crystallization time, the Si content in SAPO-34 crystals increased, which influenced the surface acidity. FT-IR spectra indicated that all samples were dominated by Lewis acid sites and the sample crystallized for 11 h exhibited the lowest number of Lewis acid sites. The catalytic performance of SAPO-34 was tested with the MTO reaction. High selectivity to olefins (C 2 H 4 + C 3 H 6 ) was obtained over the catalyst synthesized with a TEA/Al 2 O 3 ratio of 3.0 and crystallization time of 11 h. At the reaction temperature of 450• C, the methanol conversion approached 100% and the yield of C 2 -C 4 olefins was more than 80%. Hence, SAPO-34 molecular sieves were shown to be excellent catalysts for the MTO reaction. 

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Key parameters in hydrothermal synthesis and characterization of low silicon content SAPO-34 molecular sieve

Cited by 65 publications

References 25 publications

Effect of silicon content on the catalytic behavior of chabazite type silicoaluminophosphate in the transformation of methanol to short chain olefins

Effect of silicon content on the catalytic behavior of chabazite type silicoaluminophosphate in the transformation of methanol to short chain olefins

An effective route to improve the catalytic performance of SAPO-34 in the methanol-to-olefin reaction

Synthesis, characterization and catalytic performance of SAPO‐34 molecular sieves for methanol‐to‐olefin (MTO) reaction

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