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Author: search.filters.author.Sooknoi, TawanSubject: search.filters.subject.Zeolite

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    Dry-gel synthesis of Ti-beta for epoxidation of unsaturated fatty acid methyl esters (FAMEs)
    (2026-09-01)
    Yomthong, Krissanapat
    ;
    Saenluang, Kachaporn
    ;
    Soyphet, Asadawut
    ;
    Ittisanronnachai, Somlak
    ;
    Padchasri, Jintara
    The Ti-beta was synthesized via a dry-gel conversion approach with the direct incorporation of titanium from titano-aluminosilicate nanobeads (Ti-SiAl-NB). At first, the Ti-SiAl-NB was prepared and employed as the precursor for zeolite crystallization. Powder XRD (PXRD) patterns confirm the amorphous nature of the nanobeads. These Ti-SiAl-NB precursors were subsequently converted to the Ti-beta zeolite via the dry-gel conversion approach. Structural characterization using PXRD, high-resolution TEM, and selected area electron diffraction (SAED) confirmed the formation of a beta zeolite framework, with dominant lattice planes indexed to (101) and (302). UV-vis DRS indicated that Ti existed as a tetrahedrally coordinated (Ti<sup>IV</sup>) and non-framework Ti. Unfortunately, the as-synthesized Ti-beta exhibited a low catalytic activity in methyl oleate (MO) epoxidation, which is attributed to the prevalence of closed site Ti<sup>IV</sup> [Ti(OSi)<inf>4</inf>] species that restrict substrate accessibility to active sites. To address this limitation, a post-synthetic treatment involving framework etching was applied to generate open site Ti<sup>IV</sup> [Ti(OSi)<inf>3</inf>OH] species. As a result, MO conversion increased by approximately 2.73-fold, with epoxide selectivity up to 70%. Catalyst stability tests demonstrated sustained MO conversion of 65–72% and epoxide selectivity above 65% over several consecutive catalytic cycles. This work highlights a sustainable catalyst design strategy that combines the dry-gel conversion process with mild post-treatment to enhance active site accessibility and catalytic performance in the epoxidation of bulky molecules.
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    Improvement of water vapor permeability of LLDPE/EVA film with zeolite A as filler
    (2017-01-01)
    Rukchonlatee, Suparat
    ;
    Jaisomboon, Nattarika
    ;
    Sooknoi, Tawan
    In this work, water vapor permeability of linear low density polyethylene (LLDPE)/ethylene vinyl acetate copolymer (EVA) film is improved by incorporation of zeolite A as filler (0-25%wt) for prolonging shelf-life of fresh produces. All films were characterized by SEM, DSC, tensile testing, contact angle measurement and tested for water vapor permeability (WVP). The shelf-life of Bird's eye chili in the film samples was also tested at 10°C for 21 days. It was found that zeolite A particles were virtually dispersed in EVA phase. Accordingly, crystallinity and tensile properties of LLDPE/EVA/Zeolite A films is independent to zeolite loading. Despite, when zeolite loading was increased, the dispersion became low. The film's wetting behavior was enhanced by increasing zeolite content in the LLDPE/EVA/Zeolite A films. The observed increase in the film's polarity significantly enhances the WVP. Therefore, less water condensed can be found inside the package made with LL80E20Ze25 film, as compared to LLDPE or LLDPE/EVA film. The LL80E20Ze25 also possesses comparable tensile properties to the commercial LLDPE film and hence can used as packaging for extending the shelf-life of fresh produces.
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    Conversion of 1- and 2-tetralone over HY zeolite
    (2010-04-01)
    Prasomsri, Teerawit
    ;
    Galiasso Tailleur, Roberto E.
    ;
    Alvarez, Walter E.
    ;
    Sooknoi, Tawan
    ;
    Resasco, Daniel E.
    Conversion of 1- and 2-tetralone was investigated over acid HY zeolite under various reaction conditions in the vapor phase. Reactions were conducted in a fixed-bed reactor at 300, 400 and 500 °C in hydrogen atmospheric pressure. It was found that 1- and 2-tetralone are thermally unstable and thermal reaction has a contribution, particularly at high temperatures. The reactivity of 2-tetralone was significantly higher than that of 1-tetralone. This behavior is more pronounced in the presence of acid HY zeolite. For both isomers, the main products were naphthol, coupling compounds (4-ring), naphthalene and tetralin. Trace amounts of dihydronaphthalene, ring-contraction and ring-opening product were also observed. At high temperatures, isomerization and dehydration of naphthol were observed over the HY zeolite. It seems that on the acidic zeolite, hydrogen transfer plays a significant role in determining the reaction path. © 2010 Springer Science+Business Media, LLC.