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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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    Cleaner Bio-Based Plasticizer Synthesis from Waste Cooking Oil to Substitute Toxic Dioctyl Phthalate in PVC film
    (2025-01-01)
    Chaiyaraksa, Chompoonut
    ;
    Sriprom, Pongsert
    ;
    Boonkaen, Fahana
    ;
    Laemsri, Arthittaya
    ;
    Smingkaew, Arnita
    This research aimed to investigate the possibility of synthesizing a bio-based plasticizer from waste cooking oil using an epoxidation reaction to replace dioctyl phthalate (DOP) in PVC film, which is toxic and hazardous to human health and the environment. This involved synthesizing used household oil through an epoxidation reaction to introduce epoxy groups, followed by isopropyl alcohol to break the epoxy rings and form hydroxyl groups. The chemical structure of the epoxidized waste cooking oil plasticizer was analyzed using Fourier transform infrared spectroscopy (FT-IR), with a focus on confirming the presence of epoxy groups within the 3,500 – 3,000 cm-1 range. Subsequently, this bio-based plasticizer was used in various ratios to DOP to produce PVC films, including ratios of 5:0, 4:1, 3:2, 2:3, 1:4, and 0:5. These PVC films were subject to a comprehensive examination of their physical and chemical properties, including their resistance to tensile stress, elongation ability, the impact on molecular functional groups in the PVC film, and a leaching test. The results showed that the optimal proportion of epoxidized waste cooking oil plasticizer to DOP was 5:0. This ratio demonstrated superior tensile strength, enhanced elongation capacity, increased thermal stability, and exhibited the most robust resistance against solvents compared to other ratios tested.