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Dry-gel synthesis of Ti-beta for epoxidation of unsaturated fatty acid methyl esters (FAMEs)
Author(s)
Yomthong, Krissanapat
Saenluang, Kachaporn
Soyphet, Asadawut
Ittisanronnachai, Somlak
Padchasri, Jintara
Kidkhunthod, Pinit
Montoya, Alejandro
Wattanakit, Chularat
Date Issued
September 1, 2026
Type
Article
Abstract
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 (TiIV) 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 TiIV [Ti(OSi)4] 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 TiIV [Ti(OSi)3OH] 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.
Citation
Microporous and Mesoporous Materials, 413, 2026