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Author: search.filters.author.Thainoi, Suwimon

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    Synergistic effects of bimetallic Co-SnOx species in selective hydrogenation of methyl oleate: The crucial role of reduction characteristics
    (2026-09-01)
    Sooknoi, Tawan
    ;
    Thainoi, Suwimon
    ;
    Chanakha, Vichuda
    ;
    Ausavasukhi, Artit
    This study investigates the catalytic performance of bimetallic Co-Sn catalysts supported on alumina (Al<inf>2</inf>O<inf>3</inf>) for the selective hydrogenation of methyl oleate to oleyl alcohol. A strategic sequential reduction methodology, employing sodium borohydride followed by thermal hydrogen treatment (NaBH<inf>4</inf>-H<inf>2</inf>), was utilized to precisely tune the catalytic activity and chemoselectivity. Catalysts reduced solely with hydrogen at 300 °C exhibited limited efficiency, primarily favoring the formation of oleic acid via hydrogenolysis, which is attributed to the prevalence of cobalt oxide species. In contrast, the CoSnBH/Al<inf>2</inf>O<inf>3</inf> catalyst synthesized via a strategic sequential reduction methodology demonstrated a markedly enhanced selectivity toward oleyl alcohol, achieving a maximum selectivity of 54.1% at 270 °C and 8 MPa. Comprehensive characterization and kinetic analyses revealed that the superior performance stems from the synergistic coexistence of metallic cobalt (Co<sup>0</sup>) and low-valent tin oxides (SnO<inf>x</inf>), which form a bimetallic interface that preferentially polarizes the C=O bond. The catalytic efficiency was found to be highly sensitive to the nature of the support, the Co/Sn atomic ratio, and the total metal loading. Notably, turnover frequency (TOF) analysis indicated that while increased loading improves conversion, it may lead to site agglomeration and a reduction in surface-active concentration. Mechanistically, we propose that the CoSnBH/Al<inf>2</inf>O<inf>3</inf> system facilitates a direct hydrogenation pathway to oleyl alcohol, effectively bypassing the formation of heavy ester intermediates typically reported in literature.
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    Water-tolerant cerium-modified zeolite catalyst for glycerol etherification
    (2026-02-01)
    Ausavasukhi, Artit
    ;
    Thainoi, Suwimon
    ;
    Krukrathok, Nattanitcha
    ;
    Sooknoi, Tawan
    The transformation of glycerol into alkyl ethers, which are utilized as oxygenated fuel additives, is the main topic of this study. Zeolite and cerium-modified zeolite catalysts were prepared and characterized, then evaluated for their efficacy in the etherification of glycerol with tertiary butanol. In comparison to the parent HBeta catalyst, the cerium-modified HBeta catalyst (CeHBeta), which was prepared by impregnation, demonstrated high catalytic performance in glycerol etherification, particularly at lower reaction temperatures. The cerium species can be present as charge-balancing cations and inserted into the framework. CeHBeta is therefore hydrophobic, unlike the parent catalyst. The CeHBeta catalyst may become more active if the water molecules preferentially occupying the Brønsted acid sites are reduced. While Brønsted acid sites are indispensable for the reaction, a synergistic effect with surface hydrophobicity significantly enhances catalytic performance, with CeHBeta exhibiting superior activity. Furthermore, the experiments show that a higher reaction time, molar ratio of glycerol to alcohol, reaction temperature and amount of catalyst lead to a higher selectivity for di-alkyl ether and a higher glycerol conversion.
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