Numwong, Natthida

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Numwong, Natthida
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natthida.nu@kmitl.ac.th

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    Item type:Publication,
    Effect of Pd particle size on activity and cis-trans selectivity in partial hydrogenation of soybean oil-derived FAMEs over Pd/SiO2 catalysts
    (2020-06-15)
    Numwong, Natthida
    ;
    Prabnasak, Panisa
    ;
    Prayoonpunratn, Patsakol
    ;
    Triphatthanaphong, Pholawat
    ;
    Thunyaratchatanon, Chachchaya
    Partial hydrogenation of soybean oil-derived fatty acid methyl esters (FAMEs) was performed to improve oxidative stability of biodiesel. The reaction was tested in a semi-batch reactor at 100 °C, 0.4 MPa. The effect of Pd particle size on activity and cis-trans selectivity was investigated over SiO<inf>2</inf>- and MCM-41-supported Pd catalysts, with different Pd loadings (0.5 and 1 wt.%). For Pd/SiO<inf>2</inf> catalysts with relatively large Pd particle sizes (6.1–7.8 nm), the adsorption of polyunsaturated C18:2 and C18:3 FAMEs was promoted on the flat metal surface, providing 2- to 3-fold higher turnover frequency (TOF) compared with Pd/MCM-41 catalysts. In contrast, the Pd/MCM-41 catalysts with relatively small Pd particle sizes (2.7–4.0 nm), showed higher selectivity towards the desired monounsaturated C18:1 FAMEs due to lower affinity of isolated double bond (presented in C18:1) on the Pd surface. In addition, selectivity towards the desired cis-C18:1 FAMEs was found to be highly sensitive to Pd particle size. The 0.5Pd/MCM-41 catalyst with small Pd particle size (2.7 nm), provided high cis-C18:1 selectivity, resulting in a biodiesel with better cold flow property compared with the trans-isomers. With partial hydrogenation over the prepared Pd catalysts, biodiesel with significantly improved oxidative stability (>10 h) could be obtained.
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    Effects of synthetic conditions on the Pd particle sizes of Pd/SBA-15 catalysts and their performance for the partial hydrogenation of biodiesel fuels
    (2024-07-01)
    Supabunnapong, Thanadon
    ;
    Rungsi, Artita Na
    ;
    Luengnaruemitchai, Apanee
    ;
    Chen, Shih Yuan
    ;
    Mochizuki, Takehisa
    Mesoporous silica (SBA-15)-supported Pd catalysts (Pd/SBA-15) with Pd particles of various sizes (4–17 nm) were obtained under different calcination conditions. These purpose-made Pd/SBA-15 catalysts are applied in the partial hydrogenation of soybean-oil-derived biodiesel fuel, rich in polyunsaturated fatty acid methyl esters (poly-FAME), to produce partially hydrogenated fatty acid methyl esters (H-FAME), rich in monounsaturated fatty acid methyl esters (mono-FAME), under mild conditions (80 °C, 0.5 MPa H<inf>2</inf>). The Pd particle size was strongly correlated with hydrogenation rate and selectivity, thereby influencing the composition and fuel properties of H-FAME. The Pd/SBA-15 catalyst with a Pd particle size of approximately 4 nm obtained by calcination at 300 °C in O<inf>2</inf> showed the highest initial hydrogenation rate and mono-FAME selectivity. The resulting H-FAME product was rich in mono-FAME and thus exhibited high oxidative stability and cold-flow properties compliant with high-blend biofuel standards. In contrast, the analog catalysts with Pd particle sizes ranging from 8 to 17 nm obtained by calcination at 300 °C in air and nitrogen and at 500 °C featured lower hydrogenation rates and afforded larger amounts of undesired saturated fatty acid methyl esters. These findings shed light on the effect of the Pd particle size on the hydrogenation of biodiesel and can be readily applied to the hydrogenation of other biofuels.