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.