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Stabilized Pd Nanoparticles Encapsulated in MIL-101(Cr) for Chemoselective Hydrogenation of Polyunsaturated FAMEs
(2025-11-24)
Preedawichitkun, Yardthip
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Numwong, Natthida
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Chanlek, Narong
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Chung, Po Wen
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Kumar, Raju
Palladium nanoparticles (Pd NPs) were successfully encapsulated within the porous framework of MIL-101(Cr) via a double solvent method to produce highly dispersed and stable catalysts for the chemoselective hydrogenation of polyunsaturated fatty acid methyl esters (FAMEs). Pd loadings ranging from 0.5 to 1.5 wt.% were systematically studied to elucidate the effects of nanoparticle size, dispersion, and hydrogen activation behavior on catalytic performance. The 0.8Pd/MIL-101(Cr) catalyst exhibited the highest turnover frequency (TOF ∼9,700 h−1) and superior selectivity (>90%) toward monounsaturated products (C18:1), attributed to optimal Pd dispersion. In contrast, the 0.5Pd/MIL-101(Cr) showed an induction period under low H<inf>2</inf> partial pressure, indicating limitations in hydride accommodation, while the 1.5Pd/MIL-101(Cr) suffered from Pd aggregation, resulting in a reduced intrinsic activity. Product selectivity was primarily governed by overall conversion: C18:1 was favored at low conversions, whereas C18:0 formation increased at higher conversions due to secondary hydrogenation. The catalysts demonstrated excellent stability and recyclability over multiple cycles without detectable Pd leaching or structural degradation. These findings establish MIL-101(Cr) as a robust and tunable platform for dispersing Pd NPs and highlight the potential of Pd/MIL-101(Cr) catalysts for efficient, selective upgrading of bioderived feedstocks under mild reaction conditions.
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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
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Rungsi, Artita Na
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Luengnaruemitchai, Apanee
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Chen, Shih Yuan
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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.
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Conversion of palm oil into biodiesel production with heterogeneous catalyst derived from spent coffee grounds ash: Process optimization through response surface methodology
(2021-01-01)
Jitjamnong, Jakkrapong
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Numwong, Natthida
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Chuaykarn, Narinphop
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Direksilp, Chatrawee
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Luengnaruemitchai, Apanee
In the present study, the calcination of spent coffee grounds (SCG) supporting potassium hydroxide and potassium carbonate (K<inf>2</inf>CO<inf>3</inf>) was used as a novel solid heterogeneous catalyst to convert palm oil to fatty acid methyl ester. The response surface method based on Box Behnken experimental design was used to optimize the biodiesel yield. The prepared catalyst was characterized by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses. EDS analysis of the synthesis catalyst exhibited the presence of active potassium species for high catalytic activity. The 30K/SCG–600 catalysts exhibited the highest catalytic activity and were rich in K that formed a basic heterogeneous catalyst and the highest total basicity. The effects of catalyst loading (4.5–5.5 wt.%), methanol to oil molar ratio (6:1–12:1), and reaction time (60–120 min) on the transesterification were investigated. The results showed that the predicted optimum response for biodiesel yield from RSM was 97.01%, which could be obtained using methanol: oil molar ratio of 6.68:1, catalyst loading of 4.94 wt.%, and reaction time at 82.42 min. The actual biodiesel conversion of 97.08% was achieved under the predicted optimal conditions. The results of various statistics employed with high R2 (95.07%) and R2adj (88.73%) values indicated that the predicted and actual biodiesel yield was accurate and reliable.
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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
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Prabnasak, Panisa
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Prayoonpunratn, Patsakol
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Triphatthanaphong, Pholawat
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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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Effect of cobalt complex precursors on reactivity of cationic cobalt catalysts: Cyclohexane dehydrogenation
(2019-05-10)
Choojun, Kittisak
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Worathanaseth, Arucha
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Kuhatasanadeekul, Satu
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Kurato, Teeraporn
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Ketaniruj, Supanut
Effect of the cobalt precursors, including [Co(bipy)<inf>3</inf>](NO<inf>3</inf>)<inf>2</inf>, [Co(NH<inf>3</inf>)<inf>5</inf>Cl]Cl<inf>2</inf>, [Co(NH<inf>3</inf>)<inf>6</inf>]Cl<inf>3,</inf> and [Co(en)<inf>2</inf>Cl<inf>2</inf>] Cl, on reactivity of the cationic Co/SiO<inf>2</inf> prepared by strong electrostatic adsorption (SEA) was investigated for the dehydrogenation of cyclohexane as a model reaction. According to the charge density of the cobalt complex, highly dispersed Co2+ species and/or Co3+ oxide can be obtained on the silica surface. The dehydrogenation activity is in the order of Co/SiO<inf>2</inf> catalysts prepared by [Co(bipy)<inf>3</inf>](NO<inf>3</inf>)<inf>2</inf> > [Co(NH<inf>3</inf>)<inf>5</inf>Cl]Cl<inf>2</inf> > [Co(NH<inf>3</inf>)<inf>6</inf>]Cl<inf>3</inf> > [Co(en)<inf>2</inf>Cl<inf>2</inf>] Cl, correlating to the Co2+ content of the final catalysts. The cationic cobalt catalysts are more active than the pre-reduced one. Although metallic cobalt is found to be less active, the activity of cationic cobalt catalyst is enhanced under H<inf>2</inf> flow, presumably due to the formation of cobalt hydride intermediate. The inter-conversion of Co2+/cobalt hydride intermediate is readily reversible and regulated by presence of hydrogen.
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Influence of Mg modifier on cis-trans selectivity in partial hydrogenation of biodiesel using different metal types
(2016-06-25)
Thunyaratchatanon, Chachchaya
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Jitjamnong, Jakkapong
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Luengnaruemitchai, Apanee
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Numwong, Natthida
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Chollacoop, Nuwong
The catalytic performance of Pd, Pt, and Ni supported on catalysts was investigated for partial hydrogenation of soybean methyl esters, in terms of FAME composition and biodiesel properties, especially oxidative stability and cold flow properties. The effect of Mg modifier over SiO-supported catalysts on cis-trans selectivity of polyunsaturated FAMEs was also examined. The catalytic testing was performed under reaction conditions of 4 bar hydrogen pressure and 80-120 °C. Hydrogenation activity was presented by turnover frequency (TOF) of diunsaturated fatty acid (C18:2) within 4 h of the reaction time. The highest TOF was obtained over Pd catalysts, while the lowest TOF was obtained from Ni catalysts. At high reaction temperature conditions showed a large amount of cis-monounsaturated fatty acid (cis-C18:1); however, it exhibited a large amount of trans-monounsaturated fatty acid (trans-C18:1) which has a negative impact on biodiesel properties. The XPS revealed that the introduction of Mg leads to a strong metal-support interaction caused by electron transfer from the support to the metal, which decreased trans-C18:1 formation and presented the higher oxidative stability than the catalysts without Mg modifier.

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