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Bifunctional WOx/SiO2 catalysts for hydrogen-free upgrading of B100 and bio-ethylene to SAF and green diesel precursors via olefin metathesis and deoxygenation
(2026-09-15)
Solehudin, Mochamad
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Wengwirat, Kanokwan
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Promchana, Pratya
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Poo-arporn, Yingyot
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Limphirat, Wanwisa
This work presents a hydrogen-free catalytic route for upgrading palm-derived biodiesel (B100) into olefinic precursors for sustainable aviation fuel (SAF) and green diesel (GD) using bifunctional WO<inf>x</inf>/SiO<inf>2</inf> catalysts under atmospheric pressure. The catalysts integrate olefin cross-metathesis, mediated by surface W CH<inf>2</inf> species, with deoxygenation via Lewis-acidic W O sites, enabling selective C C bond exchange and C O bond cleavage without external hydrogen or noble metals. Detailed mechanistic studies revealed that methyl oleate (MO) rapidly undergoes cross-metathesis with ethylene to yield SAF-range C<inf>9</inf>–C<inf>14</inf> precursors, while methyl palmitate (MP) contributes primarily to GD (C<inf>15</inf>–C<inf>18</inf>) through ketene intermediates and decarbonylation–hydrogen transfer pathways. Contact time and temperature experiments confirmed that MO conversion is kinetically favored at milder conditions, whereas MP-derived pathways dominate at higher temperatures and extended residence times. Catalyst loading studies show that the 3 and 5 wt% WO<inf>x</inf>/SiO<inf>2</inf> catalysts are dominated by highly dispersed isolated and polymeric WO<inf>x</inf> species, which exhibit higher accessible acidity and consequently promote secondary cracking reactions. In contrast, the 8 wt% WO<inf>x</inf>/SiO<inf>2</inf> catalyst contains a higher fraction of bulk crystalline WO<inf>3</inf> domains, resulting in reduced surface acidity and suppressed cracking. Overall, 8 wt% WO<inf>x</inf>/SiO<inf>2</inf> delivers reasonable rates with high selectivity toward SAF/GD precursors, while minimizing secondary cracking. It can be regenerated and recycled with substantial recovery of catalytic performance, establishing a robust, low-pressure, and hydrogen-free pathway for scalable renewable fuel production from B100.
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Hydrogen-Free Production of Green Diesel from Deoxygenation of Methyl Palmitate via Cross-Metathesis with Bio-Ethylene Using Supported WO3 Catalyst
(2025-06-02)
Solehudin, Mochamad
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Wengwirat, Kanokwan
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Promchana, Pratya
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Poo-arporn, Yingyot
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Limphirat, Wanwisa
Traditional green diesel production from used cooking oils faces challenges in H<inf>2</inf> supply and carbon loss as CO<inf>2</inf>. This study presents a novel hydrogen-free deoxygenation process via cross-metathesis between fatty acids/FAMEs and bio-ethylene under atmospheric pressure as an alternative sustainable solution. The carboxyl end group was removed as CO and blue hydrogen, bearing the hydrocarbons as green diesel, sustainable aviation fuel (SAF), and bio-naphtha. Bifunctional WO<inf>3</inf>/SiO<inf>2</inf> was prepared and characterized by XRD, XANES, EXAFS, DR-UV, and Raman. Lewis site (W = O) promotes the formation of ketene intermediate that undergoes cross-metathesis with ethylene over tungsten carbene (WCH<inf>2</inf>) sites, yielding a C16-ene majority with trace amounts of C17-ene. Smaller hydrocarbons (<C15) are obtained as minor components from decarbonylation, hydrogen transfer, and cracking. The increased contact time (27–106 g h/mol) at 460 °C results in increased conversion (30%–87 %), green diesel (12%–57%), SAF (3.5%–12.7%), and bio-naphtha (1.3%–5.3%). Optimal green diesel production of 2.92 h⁻¹ with 73% selectivity can be achieved at 480 °C. SAF and bio-naphtha yields can be tuned by varying temperature from 460 to 500 °C. This provides a sustainable pathway for renewable liquid fuels without an external hydrogen supply.
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Reversibly interconverted Cu+/Cu+-H species as active sites for selective hydrogenation of fatty acid methyl esters to fatty alcohol over layered double hydroxide derived CuMgAlOx catalysts
(2025-03-15)
Nooto, Chanisara
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Chuaykaew, Panalee
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Singthuen, Pawanrat
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Solos, Thanasak
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Preedawichitkun, Yardthip
High fatty alcohol production (>90 % selectivity) can be achieved though the selective hydrogenation of fatty acid methyl esters over layered double hydroxide derived CuMgAlO<inf>x</inf> catalysts in a fixed-bed reactor at 250 °C under atmospheric H<inf>2</inf>. ∼17 wt.% Cu loading CuLDHs with different Mg2+/Al3+ ratios (CuMg<inf>60</inf>Al<inf>40</inf>O<inf>x</inf>, CuMg<inf>70</inf>Al<inf>30</inf>O<inf>x</inf>, CuMg<inf>75</inf>Al<inf>25</inf>O<inf>x</inf>, and CuMg<inf>80</inf>Al<inf>20</inf>O<inf>x</inf>) were prepared by co-precipitation-hydrothermal method. The Cu dispersion and species were determined by H<inf>2</inf>-TPR, consecutive H<inf>2</inf>-TPR, N<inf>2</inf>O-dissociative reaction, and in situ TR-XANES. Highly dispersed Cu metal along with cationic Cu(I) species were obtained for all CuMgAlO<inf>x</inf>. The cationic Cu(I) species (Cu+/Cu+-H) content increased with Mg2+ content. In the presence of H<inf>2</inf>, the cationic Cu(I) species undergo reversible interconversion between Cu+ and Cu+-H species, facilitating hydrogen dissociation/evolution. The hydrogenation activity was governed by the balance of the metallic Cu surface and the cationic Cu(I) species. The Cu+ species allow preferential adsorption of C[dbnd]O ester for selective hydrogenation of FAMEs to fatty alcohol (>90 % selectivity). With Cu<inf>surface</inf>/Cu(I) ratio at 0.25 (CuMg<inf>75</inf>Al<inf>25</inf>O<inf>x</inf>), the fatty alcohol production rate of 49.3 h−1 was obtained with high stability due to the reversible interconversion of Cu+/Cu+-H that prevented product re-adsorption and side reactions.
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Tuning Cu+ species/Brønsted acids of copper phyllosilicate by K+ doping for selective hydrogenation of methyl palmitate to hexadecanol
(2023-12-01)
Prasanseang, Warot
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Choojun, Kittisak
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Poo-arporn, Yingyot
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Huang, Ai Lin
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Lin, Yu Chuan
Selective hydrogenation of methyl palmitate to hexadecanol can be manipulated by tuning Cu+ species and Brønsted acid sites (BAS) of copper phyllosilicate (CuPS) catalysts with K+ doping. The catalysts were prepared by impregnating K+ onto reduced and non-reduced CuPS. The reactions were carried out in a fixed-bed flow reactor at 250 °C under atmospheric H<inf>2</inf>. In situ TR-XANES and Py-IR suggest that the presence of K+ could stabilize Cu+ species and neutralize BAS. As compared to the non-reduced sample, K+ loading (0.01–0.10 wt%) on the reduced CuPS provide higher Cu+ fraction (10–16%), lower BAS (0.82 to 0.16μ mol/g) and lower Cu dispersion (75 to 52%). A balance between Cu0 active surface and Cu+ content provides an optimum hydrogenation activity (up to 80 %). The increased Cu+ species, together with the decreased BAS, does not only enhance the catalyst stability, but also hexadecanol selectivity (from 35 to 60%, at ∼50% conversion).
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Selective acetylene removal from ethylene-rich feed by cross-metathesis over supported WO3 catalysts
(2023-01-25)
Promchana, Pratya
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Choojun, Kittisak
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Limphirat, Wanwisa
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Poo-arporn, Yingyot
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Sooknoi, Tawan
Acetylene in ethylene-rich feed can be removed via acetylene/ethylene cross-metathesis over WO<inf>3</inf>-supported catalysts at 450 °C, yielding 1,3-butadiene with cyclohexene as a minor product. The catalyst must be treated with ethylene at 600 °C to generate a genuinely active site of tungsten (IV) alkylidene species (W=CH<inf>2</inf>). The H<inf>2</inf> treatment decreases surface W[dbnd]O concentration, and hence the activity. Raman spectroscopy shows that active single-site WO<inf>3</inf> species, including mono oxo-WO<inf>3</inf> ((O=)W(O-Si)<inf>3</inf> and (O=)W(O-Si)<inf>4</inf>) and dioxo-WO<inf>3</inf> species (O=)<inf>2</inf>W(O-Si)<inf>2</inf>) were generated in 2%WO<inf>3</inf>/SiO<inf>2</inf>, while the WO<inf>3</inf> cluster and bulk WO<inf>3</inf> exist in 3–5%WO<inf>3</inf>/SiO<inf>2</inf> and 7%WO<inf>3</inf>/SiO<inf>2</inf>, respectively. The 5%WO<inf>3</inf>/NaX and 5%WO<inf>3</inf>/NaY provide lower activity due to coke formation over the acid sites. With high surface area and confined surface silanol of 5%WO<inf>3</inf>/MCM-41% and 5%WO<inf>3</inf>/SBA-15, in situ TR-EXAFS evidences the formation of only O[dbnd]W(O-Si)<inf>3</inf>. This species provides an isolated W=CH<inf>2</inf> site with relatively higher activity and is less prone to coke formation than the WO<inf>3</inf> cluster in 5%WO<inf>3</inf>/SiO<inf>2</inf>.
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Linear long-chain α-olefins from hydrodeoxygenation of methyl palmitate over copper phyllosilicate catalysts
(2022-04-05)
Prasanseang, Warot
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Choojun, Kittisak
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Poo-arporn, Yingyot
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Huang, Ai Lin
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Lin, Yu Chuan
Copper phyllosilicate (CuPS) was used as a bifunctional catalyst for hydrodeoxygenation of methyl palmitate (MP) to produce long-chain α-olefins without the loss of carbon backbone. The CuPS catalysts were prepared by ammonia evaporation-hydrothermal method. The crystal structure, surface area, reducibility, Cu dispersion, Cu particle size and acidity of the catalysts were examined by XRD, BET, H<inf>2</inf>-TPR, TEM, NH<inf>3</inf>-TPD and Py-IR. The existence of Cu2+ species (octahedral (O<inf>h</inf>)/square planar (Sq)), Cu+ and Cu0 upon calcination/reduction was investigated by in situ TR-XANES. The Cu dispersion was related to the Cu+ fraction in CuPS, while Brønsted acid sites (BAS) depends on Cu0 particles. The MP conversion to 1-hexadecene proceeds via hydrogenation-dehydration promoted by the synergy of Cu0 surface and Brønsted acid sites at the interface. The α-olefin selectivity depends on a balance between Cu+ and Cu loading. The 20CuPS possessing 10% Cu+ fraction, provides a high conversion of 72% with 45% α-olefin selectivity.
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Improving the photo-thermoelectric performance of CuAlO2 via doping with Bi
(2021-12-01)
Daichakomphu, Noppanut
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Klongratog, Bhanupol
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Rodpun, Phumin
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Pluengphon, Prayoonsak
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Harnwunggmoung, Adul
The photothermoelectric (PTE) effect enables the conversion of temperature differences induced by absorbed light to electrical voltages. For the first time, we investigated the effect of Bi doping on the photothermoelectric properties of CuAlO<inf>2</inf>. In this study, delafossite CuAl<inf>1-x</inf>Bi<inf>x</inf>O<inf>2</inf> (x = 0.01, 0.02, 0.03, 0.04, and 0.06) powders were synthesised. X-ray diffraction and X-ray absorption spectroscopy results indicated that the doping limit of Bi content was approximately 2.6–2.7 at% (x = 0.026–0.027). At x = 0.02, we successfully demonstrated the increase of electrical conductivity due to the reduced effective mass and the increased hole concentration, the increase of optical absorption due to the reduced band gaps, and lower thermal conductivity resulting from mass and strain fluctuations. At a Bi content of 2 at%, the photovoltage signals increased compared with the undoped CuAlO<inf>2</inf>. These results indicated that Bi doping could potentially improve the PTE properties of CuAlO<inf>2</inf>.
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Deoxygenation of heptanoic acid to hexene over cobalt-based catalysts: A model study for α-olefin production from renewable fatty acid
(2020-07-25)
Phichitsurathaworn, Ploynisa
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Choojun, Kittisak
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Poo-arporn, Yingyot
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Sooknoi, Tawan
Deoxygenation of heptanoic acid, a model compound, over bimetallic cobalt (Co-Pt, Co-Au, Co-Pd, Co-Ru) supported silica catalysts, was examined for α-olefin production. The catalysts were prepared by conventional impregnation of the metal precursors on silica and characterized by XRF, TEM, H<inf>2</inf>-TPR, acetic acid-TPD, and XANES. Catalytic testing was performed in a fixed-bed flow reactor under atmospheric H<inf>2</inf> pressure. Monometallic cobalt catalysts yielded mainly 1-hexene, but rapid deactivation was observed. Incorporation of 0.5%wt secondary metal, particularly Pt, increases activity and stability under H<inf>2.</inf> A relatively higher olefin/paraffin ratio can be obtained from the reaction over 5%Co+0.5%Pt/SiO<inf>2</inf> when compared to that with higher Pt loading. The co-impregnation method offers Co-Pt catalysts with stability higher than that prepared by the sequential impregnation method. Over cobalt-based catalysts, the deoxygenation is proposed to proceed via reduction of heptanoic acid to heptanal that is an intermediate for decarbonylation to hexene; while other side reactions are suppressed.
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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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