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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
;
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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Tuning spatially proximal Cu+ and Cu0 species via phyllosilicate coordination engineering for hydrogen-free upgrading of fatty acid methyl esters to fatty alcohols
(2026-01-01)
Khosukwiwat, Kanyanat
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Choojun, Kittisak
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Limphirat, Wanwisa
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Liu, Ting Hao
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Lin, Yu Chuan
Hydrogen-free upgrading of fatty acid methyl esters (FAMEs) to fatty alcohols offers a sustainable alternative to conventional hydrogenation but is limited by the inability to control metal speciation and interfacial acidity under catalytic transfer hydrogenation (CTH) conditions. A copper phyllosilicate (CuPS) is presented in which Cu loading (20–35 wt%) regulates the distribution of octahedral and square-planar Cu2+ species within the phyllosilicate structure, thereby governing reduction pathways, Cu+/Cu0 speciation, and surface acidity. Structural and in situ spectroscopic analyses (XRD, N<inf>2</inf> physisorption, TEM, and in situ TR-XANES) show that octahedral Cu2+ species embedded in Cu–O–Si layers preferentially generate and stabilize Cu+ sites upon reduction, whereas square-planar Cu2+ species favor Cu0 formation and particle growth. This coordination-dependent reducibility establishes a direct link between the CuPS precursor structure and the resulting Cu+/Cu0 ensemble and acid properties. As a result, 25CuPS, which maximizes retained octahedral Cu2+, forms the most effective spatially proximal Cu+ and Cu0 species, providing the highest Lewis acidity with suppressed Brønsted acidity and delivering the highest hexadecanol yield and methyl palmitate conversion. The catalytic behavior is consistent with cooperative ester activation on Cu+ sites and H-transfer from iso-propanol on adjacent Cu0 sites via a Meerwein–Ponndorf–Verley-type pathway. At higher Cu loadings, increased Cu0 domain growth and interfacial Brønsted acidity promote competing reactions and reduce alcohol selectivity. This work establishes coordination-controlled copper speciation as a materials design principle for hydrogen-free upgrading of biomass-derived esters.
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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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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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Bio-derived butadiene from cross-metathesis over silanol rich WO3 catalysts obtained from copper phyllosilicate
(2025-03-20)
Wengwirat, Kanokwan
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Choojun, Kittisak
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Promchana, Pratya
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Limphirat, Wanwisa
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Sooknoi, Tawan
Bio-butadiene can be produced from cross-metathesis of bioethanol-derived acetylene/ethylene over supported WO<inf>3</inf> on silanol-rich silica prepared with Cu-leached copper phyllosilicate (CuPS). 20CuPS and 30CuPS were preliminarily reduced before Cu-leaching under an acidic solution (1 M HCl). Compared with fumed SiO<inf>2</inf>29Si CPMAS NMR spectroscopy showed an increase in surface silanols, particularly the isolated silanols (Q<inf>3</inf>), from removing Cu2+ octahedral sites (Cu2+(OSi)<inf>6</inf>) encapsulated within tetrahedral silica layers of CuPS. The surface silanols in fumed SiO<inf>2</inf>, 20CuPS-Le, and 30CuPS-Le adequately accommodate single-site and polymeric WO<inf>3</inf> species, leading to a similar 1,3-butadiene production rate (∼4.7 mmol h−1 g<inf>cat</inf>) at 5 wt% loading. Only 30CuPS-Le sufficiently provides the exposed silanols to disperse 8 wt% WO<inf>3</inf> loading without bulk WO<inf>3</inf> formation. The cross-metathesis activity depends on the relative amounts of exposed silanols. Accordingly, the steady 1,3-butadiene production was obtained in the order of 8WO<inf>3</inf>/30CuPS-Le (6.3 mmol h−1 g<inf>cat</inf>) > 8WO<inf>3</inf>/20CuPS-Le (5.1 mmol h−1 g<inf>cat</inf>) > 8WO<inf>3</inf>/SiO<inf>2</inf> (2.5 mmol h−1 g<inf>cat</inf>).
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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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Highly Dispersed WOx/SiO2Catalysts Derived from W-TRIS Complex for Efficient Biobutadiene Production from Acetylene-Ethylene Cross-Metathesis
(2025-01-01)
Promchana, Pratya
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Choojun, Kittisak
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Wengwirat, Kanokwan
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Limphirat, Wanwisa
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Sooknoi, Tawan
Renewable 1,3-butadiene was selectively produced via acetylene-ethylene cross-metathesis over highly dispersed WO<inf>x</inf>/SiO<inf>2</inf>catalysts prepared by a simple impregnation method using the molecular precursor (NH<inf>4</inf>)<inf>2</inf>[W<inf>2</inf>O<inf>6</inf>(TRIS)<inf>2</inf>] (W-TRIS). Compared to catalysts derived from ammonium metatungstate (AMT), the TRIS-derived catalysts exhibited superior WO<inf>x</inf>dispersion and catalytic activity, attributed to stronger W–O–Si interactions as evidenced by XRD, DRUV–vis, Raman spectroscopy, and W L<inf>3</inf>-edge XANES/EXAFS. Systematic variation of WO<inf>3</inf>loading revealed that 5 wt % WO<inf>x</inf>/SiO<inf>2</inf>-TRIS offered the optimal balance of activity and selectivity, achieving 60% acetylene conversion, ∼74% selectivity to 1,3-butadiene, and a turnover frequency (TOF) of 23 h–1. Contact time analysis confirmed that 1,3-butadiene was the primary product, while minor byproducts such as cyclohexene and benzene originated from Diels–Alder cycloaddition followed by dehydrogenation. Reaction temperature screening identified 450 °C as the optimal operating condition; higher temperatures led to increased side reactions. Importantly, long-term testing over 100 h under continuous-flow conditions demonstrated high stability with sustained selectivity and negligible coke formation. These findings underscore the practical advantages of the W-TRIS molecular precursor strategy in designing durable WO<inf>x</inf>/SiO<inf>2</inf>catalysts for efficient and sustainable C<inf>4</inf>chemical production from bioethylene.
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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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Experimental insights into catalytic oxidation of 1,6-hexanediol to ϵ-caprolactone over (p-cymene)RuCl2(L) complexes in non-polar media
(2022-08-26)
Promchana, Pratya
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Choojun, Kittisak
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Leesakul, Nararak
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Saithong, Saowanit
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Chainok, Kittipong
1,6-Hexanediol (1,6-HD) oxidation to ϵ-caprolactone (ϵ-CL) was investigated using (p-cymene)RuCl<inf>2</inf>(L) complexes with phosphine (L<inf>P1-P5</inf>) and pyridine (L<inf>N1-N5</inf>) ligands as catalysts. Despite similar Ru electron density, the activity of (p-cymene)RuCl<inf>2</inf>(L<inf>P</inf>) increases with the decrease in phosphine steric hindrance rather than the electronic properties. The reaction rate correlates with the pocket-size dimension (θ<inf>c</inf>), defined by the (centroid of the p-cymene ring)-Ru-(centroid of 2Cl) angle of the (p-cymene)RuCl<inf>2</inf>(L) complexes. This observation supports an associative interchange mechanism previously proposed by computational studies. The readily accessible θ<inf>c</inf> (≥145°) of these L<inf>N</inf> complexes results in a similar rate, regardless of different L<inf>N</inf> ligands. For both complexes, the ϵ-CL selectivity depends only on 1,6-HD conversion. Even though bases significantly enhance the activity, they readily affect the complex stability. The methyl isobutyl carbinol (MIBC) produced during the reaction could competitively react with the Ru catalysts, leading to catalyst deactivation, especially when MIBC : 1,6-HD ≥ 2 times.
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Role of surface silanols and confinements of siliceous MFI supports on stability of active Ga species for ethane dehydrogenation
(2022-05-25)
Prakobtham, Kittipong
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Choojun, Kittisak
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Promchana, Pratya
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Sattayaporn, Suchinda
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Sooknoi, Tawan
Effect of surface silanol and confinement of siliceous MFI supports on the anchoring stability of active Ga species was demonstrated for ethane dehydrogenation. The catalysts were prepared by impregnation of Ga(NO<inf>3</inf>)<inf>3</inf> solution on siliceous MFI (Si/Al >500) and amorphous SiO<inf>2</inf>, and characterized by XRD, XRF, SEM-EDX, H<inf>2</inf>-TPR, NH<inf>3</inf>-TPD, in situ XANES, and EXAFS. Extra-framework Ga3+ species were present with different dispersions and reducibility, depending on the surface silanols. Proximity of the silanols within the surface confinement played an essential role on anchoring stability of the extra-framework Ga3+ species. All Ga catalysts provided > 93% ethylene selectivity with appreciable TOF ~60 h−1 for ethane dehydrogenation at 650°C. In situ XANES, EXAFS, and H<inf>2</inf>-TPR suggested that the highly dispersed extra-framework Ga3+ species could exist as dimeric Ga oxide [Ga<inf>2</inf>O<inf>2</inf>]2+ species. This active site could be reversibly interconverted with the less active [HGaOH]+ species under the H<inf>2</inf> flow.

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