Sooknoi, Tawan

Preferred name

Sooknoi, Tawan

Alternative Name

Sooknoi, T.

Main Affiliation

School of Science

tawan.so@kmitl.ac.th

Now showing 1 - 10 of 14

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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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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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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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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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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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Local structure of stoichiometric and oxygen-deficient A 2Ti6O13 (A = Li, Na, and K) studied by X-ray absorption spectroscopy and first-principles calculations
(2018-10-21)
Kanchanawarin, Jarin
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Limphirat, Wanwisa
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Promchana, Pratya
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Sooknoi, Tawan
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Maluangnont, Tosapol
Oxygen vacancy defects (V<inf>O</inf>) in Ti-based oxides play important roles in catalytic processes despite limited knowledge regarding their formation and characterization. Here, we demonstrate the use of X-ray absorption spectroscopy (XAS) measurements to compare the relative proportion of V<inf>O</inf> defects in as-grown alkali hexatitanate A<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> (A = Li, Na, K). Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions were studied. The similarity of measured XANES spectra of Ti K-edge in all samples indicates the presence of (Ti4+)O<inf>6</inf> units in good agreement with reported X-ray diffraction results. The small influence of cations A at the tunnel was observed and can be well reproduced in the simulated spectra. In addition, we present a semi-quantitative approach to intuitively determine the content of V<inf>O</inf> defects in oxygen-deficient K<inf>2</inf>Ti<inf>6</inf>O<inf>13-x</inf> by in situ time-resolved XAS measurements under reducing conditions (10%H<inf>2</inf>/Ar, 50-650 °C). The in situ XANES measurements indicate that the oxidation state of bulk Ti remains the same as the as-grown sample, i.e., 4+, at elevated temperatures. By in situ EXAFS measurements, the relative number of V<inf>O</inf> defects is highest at a reduction temperature of ∼550 °C and slightly decreases after that. To confirm the formation of V<inf>O</inf> defects, first-principles calculations were independently carried out using a 126-atom K<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> supercell with V<inf>O</inf> at various positions. Based on calculated EXAFS, the removal of the oxygen atom nearest to the tunnel, which is the lowest energy structure, provides a good match to the experimental spectra.
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Higher alcohol production from ethanol over occluded [Mg4(OH)4]4+ clusters in MgO/KNaX
(2022-02-25)
Yotkkham, Nattapol
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Choojun, Kittisak
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Promchana, Pratya
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Fan, Xiaolei
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Sooknoi, Tawan
Conversion of ethanol to higher alcohols was studied over MgO/KNaX, prepared by ion exchange with Mg(OAc)<inf>2</inf>, followed by KOH washing. The catalysts were characterized by XRF, XRD, SEM, BET, 27Al MAS NMR, EXAFS, NH<inf>3</inf>- and CO<inf>2</inf>-TPD. All catalysts showing MgO nanopetals and aggregates on the external surface, contained occluded [Mg<inf>4</inf>(OH)<inf>4</inf>]4+ clusters in the zeolite cavities, providing medium basic (M<inf>b</inf>) and acid (M<inf>a</inf>) sites. Ethanol conversion and higher alcohols selectivity (up to 78%) increased with M<inf>b</inf>/M<inf>a</inf> ratio due to the increase in both MgO (4–6 wt%) and K (14.7–17.3 wt%) loadings. Decreasing occluded [Mg<inf>4</inf>(OH)<inf>4</inf>]4+ clusters and/or increasing MgO aggregates led to the lower conversion and yields of higher alcohols. The essential role of the occluded [Mg<inf>4</inf>(OH)<inf>4</inf>]4+ clusters in producing higher alcohols was verified by the reactions using various control catalysts. The MgO/KNaX showed high stability even after steaming at 380 °C, as well as being regenerated by calcination (450 °C in air).
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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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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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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.

Sooknoi, Tawan

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