Choojun, Kittisak

Preferred name

Choojun, Kittisak

Main Affiliation

School of Science

kittisak.ch@kmitl.ac.th

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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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Tailoring the First Coordination Shell of Isolated Ti(IV) Active Sites in Zeolite Frameworks Boosting Catalytic Activity in Epoxidation
(2025-05-08)
Klinyod, Sorasak
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Yomthong, Krissanapat
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Suttipat, Duangkamon
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Pornsetmetakul, Peerapol
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Kidkhunthod, Pinit
We present a strategy to precisely tune the local structure of the tetrahedrally coordinated titanium (Ti) sites incorporated in the zeolite framework via a one-pot hydrothermal synthesis with the aid of NH<inf>4</inf>F without any further postmodification step. This approach effectively prevents typical issues observed in postsynthetic methods, such as Ti leaching and zeolite framework degradation. By optimizing the NH<inf>4</inf>F concentration in the synthesis precursor, the formation of open Ti(OSi)<inf>3</inf>OH and Ti(OSi)<inf>3</inf>F active species can be precisely controlled. To elucidate the relationship between various Ti active species, including closed Ti(OSi)<inf>4</inf>, open Ti(OSi)<inf>3</inf>OH, and open Ti(OSi)<inf>3</inf>F sites and their catalytic performances in methyl oleate (MO) epoxidation, we employed ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), fluorine X-ray absorption near edge structure spectroscopy (F-XANES), and density functional theory (DFT) calculations. Our findings reveal that increased positive charges on Ti active centers, in the order of closed Ti(OSi)<inf>4</inf> < open Ti(OSi)<inf>3</inf>OH < open Ti(OSi)<inf>3</inf>F, correlate with enhanced catalytic performance in MO epoxidation. However, an excessive proportion of Ti(OSi)<inf>3</inf>F species in the framework can diminish catalytic performance by promoting undesired side reactions. Therefore, we propose an optimized balance between open Ti(OSi)<inf>3</inf>OH and open Ti(OSi)<inf>3</inf>F species in the zeolite structure to maximize the catalytic activity of epoxidation.
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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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Iridium(III) coordination compounds based on organophosphorus ancillary ligands showing cytotoxicity against breast cancer cells and Fe(III) luminescent sensing
(2025-01-15)
Klaimanee, Ekkapong
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Temram, Thitirat
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Ratanaphan, Adisorn
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Saithong, Saowanit
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Sooksawat, Dhassida
Three phosphorescent iridium(III) complexes consisting bis-diphosphine ligands were prepared and characterized by single-crystal XRD, CHN analysis, spectroscopic techniques, cyclic voltammetry, and DFT. The synthesized complexes were the three monomeric [Ir(ppy)<inf>2</inf>(L<inf>1</inf>)Cl] (1), [Ir(ppy)<inf>2</inf>(L<inf>2</inf>)]Cl (2) and [Ir(ppy)<inf>2</inf>(L<inf>3</inf>)]Cl (3) where L<inf>1</inf> = bis-(diphenylphosphino)methane (dppm), L<inf>2</inf> = bis-(diphenylphosphino)propane (dppp) and L<inf>3</inf> = bis-(diphenylphosphino)benzene (dppbe). Complexes 1–3 gave an absorption band between 240 to 380 nm in both CH<inf>2</inf>Cl<inf>2</inf> and DMSO, which is assigned as a charge transfer transition based on theoretical calculation. They showed a blue-green emission at 460–520 nm in DMSO with an absolute quantum efficiency of 0.013–0.046 at room temperature. The selective photo-induced electron transfer (PET) by Fe3+ in DMSO, was studied to obey the Rehm-Weller principle. The 1:1 binding soichiometry between 1–3 and Fe3+ was established by Job's plot. The binding constants (K<inf>a</inf>) were determined using the Benesi-Hildebrand plot. All the complexes are extremely more potent than cisplatin for in vitro antiproliferative activity towards the human breast cancer cells, HCC1937, MCF-7, and MDA-MB-231. The values of IC<inf>50</inf> were in the range of 0.077–0.485 μM, and 1 exhibited the most effective IC<inf>50</inf> against MDA-MB-231 cell line, the triple-negative breast cancer cell. Their lipophilicities (log P) were also examined to explain the penetration ability of the studied complexes towards cell barriers, and transport to the molecular target.
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Highly active and stable Ni–W/SiO2 catalyst derived from W incorporated on Ni phyllosilicate for deoxygenation of triglycerides into green biofuel range hydrocarbons
(2025-10-01)
Praikaew, Wanichaya
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Prameswari, Jedy
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Ratchahat, Sakhon
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Chaiwat, Weerawut
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Sakdaronnarong, Chularat
Highly active and stable Ni–W/SiO<inf>2</inf> catalyst derived from W incorporated into Ni phyllosilicate (Ni-PS) was prepared by the ammonia evaporation (AE) method, and benchmarked with the catalyst prepared by the impregnation method (IM). Their catalytic activities were evaluated for deoxygenation of triglycerides into green biofuel-range hydrocarbons. The Ni-PS structure demonstrated a large surface area with strong interaction between Ni2+ and SiO<inf>2</inf>, resulting from the incorporation of Ni2+ into the silica framework, which led to highly dispersed Ni⁰ after H<inf>2</inf> reduction. Additionally, the H<inf>2</inf> adsorption and desorption capabilities, together with a substantial quantity of Lewis acid sites, were advantageous features of Ni-PS catalysts compared to Ni-IM and 5 W/Ni-IM catalysts. Ex situ and in situ structural characterizations revealed the generation of Ni⁰ and W⁰ states, along with remaining W4+ species after H<inf>2</inf> reduction. The 5 W/Ni-AE catalyst exhibited stable performance up to 60 h on stream, producing consistent yields of 30 % jet fuel and 40 % diesel, which was attributed to its high porosity, small Ni⁰ particle sizes, enhanced H<inf>2</inf> adsorption–desorption capacities, and abundant Lewis acid sites. Consequently, the heterogeneous 5 W/Ni-AE catalyst shows significant practical relevance for generating green biofuel from oil-derived feedstock in sustainable biorefineries.
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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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Tailoring Re-loaded core–shell Ni structures embedded in mesoporous silica for the selective transformation of levulinic acid into γ-valerolactone
(2026-05-21)
Maneewong, Yupawan
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Lakhani, Pratikkumar
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Ratchahat, Sakhon
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Sakdaronnarong, Chularat
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Limphirat, Wanwisa
Heterogeneous core–shell catalysts have attracted significant interest because they integrate multiple catalytic functions within a single, precisely engineered architecture. In this work, we report the rational synthesis and catalytic evaluation of a Re-loaded Ni core–shell catalyst embedded in mesoporous silica for the efficient hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The core–shell configuration enables effective confinement of Ni nanoparticles within the porous silica matrix and stabilizes spatially separated Ni and ReO<inf>X</inf> species with complementary catalytic functions. Comprehensive physicochemical characterization confirmed the successful formation of the core–shell structure, its high structural stability, and the presence of confined metallic Ni sites responsible for H<inf>2</inf> activation and oxophilic ReO<inf>X</inf>-derived acid sites for oxygenate activation. Under optimized conditions, the Ni<inf>12</inf>Re<inf>1.63</inf>-CS catalyst achieved complete LA conversion with a GVL yield exceeding 94% within 2 h, outperforming non-core-shell catalysts. The catalyst also displayed high intrinsic activity, with a turnover frequency of up to ∼36 h−1, and retained an excellent GVL selectivity of approximately 80% during recycling, despite a gradual decrease in LA conversion. These findings demonstrate that spatial separation of hydrogenation and oxophilic adsorption sites within a core–shell architecture is critical for enhancing activity and selectivity in biomass-derived platform molecule upgrading.
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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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Design of a rhenium-decorated mesoporous nickel phyllosilicate-derived Ni–Re/MCM-41 catalyst for efficient hydrogenation of levulinic acid to γ-valerolactone
(2026-04-27)
Maneewong, Yupawan
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Lakhani, Pratikkumar
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Ratchahat, Sakhon
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Sakdaronnarong, Chularat
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Limphirat, Wanwisa
Herein, Ni and NiRe catalysts supported on mesoporous MCM-41 were synthesized through ammonia evaporation (AE) and impregnation (IM) routes to explore structure–activity correlations in the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The AE-derived nickel phyllosilicate (Ni-PS) framework provided strong interactions through Ni–O–Si linkages, leading to high dispersion and stabilization of Ni species. Incorporation of Re significantly improved reducibility, hydrogen activation, and the balance between acidic and metallic sites, resulting in enhanced catalytic efficiency. The optimized NiRe-PS catalyst exhibited a uniform nanostructure, strong Ni–Re synergy, and the highest metallic Ni fraction, which collectively promoted superior activity and stability. Under mild conditions (140 °C, 10 bar H<inf>2</inf>), NiRe-PS achieved complete LA conversion and ∼96% GVL yield within 4 h, with a turnover frequency of 26.3 h−1 (160 °C, 10 bar H<inf>2</inf>) and with an apparent rate constant of 0.0059 min−1. Mechanistic and isotopic investigations confirmed that both molecular and solvent-derived hydrogen contributed to the hydrogenation pathway. The exceptional activity, recyclability, and structural robustness of NiRe-PS demonstrate the potential of phyllosilicate-based bimetallic systems as efficient, non-noble catalysts for sustainable biomass valorization.
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Selective Hydrogenation of Polyunsaturated Fatty Acid Methyl Esters over Bifunctional Ligand-Modified Pd/MIL-101(Cr) Catalysts
(2025-09-22)
Khenkhom, Phuwadon
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Ritvirulh, Chonlada
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Choojun, Kittisak
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Preedawichitkun, Yardthip
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Chanlek, Narong
Highly dispersed palladium nanoparticles (Pd NPs) were incorporated into MIL-101(Cr) frameworks functionalized with bifunctional ligands for the liquid-phase hydrogenation of polyunsaturated fatty acid methyl esters (FAMEs). A series of amino- and carboxylic-acid-containing ligands─ethylenediamine (en), diethylenetriamine (DET), alanine (AN), 4-aminobutyric acid (ABA), 5-aminovaleric acid (AVA), glutamic acid (GA), and adipic acid (AA)─were grafted onto MIL-101(Cr), followed by Pd loading (0.5 wt %). Spectroscopic and structural analyses confirmed ligand coordination to both Cr nodes and Pd species. Catalysts bearing ABA, AVA, and GA exhibited Pd0dispersion (<1 nm), yielding high turnover frequencies (up to ∼15,400  h–1) and >94% selectivity for monounsaturated FAMEs. In contrast, strong Pd–N interactions in en- and DET-grafted materials suppressed Pd0formation, reducing activity. Hot filtration and recyclability tests confirmed high catalyst stability and negligible Pd leaching. The bifunctional ligand architecture effectively tunes Pd speciation and activity, providing a robust platform for selective and reusable hydrogenation catalysts.

Choojun, Kittisak

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