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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
;
Liu, Ting Hao
;
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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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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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
;
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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Reversal of methanation-oriented to RWGS-oriented Ni/SiO2 catalysts by the exsolution of Ni2+ confined in silicalite-1
(2023-08-22)
Chen, Chia Hung
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Chen, Hong Kai
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Huang, Wei Hsiang
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Chen, Chi Liang
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Choojun, Kittisak
Investigation of catalytic hydrogenation of CO<inf>2</inf> to CO via the reverse water-gas shift (RWGS) was undertaken using Ni/SiO<inf>2</inf>-based catalysts. Among the array of catalysts tested, the Ni/SiO<inf>2</inf> catalyst derived from the reduction of silicalite-1-encapsulated, ligand-protected Ni2+ (Ni<inf>0.2</inf>@S-1-red) exhibited promising performance. This catalyst demonstrated a CO<inf>2</inf> conversion rate approaching the equilibrium conversion of RWGS, a selectivity for CO exceeding 99%, and a high space time yield of CO (9.7 mol g<inf>Ni</inf>−1 h−1). The outcomes observed can be attributed to several factors, such as the highly dispersed Ni0 and Niδ+ species, as well as the presence of bridging oxygen of the Ni-O-Si structure, on which CO<inf>2</inf> can be adsorbed moderately. The moderately bonded CO<inf>2</inf> on Ni<inf>0.2</inf>@S-1-red allows for the efficient desorption of its reduced intermediate, i.e. *CO, resulting in the generation of gaseous CO at a rapid rate, consequently preventing its deep hydrogenation to CH<inf>4</inf>. Complementary Density Functional Theory (DFT) calculations were performed and revealed that CO molecules have poor adsorption and higher adsorption energy on the Ni@S-1 surface compared to the S-1 surface. This supports the rapid desorption of *CO and the observed high selectivity of CO. Moreover, the structure-activity correlation analysis further supports the claim of Ni<inf>0.2</inf>@S-1-red as a promising RWGS catalyst.
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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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Ga-Supported MFI Zeolites Synthesized Using Carbon Nanotubes Containing Gallium Oxide Nanoparticles on Exterior Walls and in Interior Channels as Hard Templates for Methanol Aromatization
(2020-06-17)
Chang, Ching Jung
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Chen, Chin Han
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Lee, Jyh Fu
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Sooknoi, Tawan
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Lin, Yu Chuan
A combinative approach of steam-assisted crystallization and hard templating was employed to prepare mesostructured Ga/ZSM-5 catalysts. Carbon nanotubes (CNTs) containing gallium oxide nanoparticles supported on the exterior surface and confined in the inner space were used as the templates. A comparative study showed that by using these two templates, the crystallinities, mesoporosities, and Ga coordination environments of mesostructured Ga/ZSM-5 catalysts were similar. However, a greater strength of Lewis acid of Ga/ZSM-5 was obtained using the GaOx-encapsulated CNTs as the template. Encapsulated GaOx was less reducible than those supported on the exterior surface of the CNTs, resulting in an increased concentration of isolated (GaO)+. Moreover, compared to pristine ZSM-5, the concentration of Brønsted acid was nearly intact by using GaOx-encapsulated CNTs as the templates. A better methanol aromatization performance was achieved by the Ga/ZSM-5 made by using GaOx-encapsulated CNTs.

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