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Dry-gel synthesis of Ti-beta for epoxidation of unsaturated fatty acid methyl esters (FAMEs)
(2026-09-01)
Yomthong, Krissanapat
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Saenluang, Kachaporn
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Soyphet, Asadawut
;
Ittisanronnachai, Somlak
;
Padchasri, Jintara
The Ti-beta was synthesized via a dry-gel conversion approach with the direct incorporation of titanium from titano-aluminosilicate nanobeads (Ti-SiAl-NB). At first, the Ti-SiAl-NB was prepared and employed as the precursor for zeolite crystallization. Powder XRD (PXRD) patterns confirm the amorphous nature of the nanobeads. These Ti-SiAl-NB precursors were subsequently converted to the Ti-beta zeolite via the dry-gel conversion approach. Structural characterization using PXRD, high-resolution TEM, and selected area electron diffraction (SAED) confirmed the formation of a beta zeolite framework, with dominant lattice planes indexed to (101) and (302). UV-vis DRS indicated that Ti existed as a tetrahedrally coordinated (TiIV) and non-framework Ti. Unfortunately, the as-synthesized Ti-beta exhibited a low catalytic activity in methyl oleate (MO) epoxidation, which is attributed to the prevalence of closed site TiIV [Ti(OSi)<inf>4</inf>] species that restrict substrate accessibility to active sites. To address this limitation, a post-synthetic treatment involving framework etching was applied to generate open site TiIV [Ti(OSi)<inf>3</inf>OH] species. As a result, MO conversion increased by approximately 2.73-fold, with epoxide selectivity up to 70%. Catalyst stability tests demonstrated sustained MO conversion of 65–72% and epoxide selectivity above 65% over several consecutive catalytic cycles. This work highlights a sustainable catalyst design strategy that combines the dry-gel conversion process with mild post-treatment to enhance active site accessibility and catalytic performance in the epoxidation of bulky molecules.
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Glass-sulfur composite cathodes: A new strategy for improving the performance of lithium-sulfur batteries
(2024-10-01)
Siriroj, Sumeth
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Padchasri, Jintara
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Montreeuppathum, Amorntep
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Sonsupap, Somchai
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Maensiri, Santi
In this study, we investigated the potential of glass-sulfur composites to improve lithium–sulfur battery (LSB) performance. Glass-sulfur composites were prepared by the precipitation method, and the effect of varying carbon black content was studied. The results showed that glass addition improved the battery performance due to the high ion-conductivity of its structural motif. The 75 % glass variant demonstrated the best results, in both the low carbon and high carbon cases. The cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS) measurements showed that glass-sulfur composites had lower resistivity than pure sulfur, which was beneficial for battery performance. The XANES analysis revealed that the incorporated glass interacted with and modified the properties of sulfur, leading to a higher proportion of sulfur in the -1 oxidation state (S−1). This suggests that the high proportion of S−1 phase benefitted battery capacity. Overall, glass-sulfur composites prepared using the precipitation method and incorporating a high content of carbon show promise as a novel and improved cathode material for LSBs.
2
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Customized electrospun multilayer composite polymer electrolytes: PEO-PAN-NbO2 nanofiber membrane for enhancing the performance of lithium-ion batteries
(2024-06-01)
Yonchai, Chutarat
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Kidkhunthod, Pinit
;
Siriroj, Sumeth
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Padchasri, Jintara
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Sonsupap, Somchai
Ground-breaking research into the development of a multilayer composite polymer electrolyte aims to enhance the safety associated with liquid electrolytes utilized in lithium batteries. The electrolyte consists of two outer layers made of electrospun poly(vinylidene fluoride) (PVDF) and a middle layer comprised of a fibrous membrane containing PEO, PAN-PEO, PEO-NbO<inf>2</inf>, and PAN-PEO-NbO<inf>2</inf>. The investigated PEO-PAN-NbO<inf>2</inf> system demonstrates a higher room temperature ionic conductivity of 2.451 × 10−1 mS cm−1 than that of single-phase electrolyte systems. Incorporating inorganic fillers such as NbO<inf>2</inf> into PEO polymer electrolytes, in conjunction with PAN copolymerization, significantly enhances ionic conductivity and amplifies surface area. Consequently, the utilization of these techniques that demonstrate increased polymer membranes leads to improved efficiency and security of solid-state electrochemical devices. The multilayer composite polymer electrolyte is created by continuous electrospinning, which allows for precise control and improves safety features.
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Synthesis and characterization of CH3NH3PbI3 and CH3NH3PbI(3-x)Clx perovskite solar cell materials
(2019-11-18)
Kamonpha, Phitsamai
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Padchasri, Jintara
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Rujirawat, Saroj
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Sukkha, Usa
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Kidkhunthod, Pinit
The emerging of perovskite solar cell has attracted many interests in the synthesis and characterization of hybrid perovskite materials related to methylammonium iodide (MAI) due to various promising properties. In this work, we found a faster way to synthesize hybrid perovskite CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> and CH<inf>3</inf>NH<inf>3</inf>PbI<inf>(3-x)</inf>Cl<inf>x</inf> (x = 0,1,2) powders from a different solvent in the preparation process of MAI precursor. In addition, it was found that in CH<inf>3</inf>NH<inf>3</inf>PbI<inf>(3-x)</inf>Cl<inf>x</inf> powders, as characterized by XRD and XAS, with a solid-state method employed Cl atoms cannot directly substitute for I in the perovskite (ABX<inf>3</inf>) structure.
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