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98 results on '"Junkaew, Anchalee"'

15. Hydroxy and surface oxygen effects on 5-hydroxymethylfurfural oxidation to 2,5-furandicarboxylic acid on β-MnO2: DFT, microkinetic and experiment studies

Author

Tharat, Bunrat, primary, Ngamwongwan, Lappawat, additional, Seehamongkol, Theerada, additional, Rungtaweevoranit, Bunyarat, additional, Nonkumwong, Jeeranan, additional, Suthirakun, Suwit, additional, Faungnawakij, Kajornsak, additional, Chanlek, Narong, additional, Plucksacholatarn, Aunyamanee, additional, Nimsaila, Weerawan, additional, Prommin, Chanatkran, additional, and Junkaew, Anchalee, additional

Published
2023
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30. Roles of acidic sites in alumina catalysts for efficient d-xylose conversion to lactic acid

Author

Kiatphuengporn, Sirapassorn, primary, Junkaew, Anchalee, additional, Luadthong, Chuleeporn, additional, Thongratkaew, Sutarat, additional, Yimsukanan, Chakrit, additional, Songtawee, Siripit, additional, Butburee, Teera, additional, Khemthong, Pongtanawat, additional, Namuangruk, Supawadee, additional, Kunaseth, Manaschai, additional, and Faungnawakij, Kajornsak, additional

Published
2020
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33. Promoting Electrochemical Performance of Ti3C2O2MXene-Based Electrodes of Alkali-Ion Batteries via S Doping: Theoretical Insight

Author

Komen, Paratee, Ngamwongwan, Lappawat, Jungthawan, Sirichok, Junkaew, Anchalee, and Suthirakun, Suwit

Abstract

Ti3C2O2MXene has been proposed as a promising electrode material for alkali-ion batteries owing to its tunable physical and chemical properties without sacrificing the excellent metallic conductivity. However, it still suffers from low specific capacity due to its limited interlayer spacing, especially for a larger ion like sodium (Na). Sulfur doping was suggested as a viable strategy to improve the electrode’s storage performance. Herein, first-principles calculations and kinetic Monte Carlo (kMC) simulations were carried out to study the role of S doping on Li/Na intercalation. Based on experimental findings, two different doping sites, C (SC) and O (SO), with various S concentrations were reported and therefore used as the models in this study. Computations reveal that S doping on both C and O sites improves the electronic conductivity of the MXenes as their densities of states at the Fermi level are increased. In addition, the doped MXenes reveal an expanded lattice parameter in the normal direction, which agrees with experimental observations. However, only the SO-doped MXenes display an enlarged interlayer spacing, whereas doping at the C site only increases the layer thickness. The enlarged interlayer spacing in the SO-doped MXenes improves stabilities and transport kinetics of ion intercalation as indicated by their significantly lower insertion energies and diffusion barriers when compared with those of the pristine system. The kMC simulations were carried out to account for anisotropic diffusion in the SO-doped system. The obtained macroscopic properties of diffusion coefficients and apparent activation energies of the SO-doped system clearly confirm its superior transport kinetics. The estimated diffusion coefficients of Li(Na) are improved by 4(8) orders of magnitude upon SOdoping. A fundamental understanding of the role of S doping on the improved capacitive kinetics serves as a good guide for developing MXene-based electrode materials for Li- and Na-ion batteries.

Published
2021
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40. Enhancing V2O5Cathode Performance through Heterostructure Engineering with the Ti3C2O2MXene: A Computational Study

Author

Falun, Pariwut, Ngamwongwan, Lappawat, Singsen, Sirisak, Chotsawat, Maneerat, Komen, Paratee, Junkaew, Anchalee, and Suthirakun, Suwit

Abstract

V2O5has been proposed as a potential candidate for cathode materials of Li-ion batteries due to its high theoretical capacity and cost effectiveness, but it still suffers from high capacity fading and slow charge/discharge kinetics. To improve its electrochemical performance, heterostructure engineering with the Ti3C2O2MXene was computationally studied in this work. Herein, we carried out density functional theory calculations to study such effects on the electronic conductivity and Li intercalation kinetics of the cathode. We find that the formation of V2O5/Ti3C2O2is energetically favorable where the interaction at the interface is characterized as a weak van der Waals force. When the heterostructure is formed, electrons are transferred from Ti3C2O2to the V2O5surface where the charge accumulation induces small lattice distortion of the inner V2O5layer. Such charge accumulation and distortions, in turn, reduce the polaron–lattice interaction, leading to less stable polaron formation energy when compared with that of bulk V2O5(−0.20 vs −0.35 eV). This weakened polaron–lattice interaction enhances the polaron hopping kinetics as it correlates with smaller polaron hopping barriers. The higher hopping rate constant of the polaron alleviates the Li intercalation kinetics where the ion-coupled polaron movement, used to have polaron hopping as rate-limiting, is now ion diffusion-limiting with somewhat smaller barriers. The calculated average diffusion rate constant is slightly higher at the heterostructure (4.03 × 108s–1) than that in bulk V2O5(2.17 × 108s–1). Overall, it is suggested by our computational study that the improved electronic conductivity and ion diffusion kinetics could have their origin from the enhanced rate constant of polaron hopping at the interface of the heterostructure.

Published
2024
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46. Role of Sn promoter in Ni/Al2O3catalyst for the deoxygenation of stearic acid and coke formation: experimental and theoretical studiesElectronic supplementary information (ESI) available. See DOI: 10.1039/c9cy00268e

Author

Reangchim, Promporn, Saelee, Tinnakorn, Itthibenchapong, Vorranutch, Junkaew, Anchalee, Chanlek, Narong, Eiad-ua, Apiluck, Kungwan, Nawee, and Faungnawakij, Kajornsak

Abstract

The effect of Sn promoter on a Ni/γ-Al2O3catalyst towards the catalytic activity and catalyst stability viathe deoxygenation of stearic acid for the production of diesel-range hydrocarbons has been investigated herein. The decarboxylation (DCO2) and decarbonylation (DCO) of stearic acid using NiSn catalysts are proposed as the main pathways to produce n-heptadecane (n-C17H36), whereas hydrodeoxygenation (HDO) is a minor pathway, as confirmed by the high ratio of C17 to C18 alkanes. Moreover, the Sn promoter in Ni/γ-Al2O3significantly improves the catalyst reusability by enhancing the tolerance to the carbon-induced deactivation. This improvement was investigated by a density functional theory (DFT) calculation. The calculation results clearly explained that the Sn promoter can weaken the interaction between carbon and the catalyst surface, tending to prevent carbon segregation on the NiSn surface. This retardation of coke formation expands the life time of the catalyst, leading to a cost-effective approach for industrial processes.

Published
2019
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48. Theoretical guidance and experimental confirmation on catalytic tendency of M-CeO2 (M = Zr, Mn, Ru or Cu) for NH3-SCR of NO.

Author

Maitarad, Phornphimon, Jin Han, Namuangrukb, Supawadee, Liyi Shi, Chitpakdee, Chirawat, Meeprasert, Jittima, Junkaew, Anchalee, Kungwan, Nawee, and Dengsong Zhang

Subjects
CESIUM oxide, ADSORPTION kinetics, NITRIC oxide, STRUCTURE-activity relationships, AMMONIA, CHEMICAL synthesis, MANGANESE compounds, CATALYTIC reduction
Abstract

Herein, we demonstrate that the degrees of catalytic performance of M-CeO2-based catalysts (M=Mn, Cu, Ru or Zr) for an ammonia selective catalytic reduction (NH3-SCR) of nitric-oxide (NO) can be estimated using three theoretical terms; (i) an oxygen vacancy formation energy of a catalyst, (ii) an adsorption energy of NO and (iii) an adsorption energy of NH3. Those terms predict the trend of the catalytic performance as the order; Mn-CeO2 > Cu-CeO2 > Ru-CeO2 > Zr-CeO2 > CeO2. To verify the theoretical prediction, the catalysts were synthesized and tested their performances on the NH3-SCR of NO reaction. The normalized NO conversion rates at low temperatures (100-200°C) were measured for Mn-CeO2, Cu-CeO2, Ru-CeO2, Zr-CeO2 and CeO2 as 2.61-7.46, 1.30-6.82, 0.73-3.02, 0.81-3.31 and 1.55-2.33 mol s-1 m-2, respectively. In addition, a concept of a structure-activity relationship analysis shows a strong relationship between theoretical and experimental results. Consequently, an application of predicting the catalytic performance of catalysts from theoretical calculations prior the catalyst synthesis is useful in catalyst design and screening that can reduce time and cost. [ABSTRACT FROM AUTHOR]

Published
2017
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