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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Surface hydrophobicity and catalytic performance of cerium incorporated HZSM-5 zeolite for conversion of bio-ethanol
(2024-05-01)
Ausavasukhi, Artit
;
Sooknoi, Tawan
Cerium incorporated HZSM-5 (CeHZSM-5) catalyst prepared by impregnation method was tested for aqueous ethanol conversion at 200–400 °C. The CeHZSM-5 catalyst was found to be very active (21.02 %Conversion), compared to the parent HZSM-5 catalyst (9.39 %Conversion), especially at low reaction temperatures (200 °C) and when fed with high water content (80 wt% ethanol). FTIR, FT-Raman, DR-UV, NH<inf>3</inf>-TPD, IPA-TPD, DSC and contact angle techniques reveal that the incorporation of cerium species into zeolites results in the acidity and hydrophilic/hydrophobic nature. Cerium species are thought to tend to migrate into ZSM-5 channels and associate with the zeolite framework. As a result, the net electrostatic charge decreases due to the presence of tetrahedral cerium atoms. Therefore, the CeHZSM-5 exhibits a hydrophobic character, compared to the parent one. The decrease in competitive adsorption of water versus ethanol feed at the Brønsted acid site may lead to an increase in CeHZSM-5 catalyst activity.
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Tubular EVA copolymer/SiO2/PEG composite membrane for CO2 removal from household biogas
(2025-03-01)
Watasit, Prachya
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Ausavasukhi, Artit
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Rukchonlatee, Suparat
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Sooknoi, Tawan
;
Ritvirulh, Chonlada
The fuel efficiency of household biogas is generally regulated by its CO<inf>2</inf> content (25%–50%). To improve its heating value, atmospheric CO<inf>2</inf> removal of household biogas using a polymeric membrane was attempted to avoid a complicated separation process. A tubular membrane of poly(ethylene-co-vinyl acetate), composed of 28% and 18% vinyl acetate (E28 and E18) modified with SiO<inf>2</inf> and polyethylene glycol (PEG), was fabricated by blown film extrusion. Model biogas containing CO<inf>2</inf>/CH<inf>4</inf> (40/60 v/v) was separated in an in-house continuous gas separation module, in which CO<inf>2</inf> was mainly permeated out of the tubular membrane at atmospheric pressure. Blending the E28 matrix with E18 (10 wt%) improves the membrane processability and inhibits the CH<inf>4</inf> permeation, leading to enhanced CO<inf>2</inf>/CH<inf>4</inf> selectivity (from ~2.3 to 2.9). Well-dispersed SiO<inf>2</inf> particles (0.5 wt%) increase the membrane modulus and suppress CH<inf>4</inf> loss. However, adding more SiO<inf>2</inf> (0.75–1.0 wt%) leads to higher total gas permeation flux with lower CO<inf>2</inf>/CH<inf>4</inf> selectivity due to particle agglomeration. Incorporation of PEG (0.5–1.5 wt%) increased the membrane polarity and CO<inf>2</inf> permeability. The CO<inf>2</inf>/CH<inf>4</inf> selectivity was also improved (~5.3), only up to 1.0 wt% PEG content. Highlights: Composite EVA/SiO2/PEG membrane separates CO<inf>2</inf>/CH<inf>4</inf> at atmospheric pressure. The concentration gradient across the membrane drives CO<inf>2</inf>/CH<inf>4</inf> permeation. Adding SiO<inf>2</inf> hinders CH<inf>4</inf> permeability and enhances CO<inf>2</inf>/CH<inf>4</inf> selectivity. Increasing PEG content enhances membrane polarity and interaction with CO<inf>2</inf>.
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Oxidation of tetrahydrofuran to butyrolactone catalyzed by iron-containing clay
(2015-01-01)
Ausavasukhi, Artit
;
Sooknoi, Tawan
Thermally treated iron-containing clay was used as a greener oxidation catalyst for the conversion of tetrahydrofuran (THF) to butyrolactone (BTL). Mild liquid phase reactions were tested at 50-66 °C using hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) as an oxidizing agent. XRD, TGA, ESR, DR-UV, and FTIR revealed the dislodged iron oxide species formed by treating at ≥500 °C. Formation of active oxidizing species on the surface occurs on contact the dislodged Fe(III) oxide with H<inf>2</inf>O<inf>2</inf>. Such active species can promote the oxidation of THF, giving high yield and selectivity of BTL, whereas the iron-containing clay treated at lower temperatures (<500 °C) perform Fenton-like oxidation with lower THF conversions and non-selective products. 2-Hydroxytetrahydrofuran (THF-2-ol) was primarily produced and further oxidized to BTL with a small amount of 4-hydroxybutyric acid as a minor product. Minimal H<inf>2</inf>O<inf>2</inf>/THF ratio of 1.0 is sufficient for the production of BTL. Deactivation can be observed presumably due to deposition of the products despite slight leaching of the active iron species.
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Reversible interconversion behavior of Ag species in AgHZSM-5: XRD, 1H MAS NMR, TPR, TPHE, and catalytic studies
(2008-07-31)
Ausavasukhi, Artit
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Suwannaran, Suratsawadee
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Limtrakul, Jumrus
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Sooknoi, Tawan
1H MAS NMR, XRD, TPR, TPHE (temperature-programmed hydrogen evolution) techniques, and catalytic characterization by ethanol conversion were employed to investigate the reducibility and reversible interconversion behavior of Ag species in Ag-modified HZSM-5 (3 wt.%). The samples were prepared by ion-exchange of ZSM-5 with AgNO<inf>3</inf> (aq). It was found that charge-balancing Ag cations in AgHZSM-5(Si/Al ∼11) and AgHZSM-5(Si/Al ∼28) can be readily reduced to "cationic Ag clusters" at ∼220 °C, while a higher temperature is required for the Ag species in AgHZSM-5(28) to be reduced to "metallic Ag clusters", as compared with that for AgHZSM-5(11). Both cationic and metallic Ag clusters formed can be reversibly conversed into charge-balancing Ag cations by the reaction with neighboring Brønsted acid sites (reversible interconversion). The metallic Ag clusters were found to be more resistant to the reversible interconversion than the cationic Ag clusters. Under hydrogen stream, the reduced Ag species could be preserved and "silver hydride" species were observed, together with the active Brønsted acid sites. This phenomenon is suggested to play a decisive role on the catalytic activity of AgHZSM-5 towards BTX formation in the presence/absence of hydrogen. © 2008 Elsevier B.V. All rights reserved.
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Synergistic effects of bimetallic Co-SnOx species in selective hydrogenation of methyl oleate: The crucial role of reduction characteristics
(2026-09-01)
Sooknoi, Tawan
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Thainoi, Suwimon
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Chanakha, Vichuda
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Ausavasukhi, Artit
This study investigates the catalytic performance of bimetallic Co-Sn catalysts supported on alumina (Al<inf>2</inf>O<inf>3</inf>) for the selective hydrogenation of methyl oleate to oleyl alcohol. A strategic sequential reduction methodology, employing sodium borohydride followed by thermal hydrogen treatment (NaBH<inf>4</inf>-H<inf>2</inf>), was utilized to precisely tune the catalytic activity and chemoselectivity. Catalysts reduced solely with hydrogen at 300 °C exhibited limited efficiency, primarily favoring the formation of oleic acid via hydrogenolysis, which is attributed to the prevalence of cobalt oxide species. In contrast, the CoSnBH/Al<inf>2</inf>O<inf>3</inf> catalyst synthesized via a strategic sequential reduction methodology demonstrated a markedly enhanced selectivity toward oleyl alcohol, achieving a maximum selectivity of 54.1% at 270 °C and 8 MPa. Comprehensive characterization and kinetic analyses revealed that the superior performance stems from the synergistic coexistence of metallic cobalt (Co0) and low-valent tin oxides (SnO<inf>x</inf>), which form a bimetallic interface that preferentially polarizes the C=O bond. The catalytic efficiency was found to be highly sensitive to the nature of the support, the Co/Sn atomic ratio, and the total metal loading. Notably, turnover frequency (TOF) analysis indicated that while increased loading improves conversion, it may lead to site agglomeration and a reduction in surface-active concentration. Mechanistically, we propose that the CoSnBH/Al<inf>2</inf>O<inf>3</inf> system facilitates a direct hydrogenation pathway to oleyl alcohol, effectively bypassing the formation of heavy ester intermediates typically reported in literature.
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Catalytic deoxygenation of benzaldehyde over gallium-modified ZSM-5 zeolite
(2009-11-15)
Ausavasukhi, Artit
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Sooknoi, Tawan
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Resasco, Daniel E.
The deoxygenation of benzaldehyde has been investigated over gallium-modified ZSM-5 catalysts. In the absence of H<inf>2</inf>, Ga/HZSM-5 catalyzes benzaldehyde decarbonylation resulting in benzene and CO. The active sites for this reaction are the strong Brønsted acid sites. In the presence of H<inf>2</inf>, the main product is toluene. It is believed that Ga cationic species (Ga+ / GaH<inf>2</inf>+) generated during H<inf>2</inf> reduction can promote the hydrogenation/hydrogenolysis reactions that give toluene and water. In the absence of H<inf>2</inf>, toluene can only be observed in transient experiments when the Ga/HZSM-5 catalysts are reduced. It is suggested that the GaH<inf>2</inf>+ species generated under H<inf>2</inf> play an important role in the hydrogenation/hydrogenolysis. However, they readily decompose to Ga+ in the absence of H<inf>2</inf>. The addition of water to the feed modifies the catalytic activity and selectivity of Ga/HZSM-5 catalysts. On the one hand, water generates additional Brønsted acid sites from the reaction of extra-framework Ga with chemisorbed water (GaO(OH)) and with defect hydroxyls of the zeolite framework (GaOHSi). These additional sites enhance the production of benzene but decrease the production of toluene, due to a decrease in the density of reduced Ga cationic species. © 2009 Elsevier Inc. All rights reserved.
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Catalytic deoxygenation of benzaldehyde over supported gallium catalysts
(2008-12-01)
Ausavasukhi, Artit
;
Resasco, Daniel E.
;
Sooknoi, Tawan
The deoxygenation of benzaldehyde was investigated over supported Ga catalysts as part of a program leading to the study of model reactions involving aldehydes, acids, furfurals, and oxygenated aromatics that may be present in pyrolysis oil (bio-oil). Ga/SiO<inf>2</inf> catalysts were prepared by impregnating precipitated SiO<inf>2</inf> supports with Ga(NO<inf>3</inf>) <inf>3</inf> solution. The reaction conditions, H<inf>2</inf> concentration, Ga content, and Ga dispersion in the catalysts were varied to investigate the effect of these parameters on activity, selectivity, and stability. TPR gave evidence for a partial reduction of Ga/SiO<inf>2</inf> in the range 500-750 °C. Increasing H<inf>2</inf> concentration (3-100%v/v) was found to enhance activity (∼50-90%) and toluene selectivity (40-75%). Reaction at low temperature (< 500 °C) leads to the formation of high molecular weight oxygenates and consequently rapid catalyst deactivation (< 2 h). In contrast, no benzaldehyde conversion can be observed over a physical mixture of Ga <inf>2</inf>O<inf>3</inf> and SiO<inf>2</inf>.
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Hydrothermal sulfonation of palm kernel shells to produce a carbon-based solid acid catalyst for the glycerol etherification
(2025-04-01)
Ausavasukhi, Artit
;
Sooknoi, Tawan
Carbon-based solid acid catalysts were successfully prepared by one-step hydrothermal sulfonation of palm kernel shells. Among the solid acids studied, the catalysts with acidity and hydrophobic/hydrophilic balance were found to be more selective and efficient catalytic systems for the conversion of glycerol to glycerol ethers. The stability of the carbon-based solid acid catalyst was confirmed by a regeneration test, which showed that no leaching of acid groups into solution occurs. In addition, the carbon-based solid acid catalyst prepared by one-step hydrothermal sulfonation at 160 °C exhibits good cyclability. The etherification of glycerol with tertiary butanol occurs in a truly heterogeneous process in the presence of such an acid carbon.
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Catalytic activity enhancement by thermal treatment and re-swelling process of natural containing iron-clay for Fenton oxidation
(2014-01-01)
Ausavasukhi, Artit
;
Sooknoi, Tawan
In this research, catalytic activity of the modified natural containing Fe-clay, Fenton-like catalyst, toward successful decolorization of methylene blue (MB) and degradation of phenol (PhOH) was demonstrated. Among the natural containing Fe-clay prepared only by thermal treatment, the sample treated at 500. °C provides a high Fenton oxidation activity presumably due to high number of available Fe active sites. However, the efficient use of treated natural containing Fe-clay is restricted due to the loss in BET surface area during thermal treatment process. Interestingly, modification by the thermal treatment and subsequent re-swelling cannot only generate the active Fe species, but also enhance the basal space that facilitates diffusion of the reagents toward the active sites within the clay layers. It is expected that the active Fe species formed and retained by thermal treatment and re-swelling process which is on the surface of the catalyst reacts with hydrogen peroxide and leads to the formation of active oxidant that remove the MB and PhOH.
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Tunable activity of [Ga]HZSM-5 with H2 treatment: Ethane dehydrogenation
(2014-01-01)
Ausavasukhi, Artit
;
Sooknoi, Tawan
Ethane dehydrogenation over [Ga]HZSM-5 catalyst were studied to probe activity of various gallium species (Ga<inf>2</inf>O<inf>3</inf>, GaO +, Ga+, and GaH<inf>2</inf>+) in a pulsed reactor. H<inf>2</inf>-TPR was used for characterizing the reducible Ga species. It was found that the activity of [Ga]HZSM-5 can be regulated by the H <inf>2</inf> treatment. Among the various Ga species, the H<inf>2</inf>- incorporated species (i.e. GaH<inf>2</inf>+) displays the highest dehydrogenation activity ( 55% conversion) under the H<inf>2</inf> stream. However, this so-called GaH<inf>2</inf>+ can readily decompose in the absence of H<inf>2</inf>, presumably to Ga+ that give a lower ethane conversion ( 30%). While the Ga oxide species, which may well be retained as isolated Ga<inf>2</inf>O<inf>3</inf> and exchangeable GaO+, provide the lowest dehydrogenation activity ( 25% conversion). The lower activity is observed with an increase in the Si/Al ratio of the host zeolite, suggesting that the active site is associated with the negative framework charge, presumably as a charge balancing cation (i.e. GaH<inf>2</inf>+, Ga+, GaO+). In addition, treatment with hydrogen and steam can readily disperse occluded Ga<inf>2</inf>O<inf>3</inf> into exchangeable Ga+ and GaO+, respectively. © 2013 Elsevier B.V.

Sooknoi, Tawan

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