Sooknoi, Tawan

Preferred name

Sooknoi, Tawan

Alternative Name

Sooknoi, T.

Main Affiliation

School of Science

tawan.so@kmitl.ac.th

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Improved selectivity, response time and recovery time by [0 1 0] highly preferred-orientation silicalite-1 layer coated on SnO2 thin film sensor for selective ethylene gas detection
(2010-01-29)
Jadsadapattarakul, Damrongsak
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Thanachayanont, Chanchana
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Nukeaw, Jiti
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Sooknoi, Tawan
In this work, sensing response, response time and recovery time for selective ethylene gas detection were improved by coating a layer of [0 1 0] highly preferred-orientation silicalite-1 polycrystals on SnO<inf>2</inf> thin film sensors. The sensors were prepared by primarily depositing SnO<inf>2</inf> on borosilicate glass substrates using ultrasonic spray pyrolysis technique. Conventional and [0 1 0] preferred orientations of silicalite-1 layers were then directly coated on the SnO<inf>2</inf> thin film sensors by hydrothermal crystallization technique with different gel compositions. The silicalite-1/SnO<inf>2</inf> thin film sensors were calcined at 550 °C in dry air. The crystal structure and surface morphology of SnO<inf>2</inf> and silicalite-1 layers were characterized by XRD and SEM techniques. XANES and TPR were used to verify oxidation state and reduction temperature of the SnO<inf>2</inf> thin film sensors, respectively. The interaction of C<inf>2</inf>H<inf>4</inf> and H<inf>2</inf>O with silicalite-1 was determined by TPD. The sensing performances, such as selectivity, dynamic range, response time and recovery time were evaluated for the C<inf>2</inf>H<inf>4</inf> and H<inf>2</inf>O. The results showed that the incorporated silicalite-1 layers readily improve the C<inf>2</inf>H<inf>4</inf> selectivity and dynamic range by preferential adsorption of C<inf>2</inf>H<inf>4</inf> molecules on the silicalite-1 filtering layers. The response time and recovery time for the [0 1 0] highly preferred-orientation silicalite-1/SnO<inf>2</inf> thin film sensor (t<inf>90%</inf>, 14 and 144 s) were shorter than those of the conventional one (t<inf>90%</inf>, 25 and 208 s). It is suggested that the [0 1 0] preferred-orientation silicalite-1, with a pore direction perpendicular to SnO<inf>2</inf> thin film surface, can accelerate the molecular diffusion and reduce the diffusion pathway of ethylene to the sensing film. © 2009 Elsevier B.V.
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Selective hydrodeoxygenation of bio-oil derived products: Ketones to olefins
(2015-07-01)
Witsuthammakul, Ayut
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Sooknoi, Tawan
The hydrodeoxygenation (HDO) of various ketones (acetone, methyl ethyl ketone and cyclohexanone) to olefins via hydrogenation-dehydration was conducted in a fixed bed reactor at 373-573 K under H<inf>2</inf>. A ketone can be hydrogenated over the metal function to an alcohol intermediate that is subsequently dehydrated to an olefin over the acidic function. A preliminary study on hydrogenation of acetone to 2-propanol over metal/SiO<inf>2</inf> catalysts (Cr, Fe, Co, Ni, Cu and Pd) shows that Ni and Cu are active at >373 K. Although Ni possesses an activity higher than that of Cu, it promotes olefin hydrogenation and alcohol hydrogenolysis at >473 K. Hydrogenolysis of alcohol intermediate is suppressed over the Ni-Cu alloy catalyst. An optimum conversion with 100% selectivity to alcohol, can be obtained at 448 and 473 K for Ni and Cu, respectively. The dehydration of 2-propanol to propylene over proton zeolites (ZSM-5, Y, Mordenite and β) can be achieved at >398 K. The zeolites with three-dimensional pore structure (β and Y) provide relatively higher activity (>90% conversion). However, a bimolecular dehydration to ether is also promoted. Only HZSM-5 shows excellent selectivity to propylene (98%). Hydrodeoxygenation of ketones was tested with (i) a double bed of 5%Ni/SiO<inf>2</inf> and HZSM-5 (Si/Al ∼ 13), (ii) a physical mixed bed of 5%Cu/SiO<inf>2</inf> and HZSM-5 (Si/Al ∼ 13) and (iii) a bi-functional catalyst of 5%Cu/HZSM-5 (Si/Al ∼ 250). It was found that high alkene selectivity was readily obtained at 448 K. While, over the physical mixed bed and bi-functional catalyst, the hydrogenation activity was enhanced as the alcohol intermediate was removed from the system. The reactivity of the ketone depends on its adsorption on the metal surface and steric hindrance, i.e. acetone > cyclohexanone > methyl ethyl ketone.
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Effect of cobalt complex precursors on reactivity of cationic cobalt catalysts: Cyclohexane dehydrogenation
(2019-05-10)
Choojun, Kittisak
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Worathanaseth, Arucha
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Kuhatasanadeekul, Satu
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Kurato, Teeraporn
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Ketaniruj, Supanut
Effect of the cobalt precursors, including [Co(bipy)<inf>3</inf>](NO<inf>3</inf>)<inf>2</inf>, [Co(NH<inf>3</inf>)<inf>5</inf>Cl]Cl<inf>2</inf>, [Co(NH<inf>3</inf>)<inf>6</inf>]Cl<inf>3,</inf> and [Co(en)<inf>2</inf>Cl<inf>2</inf>] Cl, on reactivity of the cationic Co/SiO<inf>2</inf> prepared by strong electrostatic adsorption (SEA) was investigated for the dehydrogenation of cyclohexane as a model reaction. According to the charge density of the cobalt complex, highly dispersed Co2+ species and/or Co3+ oxide can be obtained on the silica surface. The dehydrogenation activity is in the order of Co/SiO<inf>2</inf> catalysts prepared by [Co(bipy)<inf>3</inf>](NO<inf>3</inf>)<inf>2</inf> > [Co(NH<inf>3</inf>)<inf>5</inf>Cl]Cl<inf>2</inf> > [Co(NH<inf>3</inf>)<inf>6</inf>]Cl<inf>3</inf> > [Co(en)<inf>2</inf>Cl<inf>2</inf>] Cl, correlating to the Co2+ content of the final catalysts. The cationic cobalt catalysts are more active than the pre-reduced one. Although metallic cobalt is found to be less active, the activity of cationic cobalt catalyst is enhanced under H<inf>2</inf> flow, presumably due to the formation of cobalt hydride intermediate. The inter-conversion of Co2+/cobalt hydride intermediate is readily reversible and regulated by presence of hydrogen.
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Improvement of water vapor permeability of LLDPE/EVA film with zeolite A as filler
(2017-01-01)
Rukchonlatee, Suparat
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Jaisomboon, Nattarika
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Sooknoi, Tawan
In this work, water vapor permeability of linear low density polyethylene (LLDPE)/ethylene vinyl acetate copolymer (EVA) film is improved by incorporation of zeolite A as filler (0-25%wt) for prolonging shelf-life of fresh produces. All films were characterized by SEM, DSC, tensile testing, contact angle measurement and tested for water vapor permeability (WVP). The shelf-life of Bird's eye chili in the film samples was also tested at 10°C for 21 days. It was found that zeolite A particles were virtually dispersed in EVA phase. Accordingly, crystallinity and tensile properties of LLDPE/EVA/Zeolite A films is independent to zeolite loading. Despite, when zeolite loading was increased, the dispersion became low. The film's wetting behavior was enhanced by increasing zeolite content in the LLDPE/EVA/Zeolite A films. The observed increase in the film's polarity significantly enhances the WVP. Therefore, less water condensed can be found inside the package made with LL80E20Ze25 film, as compared to LLDPE or LLDPE/EVA film. The LL80E20Ze25 also possesses comparable tensile properties to the commercial LLDPE film and hence can used as packaging for extending the shelf-life of fresh produces.
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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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Production of liquid fuel from palmitic acid over nanocrystalline CeO2-based catalysts with minimal use of H2
(2017-01-01)
Maluangnont, Tosapol
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Dararat, Chalinee
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Kulrat, Teerapong
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Soontontaweesub, Surachet
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Anothaiwalaikul, Thitima
The deoxygenation of palmitic acid into diesel-range hydrocarbons can be promoted over nanocrystalline ceria-based catalysts under atmospheric N<inf>2</inf> or 10% H<inf>2</inf>/N<inf>2</inf> in a fixed-bed flow reactor at 400 °C. Oxygen vacancy sites are active for ketonization of palmitic acid to C<inf>31</inf> ketone and also subsequent cracking of the formed ketone to hydrocarbons. The 22–31% selectivity of C<inf>9</inf> to C<inf>17</inf> liquid hydrocarbons can be achieved at 100% palmitic acid conversion. The deoxygenation under N<inf>2</inf> can be facilitated, presumably by hydrogen transfer from coke precursors. Catalytic activity of ceria-based catalysts can be tuned by pretreatment conditions, type of a carrier gas, or lattice modification.
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Selective ethylene-permeable zeolite composite double-layered film for novel modified atmosphere packaging
(2011-01-01)
Monprasit, P.
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Ritvirulh, C.
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Sooknoi, T.
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Rukchonlatee, S.
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Fuongfuchat, A.
The composite double-layered films, for the packaging application of postharvest fruits and vegetables, were prepared by laminating low-density polyethylene (LDPE) and poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) modified with zeolite ZSM-5. The film was characterized by scanning electron microscope and differential scanning calorimeter and tested for permeation of ethylene (C<inf>2</inf>H<inf>4</inf>), oxygen (O<inf>2</inf>), carbon dioxide (CO<inf>2</inf>), and water vapor. It was found that the C<inf>2</inf>H <inf>4</inf> permeability of the films was improved because of an enhanced adsorption of C<inf>2</inf>H<inf>4</inf> by the incorporated zeolite (0-10 wt%). The preconcentrated layer (zeolite/SEBS) leads to a higher C<inf>2</inf>H <inf>4</inf> concentration gradient across the film. Moreover, the high dispersion of zeolite increased the C<inf>2</inf>H<inf>4</inf> permeation. When compared with O<inf>2</inf> and CO<inf>2</inf>, the composite films were more selective to C<inf>2</inf>H<inf>4</inf>. However, the C<inf>2</inf>H<inf>4</inf> permeation decreased in the presence of O<inf>2</inf> because of a competitive adsorption. In addition, the films possessed appreciate tensile properties for packaging application. Copyright © 2009 Society of Plastics Engineers.
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Surface and interlayer base-characters in lepidocrocite titanate: The adsorption and intercalation of fatty acid
(2016-06-01)
Maluangnont, Tosapol
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Arsa, Pornanan
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Limsakul, Kanokporn
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Juntarachairot, Songsit
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Sangsan, Saithong
While layered double hydroxides (LDHs) with positively-charged sheets are well known as basic materials, layered metal oxides having negatively-charged sheets are not generally recognized so. In this article, the surface and interlayer base-characters of O2- sites in layered metal oxides have been demonstrated, taking lepidocrocite titanate K<inf>0.8</inf>Zn<inf>0.4</inf>Ti<inf>1.6</inf>O<inf>4</inf> as an example. The low basicity (0.04 mmol CO<inf>2</inf>/g) and low desorption temperature (50-300 °C) shown by CO<inf>2</inf>- TPD suggests that O2- sites at the external surfaces is weakly basic, while those at the interlayer space are mostly inaccessible to CO<inf>2</inf>. The liquid-phase adsorption study, however, revealed the uptake as much as 37% by mass of the bulky palmitic acid (C<inf>16</inf> acid). The accompanying expansion of the interlayer space by ~0.1 nm was detected by PXRD and TEM. In an opposite manner to the external surfaces, the interlayer O2- sites can deprotonate palmitic acid, forming the salt (i.e., potassium palmitate) occluded between the sheets. Two types of basic sites are proposed based on ultrafast 1H MAS NMR and FTIR results. The interlayer basic sites in lepidocrocite titanate leads to an application of this material as a selective and stable two-dimensional (2D) basic catalyst, as demonstrated by the ketonization of palmitic acid into palmitone (C<inf>31</inf> ketone). Tuning of the catalytic activity by varying the type of metal (Zn, Mg, and Li) substituting at TiIV sites was also illustrated.
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Condensation reactions of propanal over CexZr 1-xO2 mixed oxide catalysts
(2010-09-15)
Gangadharan, Anirudhan
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Shen, Min
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Sooknoi, Tawan
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Resasco, Daniel E.
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Mallinson, Richard G.
Vapor phase condensation reactions of propanal were investigated over Ce<inf>x</inf>Zr<inf>1-x</inf>O<inf>2</inf> mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures. Several operating parameters were investigated. These included the type of carrier gas used (H<inf>2</inf> or He) and the incorporation of acids and water in the feed. Propanal is converted to higher carbon chain oxygenates on Ce <inf>x</inf>Zr<inf>1-x</inf>O<inf>2</inf> by two pathways, aldol condensation and ketonization. The major products of these condensation reactions include 3-pentanone, 2-methyl-2-pentenal, 2-methylpentanal, 3-heptanone and 4-methyl-3-heptanone. It is proposed that the primary intermediate for the ketonization path is a surface carboxylate. The presence of acids in the feed inhibits the aldol condensation pathway by competitive adsorption that reduces the aldehyde conversion. Water also promotes ketonization and inhibits aldol condensation by increasing the concentration of surface hydroxyl groups that enhance the formation of surface carboxylates with the aldehyde. Hydrogen enhances cracking and production of light oxygenates and hydrocarbons. The light oxygenates may in turn be reincorporated into the reaction path, giving secondary products. However, the hydrocarbons do not react further. Analysis of the fresh and spent catalysts by XPS showed varying degrees of reduction of the oxide under different operating conditions that were consistent with the reaction results. Changing the proportion of the parent oxides showed that increased Zr favored formation of aldol products while increased Ce favored ketonization. This occurs by shifting the balance of the acid-base properties of the active sites. © 2010 Elsevier B.V.
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Aromatization of cyclopentane over ZSM-5 catalysts: A proposal of reaction pathway
(2012-06-19)
Peamaroon, N.
;
Sooknoi, T.
The conversion of cyclopentane over HZSM-5 and GaZSM-5 was studied at 500-600°C in a fixed bed flow reactor. The reaction over HZSM-5 showed that cyclopentane was first cracked to liquified petroleum gas (LPG) that consecutively aromatized to BTX and C<inf>9+</inf> aromatics. While over GaZSM-5, cyclopentane preferred to oligomerize to larger intermediate namely cyclic hydrocarbon pool that could be converted to C<inf>9+</inf> aromatics and then cracked to benzene toluene and xylene and LPG. The higher activity was obtained by lowering Si/Al ratio of the parent HZSM-5 and increasing reaction temperature. © 2012 Taylor & Francis Group, LLC.

Sooknoi, Tawan

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