Sooknoi, Tawan
Loading...
Preferred name
Sooknoi, Tawan
Alternative Name
Sooknoi, T.
Main Affiliation
Email
tawan.so@kmitl.ac.th
2 results
Now showing 1 - 2 of 2
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Activity enhancement by acetic acid in cyclohexane oxidation using Ti-containing zeolite catalyst(2002-07-10); Limtrakul, JumrasTitanium silicalite (TS-1) was hydrothermally crystallised from a titanosilicate gel. The solid material was characterised by XRD, IR, and SEM, and then used as a catalyst in the liquid phase oxidation of cyclohexane with hydrogen peroxide. The reaction was carried out for 6 h, at the temperature between 40 and 80 °C. It was found that a marked increase in the catalytic activity was observed in the reaction using acetic acid as the solvent, as compared to those using no solvent and methyl ethyl ketone. Further investigation was made on the cause of activity enhancement, and it was shown that acetic acid was readily oxidised to peracetic acid. This compound was believed to facilitate the complexation of the framework titanium active sites, and subsequently serve as a better oxidising agent, as compared to the original hydrogen peroxide. However, leaching of the titanium species was also observed in small amounts, from the reaction using acetic acid as the solvent. In the mechanistic point of view, there was an evidence suggesting that cyclohexanol might be a primary product from the cyclohexane oxidation, and can be consecutively re-oxidised to form cyclohexanone. It is noted that the direct oxidation from cyclohexane to cyclohexanone cannot be excluded. © 2002 Elsevier Science B.V. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Role of substrate's electrophilicity in base catalysis by zeolites: Alkylation of acetonitrile with methanol(2004-03-15); Dwyer, JohnThe role of substrate's electrophilicity in base catalysis was studied by competitive adsorption and catalytic alkylation of acetonitrile over basic zeolite catalysts. Methanol was used as alkylating agent, comparing with the side-chain alkylation of toluene. Solid base zeolite catalysts including CsNaX, CsNaY and CsNaEMT were prepared and modified by simple ion exchange and impregnating parent zeolites with caesium salt. Their physical and chemical characteristics were then determined by XRD, SEM and elemental analysis. Adsorption was studied by FTIR using a special in situ adsorption cell. The gas-phase catalytic reaction was carried in a down-flow microreactor and products from the reaction were analysed by on-line TCD-GC. Adsorption strength of the substrates was found to depend largely on their electrophilicity and basicity of the zeolite framework. The strong adsorption of acetonitrile on basic zeolite catalysts also leads to an increased alkylation activity, but reduces the decomposition of methanol to carbon monoxide and hydrogen. In addition to the reaction temperature, the competitive adsorption of acetonitrile and methanol predominantly effects on product selectivity, particularly the unsaturation/saturation ratio. Moreover, the excess caesium "clusters" present in the zeolite framework plays important role in both adsorption and alkylation of the substrates. Further investigation was made on stability of the catalysts and it was found that coke formation is small in base catalysis, as compared to those found in acid zeolites. FTIR reveals that the carbon deposits are composed mainly of high polar products and the catalysts can be readily regenerated without significant loss of catalytic activity. © 2003 Elsevier B.V. All rights reserved.