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Synthesis and characterization of zeolite NaY from rice husk silica
Jatuporn Wittayakun,Pongtanawat Khemthong,Sanchai Prayoonpokarach 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4
Rice husk silica (RHS) in amorphous phase with 98% purity was prepared from a waste rice husk from rice milling by leaching with hydrochloric acid and calcination. The RHS was used effectively as a silica source for the synthesis of zeolite Y in sodium form (NaY). The zeolite in pure phase was obtained from a two-step synthetic route in which the starting gels were mixed, aged for 24 h at room temperature and crystallized for 24 h at 90 oC. The diameter of single crystal particles from a scanning electron microscope was approximately 1.0 μm, whereas the average particle diameter from laser diffraction particle size analyzer was approximately 10 μm because of the agglomeration of small crystals. Longer crystallization time in this route resulted in a mixed phase containing NaY and zeolite P in sodium form (NaP). In addition, a one-step synthetic route (no aging) was studied and the product was also a mixed phase zeolite
Mordenite modification and utilization as supports for iron catalyst in phenol hydroxylation
Sittichai Kulawong,Jatuporn Wittayakun,Sanchai Prayoonpokarach,Arthit Neramittagapong 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.2
The goal of this work was to synthesize mordenite in sodium form (NaMOR) using rice husk silica;modify by leaching with acid, base or both; and use the obtained zeolites as supports for iron (Fe)catalysts in phenol hydroxylation. All MOR zeolites were characterized by X-ray diffraction (XRD),nitrogen adsorption/desorption and the Si/Al ratios were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The influence of zeolite modification to the phenol hydroxylation was also studied. All modified zeolites still exhibited MOR phase with higher surface area than that of the parent NaMOR. Only the sample leached by acid and base (ABMOR) showed a significant change in adsorption–desorption isotherm from type I to type IV, a characteristic of mesoporousmaterials. The major forms of Fe (5 wt.%) in all catalysts confirmed by XRD and X-ray Absorption Near Edge Structure (XANES) were Fe2O3. Because mesopores were generated in ABMOR to facilitate diffusion of reactants, the fastest reaction was obtained on Fe/ABMOR catalyst. The conversion was also highest on this catalyst probably because Fe was dispersed on the support with the highest surface area. However, the presence of mesopores did not improve the selectivity and the products observed were catechol and hydroquinone.
Grisdanurak, Nurak,Chiarakorn, Siriluk,Wittayakun, Jatuporn 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.5
The adsorption of trichloroethylene (TCE), tetrachloroethylene (PCE), and carbon tetrachloride was studied over our synthesized mesoporous material, MCM-41, from rice husk silica source, abbreviated as RH-MCM-41. More than 99% silica for RH-MCM-41 synthesis was extracted from rice husk under refluxing in HBr solution and then calcined at 873K for 4 hours. RH-MCM-41 possessed surface area around 750-1,100 ㎡/g with a uniform pore size with an average diameter of 2.95 ㎚, narrow range of pore distribution and somewhat hexagonal structure, similar to properties of parent MCM-41. The adsorption of CCl₄ to RH-MCM-41 was stronger than that of TCE and PCE. The adsorption capacity of RH-MCM-41 for CVOCs (chlorinated volatile organic compounds) was higher than commercial mordenite and activated carbons.
Nuttinee Supamathanon,Sanchai Prayoonpokarach,Jatuporn Wittayakun 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.2
Jatropha oil was extracted from seeds of Jatropha Curcas cultivated in Nakhon Ratchasima, Thailand and analyzed by various methods to determine its composition and properties. It was used as a feedstock to produce biodiesel via transesterification over heterogeneous catalysts consisting of potassium supported on NaY (K/NaY) with potassium loading of 4, 8 and 12 wt%. The catalysts were prepared by impregnation a buffer solution of potassium on NaY to prevent collapses of the zeolite structure. The transesterification was primarily monitored by thin layer chromatography and products from the most suitable condition were further analyzed by gas chromatography. The catalyst with 12 wt% of potassium loading provided the optimum biodiesel yield of 73.4% under the reaction time of 3 h, the reaction temperature of 65 8C and methanol to oil molar ratio of 16:1.
Mitchaothai, J.,Everts, H.,Yuangklang, C.,Wittayakun, S.,Vasupen, K.,Wongsuthavas, S.,Srenanul, R.,Hovenier, R.,Beynen, A.C. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.7
The influence of dietary beef tallow (BT) versus sunflower oil (SO) on meat quality and apparent digestibility and deposition of individual fatty acids in the whole carcass was investigated in pigs fed diets containing either BT or SO. The diets contained equal amounts of energy in the form of the variable fats and were fed on an iso-energetic, restricted basis. Crude fat in the SO diet was better digested (p<0.001) than in the BT diet. The dietary fat type had no effect on growth performance, physical properties of the carcass and meat quality. The pigs fed the BT diet showed lower (p<0.001) apparent digestibilities for palmitic and linoleic acid, but those of oleic and ${\alpha}$-linolenic acid were not affected. The ratio of deposition in the carcass to intake of digestible fatty acids for the whole feeding period was decreased (p<0.01) for oleic and linoleic acid in pigs fed the SO diet. The pigs fed the SO diet instead of the BT diet had a lower (p<0.05) deposition:intake ratio for mono-unsaturated fatty acids. The calculated minimum de novo synthesis of saturated fatty acids was increased for the SO diet, but that of mono-unsaturated fatty acids was not different. In conclusion, the iso-energetic replacement of BT by SO had a marked impact on the fatty acid composition of tissues, but did not affect carcass and meat quality traits in spite of the marked difference in the deposition of linoleic acid in adipose tissues, loin muscle and the whole body. In addition, it became clear that the type of dietary fat had marked, specific effects on the synthesis and oxidation of fatty acids.
Visible light-irradiated degradation of alachlor on Fe-TiO_2 with assistance of H_2O_2
Kitirote Wantala,Nurak Grisdanurak,Pongtanawat Khemthong,Jatuporn Wittayakun 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.11
0.1 Fe/Ti mole ratio of Fe-TiO_2 catalysts were synthesized via solvothermal method and calcined at various temperatures: 300, 400, and 500 ℃.The calcined catalysts were characterized by XRD, N_2-adsorption-desorption, UVDRS,XRF, and Zeta potential and tested for photocatalytic degradation of alachlor under visible light. The calcined catalysts consisted only of anatase phase. The BET specific surface area decreased with the calcination temperatures. The doping Fe ion induced a red shift of absorption capacity from UV to the visible region. The Fe-TiO_2 calcined at 400 ℃ showed the highest photocatalytic activity on degradation of alachlor with assistance of 30 mM H_2O_2 at pH 3under visible light irradiation. The degradation fitted well with Langmuir-Hinshelwood model that gave adsorption coefficient and the reaction rate constant of 0.683 L mg^−1 and 0.136 mg/L·min, respectively.
Sirinuch Loiha,Karin Fottinger,Katrin Zorn,Wantana Klysubun,Gunter Rupprechter,Jatuporn Wittayakun 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.6
This work focused on the preparation, characterization and catalytic performance of a bimetallic platinum–palladiumcatalyst for toluene hydrogenation. A catalyst with 3 wt% loading of each metal was prepared by co-impregnation on zeolite beta in proton form and denoted as 3Pt3Pd/HBEA. The structure of HBEA was retained after catalyst preparation and the metal occupied strong acidic sites of the zeolite. Compared to monometallic 3Pt/HBEA, the 3Pt3Pd/HBEA exhibited smaller Pt particle size due to better dispersion on the support. The catalytic performance of the bimetallic catalyst at various temperatures indicated that the presence of Pd enhanced toluene hydrogenation of Pt catalyst at high temperature. The most suitable temperature for toluene hydrogenation on 3Pt3Pd/HBEA was 150 8C for which a complete toluene conversion was obtained with methylcyclohexane as the only product.
Characteristics and photocatalytic degradation of methyl orange on Ti-RH-MCM-41 and TiO2/RH-MCM-41
Surachai Artkla,Kitirote Wantala,Bang-orn Srinameb,Nurak Grisdanurak,Wantana Klysubun,Jatuporn Wittayakun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6
Our purpose was to synthesize, characterize and test photodegradation of methyl orange on two catalysts containing 10 wt% titanium supported on mesoporous MCM-41 synthesized with rice husk silica. The first catalyst was Ti-RH-MCM-41 prepared by adding tetrabutyl orthotitanate (TBOT) in a synthetic gel of RH-MCM-41, and the second catalyst was TiO2/RH-MCM-41 prepared by grafting TBOT on the preformed RH-MCM-41. The mesoporous structures were observed on both catalysts and they had surface area of 1,073 and 1,006 ㎡/g. The Ti in Ti-RHMCM- 41 was in the form of Ti(IV) with tetrahedral geometry residing in the mesoporous structure. This form was less active for photodegradation of methyl orange than the other one. The Ti in TiO2/RH-MCM-41 was anatase titania with octahedral geometry located outside the mesoporous framework. This form was more an active phase for the photodegradation and the reaction parameters on this catalyst were further investigated. The optimum catalyst weight to methyl orange volume ratio was 5 g/L and the optimum initial concentration of the dye was 2.0 ppm. The degradation rate obeyed pseudo-first order and the adsorption of methyl orange on TiO2/RH-MCM-41 obeyed Langmuir isotherm.
P. Khemthong,W. Klysubun,S. Prayoonpokarach,F. Roessner,J. Wittayakun 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.4
This work investigated reducibility of cobalt species in monometallic Co/NaY and bimetallic CoPt/NaY catalysts with various Co loading (1, 6 and 10 wt.%) and fixed Pt loading (1 wt.%). The form and environment of Co species after reduction was determined by X-ray absorption spectroscopy including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)spectroscopies. The cobalt species in themono- and bimetallic catalyst with Co loading of 1 wt.% was not reduciblewhereas those with Co loading of 6 and 10 wt.% were partially reduced. The extent of reduction increased with Co loading and enhanced by the presence of Pt. Catalytic performance for n-butane hydrogenolysis mono- and bimetallic catalysts were compared. The higher extent of Co reduction in 6CoPt/NaY and 10CoPt/NaY resulted in higher conversions than the monometallic counterpart. Sequential hydrogenolysis was favored on the monometallic catalysts because methane was the only product. The presence of Pt suppressed such reaction resulting in ethane and propane. The effect of Pt on such effect was most prominent in 6CoPt/NaY.