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1.
Jatuporn Wittayakun Pongtanawat Khemthong Sanchai Prayoonpokarach 《Korean Journal of Chemical Engineering》2008,25(4):861-864
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 °C. 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. 相似文献
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3.
P. Khemthong W. Klysubun S. Prayoonpokarach F. Roessner J. Wittayakun 《Journal of Industrial and Engineering Chemistry》2010,16(4):531-538
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 the mono- and bimetallic catalyst with Co loading of 1 wt.% was not reducible whereas 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. 相似文献
4.
The electric field responses of two types of weakly nonlinear dielectric composites consisting of elliptic cylindrical inclusions, one with identical shape and the another with distributed shapes, randomly embedded in the linear host media in the dilute limit are investigated. The dielectric property of the inclusions is that the relation between the displacement (D) and electric (E) fields obey the form D = ?E + χ∣E∣βE where β is a nonlinear integer exponent and ? ? χ∣E∣β. By using the decoupling approximation, the effective nonlinear susceptibility (χe) is determined and analyzed for varying the aspect ratios and the shape distribution parameters for the composites with identical and distributed inclusion shapes, respectively. In addition, the exact analytic result of χe for the elliptical composites with distributed inclusion shapes for the case of β = 2 is derived in this article. 相似文献
5.
Kitirote Wantala Pongtanawat Khemthong Jatuporn Wittayakun Nurak Grisdanurak 《Korean Journal of Chemical Engineering》2011,28(11):2178-2183
0.1 Fe/Ti mole ratio of Fe-TiO2 catalysts were synthesized via solvothermal method and calcined at various temperatures: 300, 400, and 500 °C. The calcined
catalysts were characterized by XRD, N2-adsorption-desorption, UV-DRS, 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-TiO2 calcined at 400 °C showed the highest photocatalytic activity on degradation of alachlor with assistance of 30 mM H2O2 at pH 3 under 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. 相似文献
6.
The evaporation heat transfer coefficient and pressure drop of R-410A flowing through a horizontal aluminium rectangular multiport mini-channel having 3.48 mm hydraulic diameter are experimentally investigated. The test runs are performed at mass flux ranging between 200 and 400 kg/m2 s. The heat fluxes are between 5 and 14.25 kW/m2 and the saturation temperatures range between 10 and 30 °C. The pressure drop across the test section is directly measured by a differential pressure transducer. The effects of the imposed wall heat flux, mass flux, vapour quality, and saturation temperature on the evaporation heat transfer and pressure drop are also discussed. The results from the present experiment are compared with those obtained from the existing correlation. New correlations for the evaporation heat transfer coefficient and pressure drop of R-410A flowing through a multiport mini-channel are proposed for practical applications. 相似文献
7.
Nurak?GrisdanurakEmail author Siriluk?Chiarakorn Jatuporn?Wittayakun 《Korean Journal of Chemical Engineering》2003,20(5):950-955
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 873 K for 4 hours. RH-MCM-41 possessed surface
area around 750-1,100 m2/g with a uniform pore size with an average diameter of 2.95 nm, narrow range of pore distribution and somewhat hexagonal
structure, similar to properties of parent MCM-41. The adsorption of CC14 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. 相似文献
8.
Jatuporn?WittayakunEmail author Nurak?Grisdanurak Gerald?Kinger Hannelore?Vinek 《Korean Journal of Chemical Engineering》2004,21(5):950-955
Adsorption behavior of NO and CO as well as their reaction was investigated on cobalt supported zeolite beta (Co/BEA) prepared
by solid-state ion exchange (SSIE) and by impregnation (IMP). By temperature programmed desorption (TPD), two NO desorption
peaks at 100 and 260‡C were observed over both SSIE and IMP catalysts with complete desorption after 450‡C. CO desorbed from
SSIE catalyst between 50 and 200‡C. In the same temperature interval negligible CO2 desorption was observed, most likely due to reaction of CO with trace of cobalt oxides. Over IMP catalysts, desorption of
CO2 was found mainly at 500‡C. By comparing CO TPD profiles from physical mixtures of cobalt oxides and HBEA, SSIE catalysts
most likely contained cobalt cations in zeolite exchange position while IMP catalysts had cobalt in oxidic forms. The SSIE
catalysts were active for NO reduction at 400 and 500‡C with a maximum conversion at 500‡C. However, the activity in the presence
of water and oxygen was low. Water might inhibit the reaction by blocking active sites for NO and CO, while oxygen reacted
with CO to form carbon dioxide. The activity of SSIE was better than IMP catalyst. 相似文献
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Effect of dietary fat type on meat quality and fatty acid composition of various tissues in growing-finishing swine 总被引:1,自引:0,他引:1
Mitchaothai J Yuangklang C Wittayakun S Vasupen K Wongsutthavas S Srenanul P Hovenier R Everts H Beynen AC 《Meat science》2007,76(1):95-101
Thirty-six castrated male growing pigs were used to study the effect of dietary beef tallow (BT) versus sunflower oil (SO) on meat quality and fatty acid composition of various tissues. The diets used contained either 5% (w/w) of the variable fat source. The fat type had no significant effect on carcass traits (carcass weight, back-fat thickness, fat-lean ratio) and meat quality (colour, pH(1), pH(U), drip losses, cooking losses, shear force, sacromere length, loin moisture, loin marbling). The diet with SO instead of BT significantly increased the incorporation of polyunsaturated fatty acids in adipose tissues, loin and liver at the expense of the sum of saturated and monounsaturated fatty acids. In erythrocytes, the diet containing SO raised the contents of saturated and polyunsaturated fatty acids and lowered that of monounsaturated fatty acids. In particular, the SO diet produced an increase in the content of linoleic acid (C18:2n-6) in the various tissues. It is concluded that feeding a diet with SO instead of BT altered the fatty acid composition of tissues without simultaneously affecting various characteristics of meat quality. 相似文献