Tantirungrotechai J.,Center for Catalysis
Microporous and Mesoporous Materials | Year: 2010
In this work, a series of Mg-Al mixed-metal oxides with Mg/Al ratios of 0.125-8 were synthesized via a sol-gel method using cetyltrimethylammonium bromide as a template. All oxide samples were characterized by XRD, XRF, IR, DTA-TGA, TEM, and N2 adsorption-desorption measurements. The phases of the Mg-Al mixed-metal oxides are the mixture of γ-Al2O3 and periclase (MgO) or the mixture of hydrotalcite (Mg6Al2CO3(OH)16·4H2O) and periclase depending on the Mg/Al ratio. The Mg-Al oxides have mesoporous structure with surface areas in the range of 120-270 m2/g. These oxides were also impregnated with KI to increase their base strength, and their activities for biodiesel production were tested via the transesterification of soybean oil with methanol. The KI impregnated Mg-Al mixed-metal oxide at Mg/Al ratio of 4:1 has base strength in the range of 9.8 ≤ pKBH+ ≤ 15 and, of all the catalysts tested, it is the most efficient catalyst for transesterification of soybean oil with methanol (>90% conversion after 8 h). © 2009 Elsevier Inc. All rights reserved.
Tantirungrotechai J.,Center for Catalysis |
Thepwatee S.,Center for Catalysis |
Yoosuk B.,National Metal and Materials Technology Center
Fuel | Year: 2013
Sr/MgO catalysts for biodiesel production were synthesized by the wet impregnation method. The formation of basic sites on the catalysts was investigated by thermal analysis, XRD, and Hammett indicator method. The calcination temperature and Sr/MgO molar ratio affect the structure as well as the catalytic activities. Among the catalysts tested, the best performance catalyst was prepared with a 0.10 Sr/MgO molar ratio and a calcination temperature of 600 °C. This catalyst had a base strength in the range of 15.0-18.4 and was also active for biodiesel synthesis at room temperature. The catalytic activities under various reaction variables were also evaluated. The biodiesel yield of 93% was achieved within 30 min from the transesterification of soybean oil with methanol at 65 °C using 5 wt.% loading of the synthesized catalyst and methanol to oil molar ratio of 12:1. © 2013 Elsevier Ltd. All rights reserved.
Mar W.W.,Mahidol University |
Somsook E.,Mahidol University |
Somsook E.,Center for Catalysis
Advanced Materials Research | Year: 2012
Sulfonic-functionalized carbon material derived from the incomplete carbonization of mungbean vermicelli was reported here as a catalyst for esterification of acetic acid. The catalyst with the highest activity (S BET = 18.1 m 2/g and acid site density of 1.53 mmol H +/g cat) was obtained by carbonization at 573 K and sulfonation at 373 K due to a feasible attachment of more - SO 3H groups to flexible carbon sheets compared to the other synthesized solids. Approximate 64% yield of methyl acetate was achieved over (2:1) molar ratio of methanol to acetic acid with 3 wt% of catalyst. From the economic outlook, this environmentally benign C-SO 3H catalyst could be a promising candidate for the esterification of high free fatty acid feedstocks reducing the production cost of biodiesel. © (2012) Trans Tech Publications.
Vanmathi G.,Center for Catalysis |
Senthilkumar U.P.,Orchid Chemicals and Pharmaceuticals Ltd |
Suresh B.,Center for Catalysis
International Journal of ChemTech Research | Year: 2014
The effect of electron beam irradiation on the catalyst, 10 % Pd./C in wet and micro powder form in effecting the heterogeneous catalysis reactions like hydrogenation of Alkyl aryl ketone and Diaryl ketone was studied. The irradiation doses of 40 kGy, 60 kGy, 100 kGy, 120 kGy, 200 kGy and 250 kGy were carried out on the catalysts and the time taken for the reaction were noted. The results show that with the increase in dosage the reaction time is found to decrease progressively with a net decrease of 45 - 70% relative to that of the original system without irradiation. This reduction in reaction time upon irradiation may be attributed to the increase in surface area as given by the BET surface area studies. The effect of electron beam irradiation on the catalyst was maintained even after 9 months of irradiation. © 2014, Sphinx Knowledge House. All rights reserved.
Chairam S.,Ubon Ratchathani University |
Sroysee W.,Ubon Ratchathani University |
Boonchit C.,Ubon Ratchathani University |
Kaewprom C.,Ubon Ratchathani University |
And 6 more authors.
International Journal of Electrochemical Science | Year: 2015
A nonenzymatic hydrogen peroxide (H2O2) sensor using a carbon paste electrode (CPE) modified with a composite consisting of silver nanoparticles (AgNPs), poly(o-aminobenzoic acid) (P(ABA)) and magnetite (Fe3O4) is reported. The AgNPs-P(ABA)-Fe3O4 composite was prepared under sonication and characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Electrochemical investigations indicated that a carbon paste electrode modified with AgNPs-P(ABA)-Fe3O4 exhibits excellent performance in the electrochemical reduction of H2O2 at an applied potential of -0.4 V versus Ag/AgCl (sat. 3.0 M KCl) in phosphate buffer solution. Under optimum condition, the calibration curve for H2O2 was obtained in a wide range of 5 μM to 5.5 mM with the limit of detection (LOD) of 1.74 μM (S/N = 3). The AgNPs-P(ABA)-Fe3O4 modified electrode has a good stability in practical conditions. In addition, the fabricated sensor was applied to determine H2O2 in real samples with good results. © 2015 The Authors.