Papers by Author: Jumat Salimon

Abstract: The aim of this study was to optimize the monoepoxidation process of linoleic acid obtained from Malaysian Jatropha curcas oil using central composite design (CCD). There were four independent variable factors had been studied which involved reaction temperature (X₁), reaction time (X₂), catalyst loading (X₃) and H₂O₂ concentration (X₄). Thirty experiments were carried out based on the experimental design responses obtained. The results showed that the optimum condition was obtained at catalyst loading of 0.11% (w/w) methyltrioxorhernium (VII) (MTO), H₂O₂ mole of 99%, reaction temperature of 58.41^oC for 5 hours. The central composite design was proven to be simpler method, time saving and required less samples compared to the conventional method.

Abstract: Sol-gel silica-supported mineral acids (namely sol-gel perchloric acid (slg HClO₄), sulfuric acid (slg H₂SO₄) and phosphoric acid (slg H₃PO₄), prepared by incorporating mineral acids molecules into silica via sol-gel technique, were used as an efficient heterogeneous catalyst for the direct addition reaction of oleic acid (OA) to form estolides compound. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70°C under solvent-less conditions. Liquid chromatography-mass spectrometry time of flight (LC-MS ToF) of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-^-), and oleic-oleic diestolide acid (m/z 845.77 [M-^-). The HClO sol-gel catalyst turned out to be the best catalyst, achieving a final conversion of 76.4% with 83.4% selectivity to oleic-oleic monoestolide acid (OOM) and 16.6% selectivity to oleic-oleic diestolide acid (OOD). The activity and selectivity of the mineral acid sol-gel catalysts have been investigated and compared with homogeneous HClO₄. The samples were characterised by XRD, TPD-NH₃ and XPS.

Abstract: In this work, we were study the selective synthesis of GME from oleic acid and glycerol using two types of solid heteropoly acid catalysts, namely silicotungstic acid bulk (STAB) and STA-silica sol gel (STA-SG). The performance and selectivity of STAB and STA-SG in the esterification reaction have been investigated and compared to the sulphuric acid (H₂SO₄) as conventional homogeneous catalyst. The catalysts were then characterized their physical and chemical properties using BET, XRD, TEM and XPS. XPS analyses were shown a significant formation of W-O-Si, W-O-W and Si-O-Si bonding in STA-SG compared to that in STAB. The main spectra of O1s (90.74 %, 531.5 eV) followed by other O1s peak (9.26 %, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. The STA-SG catalyst was found to be the more environmentally benign solid acid catalyst for the esterification reaction between oleic acid and glycerol due to its lower toxicity in terms of the relatively lower pH value (pH 3.7) than the STAB (pH 2.8). In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H₂SO₄ and the STAB gave high conversion of 100 % and 98 %, but at a lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94 %, but with a significantly higher GME selectivity of 95 % rendering it the more efficient solid acid catalyst.

Abstract: Different catalysts, namely various loading of perchloric acid on various supports; HClO₄/silica (SiO₂), HClO₄/silica gel (SG) and HClO₄/alumina (Al₂O₃) were tested for the direct addition reaction of oleic acid (OA) to form estolide compounds. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70 °C under solvent-less conditions. LC-MS ToF of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-H]^-), and oleic-oleic diestolide acid (m/z 845.77 [M-H]^-). The optimum loading of HClO₄ for every support are 15 wt.% HClO₄/SiO₂ (SiO₂15), 10 wt.% HClO₄/SG (SG10) and 35 wt.% HClO₄/Al₂O₃ (Al₂O₃35). The SG10 turned out to be the best catalyst, achieving a final conversion of 97.5 % with 79.8 % selectivity to oleic-oleic monoestolide acid and 17.7 % selectivity to oleic-oleic diestolide acid. The activity and selectivity of the SG10 have been investigated and compared with homogeneous HClO₄. The optimum catalysts for every support were characterized by XPS analysis, BET, TEM and TPD-NH₃.

Abstract: Oxidation of gycerol to form various types of important short chain oxygenated derivatives became an important reaction to support biodiesel industries. In this study, a series of AuPd nanoparticles at different metal mole ratios which were 9:1 and 8:2 supported on titania (TiO2) were successfully prepared, characterized and tested for its activity and selectivity in liquid phase oxidation reaction of glycerol. All the catalysts were prepared by deposition-precipitation method with decomposition of urea. AuxPdy/TiO2 catalysts were characterized using XRD, TEM and XPS. The formation of alloy Au-Pd phase was ascertained by XRD and XPS analysis. TEM analyses have shown that the Au and Pd metal particles in the range of 10-30 nm in size were uniformly dispersed on the TiO2 support with narrower size distribution. Higher catalytic activity observed for the catalysts was attributed to the presence of metallic Au0 and PdO phases together with the ‘synergistic’ effect of Au-Pd alloy. The highest selectivity to tartronic acid (55%) was obtained by using Au9Pd1/TiO2 catalyst after 8 h of reaction time at 50oC reaction temperature.

Abstract: The syntheses of estolides via condensation reaction of oleic acid were investigated using heterogenous catalysts. In this study HClO4 is supported onto suitable support to make it environmentally friendly. A series of solid acid catalyst containing 5-45 % of perchloric acid supported onto silica was synthesized and characterized using XRD, BET surface area measurement, TEM and XPS surface analysis. Silica modified with perchloric acid was found to be efficient and environmentally benign solid acid catalyst for estolide synthesis. The reaction was performed at 70 oC for 10 hours to give oleic-oleic monoestolide acid (m/z 563.51 as M-H)-. Based on the experimental findings above, optimum catalytic performance was with 15 % HClO4 loading onto SiO2 to give 98.98 % conversion of the oleic acid with 63.98 % oleic-oleic monoestolide acid selectivity.

Abstract: Oleic acid which is one of the palm oil derivatives is known to effectively stabilize dispersions of nanomagnetite in nonpolar solvent. Stabilization occurs because the carboxylic acid group covalently reacts with the surface of the magnetite and the aliphatic chain extends out into the nonpolar solvent, preventing aggregation of the particles by a steric (entropic) mechanism. One goal of this work has been to develop a generalized methodology for stabilizing nanomagnetite dispersions using a series of novel surfactants which had been synthesized from palm oil derivatives so that the resultant modified magnetite nanoparticles can be used in a range of applications. The specialty of the surfactants which have thiol compounds attached to the long chain fatty acids have been succesfully coated with magnetite iron oxide as shown on the FTIR spectrum and exhibited a particle size in the range of 25-30 nm as shown on the FT-SEM. These nanoparticles have been characterized by Dynamic Light Scattering, Zeta-potential to examine their stabilities after coating. In addition to that, the X-ray diffraction pattern showed that the modified nanoparticles corresponds to the spinal phase of the bare magnetite iron oxide.