Spinel LiMn2O4 is one of the promising cathode materials used in commercial Li-ion batteries. In this study, Ni was partially substituted in order to give the material LiMn1.8Ni0.2O4, which was successfully synthesized using a self-propagating combustion (SPC) method. Results from Simultaneous Thermogravimetric Analysis (STA) show the small mass loss about 4.6%. The precursor then was calcined at temperature of 800 °C for 24 h, 48 h and 72 h. X-Ray Diffraction (XRD) confirms that the final products are pure and single phase with no impurities present. The morphology and crystallite size of pure samples are examined using Field Emission Scanning Electron Microscope (FESEM). The result shows that all the materials consist of crystalline particles with smooth surface and polyhedral shaped materials.
The palm fatty acid distillate (PFAD), as a low-cost feedstock, was catalytically esterified into biodiesel (also known as fatty acid methyl ester, FAME) using sulfonated iron oxide (HSO3ˉ/Fe2O3) catalyst. In this work, the catalyst was synthesised via self-propagating combustion (SPC) method, towards a greener synthesis technique, followed by sulfonation with chlorosulfonic acid (HSO3Cl) to enhance the catalyst's acid properties. The catalysts were characterised and the success of sulfonation process was determined. From this study, Fe2O3 catalysts were proven to be pure and single-phase. The success of the sulfonation then was verified by the presence of sulfur, functional groups of S-O asymmetric vibration and S=O symmetric vibration, and increasing total acidity. Then, the sulfonated Fe2O3 catalyst was used to esterify the PFAD feedstock in methanol in which the esterification parameters were also optimized to obtain maximum free fatty acid (FFA) conversion. It was found that 15:1 of methanol-to-PFAD molar ratio, 4 wt.% of catalyst loading, 80 °C of reaction temperature and 5 h of reaction time produced 95.5% of FFA conversion. Interestingly, the sulfonated Fe2O3 catalyst can be considered as a superacid solid catalyst that enables boosting the esterification of the PFAD feedstock into biodiesel.
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