Kinetic and Catalytic Studies on The Use of some Local Materials For Biodiesel Production From Soybean Feedstock

Abstract   

This \ork. is aimed at developing solid base catalysts from locally sourced materials and applying them to an environmentally beneficial reactive distillation process for transesterification of vegetable oils with methanol into biodiesel. Solid base catalysts include calcium oxides (prepared from the calcinations of poultry eggshell, limestone, chalk clay and marble stone). By investigating these processed solid base catalysts samples catalytic behaviors in the transesterification of soybean oil with methanol performed in this study, it was found that the catalytic activities significantly depended upon their surface area and basic sites strengths. The CaO-based samples exhibited relatively lower surface areas than typical catalysts (below I 0 m2 /g); ranging from 2.26 m2 /g (poultry eggshell), 2.59 m2 /g (marble), 4.41 m2 /g (limestone) to 9.73 m 2 /g (chalk clay), while the number of basic sites ranged rrom 0. 13 mmoles/g (poultry eggshell), 0. 16 mmoles/g (limestone), 0. 19 mmoles/g (marble) to 0.2 1 mmoles/g (chalk clay). The X-ray diffraction analysis confirmed the total conversion of the carbonates of raw samples to their corresponding oxides. The diffractograms were all consistent with X-ray diffractograms of CaO. The spectral characteristics of CaO powder from the processed catalyst samples with Fourier Transform Infrared (FTIR) indicated no presence of calcium hydroxide. The result also showed absorption values at 1 646.30 cm-1 and 1 685.24 cm·1 • in the IR spectra of Samples A to D indicating C=O stretching due to adsorption of C02 by CaO. The effects of these processed solid catalysts samples on fatty acid methyl esters (FAME) yield proved positive with kinematic viscosity in the range of 4.4 1 mm2 /s (chalk clay), 4.49 mm2 /s (limestone), to 5.39 mm2 /s (poultry eggshell and marble); flash point range of 101 °C (chalk clay and marble), 1 03 °C (limestone) to 1 07 °C (poultry eggshell); and density range of 0.8688 g/cm3 (poultry eggshell and chalk clay), 0.8691 g/cm3 (marble) to xxii 0.8824 g/cm3 (l imestone) measured at 30 °C. The GC-MS quantitative study based on external standard method -vas performed on the yield of biodiesel to investigate the catalytic effects of the processed CaO samples. The results proved positive as the fAME samples mainly composed of methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linolenate. The reaction kinetics study was performed using the experimental data obtained. A reaction mechanism based on LangmuirHinshelwood (LH) model was proposed for this reaction. A kinetics model was developed and the limiting-step was determined based on this proposed mechanism. The pseudo-first order kinetics was found suitable in predicting the reaction rate due to adsorption of excess methanol. The effective reaction constants, effective activation energies and pre-exponential factors were all calculated. The major results in conclusion support the potentials of these processed CaO from local !y sourced raw materials and agricultural wastes to serve as heterogeneous catalysts in the sustainable production of biodiesel.