Synthesis and characterization of highly ordered mesoporous nanomaterials Al-MCM-41 and Al-SBA-15 from bentonite as efficient catalysts for the production of biodiesel MELA and EELA

Abstract

Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents and used in the esterification of lauric acid under conventional conditions. Effects of methanol and ethanol as solvent and mass ratios of both materials on the esterification reaction are also studied. The obtained materials have been characterized using X-ray diffraction, nitrogen sorption measurements, Fourier transform IR spectroscopy, and transmission electron microscopy. As a result, it has been found that MCM-41 and SBA-15 solids obtained via alkaline fusion of an Algerian bentonite are well crystallized as those synthesized from commercial sources. Based on EDX result, the amount of aluminum in MCM-41 is much higher than that in SBA-15. N2 adsorption–desorption is observed for both mesoporous materials with high textural parameters, i.e., specific surface area (SSA) around 1550 m2/g and pore diameter ca. 6.58 nm for SBA-15 as well as SSA of 760 m2/g, and pore diameter 3.57 nm for MCM-41. The later leads to a higher conversion of lauric acid compared to SBA-15 about 20% the difference. It is also noticed that methanol prefers the conversion 74% of lauric acid to methyl ester of lauric acid in comparison with ethanol 63%. The increase in mass ratios (catalyst/lauric acid) enhances the rate of esterification by 25% the conversion.