One-pot synthesized mesoporous Ca/SBA-15 solid base for transesterification of sunflower oil with methanol Original Research Article

A series of Ca/SBA-15 samples with Ca/Si atomic ratios of 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared by using a one-pot synthesis method. They were used in the transesterification of sunflower oil with methanol. For comparison, 0.3Ca/SBA-15 was also synthesized by an incipient impregnation method (0.3Ca/SBA-15-IM). Small-angle XRD, N2 adsorption, TEM, SEM, TG-DTA, FTIR, CO2-TPD techniques were used to determine the textual structure and physicochemical properties of Ca/SBA-15 samples. The mesoporous structure of SBA-15 was well preserved with Ca/Si ratios up to 0.5. Compared with 0.3Ca/SBA-15-IM sample, the Ca/SBA-15 showed not only a better calcium species distribution, but also higher BET surface area and larger medium basic sites. A biodiesel yield of as high as 99.1% was achieved on the 0.5Ca/SBA-15 catalyst at a reaction temperature of 200 °C for 8 h. In the meantime, no deactivation was found after five cycles on Ca/SBA-15 sample prepared by one-pot synthesis method in the transesterification reaction, which showed a much better stability than that of prepared by conventional impregnation method. Besides, a water content of up to 5% and/or free fatty acids (FFAs) content of 3% did not affect the catalytic activity of Ca/SBA-15 catalyst in the transesterification reaction.