Effects of Heterogeneous Sulfated Acid Photocatalysts and Irradiation of Ultraviolet Light on the Chemical Conversion and Characteristics of Antifreeze from Bioglycerol

Abstract

The purity of crude glycerol, a by-product of biodiesel production, may be as low as 50%. Thus, it has relatively low economic value without previously applying adequate physical purification or chemical conversion processes. A solid-state sulfated acid photocatalyst, TiO2/SO42- was prepared in this study to catalyze the chemical conversion of bioglycerol with acetic acid to produce an antifreeze of glycerine acetate to improve the low-temperature fluidity of liquid fuel. The experimental results show that similar X-ray intensity structures appeared between the catalysts of TiO2/SO42- and SO42-. An infrared spectra analysis using a Fourier transform infrared (FTIR) spectrometer confirmed the successful sintering of SO42- and ligating with TiO2 for preparing TiO2/SO42-. The effects of the photocatalyst were further excited by the irradiation of ultraviolet light. The highest weight percentage of glycerine acetate was obtained under a reaction time and reaction temperature of 10 hours and 120°C, respectively. In addition, it was observed that the glycerol conversion ratio reached 98.65% and the triacylglycerols compound amounted to 40.41 wt.% when the reacting molar ratio was 8. Moreover, the freezing point of the product mixture of glycerine acetate under the same molar ratio reached as low as -46.36°C; the lowest among the products made using various molar ratios of acetic acid/glycerol. The UV light irradiation rendered higher triacylglycerols and diacylglycerols with lower diacylglycerol formation ratios than those without light irradiation.

Influences of Cosolvents and Antifreeze Additives Derived from Glycerol through Esterification on Fuel Properties of Biodiesel

“…A molar ratio of acetic acid/glycerol higher than 8 may retard the dehydration condensation reaction between -COOH radicals in the acetic acid molecules and OH − radicals in diacylglycerol (DAG) to produce a reverse reaction [22], resulting in lower TAG formation, and thus, a higher freezing point at a molar ratio of 9. Lin and Chen [23] also found that the TAG formation decreased from the highest amount of 40.41% to 34.63% when the molar ratio of acetic acid/glycerol increased from 8 to 9. Under UV irradiation on the solid-state strong acid photocatalyst surface, the photocatalyst will form an electron-electron hole pair.…”