Preparation of diesel fuel blends and study of their physical properties

The aim of the present work was to synthesize biodiesel fuels from sunflower oil through a transesterification reaction in the presence of a novel catalytic system. Under the molar oil-to-methanol ratio of 1:3 and the temperature of 55 °C, the product yield was 83 %. Physical properties of the biodiesel and diesel fuels under study, as well as their blends containing 20 and 50 vol% of biodiesel fuel (B20 and B50), were investigated against ASTM standards. An increase in the proportion of biodiesel fuel increases both the density of the B20 and B50 blends, as well as their kinematic viscosity, which remains within the 2–5 mm 2 /s range at 40 °C thus meeting ASTM requirements. It is shown that the content of unsaturated compounds in the biodiesel blends altered within the range specified by ASTM. The flash temperature of the B20 and B50 biodiesel blends was shown to be higher than that of diesel fuel. This led to some deterioration in their flammability, at the same time as making the transportation and storage of these fuels safer. The sulphur content in the biodiesel blends under study decreased significantly with an increase in the biodiesel content: from 50 m.c. in diesel fuel up to 27 m.c. in the B50 blend. The use of such biodiesel blends reduces the content of sulphur oxides in exhaust gases, which has a beneficial effect on the environment and human health. The use of the proposed catalytic system reduces the amount of foam produced by biodiesel washing, thus simplifying its synthesis. Due to the absence of the neutralization stage, the described catalytic system can be reused after water removal through distillation.