Effect of poly-alpha-olefin pour point depressant on cold flow properties of waste cooking oil biodiesel blends

Improving the flow ability at a low temperature is vital for the utilization and popularization of biodiesel. The cold flow properties of waste cooking oil biodiesel-0# diesel blends with poly-alpha-olefin (PAO) pour point depressants were studied. Here results showed that B20 (20 vol.% biodiesel-80 vol.% diesel) treated with 400 ppm PAO exhibited the best depression in cloud point, cold filter plugging point and pour point by 8 degrees C, 9 degrees C and 7 degrees C, respectively. The other fuel properties of B20 were also determined and compared with the limits indicated in the ASTM D7467 standard. Viscosity-temperature curves, polarized optical microscopy, low-temperature X-ray diffraction, and differential scanning calorimetry were used to explore the performance mechanism of PAO in biodiesel blends; and results presented that PAO could effectively lower the low-temperature viscosity, delay the aggregation of wax crystals and modify their crystallization behavior by transforming the shape of crystals and depressing the formation of large wax crystals. (C) 2016 Elsevier Ltd. All rights reserved.