Researchers from the Shanghai Institute of Technology report that fatty acid esters can be used as cetane improvers for diesel fuel produced via direct coal liquefaction (DCL). A paper on theier work is published in the journal Fuel.
Compared to petrodiesel, diesel from direct coal liquefaction (DDCL) contains almost no sulfur. Other than this feature, several other properties of DDCL are similar to those of petrodiesel, making DDCL a viable automobile diesel fuel. However, the cetane number (CN) of DDCL is only 44.
The Shanghai team explored the use of fatty acid esters—up to 1 vol% of which can be added to diesel fuel under the China V fuel quality standard GB 19147-2013—as potential CN improvers for DDCL.
They found that the structures of fatty acid esters, such as chain length, double bonds, and different alkyl head groups on the fatty acid alkyl esters, can affect the performance of CN improvers. Methyl palmitate (C16:0M) and methyl stearate (C18:0M) were found to be suitable CN improvers, increasing the CN number from 44 to up to 46 at 1 vol%.
Moreover, the obtained wear results showed that 1% of fatty acid esters can improve fuel lubricity from 630 μm to 514 μm. The other properties of DDCL are changed a little after fatty acid esters are added.
Hui Liu, Shuangshuang Jiang, Jieni Wang, Chao Yang, Hongshuang Guo, Xinjing Wang, Sheng Han (2015) “Fatty acid esters: a potential cetane number improver for diesel from direct coal liquefaction,” Fuel, Volume 153, Pages 78-84 doi: 10.1016/j.fuel.2015.02.068