Comparison of Diesel Fuel Oxygenate Additives to the Composition-Explicit Distillation Curve Method. Part 2: Cyclic Compounds with One to Two Oxygens

There is a great deal of interest in formulating oxygenated diesel fuels that produce low particulate emissions. The most common oxygenating additives for diesel fuels include the glycol ethers, glycol esters, alcohols, ethers, and ketones. It is important to characterize the mixture properties of diesel fuel with oxygenate additives, to assess the degree of departure of the oxygenated fuels from the base fuel. In part 1 of this series (10.1021/ef2003415), we explored a series of linear oxygenating fluids with the advanced distillation curve method to assess the mixture volatility. Here, we apply that technique to a series of cyclic molecules: 2-methyl-1,3-dioxolane, 1,4-dioxane, 1,3-dioxane, cyclohexanone, and 2-cyclohexylethanol. We find that the more volatile additives cause significant early departures from the distillation curves of diesel fuel, while the less volatile additives act more to displace the entire curve. We also note that the additive affects the curve shape and temperature profile even after being totally depleted, an observation similar to that made in earlier studies of oxygenate additive mixtures.