Study on the Solubility between Diesel and Acetone–Butanol–Ethanol with or without Water

Acetone–butanol–ethanol (ABE) is an intermediate product in the microbial fermentation process for producing biobutanol. ABE not only retains the advantages of oxygen-containing fuels but also reduces the cost of single-component fuel recovery during the fermentation process. In this study, ABE fuels of different component volumetric ratios (A/B/E of 1:1:1, 3:6:1, and 6:3:1) were mixed with diesel to investigate the mutual solubility of blends with and without water. Meanwhile, the effects of the ABE single component on the mutual solubility of ABE and diesel with and without water systems were further studied. The blending ratio of ABE in the blends changed from 10 to 90% in volume with an increment of 10%. Four environmental temperatures (0, 20, 40, and 60 °C) were adopted to investigate the influence of the temperature on the mutual solubility. Results show that both ABE and diesel fuel are intersoluble and can keep single-phase transparency, which is an important reference value for ABE to be mixed with diesel fuel and used for the achievability of diesel engines. Among of all different volumetric ratios in ABE fuels, the concentration of water added to diesel and ABE blend increases gradually with the increase of the circumstance temperature from 0 to 60 °C. Meanwhile, ABE (3:6:1) is well-balanced to maintain mutual miscibility with water and diesel compared to ABE (1:1:1) and ABE (6:3:1). The reason is that the amount of n-butanol contained in ABE has a great influence on the water retention capacity. Thus, ABE (3:6:1), which is produced by microbial fermentation processes (no dehydration and no surfactant added), should be a good substitute for diesel fuel.