Optimize the co-solvent for methanol in diesel with group of oxygen-containing reagents: Molecular structure and intermolecular forces analysis

Abstract Oxygen-containing fuels or additives used to reduce the pollutant emissions from diesel combustion have the potential as a co-solvent to prepare methanol/diesel blends, however their performance has less been evaluated, especially how their molecular structure affects the solubility of methanol in diesel. In this work, the abilities of higher alcohols, long-chain ethers and esters to improve the solubility of methanol in diesel were investigated, and intermolecular forces were also analyzed according to the solubility parameters. Results show that different performance for oxygen-containing chemicals as a co-solvent to prepare methanol/diesel blends originates from different contribution of various functional groups to their Hansen solubility parameters (HSPs) and the fraction of HSPs. And dispersion solubility parameter larger than 15.9 and its fraction in the range of 0.45–0.64 were proposed as a reference for choosing a suitable co-solvent to prepare methanol/diesel blends. Besides, it was found that 1-Octanol exhibits excellent performance as a co-solvent to prepare stable methanol/diesel blends, and can substantially reduce the PODE or methyl palmitate usage when they being used in preparing methanol/diesel mixtures.