Synthesis and Application of Polyoxymethylene Dimethyl Ethers

Polyoxymethylene dimethyl ethers (DMMn) were synthesized in moderate yields by the reaction of methylal and paraformaldehyde catalyzed by solid acid. The pure components of DMM2, DMM3, DMM4, and DMM5 obtained by rectification were characterized by 1H NMR and mass spectra. The suitable components for blending into fuel were obtained by distillation separation. Furthermore, the combustion and emission characteristics of a diesel engine fueled with diesel and a blended fuel of DMM3-5 and diesel were investigated respectively.