Synthesis Of Polyoxymethylene Dimethly Ethers As Novel Diesel Additives

Polyoxymethylene dimethyl ethers (PODEn) with the general structure CH3O(CH2O)nCH3have a high oxygen content (45～49%) and high cetane number (>63) and therefore are attractive as diesel fuel additives, in which n=2-6can be blended to diesel fuel to improve the combustibility and reduce the release of soot, COx, NOx and used without changing the engine’s infrastructure.The synthesis of PODEn was carried out in a batch autoclave in this study. The synthesis route and react conditions were optimized and the mechanism and reaction kinetics were studied.The results show that good outcome was obtained when choosing DMM and POM as raw material and liquid acid A as catalyst. Under the optimized conditions(temperature is115℃, rotate speed is300r/min,mDMM/mPOM is2, amount of liquid acid A is0.05wt%, the reaction time is2h), the conversion of DMM and POM, and the yield of targeted products is up to82.6%,84.4%,62.7%, respectively. The kinetics of PODEW synthesis is described with a multi-step serial reaction model, and the reaction order of each step is1. The apparent activation energy of each step is73.92,74.97,88.76,100.34,110.22kJ·mol-1, respectively.