Industrial production and application of polyoxymethylene dimethyl ethers (PODEn, CH3O(CH2O)nCH3, where n&gt;1) play a central role on the use of the existing diesel engines, development of petrochemical industry technology and extension of C1 chemical industry. Ionic liquids (ILs) have been used to replace traditional liquid acids as the catalyst in chemical processes. In this work, a series of pyrrolidione based Brønsted acidities ionic liquids were synthesized, investigated and firstly used as the catalyst for the synthesis of PODEn from methylal and trioxane. The Hammett function values were measured to indicate the connection between catalytic performance and acidity-activity of ionic liquids. The optimal experimental conditions for synthesis of PODEn were analysed. The conversion of raw material and the selectivity of PODE3-8 have the maximum value with [NOP][TFO] (1-octyl-2-pyrrolidinone trifluoromethanesulfonate) as catalyst. The corresponding optimum reaction conditions is that the molar radio of methylal:trioxane:ILs is 180:90:1, temperature is 383.15K, pressure is 0.4Mpa, and reaction time is 5h. Moreover, the selectivity of PODE3-4 overides the traditional catalyst such as H2SO4 and CF3SO3H. In addition, the ionic liquids [NOP][p-ClBSA] (1-octyl-2-pyrrolidinone 4-chlorobenzenesulfonate), [NOP][DNBSA] (1-octyl-2-pyrrolidinone 2,4-dinitrobenzenesulfonate) and [NOP][HSO4] (1-octyl-2-pyrrolidinone hydrogen sulfate) also show a remarkable activity in the synthesis of PODEn.

Synthesis of polyoxymethylene dimethyl ethers catalyzed by the pyrrolidione-based ionic liquids

251st National Meeting (2016)

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