Study On The Synthetic Of Polyoxymethylene Dimethyl Ethers

The DME is a new type fuel being synthesized from methylal as the downstream products of methano. In this paper, the advantages and prospect of some popular substitute fuels are introduced. Firstly, the synthesis route of polyoxymethylene dimethyl ethers from methylal is studied. The proper catalyst suiting for the reaction system is screened out by doing batch experiments in the high pressure reactor. HD-8 macroporous strong acid ion can be separated easily, has high catalytic activity, and can be recycled for using. Then, in order to find the good reaction conditions, the factors such as the molar ratios of the reactants, the amount of catalyst, reaction temperature, reaction time and the pressure of N2 are studied to enhance the high conversation, selectivity and yield. The reasonable reaction conditions are fixed. And the better process conditions can be determined:reaction temperature is 90℃, molar ratio of n (DMM):n(HCHO)=1:1, catalyst is 3wt%, N2 pressure is lead to 0.8MPa, stirring speed is 650r/min, the reaction time is 6h. Accordingly, the conversion of methylal and selectivity of the product are 61% and 92% respectively.