Synthesis Of Polyoxymethylene Dimethyl Ethers Catalyzed By Sulfonic Ion Exchange Resin

The fossil fuels have been consumed with the rapid development of the world economy.Energy shortage has become a very serious problem that the whole world faced.As a new kind of diesel additive,polyoxymethylene dimethyl ethers have attracted much attention due to its excellent combustion performance.Sulfonic ion exchange resin catalyst has very good catalytic performance.Because of its large pore size,specific surface area,high acid content and mechanical strength,the in the sulfonic ion exchange resin catalyst is widely used in the chemical field.Sulfonic ion exchange resin was used as catalyst to synthesize polyoxymethylene dimethyl ethers in this work.The sulfonic ion exchange resins were characterized by infrared spectrum?IR?,scanning electron microscope?SEM?,thermogravimetric analysis?TG?,N₂ physical adsorption and desorption,respectively.Their surface acidity was also determined.D002 sulfonic ion exchange resin catalyst has a larger pore volume,pore size distribution,medium acid strength and higher acid content.The catalytic properties of polyoxymethylene dimethyl ethers catalyzed by different sulfonic acid resins were investigated using trioxymethylene and methylal as raw materials.The results showed that these sulfonic ion exchange resins had a good catalytic activity,and the catalytic activity of D002 sulfonic acid resin was better than that of another one.The target products can reach 74%under the condition of the molar ratio of methylal to trioxymethylene was 3:1,the reaction time was 6 h,the amount of catalyst was 4 wt.%.This sulfonic ion exchange resin catalyst has better recycling stability.The catalytic properties of polyoxymethylene dimethyl ethers catalyzed by different sulfonic acid resins were investigated using formaldehyde and methylal as raw materials.The extraction agent is introduced to combine catalytic reaction and extraction.This reaction has a good catalytic performance and can improve the conversion of formaldehyde and selectivity of product.It can also avoid the products contacting with water and producing side reactions.With D002 sulfonic ion exchange resin as catalyst,six different kinds of organic solvents were used as extractant to increase the catalytic activity.With dichloroethane as extractant,the target product had a higher selectivity.The selectivity of target products can reach 57%when the molar ratio of formaldehyde to methylal is 2:1,the reaction time is 8 h,the amount of catalyst is 4 wt.%,the ratio of the extractant to the total volume of raw materials is 1:1.