Acid Resin Catalytic Research Of Polyoxymethylene Dimethyl Ethers

As the diesel fuel additives,mixed fuel of Polyoxymethylene dimethyl ethers(PODEn)and diesel is environmental and efficient,and can effectively save energy and reduct emissions.This experiment used low cost raw materials methanol,formaldehyde and low-cost acid resin catalysts to synthetic PODEn for a new route.In this paper,using methanol and formaldehyde as raw materials and acid resin as catalysts to synthetic PODEn.The main experimental work is the study of the catalysts and synthesis process conditions.For the catalysts research,firstly,we filtered resin catalysts.Secondly,we analysised catalytic mechanism and introduced the acid groups that contain proton acid in resin.Thirdly,we introduced the lewis acid to modify the acidity of acid resin atalysts.At the same time,we explored the regeneration conditions of catalysts.We ptimized the synthetic process conditions of PODEn,and we got the optimized process conditions.First,we explore the polymerization mechanism of the synthesis of PODEn by methanol and formaldehyde,and we learned the polymerization reaction is acetal reaction.Using methanol and formaldehyde as raw materials filtrated several kinds of commercially acid resin.The results showed that:strongly acid resin D001 on polymerization reaction had a better catalytic effect.At that time,the methanol conversion was 43.5%,and the products selectivity was 40.8%.Second,we used the polystyrene white balls resin as the substrate and used sulfuric acid,oleum,sulfamic acid and phosphate to put the resin acidification.The results showed that:Strong acidic resin prepared by oleum,has higher catalytic activity.At that time,the methanol conversion was 45.8%,and the products selectivity was 46.3%.At the same time,we used lewis acid to modified acid resin aiming at improving the performance of catalyst.The results of experimental showed that we used FeCl3 as the modifier,65℃ fully mixing reaction 3h to get the best catalytic properties of modified resin.At that time,the methanol conversion was 53.0%,and products selectivity was 49.0%.We analysised the best modified resin and the strong acidic resin.The results showed that:the combination of ferric chloride and the resin is stable,and its structure has not changed after modification.However,the acid strength of modified catalyst was reduced,the the acid center numbers were rised.Then,we use FeCl3 modified catalysts for the synthesis of methanol and formaldehyde solution to explore the optimal process conditions.The results of experimental showed that:optimal reaction temperature was 90～96℃ pressure was 1.0MPa,material ratio was n(CH2O):n(CH3OH)=3:l,quality airspeed was 1.5h-.At that time,the methanol conversion was 57.0%,and the products selectivity was 52.8%.Finally,we explored the causes of acid resin catalyst deactivation.We used hydrochloric acid to regenerate recovery catalysts.Kowning that the main reason of catalyst deactivation is the loss of the H+.So,using hydrochloric acid to regenerated catalysts can receive better regenerated resin.