| Methylal is a new generation of methyl alcohol and methanal derivative, has excellentphysical and chemical properties. It has been widely used in detergents, rubber, paints,coatings and other industries. Methylal synthesis in the study, most of them are common tomethyl alcohol and methanal as raw materials in the acid catalytic reaction carried out underthe acetal. Differences are the catalyst and synthesis of the selection process. Previously usedinorganic acid catalyst （such as H2SO4, HF, H3PO4, etc.） as well as the Lewis acid （such asAlCl3, FeCl3, etc.）, although with a better catalytic activity, but there is separation andrecovery difficulties, corrosion of equipment and many other serious disadvantage. Methylalsynthesis process is generally intermittent, continuous and catalytic distillation operation inthree ways.In recent years ionic liquids are in the framework of green chemistry to develop newmedium and soft functional materials with a non-volatile, liquid-way width, dissolved, in thatthey can adjust, such as the characteristics of a broad range of applications. Acidic ionic liquidwith its strong alternative to traditional corrosion, strong polluting inorganic acid such asconcentrated sulfuric acid catalyst, the catalytic effect of a good implementation to meet theenvironment-friendly green features, is receiving increasing attention.In methanal and methyl alcohol as raw materials for preparation of methylal, this issue wasfirst introduced acidic ionic liquids as solvent and catalyst. They not only have high catalyticactivity and reaction selectivity, but also reduce environmental pollution and achieve cleanand green production processes.Through the research of different types of acidic ionic liquids for the reaction, the studyfound,[mim]+HSO4-ionic liquid is a good catalyst during the systhesis of the methylal.In thebatch reactor system, the influence of reaction temperature, molar ratio of raw materials,reaction time, catalyst amount, cycle number and methanol concentration and methanalconcentration of raw materials on reaction were investigated. Reaction temperature at50℃boiling range for good, temperature5560℃at the best time; the amount of catalyst toreactant volume for58%better, methanol and methanal in the molar ratio to2.0:1.03.5:1.0for better, one of the best2.3:1.02.8:1.0; control of reaction time at80100minappropriate; The catalyst can be recycled three times; methanol and methanal concentration decreased the conversion rate of formaldehyde and methylal yield are significantlyaffected.the conversion rate of methanal and methylal have lower yield. By orthogonalexperiments, the optimum conditions obtained for the best reaction temperature=60℃,reaction time100min methanol and methanal molar ratio of2.3:1.0, the mass fraction ofcatalyst was6%of the conditions. Under these conditions, methanal conversion is83.58%,methylal content is39.73%.The experiment proved,[mim]+HSO4-acidic ionic liquids as methylal synthesis reactioncatalyst, the catalytic effect of good preparation, performance and cost are far superior toconventional catalysts. Methylal in future technology research and production,[mim]+HSO4-will bring substantial social and economic effects. |
