Process for the recovery of pure methylal from methanol-methylal mixtures

摘要

In a process for recovering pure methylal from methanol- methylal mixtures, which can optionally contain still further compounds, the separation conducted in a rectification device comprising two rectifying columns. In the first rectifying column, the mixture to be separated is rectified under a pressure lower than that in the second column, into a methylal-rich, methanol-poor distillate, and into a practically methylal- free, methanol-rich sump product. The methylal-rich distillate of the first rectification is then separated in a second rectifying column, operated under a higher pressure than the first rectification column, into a compound stream containing methanol and methylal, which is then recycled to the first rectifying column, and into pure methylal as the sump product. In a specific refinement, the first rectification is preferably operated under a pressure of 1-22 bar absolute and the second rectification preferably under a pressure of 9-30 bar absolute, with the second rectification being operated under a pressure which is at least 8 bar higher than that of the first rectification.