Purification of synthetic methanol by plural stage distillation

Claim 1

A PROCESS FOR THE PURIFICATION OF CRUDE SYNTHETIC METHANOL CONTAINING LOW BOILING AND HIGH BOILING ORGANIC IMPURITIES WHICH COMPRISES INTRODUCING THE CRUDE FEED STREAM INTO THE MIDDLE REGION OF A DISTILLATION ZONE, SAID MIDDLE REGION HAVING A PROPORTION OF HIGH BOILERS RELATIVE TO METHANOL IN THE LIQUID PHASE WHICH IS SUBSTANTIALLY GREATER THAN IN THE CRUDE FEED, ADMITTING WATER INTO THE UPPER PORTION OF SAID ZONE WHEREBY EXTRACTIVE DISTILLATION OF LOW BOILERS AND PART OF THE HIGH BOILERS TAKES PLACE, REMOVING AN OVERHEAD VAPOR STREAM FROM SAID ZONE COMPRISING LOW BOILERS, PART OF THE HIGH BOILERS, METHANOL, AND WATER VAPOR, WITHDRAWING A LIQUID SIDE STREAM FROM SAID MIDDLE REGION, DILUTING SAID SIDE STREAM WITH WATER WHEREBY A SEPARATE AND WATER-IMMISCIBLE LIQUID LAYER COMPRISING HIGH BOILERS IS FORMED, SEPARATING SAID IMMISCIBLE LIQUID LAYER FROM THE RESIDUAL AQUEOUS SIDE STREAM, RECYCLING SAID RESIDUAL AQUEOUS SIDE STREAM TO SAID MIDDLE REGION, AND WITHDRAWING FROM THE BOTTOM OF SAID ZONE A PRODUCT STREAM COMPRISING AQUEOUS METHANOL SOLUTION OF LOWERED IMPURITY CONTENT.