Extractive distillation of aromatic compounds

Claim 1

IN AN EXTRACTIVE DISTILLATION PROCESS USING PHENOL AS THE SOLVENT FOR THE RECOVERY OF TOLUENE FROM A HYDROCARBON FEED CONTAINING A COMPOUND WHICH NORMALLY AZEOTROPES WITH THE PHENOL SOLVENT, THEREBY CAUSING SOME OF THE PHENOL TO ESCAPE OVERHEAD WITH THE RAFFINATE AND WHEREIN THERE IS PROVIDED A RECTIFICATION ZONE HAVING A NUMBER OF LIQUID CARRYING PLATES BEYOND THE EXTRACTIVE DISTILLATION ZONE TO FURTHER THE SEPARATION OF THE SOLVENT FROM THE RAFFINATE, THE IMPROVEMENT COMPRISING MAINTAINING METHANOL IN THE LIQUID OF AT LEAST SOME OF THE TRAYS OF THE RECTIFICATION ZONE IN AMOUNTS ADEQUATE TO REDUCE SIGNIFICANTLY THE VOLATILITY OF THE PHENOL RELATIVE TO ITS NORMAL AZEOTROPIC MIXTURE BETWEEN THEPHENOL SOLVENT AND OF AN AZEOTROPIC MIXTURE BETWEEN THE PHENOL SOLVENT AND SAID METHANOL, THEREBY PERMITTING A SUBSTANTIALLY MORE COMPLETE RECTIFICATION OF THE PHENOL FROM THE RAFFINE AND WITHDRAWING METHANOL AND THE RAFFINATE FROM THE RECTIFICATION ZONE, SAID RAFFINATE HAVING A SIGNIFICANTLY REDUCED PHENOL CONTENT RELATIVE TO THAT EXPERIENCED IN THE ABSENCE OF THE METHANOL