Purification of a benzene fraction by mild liquid

Claim 1

IN A PROCESS FOR SEPARATING SUBSTANTIALLY PURE BENZENE FROM A CRACKED PETROLEUM HYDROCARBON NAPHTHA CONTAINING MAINLY UNSATURATED HYDROCARBONS WITH BENZENE, THE STEPS OF PREPARING A BENZENE CONCENTRATE FROM SAID NAPHTHA FOR EXTRACTIVE DISTILLATION WHICH COMPRISE FRACTIONALLY DISTILLING FROM SAID NAPHTHA AN INTERMEDIATE BENZENE CUT BOILING IN THE RANGE FROM 165* F. TO 185* F. TO OBTAIN A CUT WHICH CONTAINS FROM 35 TO 50 VOLUME PER CENT BENZENE CUT WHICH IS SUBSTANTIALLY FREED OF DIENES HAVING BOILING POINTS BELOW 165* F., CINTACTING SAID BENZENE CUT IN LIQUID PHASE WITH A CLAY UNDER CONDITIONS AT 250* F. TO 400* F. FOR POLYMERIZING A PORTION OF DIENE COMPONENTS IN THE CUT, FLOWING THE CLAY-CONTACTED BENZENE CUT CONTAINING UNREACTED UNSATURATED HYDROCARBONS WITH POLYMERS THUS FORMED INTO A SECOND FRACTIONAL DISTILLATION ZONE, FRACTIONALLY DISTILLING THE BENZENE WITH MONOMERIC C6 TO C7 UNSATURATED HYDROCARBON COMPONENTS AWAY FROM THE POLYMERS UNDER CONDITIONS TO PREVENT DECOMPOSITION OF THE POLYMERS, AND RECOVEING AS A DISTILATE FROM SAID SECOND FRACTIONAL DISTILLATION ZONE THE BENZENE CONCENTRATE FOR THE EXTRACTIVE DISTILLATION.