Production of benzene

Claim 1

A PROCESS FOR HYDRODEALKYLATING A STREAM COMPRISING ALKYL AROMATIC COMPOUNDS HAVING AT MOST ABOUT SIX ALKYL CARBON ATOMS PER MOLECULE WHICH COMPRISES PASSING SAID STREAM TO A PRE-HEATING ZONE, ADDING HYDROGEN AND A MINOR PROPORTION OF C5-C8 NON-AROMATIC COMPOUNDS SUFFICIENT TO HEAT SAID STREAM IN SAID PRE-HEATING ZONE FROM ABOUT 900*F. TO A TEMPERATURE OF AT MOST ABOUT 1200*F. BY SUBSTANTIAL HYDROCRACKING OF SAID NONAROMATIC COMPOUNDS, SAID HEATING IN SAID HYDROCRACKING ZONE RESULTING FROM SAID HYDROCRACKING REACTION ONLY, RECOVERING THE EFFLUENT FROM SAID PRE-HEATING ZONE AND PASSING SAID EFFLUENT TO A REACTION ZOEN DEFINED BY REFRACTORY SURFACES, HEATING SAID EFFLUENT IN SAID REACTION ZONE TO A TEMPERATURE IN THE RANGE OF FROM AOUT 1100*F. TO ABOUT 1500*F., RECOVERING FROM SAID REACTION ZONE A SECOND EFFLUENT STREAM, SEPARATING SAID SECOND EFFLUENT STREAM INTO A FIRST BENZENE-CONTAINING PRODUCT FRACTION AND A SECOND HEAVY FRACTION BOILING ABOVE ABOUT 500* F., AND RETURNING SAID SCOND HEAVY FRACTION AS A PORTION OF SAID STREAM TO THE PROCESS.