Selective solvent extraction process for the separation of mixtures of aromatic and non-aromatic hydrocarbons

Claim 1

A PROCESS FOR THE SEPARATION OF A HYDROCARBON MIXTURE CONTAINING NON-AROMATIC HYDROCARBONS AND AT LEAST ONE AROMATIC HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BENZENE, TOLUENE AND XYLENE, WHICH COMPRISES INTRODUCING SAID MIXTURE TO AN INTERMEDIATE POINT IN THE HEIGHT OF AN EXTRACTION ZONE, COUNTERCURRENTLY CONTACTING SAID MIXTURE IN THE ZONE WITH A SOLVENT WHICH IS SELECTIVE FOR AROMATIC HYDROCARBONS AT AN ELEVATED TEMPERATURE AND AT A PRESSURE SUFFICIENT TO MAINTAIN SAID SOLVENT AND SAID MIXTURE IN SUBSTANTIALLY LIQUID PHASE, THEREBY FORMING A LIQUID RAFFINATE PHASE AND A LIQUID EXTRACT PHASE, REMOVING THE RAFFINATE PHASE FROM THE UPPER PORTION OF SAID ZONE, COMMINGLING WITH THE EXTRACT PHASE IN THE LOWER PORTION OF SAID ZONE A LIGHT PARAFFINIC HYDROCARBON WHICH BOILS IN THE PRESENCE OF THE SOLVENT AT A TEMPERATURE BELOW THE BOILING POINT OF THE AROMATIC HYDROCARBON BEING EXTRACTED, BUT WHICH REMAINS IN THE LIQUID STATE AT SAID TEMPERATURE AND PRESSURE, SAID LIGHT PARAFFIN BEING INTRODUCED INTO THE LOWER PORTION OF THE EXTRACTION ZONE IN SUFFICIENT AMOUNT TO REPLACE THE NON-AROMATIC HYDROCARBONS OF SAID MIXTURE IN THE EXTRACT PHASE WITH SAID