PROCESS FOR SEPARATING PARAXYLENE COMPRISING AT LEAST TWO CRYSTALLIZATION STAGES AT HIGH TEMPERATURE.

摘要

A PROCESS FOR PRODUCING PARAXYLENE OF VERY HIGH PURITY FROM A CHARGE CONTAINING A MIXTURE OF AROMATIC HYDROCARBONS HAVING 7 TO 9 CARBON ATOMS IN WHICH AT LEAST A PORTION OF THE CHARGE IS MADE TO CIRCULATE IN A ZONE (8) SUITED TO ENRICH A FIRST FRACTION OF PARAXYLENE AND AT LEAST A PORTION OF SAID FIRST FRACTION IS PURIFIED BY AT LEAST ONE HIGH-TEMPERATURE CRYSTALLIZATION IN AT LEAST ONE CRYSTALLIZATION ZONE (50, 70), THE PROCESS BEING CHARACTERIZED IN THAT SAID FIRST PARAXYLENE-ENRICHED FRACTION IS CRYSTALLIZED IN A CRYSTALLIZATION ZONE COMPRISING AT LEAST TWO CRYSTALLIZATION STAGES (50, 70) AT HIGH TEMPERATURE, AND ADVANTAGEOUSLY BETWEEN +10 AND -25°C. THE PARAXYLENE ENRICHING ZONE CAN BE A CRYSTALLIZATION AT VERY LOW TEMPERATURE, A SELECTIVE ADSORPTION OR A TOLUENE DISPROPORTIONATION ZONE. (FIG. 1)