Production of para-xylene from an effluent from paraselective toluene disproportionation using a crystallization process combined with simulated moving bed adsorption

摘要

Para-xylene is produced from a paraselective toluene disproportionation reactor, effluent (3) is distilled to eliminate toluene and benzene in at least 2 distillation columns (C1), (C2), and the xylenes (8) are crystallized at least once (10) at between +10 DEG C. and -30 DEG C. The separated mother liquor (14) is adsorbed on a zeolitic sieve in the presence of toluene in a simulated moving bed (15). This latter produces a raffinate (16) containing toluene which is depleted in para-xylene which is distilled in a distillation column (C4), and an extract which is enriched in para-xylene and contains toluene, which is recycled to columns (C1, C2). The para-xylene crystals are purified by washing with toluene and distillation or by partial melting (30) followed by washing with molten high purity para-xylene.