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Process for the preparation of para-xylene from an effluent of the paraselective dismutation of toluene by a cristallisation process linked to adsorption in a simulated moving bed
Process for the preparation of para-xylene from an effluent of the paraselective dismutation of toluene by a cristallisation process linked to adsorption in a simulated moving bed
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机译:通过与模拟移动床中的吸附有关的增效法从甲苯的亚选择性歧化废水中制备对二甲苯的方法
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摘要
Prepn. of para-xylene from a toluene charge comprises: (a) a para-selective dismutation stage of toluene in the presence of H2 and a catalyst in a zone giving an effluent contg. benzene, toluene, xylenes enriched in para-xylene, ethylbenzene and aromatics of at least 9C; (b) a distillation stage of xylenes, separating benzene toluene and xylenes, in at least two columns; and (c) a high temp. crystallisation stage, pref. at +10 to -30 degrees C in at least one crystallisation zone producing para-xylene of a high purity and a mother liquor depleted in para-xylene. The mother liquor is contacted in an adsorption zone using a simulated mobile bed with a zeolite adsorbent in the presence of a desorbent (toluene) in conditions such as to give a prim. fraction (depleted in para-xylene and contg. toluene) and a secondary fraction enriched in para-xylene and contg. toluene. At least part of the secondary fraction is recycled to the crystallisation zone after having distilled off the toluene.
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