| 摘要 |
An adsorptive separation process for separating ortho- and/or para- nitrotoluene from a feed mixture comprising the isomer to be separated and at least one isomeric nitrotoluene, comprises contacting the feed mixture with an adsorbent comprising a type X or type Y zeolite, containing at exchangeable cationic sites cations rendering the zeolite selective towards the isomer(s) to be separated, thereby selectively adsorbing said isomer(s) to the substantial exclusion of the remaining isomer(s) and thereafter recovering the selectively adsorbed isomer(s). A desorption step may be used to desorb the adsorbed isomer(s). For the separation of the ortho-isomer the cations are chromium on type X and calcium on type Y. For the separation of the para- isomer the cations are potassium, zinc, nickel, barium, calcium, cobalt, strontium, copper and/or magnesium on type X and cesium, potassium (with or without barium), sodium, iron or cobalt on type Y. For the separations of a mixture of the ortho- and para-isomers the cations are sodium, nickel, barium, copper, magnesium, calcium, cobalt and/or strontium on type X and calcium, sodium, iron, cobalt and or potassium (with or without barium) on type Y.
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