Meta- and para-di:chloro-benzene sepn. by adsorption on pentasil zeolite - from soln. in organic solvent, giving very selective adsorption of para-isomer

摘要

Sepn. of mixts. (I) of m- and p-dichlorobenzene (m-DCB, p-DCB) involves treatment in the liquid phase with zeolites. (I) dissolved in a solvent (II) is treated at 20-250 deg.C with a pentasil zeolite (III) with exchangeable H, gp. IA-IIA metal and/or lanthanide metal cations, (II) being 5-15 C cyclic satd. hydrocarbon(s) (IIA), 8-12 C alkyl-aromatic hydrocarbon(s) and/or 6-10 C aromatic halohydrocarbon(s) with 1-3 halogen atoms, except ethylbenzene, chlorobenzene, p-xylene, p-chlorotoluene and dichlorobenzene. Enriched m-DCB is obtd. as filtrate and p-DCB is recovered from (III) by desorption. (III) is pref. Zeta 1, Zeta 3, ZBM 10, Ultrasil, Ultrazet, TZ-01, NU-4, NU-5, AZ-1, pref. ZSM 8, ZSM 5/ZSM 11 intermediates or esp. ZSM 5 and ZSM 11. The amt. is 0.05-2, pref. 0.1-1, esp. 0.2-0l8 pts. (I)/pt. (III). (I) contains 50-70 (wt.)% m-CDB. (II) is (IIA) with 5-12 C, esp. cyclohexane; 8-10 C alkylbenzenes with one to three 1-3 C alkyl gps. contg. a total of max. 4 C, esp. o- or m-xylene or mesitylene; or 6-8 C chlorobenzenes with 1-3 Cl atoms, esp. 1,2,4-trichlorobenzene (IIB) or 3,4-dichlorotoluene; or a mixt. of these. ADVANTAGE - Sepn. of p-DCB from m-DCB is very highly selective and the process is suitable for both batch and continuous operation.