| 摘要 |
1420796 Separating C 8 aromatic isomers by adsorption MOBIL OIL CORP 19 Nov 1973 [28 Nov 1972] 53612/73 Heading C5E A C 8 aromatic mixture is separated into a first stream comprising meta and ortho xylenes and a second stream comprising para xylene and ethylbenzene by selective adsorption of the latter stream on a ZSM.5 or ZSM.8 zeolite which is disposed in at least two parallel columns which are operated such that adsorption is carried out in one column while desorption is effected in the other and vice versa, m and o xylenes being recovered during the adsorption stages and p-xylene and ethylbenzene during the desorption stages. The meta and ortho xylene stream may be distilled to recover the components, the latter being isomerized and recycled to the adsorption. The isomerization may be carried out at 250-1000‹ F. with a zeolite catalyst and in the presence of toluene as diluent. The second stream may be subjected to crystallization to recover p-xylene and ethylbenzene. Desorption may be effected by (1) reduction in the partial pressure of the sorbed materials in the vapour phase surrounding the adsorbent, (2) lowering the total pressure of the system, (3) heating the adsorbent or preferably (4) purging with an inert desorbent gas or vapour, e.g. steam, He, N 2 , toluene or benzene. |
