| 摘要 |
1,208,328. Para-xylene. SINCLAIR RESEARCH Inc. 23 April, 1968 [22 May, 1967], No. 19050/68. Heading C5E. Para-xylene of at least 94 mole per cent purity is obtained from a C 8 aromatic hydrocarbon mixture containing 5-50% para-xylene and other xylene isomers by cooling the mixture in a crystallization zone to crystallize substantially only para-xylene (e.g. at from - 60‹ to - 100‹ F.), separating a para-xylene cake by centrifugation, washing the cake with toluene in an amount sufficient to provide toluene in the wash effluent, and recycling said effluent to said crystallization zone whereby the eutectic temperature of the mixture in said zone is lowered. The separated cake normally contains 10-30 wt. per cent occluded liquid and is washed with 0À5-10 moles of toluene per mole of said liquid. |
