SEPARATION OF ISOMERIC XYLENES BY PERMEATION THROUGH MODIFIED PLASTIC FILMS

The modification of poly(vinylidene fluoride) membranes by including Werner complexes in them was investigated for the separation of the xylene isomers. The two basic additives investigated were Ni(SCN)2(4-methylpyridine)4 p-xylene and Ni(SCN)2(α-methylbenzylamine)4 o-xylene. It was found that both of these clathrates made the poly(vinylidene fluoride) film selective for p-xylene, but the second compound produced the larger p-xylene separations. The best p-xylene product-feed composition differences obtained were in the range of 8 percent beginning with a feed containing an equimolar mixture of the three xylene isomers. The total product flow rates obtained were about 1 ml/(h-ft2) at the best separations, but ranged up to over 100 ml/(h-ft2). © 1978.