THE SEPARATION OF META-XYLENE AND PARA-XYLENE BY PERVAPORATION IN THE PRESENCE OF CBR4, A SELECTIVE FEED-COMPLEXING AGENT

Carbon-tetrabromide selectively forms a solid molecular complex with p-xylene; at temperatures below about 5-degrees-C, the presence of 24 mol% CBr4 in the feed results in a pervaporation process very selective for m-xylene. This occurs even though the polypropylene membrane is selective for p-xylene. At higher temperatures, the process is selective for p-xylene when CBr4 is present. Separation factors (alpha(P/M)) varied from about 1.2 to 0.05 depending upon (1) temperature, (2) p-xylene concentration, and (3) the amount of CBr4 present.