Patent ID: 7048846

Claim:
A method for lowering the sulfur content of a naphtha hydrocarbon feed stream while substantially maintaining the yield of olefin compounds in the feed stream, said method comprising i) contacting a naphtha feed with a membrane separation zone, said separation zone containing a membrane having a sufficient flux and selectivity to separate a sulfur-enriched permeate fraction and a sulfur deficient retentate fraction, said sulfur deficient retentate fraction having a sulfur content of less than 100 ppm sulfur and comprising at least 50 wt % of olefins present in the naphtha feed under pervaporation conditions, said membrane having a sulfur enrichment factor of greater than 1.5, said naphtha feed being selected from the group consisting of a light naphtha, an intermediate naphtha, a coker naphtha, a straight run naphtha and mixtures thereof, and comprising sulfur containing aromatic hydrocarbons, sulfur containing non-aromatic hydrocarbon and olefin compounds, said sulfur enriched permeate fraction being enriched in sulfur containing aromatic hydrocarbons and sulfur containing non-aromatic hydrocarbons as compared to the naphtha feed; ii) recovering the sulfur deficient retentate fraction as a product stream; iii) subjecting the sulfur enriched permeate fraction to a non-membrane process to reduce sulfur content; and iv) recovering a reduced sulfur permeate product stream.