feedstock which contained sulfur containing impurities analysis of the naphtha feedstock using a multi column gas chromatographic technique showed it to contain on a weight basis 42 5 percent olefins 7 75 percent cyclic olefins 15 6 percent aromatics and 32 3 percent paraffins 9 41 percent cyclic paraffins this naphtha feedstock was admixed with isopropyl alcohol to provide feedstock having an alkanol level of 240 parts per million except were stated otherwise the catalyst used for the examples was a solid phosphoric acid catalyst c84 5 01 supplied by sud chemie inc louisville ky usa which was crushed to a tyler screen mesh size of u2212 12 20 usa standard testing sieve by w s tyler unless otherwise indicated percentages and parts per million ppm are on the bases of an appropriate weight in this example of the invention the two reactors were charged with the solid phosphoric acid catalyst having particle sizes tyler screen mesh u2212 12 20 and operated at a liquid hourly space velocity of 1 5 hr u2212 1 reactor one was maintained at a temperature of about 172 u00b0 c and reactor two at a temperature of about 122 u00b0 c i e a temperature differential between the serial reactors of negative 50 u00b0 c analysis of the process stream is shown in table viii the reduction in the total of 2 methyl and 3 methyl thiophenes was from about 254 ppm to about 3 ppm a reduction of about 98 8 percent the total of c2 thiophenes was reduced from about 125 ppm to about 29 ppm a reduction of 76 8 percent the.