GB789679A - A process for the upgrading of cracked naphtha - Google Patents

Abstract

A gasoline having a F-1 clear octane rating above 80 is produced by fractionally distilling a hydrogenated cracked naphtha having a boiling range within 125-450 DEG F. to separate an overhead fraction having a 90 per cent point below 350 DEG F. and a higher boiling bottoms fraction having a 90 per cent point above 400 DEG F., and separately contacting the two fractions with hydrogen in the presence of a hydrogenation catalyst so as to produce a normally liquid product having less than 0.2 per cent by weight of sulphur and less than 22 parts per million of nitrogen. Cobalt-molybdenum is the preferred catalyst, but tungsten sulphide, tungsten nickel sulphide, molybdenum oxide or molybdenum sulphide may be used in the hydrogenation step. As a modification, the cracked naphtha is first hydrogenated under the hydrogenating conditions and is then distilled to form said fractions having said 90 per cent points and the hydrogenated cracked naphtha fractions are separately contacted with a platinum catalyst under sufficiently severe dehydrating conditions to produce a liquid product having an F.I. clear octane rating above 80, the conditions being substantially less severe in the case of the bottoms fraction. The platinum is preferably supported on alumina or silica-alumina.