Patent GB-1408758-A (GB)
Title: Process for producing from gasoline starting material containing  c5and hydrocarbons including normal paraffins a gasoline product  of higher octane number than said gasoline starting material
IPC: C10L1/06
Filed: 1971-12-06
Abstract: 1408758 Cracking and reforming naphtha SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV 27 Sept 1972 [6 Dec 1971] 56525/71 Heading C5E A gasoline containing normal paraffins is treated to raise its octane number by (i) reforming a heavy fraction (hexane and above, heptane and above or octane and above) of the gasoline, (ii) isomerizing a light fraction of the gasoline (pentanes or pentanes and hexanes), (iii) selectively hydro-cracking the normal paraffins in (a) the isomerizate or a fraction thereof, or (b) the reformate or a fraction thereof, or (c) the isomerizate or a fraction thereof in combination with the reformate or a fraction thereof, and (iv) debutanizing the hydrocrackate. Sixteen process schemes are described, in each of which the gasoline is first fractionated into two or three fractions, of which the heaviest and lightest are reformed and isomerized respectively. In scheme I the isomerizate is hydrocracked and combined with the reformate; in scheme II the isomerizate and reformate are combined and then hydrocracked. In each of schemes III to XVI, the reformate is debutanized and then fractionated into two or three fractions, of which the heaviest is taken off as product. Thereafter: (III to V) the light fraction from the reformate is combined with the light fraction from the feed before or after the isomerization or is isomerized separately and then combined, in each case the combined material is then hydrocracked; (VI and VII) the light fraction from the reformate is combined with that from the feed and isomerized, a heptane fraction from the reformate or from the feed is combined with the isomerizate and hydrocracked; (VIII) the feed is fractionated into three, the reformate into two, and the light fraction of the reformate and the heptane fraction of the feed are combined with the isomerizate and hydrocracked; (IX) the fraction fed to isomerization comprises pentanes only, a pentanes fraction from the reformate is combined with the isomerizate and fractionated, normal pentane from this fractionation is recycled to the isomerization, a hexane-heptane fraction from the reformate is hydrocracked and the hydrocrackate is combined with the isopentane fraction from the isomerizate; (X) pentane fractions from the feed and the reformate are refractionated to separate normal pentane from isomers, only the normal pentane is isomerized and is then returned to the refractionation, a hexane-heptane fraction of the reformate is hydrocracked and then mixed with the isopentane fraction from feed and reformate; (XI) light fractions of the feed and the reformate are combined and isomerized, the isomerizate is fractionated to separate isopentane, normal pentane and hexane fractions of which the last is hydrocracked and then combined with the isopentane fraction, while the normal pentane fraction is recycled to the isomerization; (XII) as XI except that a heptane fraction from the reformate is combined with the hexane fraction from the isomerization before the hydrocracking step; (XIII) a light fraction pentanes and hexanes from the reformate is combined with the light fraction from the feed after the latter has been isomerized, the combined material is fractionated to separate isopentanes, normal pentane and hexanes, the normal pentanes are recycled to the isomerization, the hexanes are combined with a heptane fraction from the feed and hydrocracked, and the isopentane fraction is combined with the hydrocrackate; (XIV) pentane-hexane fractions from the feed and the reformate are combined and isopentanes separated by fractionation, the residue is isomerized and fractionated, the pentanes being recycled to the isopentane-separating step, the hexane fraction of the isomerizate is hydrocracked and then combined with the isopentane fraction; (XV) and (XVI) as (XIV) except that a heptane fraction from the reformate or from the feed is combined with the hexanes from the isomerizate before these are hydrocracked. In each case also the hydrocrackate or blend containing it is debutanized. Suitable catalysts and reaction conditions for each step are disclosed. The separate product streams can be blended. Heptane fractions can be dehydrocyclized instead of being hydrocracked. Additional light, intermediate or heavy fractions from other sources may be combined with the process streams.