PROCESS FOR PREPARING ISOPENTANE AND ISOHEXANE BY ISOMERIZING MIXTURES CONTAINING N-PENTANE AND N-HEXANE

摘要

1421933 Preparing isopentane and isohexane from n-pentane and n-hexane INSTITUT FRANCAIS DU PETROLE 14 May 1973 [17 May 1972] 22855/73 Heading C5E Branched chain pentanes 17 (referred to as isopentane) and branched chain hexanes 20 (referred to as isohexanes) are produced from a mixture 15 comprising n-pentane and nhexane by distilling it together with a recycle stream 14 comprising n-hexane and isopentane to produce a top isopentane stream 17 and a bottom fraction 18 rich in n-pentane, n-hexane and isohexane if present; isomerizing the fraction 18 at 100-250‹ C. with a catalyst comprising alumina, 0À1-2 wt. per cent Pt and at least 4% wt chlorine to produce a fraction 11 enriched with isopentane and isohexane; contacting the isomerizate 11 with a molecular sieve bed T which has previously been charged with npentane to absorb n-hexane; distilling the outlet stream 12 from the bed T at DII to produce a bottom isohexane stream 20 and a top fraction 19 comprising n-pentane and isopentane; and contacting the fraction 19 with the molecular sieve bed T which has been charged with n-hexane to absorb n-pentane and produce the recycle stream 14. In a modification (Fig. 2, not shown) the n-pentane, n-hexane and isohexane containing bottoms stream from the first distillation is distilled to produce n-pentane and n-hoxane fractions which are separately isomerized to produce C 5 and C 6 isomerizates. The C 6 isomerizate is passed through a molecular sieve bed which has been previously charged with n-pentane and the outlet stream is distilled to produce an n-pentane fraction 9 and an isohexane fraction 10. The C 5 isomerizate is passed through the molecular sieve bed which has been previously charged with n-hexane to produce a stream comprising n-hexane and isopentane which is recycled.