GB818836A - Improvements in or relating to reforming naphtha - Google Patents

Abstract

<PICT:0818836/IV (b)/1> A naphtha is reformed by first distilling to obtain a light naphtha boiling up to about 200 DEG F. and a heavy naphtha which latter is reformed over a platinum-alumina catalyst and the reformate distilled to obtain a light reformate boiling up to about 200 DEG F. which is combined with the light naphtha and reformed over an alkalized chromia-alumina catalyst at 0-200 p.s.i.g. in the presence or absence of hydrogen and the reformate so obtained blended with the heavy platinum reformate. The naphtha is fed into distillation tower 11 from which C4 and lighter hydrocarbons are removed overhead, a C5-C7 fraction having an end point of 200 \sB 15 DEG F. is removed by line 13, a 200-360 DEG F. fraction by line 14 and heavier materials as bottoms. The fraction in line 14 may be desulphurized before reforming; the charge to the reforming stage 16 may contain 5-30 p.p.m. sulphur, 1-10 p.p.m. chloride, 2-20 p.p.m. water and less than 5 p.p.m. nitrogen. It is reformed over a platinum catalyst in the presence of hydrogen at 100-400 p.s.i.g. and 850-1000 DEG F. with a space velocity of 0.1-10 vol./vol./hr. and a hydrogen recycle rate of 1000-8000 S.C.F./barrel of hydrogen employing three heater-reactor stages. The reformate is debutanized and then fractionated in tower 22, the heavier product being removed by line 29 and the C5-200 DEG F. overhead being recycled by line 28 to join the light naphtha charge in line 13. This light feed is reformed over an alkalized chromia-alumina catalyst containing for example 18 per cent Cr2O3, 4 per cent K2O, 4 per cent SiO2 and 74 per cent Al2O3. Conditions employed are 0-200 p.s.i.g., preferably about 25 p.s.i.g., 975-1125 DEG F. and a space velocity of 0.1-10 vol./vol./hr. Hydrogen may be recycled if a fluidized catalyst is used. The reformate is debutanized and led by line 35 to be blended with the heavy platinum reformate in line 29.