GB826909A - Process for reforming hydrocarbon fractions boiling in the gasoline range - Google Patents

Abstract

Gasoline, prior to reforming, is hydrodesulphurized to a sulphur content below 0.002% preferably below 0.001%. The catalyst is one containing 1-20% molybdenum and 0.1-15% cobalt supported on a refractory oxide such as alumina, silica, zirconia, magnesia, boria, thoria, strontia, or mixtures thereof or may contain tungsten, copper, nickel and iron as such or in conjunction with cobalt and molybdenum. The hydrogen used may be obtained from the subsequent reforming and is used in amounts of 17.5-90 litres per litre of liquid hydrocarbon. Other conditions used are 235-375 DEG C., 20-60 atmospheres and an L.H.S.V. of 1-30. Arsenic, lead and nitrogenous impurities are also removed.ALSO:A sulphur-free gasoline is reformed in the presence of a recycle gas and a platinum-group metal and the recycle gas is provided initially with hydrogen sulphide in a maximum amount of 35 grams per 100 cubic metres and the content of hydrogen sulphide is lowered as the operation proceeds. In a preferred operation gasoline is hydrodesulphurized over a cobalt molybdate catalyst employing as hydrogen recycle gas from the reforming reaction to give a product of sulphur content below 0.002% (see Group III). The liquid and gaseous products are separated and if necessary material boiling above 205-218 DEG C. removed. To this feed is added a hydrogen sulphide precursor in an amount sufficient to provide in the recycle gas a hydrogen sulphide content of 18-35 grams per 100 cubic metres. Suitable additives are alkyl mercaptans, especially tert.-butyl or -amyl mercaptan, thiophenols and benzene or toluene sulphonic acids. The amount added is reduced during the initial 10-14 days of operation until the content of hydrogen sulphide in the gas is below 5 grams per 100 cubic metres and addition is then discontinued. The catalyst used may contain 0.01-5% of platinum, palladium, iridium, rhodium or ruthenium and may also contain caesium, vanadium, chromium, tungsten, sodium, silver, or rhenium as metal, halide or oxide in an amount of 0.01-5% and combined chlorine and/or fluorine in an amount of 0.1-8%. Suitable supports are silica, alumina, zirconia, magnesia, boria, thoria, or strontia or mixtures thereof. Reforming is effected at 425-565 DEG C. and 20-60 atmospheres with an LHSV of 0.5-20 and a recycle rate giving 2-20 mols. of hydrogen per mol. of gasoline.