GB1431491A - Process for the desulphurization of petroleum oil stocks - Google Patents

Abstract

1431491 Desulphurizing oils EXXON RESEARCH & ENG CO 8 May 1973 [24 May 1972] 21875/73 Heading C5E Sulphur is removed from whole or reduced crude oils or from heavy distillates by contacting with alkali metal or with an alloy thereof and the mixture of oil and alkali metal salts formed is treated with hydrogen sulphide, e.g. 10- 400 mole per cent hydrogen sulphide (based upon the total moles of salt in the mixture). The desulphurization of the oil can be carried out at 450-750‹ F. and 10-600 p.s.i.g. and the treatment with H 2 S can be carried out at 600- 800‹ F. and 25-50 p.s.i.g. A sulphur containing feed 1 is contacted in the column 18 with a dispersion of the alkali metal 67 and the resultant stream 21 is contacted at 22 with 30-80 mole per cent hydrogen sulphide. The H 2 S-treated stream 24 is separated in the hydrocyclones 27 and 28 into salt slurries 39 and 40 and an oil stream 29 which can be treated with dilute sulphuric or acetic acid 32 and stripped with steam at 37. The salt slurries 39 and 40 are washed with a light hydrocarbon to remove oil and dried at 45, the solids 47 are mixed with sulphur-rich alkali metal polysulphide 49 to produce hydrogen sulphide 50 and sulphurdepleted polysulphide 52 which is passed to an electrolytic cell 56 in which it is converted to an alkali metal stream 62 and sulphur-rich polysulphide 57 which is stripped at 60 to remove sulphur as vapour. Fig. 2 (not shown) illustrates a modification of Fig. 1 in which the oil is desulphurized using an alloy (e.g. Na-Pb or Na-Sn) which is then regenerated with alkali metal from the electrolytic cell. Fig. 3 (not shown) illustrates a modification of Fig. 1 in which the oil-salt dispersion 26, after treatment with H 2 S is not separated in the hydrocyclones (27 and 28, Fig. 1) but is contacted in a tower 80 with a countercurrent of molten sulphur-rich sodium polysulphide 49 and if desired with additional H 2 S 91. Fig. 4 (not shown) illustrates a modification of Fig. 1 in which the oil-salt dispersion 21 is contacted with an excess of H 2 S in the tower 22 and is separated at 82 into a stream 83 of molten sodium hydrosulphide which is either contacted with sulphurrich sodium polysulphide in the polysulphide blending vessel 48 or is contacted with molten sulphur in a vessel 86 to liberate a H 2 S stream 50 and a sodium polysulphide product 99 which is blended with the pyrolysed polysulphide product 49.