Patent GB-665618-A (GB)
Title: Improvements relating to the thermal reforming of naphthas
IPC: C10G59/04
Filed: 1948-11-26
Abstract: <PICT:0665618/IV (b)/1> Petroleum naphtha is desulphurized by passing it in vapour form in admixture with hydrogen over a catalyst which combines activity for dehydrogenation of naphthenes to aromatics with activity for the conversion of organically combined sulphur to hydrogen sulphide.  The temperature and pressure employed are sufficient to effect the conversion of sulphur contained in the naphtha into hydrogen sulphide and to produce a hydrogen-rich gas mixture which is separated from the treated naphtha and recycled to the desulphurization zone at a rate sufficient to maintain the necessary partial pressure of hydrogen therein, the hydrogen produced in the desulphurization zone constituting the whole of the hydrogen fed to the zone.  The desulphurized naphtha is finally passed to a thermal reforming zone.  Cobalt molybdate, preferably supported on alumina, is the preferred catalyst but molybdenum oxide on alumina, mixtures of tungsten and nickel sulphides, and molybdenum sulphide may also be used.  The desulphurization zone may be maintained at a temperature of 650-800 DEG  F. and a pressure of 25-500 p.s.i.  The diagram shows a method of carrying out the process in which the crude naphtha is fed by pump 10 through a heat exchanger 11 to furnace 12 and thence to an autofining chamber 13.  The products are passed to a separator 14 in which hydrogen and hydrogen sulphide are separated. The hydrogen is recycled by means of compressor 15 and the naphtha after removal of hydrogen sulphide in chamber 32, is fed to a thermal reforming furnace 17.  The products are passed to an evaporator 18 from which the overhead is passed to a fractionator 19.  The bottoms product is passed to a residues stripper 20, from which residue is removed through line 21, and overhead returned to the fractionator 19, from which the overhead product is passed to a clay treating tower 23 and an absorber-stripper 24.  The bottoms product is passed to a stabilizer 25 from which C3 and C4 hydrocarbons are removed as overhead through line 27.  The finished gasoline is removed through line 26 and part is recycled through line 28 to the absorber-stripper 24, from which the overhead is passed to absorber 29, to the top of which is fed the product from the base of the fractionator 19 through line 30.  The bottoms product from 29 is returned to the fractionator 19 and the gas is removed overhead by line 31.  In an example, the autofining was carried out at 780 DEG  F., and 100 p.s.i. ga. pressure using cobalt molybdate as catalyst, and the thermal reforming at 1010 DEG  F. and 1000 p.s.i. ga. pressure. Specification 654,152, [Group III], is referred to.ALSO:<PICT:0665618/III/1> Petroleum naphtha is desulphurized by passing it in vapour form in admixture with hydrogen over a catalyst which combines activity for dehydrogenation of naphthenes to aromatics with activity for the conversion of organically combined sulphur to hydrogen sulphide.  The temperature and pressure employed are sufficient to effect the conversion of sulphur contained in the naphtha into hydrogen sulphide and to produce a hydrogen-rich gas mixture which is separated from the treated naphtha and recycled to the desulphurization zone at a rate sufficient to maintain the necessary partial pressure of hydrogen therein, the hydrogen produced in the desulphurization zone constituting the whole of the hydrogen fed to the zone.  The desulphurized naphtha is finally passed to a thermal reforming zone.  Cobalt molybdate, preferably supported on alumina, is the preferred catalyst but molybdenum oxide of alumina, mixtures of tungsten and nickel sulphides, and molybdenum sulphide may also be used.  The desulphurization zone may be maintained at a temperature at 650-800 DEG F. and a pressure of 25-500 per square inch.  The diagram shows a method of carrying out the process in which the crude naphtha is fed by pump 10 through a heat-exchanger 1 to furnace 12 and thence to an autofining chamber 13.  The products are passed to a separator 14 in which hydrogen and hydrogen sulphide are separated.  The hydrogen is recycled by means of compressor 15 and the naphtha, after removal of hydrogen sulphide in chamber 32, is fed to a thermal reforming furnace 17.  The products are passed to an evaporator 18 from which the overhead is passed to a fractionator 19. The bottoms product is passed to a residues stripper 20, from which residue is removed through line 21, and overhead returned to the fractionator 19, from which the overhead product is passed to a clay treating tower 23 and an absorber-stripper 24.  The bottoms product is passed to a stabilizer 25 from which C3 and C4 hydrocarbons are removed as overhead through line 27.  The finished gasoline is removed through line 26 and part is recycled through line 28 to the absorber-stripper 24, from which the overhead is passed to absorber 29, to the top of which is fed the product from the base of the fractionator 19 through line 30.  The bottoms product from 29 is returned to the fractionator 19 and the gas removed overhead by line 31.  In an example, the autofining is carried out at 780 DEG F. and 100 per square inch ga pressure using cobalt molybdate as catalyst, and the thermal reforming at 1010 DEG F. and 1000 per square inch ga pressure.  Specification 654,152 is referred to.