Patent GB-842580-A (GB)
Title: Purification of naphtha feedstocks for reforming processes
IPC: C10G69/08
Filed: 1957-10-10
Abstract: <PICT:0842580/IV(b)/1> Naphtha feedstocks to reforming processes operated below 500 p.s.i.g. (35 Kg/Cm2) are freed of excessive amounts of sulphur and nitrogen contaminants by hydrogenating at below 500 p.s.i.g. in the presence of a hydrogenation catalyst with hydrogen produced in the reforming process thereby effecting a substantial conversion of the sulphur contaminants and an at least partial conversion of the nitrogen compounds to readily separable forms, separating the converted contaminants, and contacting the hydrogenated naphtha in the liquid phase with an adsorbent capable of adsorbing at least a substantial proportion of the remaining nitrogen contaminants.  The hydrogenation may be carried out under the following conditions:-600-850 DEG F.; 0-500 p.s.i.g. (preferably 300 p.s.i.g.); 1-10 V/V/Hr; and 50-1000 S.C.F.H2/bbl. supplied from the reformer to the pretreater and 100-10,000 S.C.F./bbl. of hydrogen rich gas recycled with the pretreater.  Hydrogenation catalysts mentioned are bauxite; fuller's earth; Group VI metal oxides, e.g. chromia, and Group V and VI metal oxide mixtures, e.g. nickel tungstate or cobalt molybdate, on alumina; and relatively deactivated platinum on alumina reforming catalysts.  Examples of adsorbents are fuller's earth, kieselguhr, activated alumina and activated bauxite. Reforming catalysts mentioned are platinum on alumina catalysts, e.g. platinum sulphide obtained by reacting chloroplatinic acid with ammonium sulphide in aqueous solution, combining with hydrous alumina, drying, and calcining.  The catalyst may contain halogens, e.g. chlorine or fluorine, but should be substantially free from sodium, iron and molybdenum oxides.  Reforming conditions may be 850-1,050 DEG F.; below 500 p.s.i.g. e.g. 300 to 350 p.s.i.g., and 0,5-10 V/V/Hr., and there is a net production of hydrogen.  Hydrogen from the reforming process from line 13 joins the naphtha feed in line 12 which is then passed through heat exchanger 14 and preheater 16 to the top of hydrogen treater 20 via line 18.  The hydrogenated naphtha leaves the bottom of treater 20 and passes via line 22, heat exchanger 14, line 23, cooler 24 and line 25 to stripper 26 where it is stripped of H2S and NH3 by hydrogen diverted from line 13 by branch 27.  The stripped naphtha from the bottom of the stripper is passed to the top of percolator 32 via line 29, cooler 30 and line 31.  After percolating through the adsorbent the naphtha passes to the reforming process via line 34.  When the adsorbent requires renewal the feed may be replaced by a low nitrogen (e.g. virgin) naphtha and the percolator bypassed via line 33 whilst the adsorbent is renewed.ALSO:Naphtha feedstocks to reforming processes operated below 500 p.s.i.g. (35 Kg/Cm2) are freed of excessive amounts of sulphur and nitrogen contaminants by hydrogenating at below 500 p.s.i.g. in the presence of a hydrogenation catalyst with hydrogen produced in the reforming process thereby effecting a substantial conversion of the sulphur contaminants and an at least partial conversion of the nitrogen compounds to readily separable forms, separating the converted contaminants and con <PICT:0842580/III/1> tacting the hydrogenated naphtha in the liquid phase with an adsorbent capable of adsorbing at least a substantial proportion of the remaining nitrogen contaminants.  The hydrogenation may be carried out under the following conditions:- 600-850 DEG F; 0-500 p.s.i.g. (preferably 300 p.s.i.g.); 1-10 V/V/Hr; and 50-1000 S.C.F.H.2/bbl. supplied from the reformer to the pretreater and 100-10,000 S.C.F./bbl. of hydrogen-rich gas recycled with the pretreater.  Hydrogenation catalysts mentioned are bauxite; fuller's earth; Group VI metal oxides, e.g. chromia, and Group V and VI metal oxide mixtures, e.g. nickel tungstate or cobalt molybdate, on alumina; and relatively deactivated platinum on alumina reforming catalysts.  Examples of adsorbents are fuller's earth, kieselguhr, activated alumina and activated bauxite. Reforming catalysts mentioned are platinum on alumina catalysts e.g. platinum sulphide obtained by reacting chloroplatinic acid with ammonium sulphide in aqueous solution, combining with hydrous alumina, drying, and calcining.  The catalyst may contain halogens, e.g. chlorine or fluorine, but should be substantially free from sodium, iron and molybdenum oxides.  Reforming conditions may be 850-1050 DEG F; below 500 p.s.i.g. e.g. 300 to 350 p.s.i.g., and 0.5-10 V/V/Hr., and there is a net production of hydrogen.  Hydrogen from the reforming process from line 13 joins the naphtha feed in line 12 which is then passed through heat exchanger 14 and preheater 16 to the top of hydrogen treater 20 via line 18.  The hydrogenated naphtha leaves the bottom of treater 20 and passes via line 22, heat exchanger 14, line 23, cooler 24 and line 25 to stripper 26 where it is stripped of H2S and NH3 by hydrogen diverted from line 13 by branch 27.  The stripped naphtha from the bottom of the stripper is passed to the top of percolator 32 via line 29, cooler 30 and line 31.  After percolating through the adsorbent the naphtha passes to the reforming process via line 34.  When the adsorbent requires renewal the feed may be replaced by a low nitrogen (e.g. virgin) naphtha and the percolator by-passed via line 33 whilst the adsorbent is renewed.