Method of converting saturated sulfur compounds of a hydrocarbon cut containing few or no olefins

Abstract

The invention relates to a method of converting the mercaptans contained in a hydrocarbon cut containing few or no olefins to heavier sulfur compounds. The method comprises a first stage of mixing the cut to be treated with hydrogen and possibly an olefin cut, then a second stage of reaction of the mixture from the first stage on a catalyst containing at least one group VIII metal. The invention also relates to the application of the method to treatment of a straight-run gasoline.

1 ) A method of converting mercaptans contained in a hydrocarbon feed containing less than 5% by weight of olefins, comprising at least two stages: 
 a first stage of mixing the feed to be treated with an amount of hydrogen, and optionally a stream containing the resulting mixture having a H 2 /olefin molar ratio ranging between 0.03 and 2, and an olefin/mercaptan molar ratio ranging between 5 and 5000, and    a reaction stage comprising reacting of the mixture formed at the end of the first stage on a supported catalyst containing at least one group VIII metal, so as to convert mercaptans to heavier sulfur compounds with a conversion rate of at least 50%.    
   
   
       2 ) A mercaptan conversion method as claimed in  claim 1 , wherein said hydrocarbon feed contains less than 1% by weight of olefins.  
   
   
       3 ) A mercaptan conversion method as claimed in  claim 1 , wherein the reaction stage is carried out at a temperature ranging between 100° C. and 250° C.  
   
   
       4 ) A mercaptan conversion method as claimed in  claim 1 , wherein the reaction stage is carried out at a pressure ranging between 0.5 MPa and 5 MPa.  
   
   
       5 ) A mercaptan conversion method as claimed in  claim 1 , wherein the reaction stage is carried out at a space velocity ranging between 1 h −1  and 10 h −1 .  
   
   
       6 ) A mercaptan conversion method as claimed in  claim 1 , wherein the feed to be treated is a straight-run gasoline.  
   
   
       7 ) A mercaptan conversion method as claimed in  claim 1  comprising adding to the feed to be treated an amount of catalytically cracked gasoline.  
   
   
       8 ) A mercaptan conversion method as claimed in further comprising withdrawing mercaptan-depleted effluent from the reaction stage and separating said effluent from the sulfur compounds formed during said reaction stage so as to produce an effluent containing less than 50% sulfur compounds present in the feed, and a cut containing the major part of the sulfur compounds.  
   
   
       9 ) A mercaptan conversion method as claimed in  claim 8 , wherein said separating is conducted by flashing or by distillation.  
   
   
       10 ) A mercaptan conversion method as claimed in  claim 1 , wherein the catalyst used in the reaction stage also contains at least one group VIb metal.  
   
   
       11 ) A mercaptan conversion method as claimed in  claim 1 , wherein the catalyst used in the reaction stage contains between 1% and 30% by weight of group VIII metal in oxide form, and 0% to 20% by weight of group VIb metal in oxide form.  
   
   
       12 ) A mercaptan conversion method as claimed in  claim 1 , wherein the catalyst used in the reaction stage contains between 1% and 30% by weight of NiO, and between 0% to 20% by weight of MoO 3 .  
   
   
       13 ) A mercaptan conversion method as claimed in  claim 1 , wherein the catalyst used in the reaction stage is first subjected to a sulfurization stage so that the proportion of metal present in sulfide form is above 50%.  
   
   
       14 ) A method according to  claim 1  wherein said resulting mixture has an H 2  olefin molar ration between 0.05 and 1.  
   
   
       15 ) A method according to  claim 1  wherein said olefin/mercaptan molar ration is between 10 and 1000.  
   
   
       16 ) A method according to  claim 14  wherein said olefin/mercaptan molar ration is between 10 and 1000.  
   
   
       17 . A method as claimed in  claim 1  wherein the reaction s conducted at a temperature of 140°-240° C. and a pressure of 1 MPa to 3 MPa, and a space velocity of between 1.5 h −1  and 8 h −1 .  
   
   
       18 ) A method according to  claim 11  wherein the catalyst contains said group VIb metal in oxide form.  
   
   
       19 ) A method according to  claim 12  wherein the catalyst contains MoO 3 .  
   
   
       20 ) A method according to  claim 13  wherein the proportion of metal present in sulfide form is above 90%.