Process of removal of sulphur compounds from hydrocarbon streams using adsorbents

Abstract

The invention concerns a process for the removal of sulphur compounds from a hydrocarbon stream, especially a gaseous hydrocarbon gas stream, which process comprises contacting said gas stream with an adsorbent comprising at least a zeolite having a pore diameter of at least 5 Å to adsorb the sulphur compounds thereon, the adsorption procedure followed by a regeneration procedure of used, loaded adsorbent by contacting the said loaded adsorbent with a regeneration gas stream having a relative water humidity between 1-100% for certain steps of the regeneration and a water content of below 5 ppmV for other steps thus to replace the adsorbed sulphur compounds by water. Suitably the regeneration is followed by a dry regeneration treatment to finalize the regeneration. The process of the invention allows to send the sulphur compounds containing regeneration gas without further treatment of e.g. physical/chemical absorption for sulphur components concentration to an appropriate treatment for sulphur removal such as e.g. a Claus unit.

1 . A process for the removal of sulphur compounds from a hydrocarbon stream, especially a gaseous hydrocarbon gas stream, comprising said sulphur compounds, which process comprises contacting said gas stream with at least an adsorbent comprising a zeolite having a pore diameter of at least 5 Å to adsorb the sulphur compounds thereon and to obtain a treated gas, the adsorption process is followed by a regeneration procedure of used, loaded adsorbent, characterized in that the regeneration procedure comprises the following steps: 
 a/ contacting the said loaded adsorbent with a first dry gas having a temperature within the range from 15-200° C. and a pressure of 5-70 bara in a turn-around way by recycling the first dry gas at least partially and preferably completely through the adsorbent,    b/ then contacting the loaded adsorbent with a regeneration gas stream having a relative water humidity between 1 and 100% saturation, a temperature of 15-200° C. and a pressure of 5-70 bara being partially recycled through the adsorbent or not,    c/ and finally contacting the said loaded adsorbent with a second dry gas having a temperature within the range from 50-350° C. and a the pressure of 5-70 bara.    
   
   
       2 . A process according to  claim 1 , in which the contacting of gas in step a) and b) are performed in the same flow direction as the contacting in the adsorption process.  
   
   
       3 . A process according to  claim 1 , in which the hydrocarbon stream is natural gas, associated gas, a natural gas liquids stream, a natural gas condensate stream or a refinery gas stream.  
   
   
       4 . A process according to  claim 1 , in which the sulphur compounds are hydrogen sulphide, carbonyl sulphide, mercaptans, especially C 1 -C 6  mercaptans, organic sulphides, especially di-C 1 -C 4 -alkyl sulphides, organic disulphides, especially di-C 1 -C 4 -alkyl disulphides, thiophene compounds, aromatic mercaptans, especially phenyl mercaptan, or mixtures thereof, preferably mercaptans, more especially C 1 -C 4  mercaptans, the total amount of sulphur compounds preferably being up to 3 vol % based on total gas stream, more preferably up till 1.5% Vol, more preferably up till 0.1% Vol, still more preferably between 1 and 700 ppmV, most preferably between 2 and 500 ppmV.  
   
   
       5 . A process according to  claim 1 , in which the gas stream also comprises water.  
   
   
       6 . A process according to  claim 1 , in which the gas stream also comprises hydrogen sulphide and optionally carbon dioxide.  
   
   
       7 . A process according to  claim 1 , in which the temperature of the zeolite adsorption process is between 10 and 60° C., the pressure is between 10 and 150 bara, and the superficial gas velocity is between 0.03 and 0.6.  
   
   
       8 . A process according to  claim 1 , in which the temperature of the first and second steps of the regeneration process is between 100 and 350° C., and the pressure between 5 and 70 bara.  
   
   
       9 . A process according to  claim 1 , in which the adsorbent(s) comprises at least a zeolite dispersed in a binder.  
   
   
       10 . A process according to  claim 1 , in which the adsorbent is in the form of at least two beds, one bed comprising zeolite having a pore diameter inferior or equal to 5 Å, preferably 3 or 4 Å, such as a 3 Å or 4Å zeolite, the second and eventually further beds comprising at least a zeolite having a pore diameter of more or equal to 5 Å.  
   
   
       11 . A process according to  claim 1 , in which the regeneration steps are carried out at a superficial gas velocity of less than 0.20 m/s.  
   
   
       12 . A process according to  claim 1 , in which the regeneration gas stream for step b) of the regeneration is a gas stream obtained by saturating the stream with water at a temperature below the regeneration temperature.  
   
   
       13 . A process according to  claim 1 , in which the regeneration gas stream for the step b) of the regeneration procedure has a relative humidity between 1 and 50%.  
   
   
       14 . A process according to  claim 5 , in which the water is removed before the removal of the sulphur compounds.  
   
   
       15 . A process according to  claim 14 , in which the water is removed by adsorbing it on a zeolite having a pore diameter of inferior or equal to 5 Å.  
   
   
       16 . A process according to  claim 15 , in which the water is removed by adsorbing it on a zeolite having a pore diameter of 3 to 4 Å.  
   
   
       17 . A process according to  claim 6 , in which the carbon dioxide is contained in the gas stream in an amount up to 2 Vol % hydrogen sulphide.  
   
   
       18 . A process according to  claim 6 , in which the carbon dioxide is contained n the gas stream in an amount up to 0.5% Vol % hydrogen sulphide.  
   
   
       19 . A process according to  claim 16 , in which the hydrogen sulphide and part of the carbon dioxide is removed by means of washing the gas stream with a chemical and/or physical solvent.  
   
   
       20 . A process according to  claim 19 , in which the chemical and/or physical solvent is an aqueous alkaline solution.  
   
   
       21 . A process according to  claim 19 , in which the chemical and/or physical solvent is a aqueous amine solution.  
   
   
       22 . A process according to  claim 7 , in which the superficial gas velocity is between 0.05 and 0.40 m/s.  
   
   
       23 . A process according to  claim 11 , in which the regeneration steps are carried out at a superficial gas velocity between 0.02 and 0.15 m/s.  
   
   
       24 . A process according to  claim 11 , in which the regeneration gas stream(s) comprise nitrogen, hydrogen or a hydrocarbon gas stream.  
   
   
       25 . A process according to  claim 24 , in which the regeneration gas stream(s) comprises a treated gas stream treated according to the process.