Process for the production of hydrogen with total recovery of co2 and recycling of unconverted methane

Abstract

This invention relates to a process for the production of hydrogen from a hydrocarbon feedstock and steam comprising: A stage for the production of a synthesis gas in a unit for the steam-reforming of the hydrocarbon feedstock, A stage for shift conversion with steam of the synthesis gas that is obtained in the preceding stage producing a hydrogen stream that contains methane and carbon dioxide, A stage for recovering carbon dioxide and methane, present in the stream that is obtained in the shift conversion stage, in the form of hydrates that produce a stream of pure hydrogen, A stage for regeneration of methane, A stage for recycling methane to steam reforming.

1 ) A process for the production of hydrogen from a hydrocarbon feedstock and steam comprising:
 A stage for the production of a synthesis gas in a steam-reforming unit of the hydrocarbon feedstock in the presence of steam and a fuel provides the heat that is necessary to the reaction,   A stage shift conversion of the synthesis gas that is obtained in the preceding stage to produce a stream containing additional hydrogen additional CO 2  and residual methane,   A stage for recovering carbon dioxide and methane, present in the stream that is obtained from the shift conversion stage, in the form of hydrates separating a stream of enriched hydrogen,   A stage for regeneration of methane,   A stage for recycling methane to said steam reforming unit.   
     
     
         2 ) A process for the production of hydrogen according to  claim 1 , in which the stage for recovery of carbon dioxide and methane in the form of hydrates is followed by a stage for regeneration of carbon dioxide. 
     
     
         3 ) A process for the production of hydrogen according to  claim 1 , in which a stage for regeneration of carbon dioxide is carried out at the same time as the stage for regeneration of methane. 
     
     
         4 ) A process for the production of hydrogen according to  claim 1 , in which the hydrocarbon feedstock is natural gas. 
     
     
         5 ) A process for the production of hydrogen according to  claim 1 , in which the stage for recovery of carbon dioxide and methane in hydrate form is carried out in a mixture that comprises water and a non-water-miscible solvent. 
     
     
         6 ) A process for the production of hydrogen according to  claim 5 , in which the mixture also comprises at least one amphiphilic compound. 
     
     
         7 ) A process for the production of hydrogen according to  claim 1 , in which the stage for recovery in hydrate form is carried out at a temperature of between 0 and 60° C. and a pressure of between 0.2 and 6 MPa. 
     
     
         8 ) A process for the production of hydrogen according to  claim 2 , in which the stage for regeneration of carbon dioxide is carried out at a temperature of between 0 and 40° C. and a pressure of between 0.2 and 6 MPa. 
     
     
         9 ) A process for the production of hydrogen according to  claim 1 , in which the stage for regeneration of methane is carried out at a temperature of between 0 and 40° C. and a pressure of between 0.2 and 6 MPa. 
     
     
         10 ) A process for production of hydrogen according to  claim 3 , in which the stage for regeneration of carbon dioxide and methane is carried out at a temperature of between 0 and 40° C. and a pressure of between 0.2 and 6 MPa. 
     
     
         11 ) A process for the production of hydrogen according to  claim 1  comprising a stage for the production of electricity from the hydrogen stream that is obtained in the stage for recovery of carbon dioxide and methane. 
     
     
         12 ) A process for the production of hydrogen according to  claim 11 , in which the production of electricity comprises passing the hydrogen stream into a combustion chamber for supplying energy to a generator. 
     
     
         13 ) A process for the production of hydrogen according to  claim 12 , in which hot flue gasses obtained at the end of the combustion stage are recycled to the steam-reforming reactor.