Process for separating synthesis gas into fuel cell quality hydrogen and sequestration ready carbon dioxide

Abstract

A method and apparatus for separating gas mixtures containing synthesis gas (syngas) into separate streams of wet hydrogen containing significantly reduced amounts of CO 2 and CO, with the CO 2 being “sequestration ready” and containing less than 1% fixed gases. In the preferred embodiment, a mixture of limestone and iron oxide circulates between two fluidized beds whereby one bed is fluidized with a gas containing syngas, while the other bed is fluidized with a gas containing steam and oxygen. As the fluidizing gas containing syngas passes through the bed, the CO 2 reacts with CaO to form CaCO 3 . Virtually all of the CO is removed by a water gas shift reaction, forming hydrogen and CO 2 , with the remainder being removed by reaction with the iron oxide, reducing Fe 2 O 3 to FeO. Some hydrogen is also removed by reaction with the iron oxide, reducing Fe 2 O 3 to FeO, while the remainder of the hydrogen passes through the fluid beds, leaving in a purified state, i.e., PEM fuel cell quality.

What is claimed is:  
     
         1 . An apparatus for separating syngas into fuel cell quality hydrogen and sequestration ready carbon dioxide, comprising 
 first and second fluidized bed reactors containing solids containing calcium compounds present as CaO, Ca(OH) 2  and CaCO 3  and mixtures thereof and iron compounds present as FeO, Fe 3 O 4  and Fe 2 O 3  and mixtures thereof;    first and second solids transfer lines for circulating said solids mixtures between said first and second fluidized bed reactors;    a first inlet feed for charging said first fluidized bed reactor with high temperature steam and syngas;    a second inlet feed for charging said second fluidized bed reactor with high temperature steam and oxygen;    means for removing substantially pure hydrogen from said first fluidized bed reactor; and    means for removing CO 2  and SO 2  from said second fluidized bed reactor.    
     
     
         2 . An apparatus according to claim  11  further comprising steam purge lines in fluid communication with said first and second solids transfer lines.  
     
     
         3 . An apparatus according to claim  11  wherein said first fluidized bed reactor is a bubbling reactor or entrained flow reactor  
     
     
         4 . An apparatus according to claim  11  wherein said second fluidized bed reactor is a counterflow reactor.  
     
     
         5 . An apparatus according to claim  11  wherein a means such as a cyclone or other device for separating solids from fluids is provided at the outlet of said first fluidized bed reactor.