Apparatus and process for improved hydrogen sulfide removal

Abstract

Provided is a trap and method for removing hydrogen sulfide from a gas stream. The hydrogen sulfide trap includes a monolith substrate on which is disposed zinc oxide, and a second metal or oxide thereof. In some aspects, the hydrogen sulfide trap is advantageously incorporated into systems for producing hydrogen for PEM fuel cells.

What is claimed:  
     
         1 . A hydrogen sulfide trap comprising: a monolith substrate on which is disposed, 
 zinc oxide; and    a second metal or oxide thereof selected from the group consisting of copper, nickel, iron, manganese, and combinations thereof dispersed on a support.    
     
     
         2 . The hydrogen sulfide trap of  claim 1 , wherein the support is selected from the group consisting of zinc oxide, ceria, titania, zirconia, alumina, oxides of iron and combinations thereof.  
     
     
         3 . The hydrogen sulfide trap of  claim 1 , wherein the support comprises zinc oxide.  
     
     
         4 . A hydrogen sulfide trap comprising a monolith substrate on which is disposed zinc oxide, and 
 copper or an oxide thereof dispersed on a support.    
     
     
         5 . The hydrogen sulfide trap of  claim 4 , wherein the supported copper or oxide thereof forms a first layer adhering to the monolith substrate, and the zinc oxide forms a second layer overlying and adhering to the first layer.  
     
     
         6 . The hydrogen sulfide trap of  claim 4 , wherein the zinc oxide forms an upstream zone disposed on an upstream segment of the monolith substrate, and the supported copper or oxide thereof forms a downstream zone on a downstream segment of the monolith substrate.  
     
     
         7 . The hydrogen sulfide trap of  claim 4 , wherein the support comprises a second portion of zinc oxide.  
     
     
         8 . The hydrogen sulfide trap of  claim 7 , wherein the zinc oxide and the zinc oxide-supported copper or oxide thereof form a layer adhering to the monolith substrate.  
     
     
         9 . The hydrogen sulfide trap of  claim 7 , wherein the zinc oxide-supported copper or oxide thereof is in the form of a first layer adhering to the monolith substrate, and the zinc oxide is in the form of a second layer overlying and adhering to the first layer.  
     
     
         10 . The hydrogen sulfide trap of  claim 7 , wherein the zinc oxide forms an upstream zone disposed on an upstream segment of the monolith substrate, and the zinc oxide supported copper or copper oxide thereof forms a downstream zone disposed on a downstream segment of the monolith substrate.  
     
     
         11 . The hydrogen sulfide trap of  claim 4 , further comprising a binder.  
     
     
         12 . A process for removing hydrogen sulfide in a gas stream comprising hydrogen sulfide, the process comprising: contacting the gas stream with a hydrogen sulfide trap comprising a monolith substrate on which is disposed; 
 zinc oxide, and    a second metal or oxide thereof selected from the group consisting of copper, nickel, iron, manganese, and combinations thereof dispersed on a support.    
     
     
         13 . The process of  claim 12 , wherein the second metal or oxide thereof is copper.  
     
     
         14 . The process of  claim 12 , wherein the second metal or oxide thereof is copper and the support is zinc oxide.  
     
     
         15 . The process of  claim 14 , wherein the zinc oxide and the zinc oxide supported copper or oxide thereof is in the form of a layer.  
     
     
         16 . The process of  claim 12 , wherein the gas stream has a space velocity of at least 300 hr −1.    
     
     
         17 . The process of  claim 12 , wherein the gas stream has a temperature below about 500° C.  
     
     
         18 . The process of  claim 12 , wherein the gas stream has a sulfur concentration of no more than 10 ppm.  
     
     
         19 . The process of  claim 18 , wherein the gas stream has a sulfur concentration of no more than 100 ppb.  
     
     
         20 . In a system for producing hydrogen for a PEM fuel cell, the system having a hydrocarbon reformer reactor, a water-gas shift reactor, and a selective carbon monoxide oxidation reactor, the improvement comprising: 
 a monolith substrate on which is disposed zinc and a second metal oxide selected from the group consisting of copper, nickel, iron, manganese, and combinations thereof dispersed on a support,    wherein the monolith substrate is downstream and in train with the hydrocarbon reformer reactor, and upstream and in train with the water-gas shift reactor.    
     
     
         21 . The system of  claim 20 , wherein the second metal or oxide thereof is copper.  
     
     
         22 . The system of  claim 21 , wherein the support comprises a second portion of zinc oxide.