Exhaust gas purification system and method for purifying exhaust gas

Abstract

An exhaust gas emitted from an engine ( 10 ) that contains nitrogen oxides is supplied to the cathode of a fuel cell ( 20 ), and a hydrogen-rich gas generated by the hydrogen gas generator ( 30 ) is supplied to the anode of the fuel cell ( 20 ). In the fuel cell ( 20 ), the nitrogen oxides are decomposed and electricity are generated by an electrochemical reaction between hydrogen and the nitrogen oxides. A hydrogen-separation membrane fuel cell, which operates at a temperature that is substantially the same temperature as that of the exhaust gas emitted from the engine ( 10 ) is used as the fuel cell ( 20 ).

1 .- 7 . (canceled) 
   
   
       8 . An exhaust gas purifying system comprising:
 an internal combustion engine that combusts gasoline and emits an exhaust gas that contains nitrogen oxides;   a hydrogen-supplying source that supplies a hydrogen-rich gas; and   a fuel cell that is supplied with the exhaust gas and the hydrogen-rich gas, wherein the fuel cell operates within a prescribed temperature range that includes the temperature of the exhaust gas and generates electricity by an electrochemical reaction between hydrogen contained in the hydrogen-rich gas and the nitrogen oxides contained in the exhaust gas,   wherein the fuel cell comprises an electrolyte membrane in which a hydrogen-permeable metal layer that selectively allows the hydrogen to permeate and an electrolyte layer having a proton-conductivity are laminated.   
   
   
       9 . The exhaust gas purifying system according to  claim 8 , wherein the electrochemical reaction also decomposes the nitrogen oxides. 
   
   
       10 . The exhaust gas purifying system according to  claim 8 , wherein a cathode of the fuel cell has a platinum-based catalyst that promotes the electrochemical reaction. 
   
   
       11 . The exhaust gas purifying system according to  claim 8 , further comprising a secondary battery that stores the electricity generated by the fuel cell. 
   
   
       12 . A method for purifying exhaust gas emitted from an internal combustion engine that contains nitrogen oxides, comprising:
 providing a fuel cell that operates within a prescribed temperature range including the temperature of the exhaust gas and generates electricity by an electrochemical reaction between hydrogen contained in a prescribed fuel gas and the nitrogen oxides contained in the exhaust gas,   wherein the fuel cell comprises an electrolyte membrane in which a hydrogen-permeable metal layer that selectively allows the hydrogen to permeate and an electrolyte layer having a proton-conductivity are laminated;   supplying the prescribed fuel gas to an anode of the fuel cell and the exhaust gas to a cathode of the fuel cell; and   decomposing the nitrogen oxides along with generating electricity by the electrochemical reaction.   
   
   
       13 . The exhaust gas purifying system according to  claim 9 , wherein a cathode of the fuel cell has a platinum-based catalyst that promotes the electrochemical reaction. 
   
   
       14 . The exhaust gas purifying system according to  claim 9 , further comprising a secondary battery that stores the electricity generated by the fuel cell. 
   
   
       15 . The exhaust gas purifying system according to  claim 10 , further comprising a secondary battery that stores the electricity generated by the fuel cell.