Catalysts for nox reduction employing h2 and a method of reducing nox

Abstract

Disclosed is a catalyst composition for reducing NOx through two steps including reacting NOx with H2 thus producing ammonia which is then reacted with NOx, instead of direct NOx reduction by H2, and a method of reducing NOx using the catalyst composition.

1 . A mixed oxide catalyst for reducing NO x  using H 2  as a reducing agent, comprising one or more A metal oxides selected from the group of consisting of Fe 2 O 3 , CO 2 O 3 , NiO and CuO; and one or more B metal oxides selected from the group consisting of V 2 O 5 , Cr 2 O 3 , MnO 2  and MoO 3 , which are co-precipitated and mixed. 
     
     
         2 . The mixed oxide catalyst according to  claim 1 , wherein a ratio of A metal oxide to B metal oxide ranges from 2:1 to 1:0.5. 
     
     
         3 . The mixed oxide catalyst according to  claim 1 , wherein a precious metal selected from the group consisting of platinum and palladium is supported in an amount of from 0.1 to 2 wt %. 
     
     
         4 . The mixed oxide catalyst according to  claim 3 , further comprising an ammonia-selective catalytic reduction catalyst. 
     
     
         5 . A method of preparing a mixed oxide catalyst for reducing NO x  using H 2  as a reducing agent, comprising:
 dissolving in aqueous nitrate or acetate one or more metal oxide precursors of A metal oxides, wherein the A metal oxides are selected from the group consisting of Fe 2 O 3 , CO 2 O 3 , NiO and CuO, and one or more metal oxide precursors of B metal oxides, wherein the B metal oxides are selected from the group consisting of V 2 O 5 , Cr 2 O 3 , MnO 2  and MoO 3 , thus preparing a solution;   adding barium nitrate oxide to the solution;   adding ammonia water or aqueous sodium bicarbonate as a precipitating agent to the solution so that pH of the solution is from 7 to 7.3, thus forming a precipitate; and   subjecting the precipitate to post treatment comprising filtering, washing, drying and burning.   
     
     
         6 . The method according to  claim 5 , wherein a ratio of A metal oxide to B metal oxide ranges from 2:1 to 1:0.5. 
     
     
         7 . The method according to  claim 5 , further comprising, after subjecting the precipitate to post treatment, supporting either or both precious metals of platinum and palladium in an amount of from 0.1 to 2 wt % on the catalyst, burning the precious metal-supported catalyst, and subjecting the burned catalyst to reduction treatment using a gas mixture containing N 2  and H 2  at a molar ratio of 1. 
     
     
         8 . A method of reducing NO x  at from 150 to 350° C. using H 2  as a reducing agent in presence of the mixed oxide catalyst of  claim 1 . 
     
     
         9 . The method according to  claim 8 , wherein the method is performed under conditions in which O 2  content is equal to or less than 10% by volume based on a volume of the NO x .