Jmz-1, a cha-containing zeolite and methods of preparation

Abstract

JMZ-1, a zeolite having a CHA structure and containing trimethyl(cyclohexylmethyl)ammonium cations as a structure directing agent is described. A calcined zeolite, JMZ-1C, that does not contain a structure directing agent, is also described. Metal containing JMZ-1C has improved SCR activity compared to CHA-containing zeolites having the same metal loading and comparable silica:alumina ratios (SAR). Methods of preparing JMZ-1, JMZ-1C and metal containing calcined counterparts of JMZ-1C are described along with methods of using JMZ-1C and metal containing calcined counterparts of JMZ-1C in treating exhaust gases.

What is claimed is: 
     
         1 . A composition comprising zeolite crystals having a CHA framework, wherein the zeolite crystals have a framework structure comprising tetravalent silicon oxide, a trivalent aluminum oxide, and have a trimethyl(cyclohexylmethyl) ammonium cation present in the crystal structure, wherein the zeolite crystals are anhydrous and are free of substituted or unsubstituted 5,4-azonium anions and are free of ammonium anions having a substituents selected from bridged polycyclics, cycloaryls, heterocyclics, cycloalkyls other than cyclohexylmethyl, and C2-C4 alkyls. 
     
     
         2 . A zeolite comprising a framework structure comprising a CHA type framework and having a composition having the molar relationship: SiO 2 :(n)Y 2 O 3 , where Y=Al, Fe, B or Ga and n=0 to 0.1, and having a characteristic X-ray powder diffraction pattern comprising 2-theta positions at 9.59 (VS), 13.03 (M), 16.21 (W), 17.99 (W), 20.83 (M-S), 23.31 (W), 25.24 (W), 26.22 (W), 30.98 (M-W) and 31.43 (W)±0.2 with the corresponding relative intensity shown in parenthesis, wherein the zeolite does not comprise a structure directing agent (SDA). 
     
     
         3 . The zeolite of  claim 1 , wherein the zeolite comprises an extra-framework transition metal or noble metal. 
     
     
         4 . The zeolite of  claim 2 , wherein the zeolite comprises about 0.1 to about 5 weight percent of a transition metal or noble metal. 
     
     
         5 . A composition comprising a zeolite of  claim 2  and one or more of a filler, a binder, a stabilizer and a rheology modifier. 
     
     
         6 . A catalyst article comprising: (a) a composition according to  claim 5 ; and (b) a monolith substrate onto or within which said catalytic composition is incorporated. 
     
     
         7 . A system comprising an engine that produces NOx, a catalytic article of  claim 6 , a conduit for directing a flowing exhaust gas from the engine to the catalytic article, and a source of nitrogenous reductant disposed upstream of the catalytic article. 
     
     
         8 . A composition comprising a mixture of water, a silica source, an alumina source, a base, an alkali metal cation, and trimethyl(cyclohexylmethyl) ammonium cations, wherein the composition has a molar compositional ratio of: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   SiO 2 /Al 2 O 3   
                    10-100 
                 
                     
                   OH − /SiO 2   
                   0.05-1   
                 
                     
                   R/SiO 2   
                   0.05-0.5  
                 
                     
                   Alkali metal cation/SiO 2   
                   0.1-1.0 
                 
                     
                   H 2 O/SiO 2   
                    5-80 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
               
            
           
         
       
       wherein R is trimethyl(cyclohexylmethyl) ammonium cations. 
     
     
         9 . A method for treating an exhaust gas from an engine by contacting the exhaust gas with a zeolite of  claim 2 . 
     
     
         10 . A method for treating an exhaust gas comprising: (a) contacting a combustion exhaust gas containing NO x  and/or NH 3  with a catalyst article according to  claim 6  and (b) selectively reducing at least a portion of the NO x  into N 2  and H 2 O and/or oxidize at least a portion of the NH 3 .