Porous ceramic laminate and production thereof

Abstract

A porous ceramic laminate has a porous silicon nitride substrate and a porous silicon nitride separation film supported thereon and having minute pores of sizes capable of Knudsen separation or molecular sieve by sintering a porous silicon nitride substrate supporting a formed layer containing polysilazane at 800° C. in a nitrogen atmosphere.

1 . A porous ceramic laminate comprising a porous ceramic separation membrane and a porous ceramic substrate supporting said separation membrane, 
 said separation membrane and said substrate each comprising ceramics of Si and N, or Si and C as a main component,    said separation membrane is thermally stable even at temperature of 500° C. or more, and    said separation membrane having micropores essentially of sizes small enough to realize molecular sieve separation such that, if measured, H 2 /N 2  permeability ratio is about 15 or more,    wherein said pores have an angstrom order of pore sizes in an amount of at least 70% of the entire pores.    
     
     
         2 . The laminate as defined in  claim 1 , wherein said substrate supports said separation membrane through an intermediary of at least one porous ceramic interlayer.  
     
     
         3 . The laminate as defined in  claim 2 , wherein said separation membrane comprises one or more laminated layers.  
     
     
         4 . The laminate as defined in  claim 2 , wherein said laminate is substantially defect free.  
     
     
         5 . The laminate as defined in  claim 2 , wherein said separation membrane comprises three or more laminated layers.  
     
     
         6 . The laminate as defined in  claim 1 , wherein said separation membrane comprises one or more laminated layers.  
     
     
         7 . The laminate as defined in  claim 1 , wherein said laminate is substantially defect free.  
     
     
         8 . The laminate as defined in  claim 1 , wherein said separation membrane comprises three or more laminated layers.  
     
     
         9 . The laminate as defined in  claim 1 , wherein said porous ceramic laminate is thermally stable to a temperature of at least 700° C.  
     
     
         10 . A porous ceramic laminate comprising a porous ceramic separation membrane portion and a porous ceramic substrate supporting said separation membrane portion, 
 said separation membrane portion and said substrate each comprising ceramics of Si and N, or Si and C as a main component,    said separation member is thermally stable at temperature of 500° C. or more, and    said separation membrane portion comprising a plurality of pores, said pores being of such sizes that provide molecular sieve separation,    wherein said pores have an angstrom order of pore sizes in an amount of at least 70% of the entire pores.