Synthesis of molecular sieves by hydrothermal treatment with acid

Abstract

Molecular sieves containing structure directing agents are treated by heating the SDA-containing molecular sieve at a temperature and for a time sufficient to remove the SDA from the molecular sieve, followed by heating the molecular sieve in an aqueous, acidic medium.

1 . A method of treating a molecular sieve containing a structure directing agent, the method comprising the steps of: 
 A. heating the structure directing agent-containing molecular sieve to a temperature and for a time sufficient to remove the structure directing agent from the molecular sieve; and    B. heating the molecular sieve from step a in an aqueous, acidic medium:    
     
     
         2 . The method of  claim 1  wherein the heating in step A is calcination.  
     
     
         3 . The method of  claim 1  wherein the aqueous, acidic medium is an aqueous solution of an organic acid or a mineral acid.  
     
     
         4 . The method of  claim 3  wherein the aqueous, acidic medium is an aqueous solution of acetic acid, propionic acid or oxalic acid.  
     
     
         5 . The method of  claim 4  wherein the aqueous, acid medium is an aqueous solution of acetic acid.  
     
     
         6 . The method of  claim 3  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid.  
     
     
         7 . The method of  claim 6  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid.  
     
     
         8 . The method of  claim 1  wherein the aqueous, acid medium has a pH below the isoelectric point of silica.  
     
     
         9 . The method of  claim 8  wherein the aqueous, acid medium has a pH of greater than 0 to about 2.5.  
     
     
         10 . The method of  claim 1  wherein the aqueous, acid medium in step B is heated at a temperature of about 135° C.  
     
     
         11 . The method of  claim 1  wherein the aqueous, acid medium in step B is heated at a temperature of about 160° C. to about 185° C.  
     
     
         12 . The method of  claim 1  wherein the molecular sieve is a zeolite.  
     
     
         13 . The method of  claim 12  wherein the zeolite has the CON, MWW, MFI or *BEA crystal topology.  
     
     
         14 . The method of  claim 12  wherein the zeolite contains silicon.  
     
     
         15 . The method of  claim 12  wherein the zeolite contains silicon and aluminum.  
     
     
         16 . A method of increasing the hydrophobicity of a molecular sieve containing a structure directing agent, the method comprising the steps of: 
 A. heating the structure directing agent-containing molecular sieve to a temperature and for a time sufficient to remove the structure directing agent from the molecular sieve; and    B. heating the molecular sieve from step A in an aqueous, acidic medium 
 wherein the molecular sieve from step B is more hydrophobic than the molecular sieve used in step A.  
   
     
     
         17 . The method of  claim 16  wherein the heating in step A is calcination.  
     
     
         18 . The method of  claim 16  wherein the aqueous, acidic medium is an aqueous solution of an organic acid or a mineral acid.  
     
     
         19 . The method of  claim 18  wherein the aqueous, acidic medium is an aqueous solution of acetic acid, propionic acid or oxalic acid.  
     
     
         20 . The method of  claim 19  wherein the aqueous, acid medium is an aqueous solution of acetic acid.  
     
     
         21 . The method of  claim 18  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid.  
     
     
         22 . The method of  claim 21  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid.  
     
     
         23 . The method of  claim 16  wherein the aqueous, acid medium has a pH below the isoelectric point of silica.  
     
     
         24 . The method of  claim 23  wherein the aqueous, acid medium has a pH of greater than 0 to about 2.5.  
     
     
         25 . The method of  claim 16  wherein the aqueous, acid medium in step B is heated at a temperature of about 135° C.  
     
     
         26 . The method of  claim 16  wherein the aqueous, acid medium in step B is heated at a temperature of about 160° C. to about 185° C.  
     
     
         27 . The method of  claim 16  wherein the molecular sieve is a zeolite.  
     
     
         28 . The method of  claim 27  wherein the zeolite has the CON, MWW, MFI or *BEA crystal topology.  
     
     
         29 . The method of  claim 27  wherein the zeolite contains silicon.  
     
     
         30 . The method of  claim 27  wherein the zeolite contains silicon and aluminum.  
     
     
         31 . A molecular sieve produced by the process comprising the steps of: 
 A. heating a structure directing agent-containing molecular sieve to a temperature and for a time sufficient to remove the structure directing agent from the molecular sieve; and    B. heating the molecular sieve from step A in an aqueous, acidic medium.    
     
     
         32 . The molecular sieve of  claim 31  wherein the heating in step A is calcination.  
     
     
         33 . The molecular sieve of  claim 31  wherein the aqueous, acidic medium is an aqueous solution of an organic acid or a mineral acid.  
     
     
         34 . The molecular sieve of  claim 33  wherein the aqueous, acidic medium is an aqueous solution of acetic acid, propionic acid or oxalic acid.  
     
     
         35 . The molecular sieve of  claim 34  wherein the aqueous, acid medium is an aqueous solution of acetic acid.  
     
     
         36 . The molecular sieve of  claim 33  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid.  
     
     
         37 . The molecular sieve of  claim 36  wherein the aqueous, acid medium is an aqueous solution of hydrochloric acid.  
     
     
         38 . The molecular sieve of  claim 31  wherein the aqueous, acid medium has a pH below the isoelectric point of silica.  
     
     
         39 . The molecular sieve of  claim 38  wherein the aqueous, acid medium has a pH of greater than 0 to about 2.5.  
     
     
         40 . The molecular sieve of  claim 31  wherein the aqueous, acid medium in step B is heated at a temperature of about 135° C.  
     
     
         41 . The molecular sieve of  claim 31  wherein the aqueous, acid medium in step B is heated at a temperature of about 160° C. to about 185° C.  
     
     
         42 . The molecular sieve of  claim 31  wherein the molecular sieve is a zeolite.  
     
     
         43 . The molecular sieve of  claim 42  wherein the zeolite has the CON, MWW, MFI or *BEA crystal topology.  
     
     
         44 . The molecular sieve of  claim 42  wherein the zeolite contains silicon.  
     
     
         45 . The molecular sieve of  claim 42  wherein the zeolite contains silicon and aluminum.  
     
     
         46 . An all-silica molecular sieve having the CON crystal topology.