Aromatics processing catalysts

Abstract

A method of preparing aromatics processing catalysts which comprises incorporating a noble metal with a member or members of a useful class of zeolites, with such incorporation occurring after zeolite crystallization, but prior to final catalyst particle formation, i.e. extrusion into particles. Said useful class of zeolites is characterized by a silica to alumina mole ratio of at least 12 and a Constraint Index in the approximate range of 1 to 12.

What is claimed is: 
     
       1. A method for preparing a noble metal-containing zeolite catalyst which comprises incorporating a noble metal in a cationic form with a zeolite after crystallization of the zeolite, prior to final catalyst particle formation and prior to any calcination or steaming of said zeolite, said zeolite being characterized by a silica to alumina mole ratio of at least 12 and a Constraint Index in the approximate range of 1 to 12. 
     
     
       2. The method of claim 1 wherein said noble metal is one or more members selected from the group consisting of ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold. 
     
     
       3. The method of claim 2 wherein said noble metal is platinum. 
     
     
       4. The method of claim 1 wherein said zeolite is one or more members selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38 and ZSM-48. 
     
     
       5. The method of claim 4 wherein said zeolite is ZSM-5. 
     
     
       6. The method of claim 1 wherein incorporating said noble metal with said zeolite occurs via ion exchange. 
     
     
       7. The method of claim 1 wherein incorporating said noble metal with said zeolite occurs via impregnation. 
     
     
       8. The method of claim 1 wherein incorporating said noble metal with said zeolite occurs via physical initimate admixing. 
     
     
       9. The method of claim 1 wherein the noble metal content ranges from between about 0.005 wt. % and about 0.5 wt. % of total catalyst. 
     
     
       10. The method of claim 9 wherein the noble metal content ranges from between about 0.05 wt. % and about 0.20 wt. % of total catalyst. 
     
     
       11. The method of claim 1 wherein said zeolite is mulled with a binder before said incorporation with the noble metal, but prior to final catalyst particle formation. 
     
     
       12. The method of claim 1 wherein a binder is added after incorporating the noble metal with the zeolite, but prior to final catalyst particle formation. 
     
     
       13. The method of claim 11 wherein said binder is alumina. 
     
     
       14. The method of claim 12 wherein said binder is alumina. 
     
     
       15. The method of claim 1 wherein said catalyst is of controlled acid activity. 
     
     
       16. The method of claim 15 wherein said controlled acid activity is achieved by utilizing a zeolite with a high silica to alumina mole ratio. 
     
     
       17. The method of claim 16 wherein said high silica to alumina mole ratio is above 200. 
     
     
       18. The method of claim 17 wherein said high silica to alumina mole ratio is above 500. 
     
     
       19. The method of claim 15 wherein said controlled acid activity is achieved by steam treatment of the catalyst. 
     
     
       20. The method of claim 15 wherein said controlled acid activity is achieved by utilizing a zeolite having a significant proportion of its cationic sites occupied by basic cations. 
     
     
       21. The method of claim 20 wherein said basic cations are sodium cations. 
     
     
       22. The method of claim 15 wherein said controlled acid activity is achieved by utilizing a zeolite with a high silica to alumina mole ratio in combination with steam treatment of the catalyst. 
     
     
       23. The method of claim 22 wherein said high silica to alumina mole ratio is above 200. 
     
     
       24. The method of claim 23 wherein said high silica to alumina mole ratio is above 500. 
     
     
       25. The catalyst produced by the method of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24. .Iadd. 
     
     
       26.  An improved method for preparing a composite zeolite-alumina catalyst wherein a crystalline zeolite having a silica to alumina mole ratio of at least 200 and a Constraint Index of about 1 to 12 has controlled acid activity by utilizing said zeolite in combination with alumina binder and steam treatment at elevated temperature; which comprises incorporating a noble metal in a cationic form with the zeolite after crystallization of the zeolite, prior to final composite catalyst formation and prior to any calcination or steaming of the zeolite..Iaddend. .Iadd.27. In the method for preparing a composite zeolite-alumina catalyst according to claim 26, the further improvement wherein said noble metal consists essentially of platinum and wherein said zeolite consists essentially of acid ZSM-5 and wherein said zeolite noble metal and alumina are intimately mixed by mulling prior to final composite catalyst particle formation..Iaddend. .Iadd.28. In the method for preparing a composite zeolite-alumina catalyst according to claim 27, the further improvement wherein said zeolite mole ratio is about 500 and platinum content ranges between about 0.005 wt. % and about 0.05 wt. % of total catalyst..Iaddend. .Iadd.29. In the method for preparing a composite zeolite-alumina catalyst wherein a crystalline zeolite having a silica to alumina mole ratio of at least 200 and a Constraint Index of about 1 to 12 has controlled acid activity by utilizing said zeolite in combination with alumina binder and steam treatment at elevated temperature; the improvement which comprises mulling alumina binder with the zeolite and water to form an extrudable mass; forming the composite catalyst by extrusion of the zeolite-alumina mixture, calcining the extrudate composite, and steam treating the calcined composite..Iaddend. .Iadd.30. In the method for preparing a composite zeolite-alumina catalyst according to claim 29, the further improvement wherein acid ZSM-5 zeolite is incorporated with about 0.005 wt. % to 0.5 wt. % platinum prior to final composite catalyst formation and prior to any calcination of the zeolite..Iaddend. .Iadd.31. A catalyst produced by the method of claim 26, 27, 28, 29 or 30..Iaddend.