Catalysts

Abstract

The dehydrogenation of an alkane to an alkene, especially isobutane to isobutene, is carried out in admixture with oxygen and in the absence of added steam over a dehydrogenation and oxidation catalyst comprising a platinum group metal deposited upon a support. A catalyst comprising platinum deposited on a support which is a mixture of tin oxide and zirconium oxide possesses good activity for the dehydrogenation of an alkane, especially carried out in this way.

We claim:  
     
       1. A catalyst for alkane dehydrogenation, comprising by weight 0.1 to 3% platinum, calculated as metal, 6 to 60% tin oxide, and 37 to 94.9% zirconium oxide, the platinum deposited upon a support which is a mixture of the tin oxide and the zirconium oxide. 
     
     
       2. A catalyst according to  claim 1 , containing 10 to 60% by weight of the tin oxide. 
     
     
       3. A catalyst according to  claim 1 , wherein the support contains substantially no alumina. 
     
     
       4. A catalyst according to  claim 1 , consisting essentially of 0.1 to 3% by weight of platinum, calculated as metal, 10 to 60% by weight of tin oxide, 37 to 94.9% zirconium oxide, and at least one member selected from the group consisting of stabilisers and promoters. 
     
     
       5. A catalyst according to  claim 1 , wherein the support comprises SnO 2  and ZrO 2  in a weight ratio of approximately 1:4. 
     
     
       6. A catalyst according to  claim 5 , comprising approximately 1% by weight of platinum, impregnated onto a co-precipitate of SnO 2  and ZrO 2  in a weight ratio of approximately 1:4. 
     
     
       7. A catalyst according to  claim 1 , wherein the catalyst has substantially an absence of alumina. 
     
     
       8. A catalyst according to  claim 1 , wherein the catalyst contains 15-30% by weight of tin oxide. 
     
     
       9. A catalyst according to  claim 1 , wherein the catalyst contains 70-85% by weight zirconium oxide. 
     
     
       10. A catalyst according to  claim 1 , wherein the catalyst has a weight ratio of the tin oxide to the zirconium oxide of 1:3-9. 
     
     
       11. A catalyst according to  claim 1 , wherein the catalyst has a weight ratio of the tin oxide to the zirconium oxide of 1:3-5. 
     
     
       12. A catalyst for alkane dehydrogenation comprising a catalytically effective amount of platinum,  6  to  60 %  tin oxide, and  37   %  to  94 . 9   %  zirconium oxide, the platinum being deposited on a support comprising a mixture of the tin oxide and the zirconium oxide.    
     
     
       13. A catalyst support consisting of  6  to  60 %  tin oxide and  37   %  to  85   %  zirconium oxide.    
     
     
       14. A catalyst for alkane dehydrogenation, comprising a catalytically effective amount of platinum,  6  to  60 %  tin oxide, and  37   %  to  94 . 9   %  zirconium oxide, the platinum being deposited on a support comprising a mixture of the tin oxide and the zirconium oxide, made by a process comprising the steps of:    
         making the support by a co - precipitation process comprising adding NaOH to a mixture of tin and zirconium salts in aqueous solution, and drying and calcining the NaOH - containing mixture to which NaOH was added, wherein the dried and calcined mixture comprises  6  to  60   %  tin oxide and at least  37   %  zirconium oxide; impregnating the calcined mixture with an aqueous solution of a platinum salt; and drying and calcining the impregnated mixture.    
     
     
       15. A catalyst of  claim 1 , wherein the catalyst comprises  37  to  85 %  zirconium oxide.    
     
     
       16. A catalyst of  claim 1 , wherein the catalyst comprises  37  to  85 %  zirconium oxide.    
     
     
       17. A catalyst support of  claim 13 , wherein the catalyst support consists of tin oxide and zirconium oxide in a weight ratio of approximately  1 : 3 - 9 .  
     
     
       18. A catalyst support, wherein the catalyst support consists essentially of  30 - 15 %  tin oxide and  70 - 85   %  zirconium oxide.    
     
     
       19. A catalyst support of  claim 18 , wherein the catalyst support substantially lacks alumina.  
     
     
       20. A catalyst support of  claim 18 , wherein the catalyst support consists essentially of  20 %  tin oxide and  80   %  zirconium oxide.    
     
     
       21. A catalyst of  claim 14 , wherein the catalyst comprises SnO 2    and ZrO   2    in a weight ratio of approximately  1 : 3 - 9 .