Catalytic isomerization of butane using ionic liquids

Abstract

Processes for the disproportionation and isomerization of a C 4 hydrocarbon feed using a liquid catalyst comprising an ionic liquid and a carbocation promoter are described. The ionic liquid is unsupported, and the reactions occur at temperatures below about 300° C.

What is claimed is: 
     
         1 . A hydrocarbon conversion process comprising:
 isomerizing a hydrocarbon feed comprising normal C 4  alkane or branched C 4  alkane by contacting the hydrocarbon feed with a liquid catalyst in a reaction zone under isomerization conditions to form a product mixture having a ratio of branched C 4  alkane to normal C 4  alkane of at least about 0.3:1 in 1 hr, wherein the liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter, and wherein a mass ratio of liquid catalyst to hydrocarbon feed is less than 0.75:1.   
     
     
         2 . The process of  claim 1  wherein the ionic liquid comprises an organic cation and an anion and wherein the organic cation is selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       where R 1 -R 21  are independently selected from C 1 -C 20  hydrocarbons, C 1 -C 20  hydrocarbon derivatives, halogens, and H. 
     
     
         3 . The process of  claim 1  wherein the ionic liquid comprises an organic cation and an anion and wherein the anion is derived from halides, sulfates, bisulfates, nitrates, sulfonates, fluoroalkanesulfonates, or combinations thereof. 
     
     
         4 . The process of  claim 1  wherein the ionic liquid comprises an organic cation and an anion and wherein the anion is selected from the group consisting of AlCl 4   − , Al 2 Cl 7   − , Al 3 Cl 10   − , AlCl 3 Br − , Al 2 Cl 6 Br − , Al 3 Cl 9 Br − , AlBr 4   − , Al 2 Br 7   − , Al 3 Br 10   − , GaCl 4   − , Ga 2 Cl 7   − , Ga 3 Cl 10   − , GaCl 3 Br − , Ga 2 Cl 6 Br − , Ga 3 Cl 9 Br − , CuCl 2   − , Cu 2 Cl 3   − , Cu 3 Cl 4   − , ZnCl 3   − , FeCl 3   − , FeCl 4   − , Fe 3 Cl 7   − , PF 6   − , and BF 4   − . 
     
     
         5 . The process of  claim 1  wherein the carbocation promoter comprises a haloalkane, a mineral acid, or combinations thereof. 
     
     
         6 . The process of  claim 5  wherein the haloalkane comprises 2-chloro-2-methylpropane, 2-chloropropane, 2-chlorobutane, 2-chloro-2-methylbutane, 2-chloropentane, 1-chlorohexane, 3-chloro-3-methylpentane, or combinations thereof. 
     
     
         7 . The process of  claim 1  further comprising stirring the hydrocarbon feed and the liquid catalyst while contacting the hydrocarbon feed with the liquid catalyst. 
     
     
         8 . The process of  claim 1  wherein a molar ratio of the carbocation promoter to ionic liquid is in a range of about 0:1 to about 3:1. 
     
     
         9 . The process of  claim 1  further comprising separating the ionic liquid from the product mixture. 
     
     
         10 . The process of  claim 9  further comprising regenerating the separated ionic liquid. 
     
     
         11 . The process of  claim 1  wherein a concentration of acid within the liquid catalyst is less than about 2.5 M. 
     
     
         12 . The process of  claim 1  further comprising disproportionating the hydrocarbon feed concurrently with isomerizing the hydrocarbon feed. 
     
     
         13 . The process of  claim 1  wherein the hydrocarbon feed comprises a mixture of at least C 4  and C 5  alkanes. 
     
     
         14 . The process of  claim 1  wherein a conversion rate for volume is at least about 60 in the absence of an added metal salt. 
     
     
         15 . A hydrocarbon conversion process comprising:
 isomerizing a hydrocarbon feed comprising normal C 4  alkane by contacting the hydrocarbon feed with a liquid catalyst in a reaction zone under isomerization conditions to form a product mixture comprising at least about 10 wt % branched C 4  alkanes in 1 hr based on the normal C 4  alkane in the hydrocarbon feed, wherein the liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter, and wherein a mass ratio of liquid catalyst to hydrocarbon feed is less than 0.75:1.   
     
     
         16 . The process of  claim 15  wherein the ionic liquid comprises an organic cation and an anion and wherein the organic cation is selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       where R 1 -R 21  are independently selected from C 1 -C 20  hydrocarbons, C 1 -C 20  hydrocarbon derivatives, halogens, and H. 
     
     
         17 . The process of  claim 15  wherein the ionic liquid comprises an organic cation and an anion and wherein the anion is derived from halides, sulfates, bisulfates, nitrates, sulfonates, fluoroalkanesulfonates, or combinations thereof. 
     
     
         18 . The process of  claim 15  wherein the carbocation promoter comprises a haloalkane, a mineral acid, or combinations thereof. 
     
     
         19 . The process of  claim 15  wherein a concentration of acid within the liquid catalyst is less than about 2.5 M. 
     
     
         20 . The process of  claim 15  further comprising disproportionating the hydrocarbon feed concurrently with isomerizing the hydrocarbon feed.