Process for producing gasoline blending components from jet range and heavier aromatics

Abstract

A process for producing gasoline blending components from a heavy hydrocarbon composition comprising alkyl aromatics by transalkylation of said alkyl aromatics with benzene is provided. In a preferred embodiment, the process comprises (a) feeding said heavy hydrocarbon composition comprising alkyl aromatics and said benzene as feed to a cracking unit; and (b) contacting said alkyl aromatics and said benzene with cracking catalyst at catalytic cracking conditions of elevated temperature and pressure to produce transalklyation products. Also, provided is a process, for producing gasoline blending components from the jet aromatics content of jet fuel and reducing the benzene content of a benzene-rich light gasoline stream, said process comprising operating a catalytic cracker at conventional catalytic cracking conditions and reacting in said catalytic cracking reactor said aromatic jet fuel with said benzene-rich light gasoline stream to convert at least a portion of said benzene-rich gasoline and at least a portion of said jet aromatics to toluene and xylenes. The catalytic cracker can be a fluid catalytic cracker, moving bed catalytic cracker and fixed bed catalytic cracker.

What is claimed is: 
     
       1. A process for producing gasoline blending components from a hydrocarbon composition comprising jet range alkyl aromatics and which boils in a range of from about 300° F. to about 690° F. by transalkylation of said jet range alkyl aromatics with benzene, said process comprising: a. feeding said hydrocarbon composition comprising said jet range alkyl aromatics and said benzene as feed to a second reaction zone of a cracking unit, said cracking unit separately cracking in a first reaction zone and in the presence of cracking catalyst, a heavy feed comprising hydrocarbons which boil at a temperature greater than about 690° F. to a cracked product which comprises a first alkyl aromatic product;   b. contacting said hydrocarbon composition comprising said jet range alkyl aromatics and said benzene with a cracking catalyst at catalytic cracking conditions in the second reaction zone to produce transalkylation products, said contact conducted such that the transalkylation products do not contact the cracking catalyst in the presence of said first alkyl aromatic product produced by cracking said heavy feed in the first reaction zone;   c. separating the cracking catalyst from the cracked product of the first reaction zone;   d. separating the cracking catalyst from the transalkylation products of the second reaction zone; and   e. thereafter mixing the cracked product of the first reaction zone and the transalkylation products of the second reaction zone.   
     
     
       2. A process in accordance with claim 1 wherein said transalkylation products are aromatic-containing gasoline blending components. 
     
     
       3. A process in accordance with claim 1 wherein said benzene is a component of a concentrated benzene stream comprising in the range of about 5 volume percent to about 100 volume percent benzene. 
     
     
       4. A process in accordance with claim 1 wherein said jet range alkyl aromatics are a component of a concentrated alkyl aromatic stream comprising in the range of about 20 volume percent to about 100 volume percent of said jet range alkyl aromatics. 
     
     
       5. A process in accordance with claim 1 wherein said hydrocarbon composition feed to said cracking unit contains less than about 5 volume percent total of toluene, xylenes, and ethylbenzene. 
     
     
       6. A process in accordance with claim 1 wherein said benzene and said jet range alkyl aromatics comprise more than about eighty percent of the total feed to the cracking unit. 
     
     
       7. A process in accordance with claim 1 wherein said benzene and said jet range alkyl aromatics are fed to said cracking unit at separate feed locations. 
     
     
       8. A process in accordance with claim 1 wherein said cracking unit is a fluid catalytic cracking unit which comprises a first riser, a stripping zone, and a catalyst regenerator which produces regenerated catalyst. 
     
     
       9. A process in accordance with claim 8 wherein said benzene and said jet range alkyl aromatics are fed to said fluid catalytic cracking unit at separate feed locations. 
     
     
       10. A process in accordance with claim 9 wherein said benzene is fed to said first riser at a feed location before said jet range alkyl aromatics are fed to said first riser wherein said benzene is first to contact catalyst. 
     
     
       11. A process in accordance with claim 8 wherein said fluid catalytic cracking unit comprises a second riser and said benzene and said hydrocarbon composition comprising said jet range alkyl aromatics are fed to said first riser and said heavy feed is fed to said second riser. 
     
     
       12. A process in accordance with claim 11 wherein said benzene and said composition comprising said jet range alkyl aromatics are the sole feed to said first riser. 
     
     
       13. A process in accordance with claim 8 wherein said benzene and said jet range alkyl aromatics are fed to said stripping zone of said fluid catalytic cracking unit and are contacted with regenerated catalyst. 
     
     
       14. A process in accordance with claim 13 wherein said benzene is contacted with said regenerated catalyst before said jet range alkyl aromatics are contacted with said regenerated catalyst. 
     
     
       15. A process in accordance with claim 13 wherein said stripping zone comprises a fluidized bed of spent catalyst to which regenerated catalyst and said benzene and said composition comprising said jet range alkyl aromatics are fed. 
     
     
       16. A process in accordance with claim 1 wherein said cracking unit is a moving bed catalytic cracking unit. 
     
     
       17. A process in accordance with claim 1 wherein said cracking unit is a fixed bed cracking unit. 
     
     
       18. A process in accordance with claim 1 wherein said cracking unit comprises a cracking riser for cracking said heavy feed to cracked products and a fixed bed cracking reactor for contacting said benezene and said hydrocarbon composition comprising said jet range alkyl aromatics with said cracking catalyst. 
     
     
       19. A process, for producing gasoline blending components from the jet aromatics content of a jet fuel comprising hydrocarbons which boil in a range of from about 300° F. to about 525° F. and reducing the benzene content of a benzene-rich light gasoline stream, said process comprising: operating a catalytic cracker unit at catalytic cracking conditions wherein said catalytic cracker cracks a heavy feed comprising hydrocarbons which boil at a temperature greater than about 690° F. in a first reaction zone and in the presence of cracking catalyst to a lighter product which comprises a first alkyl aromatic product; reacting separately in a second reaction zone of said catalytic cracking unit said aromatic jet fuel with said benzene-rich light gasoline stream by contact with a cracking catalyst to convert at least a portion of said benzene-rich gasoline and at least a portion of said jet aromatics to an aromatic-containing product comprising toluene and xylenes, said contact conducted such that the toluene and xylenes do not contact the cracking catalyst in the presence of said first alkyl aromatic product produced by cracking said heavy feed in the first reaction zone; separating out the cracking catalyst from the lighter product and the aromatic-containing product; and thereafter mixing the lighter product and the aromatic-containing product. 
     
     
       20. A process in accordance with claim 19 wherein said light gasoline comprises benzene in a concentration of from about 5 volume percent up to about 100 volume percent and less than about 5 volume percent of other aromatics. 
     
     
       21. A process in accordance with claim 19 wherein said catalytic cracker comprises a first reactor riser and a second reactor riser and said reaction between benzene and jet aromatics occurs in said first reactor riser while cracking of said heavy feed to lighter products occurs in said second reactor riser. 
     
     
       22. A process in accordance with claim 21 wherein said jet aromatics are a component of said lighter products cracked from said heavy feed. 
     
     
       23. A process for producing gasoline blending components from the jet aromatics content of a jet fuel comprising hydrocarbons which boil in a range of from bout 300° F. to about 525° F. and reducing the benzene content of a light gasoline stream, the process comprising: operating a fluidized bed reactor unit with a conventional fluidized catalytic cracking catalyst at catalytic cracking conditions wherein said reactor cracks in a first reaction zone a heavy feed comprising hydrocarbons which boil at a temperature greater than about 690° F. to a lighter product which comprises a first alkyl aromatic product; and, reacting separately in a second reaction zone of said fluidized bed reactor unit said aromatic jet fuel with said light gasoline by contact with the cracking catalyst to convert at least a portion of said benzene and at least a portion of said jet aromatics to an aromatic-containing product comprising toluene and xylenes, said contact conducted such that the toluene and xylenes do not contact the cracking catalyst in the presence of said first alkyl aromatic product produced by cracking said heavy feed in the first reaction zone; separating out the cracking catalyst from the lighter product and the aromatic-containing product; and, thereafter mixing the lighter product and the aromatic-containing product. 
     
     
       24. A process in accordance with claim 23 wherein said fluidized bed reactor is the stripping zone of a fluid catalytic cracker. 
     
     
       25. A process in accordance with claim 24 wherein said jet aromatics are a component of said lighter products cracked from said heavy feed. 
     
     
       26. A process for producing gasoline blending components from the jet aromatics content of a jet fuel comprising hydrocarbons which boil in a range of from about 300° F. to about 525° F. and reducing the benzene content of a light gasoline stream, said process comprising: operating a moving bed reactor unit with a moving bed catalytic cracking catalyst at catalytic cracking conditions wherein said reactor unit in a first reaction zone cracks a heavy feed comprising hydrocarbons which boil at a temperature greater than about 690° F. to a lighter product which comprises a first alkyl aromatic product; and, reacting separately in a second reaction zone in said moving bed reactor said jet aromatics with said light gasoline by contact with the cracking catalyst to convert at least a portion of said benzene and at least a portion of the jet aromatics to an aromatic-containing product comprising toluene and xylenes, said contact conducted such that the toluene and xylenes do not contact the cracking catalyst in the presence of said first alkyl aromatic product produced by cracking said heavy feed in the first reaction zone; separating out the cracking catalyst from the lighter product and the aromatic-containing product; and, thereafter mixing the lighter product and the aromatic-containing product. 
     
     
       27. A process for producing gasoline blending components from the jet aromatics content of a jet fuel comprising hydrocarbons which boil in a range of from about 300° F. to about 525° F. and reducing the benzene content of a light gasoline stream, said process comprising operating a fixed bed reactor unit with an acidic cracking catalyst at hydrocracking conditions wherein a first reaction zone of said reactor unit cracks a heavy feed comprising hydrocarbons which boil at a temperature greater than about 690° F. to a lighter product which comprises a first alkyl aromatic product; and, reacting separately in a second reaction zone of said fixed bed reactor said jet aromatics with said light gasoline by contact with the cracking catalyst to convert at least a portion of said benzene and at least a portion of said jet aromatics to an aromatic-containing product comprising toluene and xylenes, said contact conducted such that the toluene and xylenes do not contact the cracking catalyst in the presence of said first alkyl aromatic product produced by cracking said heavy feed in the first reaction zone; separating out the cracking catalyst from the lighter product and the aromatic-containing product; and thereafter mixing the lighter product and the aromatic-containing product.