Low-sulfur fuel

Abstract

The invention relates to a process for forming a low-sulfur motor gasoline and the product made therefrom. In one embodiment, process involves separating a catalytically cracked naphtha into at least a light fraction boiling below about 165° F. and a heavy fraction boiling above about 165° F. The light fraction is treated to remove sulfur by a non-hydrotreating method, and the heavy fraction is hydrotreated to remove sulfur to a level of less than about 100 ppm.

1 . A method for forming a low-sulfur, high-octane naphtha suitable for gasoline blending, the process comprising 
 (a) separating a catalytically cracked naphtha into at least a light fraction and a heavy fraction, the heavy fraction having an olefin portion containing C 5  olefins, C 6  olefins, and olefins having a molecular weight greater than C 6 ;    (b) treating the light fraction to remove sulfur at a hydrogen partial pressure of less than about 50 psig H 2  to form a treated light fraction having a sulfur content less than about 150 ppm; and then    (c) treating the heavy fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of a hydroprocessing catalyst under catalytic conversion conditions in order to form a treated heavy fraction having a sulfur content less than about 150 ppm and wherein the hydrotreated heavy fraction contains at least 10% of the C 6 + olefins in the heavy fraction.    
     
     
         2 . The method of  claim 1  further comprising adding to at least one of the treated light fraction and hydrotreated heavy fraction a hydrocarbon containing at least one of light virgin naphtha, reformate, alkylate, isomerate, and butanes.  
     
     
         3 . The method of  claim 2  wherein the catalytically cracked naphtha contains 
 (i) about 20 wt. % to about 40 wt. % olefins;  
 (ii) about 20% to about 30 wt. of the olefins are C 5  olefins;  
 (iii) about 45% to about 65% of the C 5 + olefins are C 5  and C 6  olefins; and  
 (iv) the catalytically cracked naphtha has a boiling point ranging from about 65° F. to about 430° F.  
 
     
     
         4 . The method of  claim 3  wherein the light fraction has a boiling point ranging from about 65° F. to about 165° F., wherein the heavy fraction has a boiling point ranging from about 165° F. to about 430° F., and wherein the heavy fraction contains more than about 50% of the C 7  olefin contained in the naphtha.  
     
     
         5 . The method of  claim 3  wherein the treated light fraction contains less than about 50 ppm sulfur, based on the weight of the light fraction, and wherein the treated light fraction contains more than about 75% of the C 5  olefin contained in the naphtha.  
     
     
         6 . The method of  claim 3  wherein the hydroprocessed heavy fraction contains at least 10% of the catalytically cracked naphtha's olefin portion.  
     
     
         7 . The method of  claim 1  wherein the catalytic conversion conditions include a temperature ranging from about 200° C. to about 400° C., a reaction pressure ranging from about 50 psig to about 1000 psig, a space velocity ranging from about 0.1 to about 10 V/V/Hr, and a hydrogen-containing gas rate ranging from about 500 SCF/B to about 5000 SCF/B.  
     
     
         8 . The method of  claim 8  wherein the hydroprocessing catalyst contains about 0.5 wt. % to about 20 wt. % of at least one Group VIII metal and about 1 wt. % to about 50 wt. % of a Group IV metal on an inorganic support.  
     
     
         9 . The method of  claim 9  wherein the catalyst contains about 1 wt. % to about 10 wt. % M 0 O 3  and about 0.1 wt. % to about 5 wt. % CoO, wherein the support contains at least one of silica and alumina, wherein the catalyst has a metals dispersion by the Oxygen Chemisorption Test ranging from about 800 μmol oxygen/gram of MoO 3 , and wherein the catalytic conversion conditions are selective hydroprocessing conditions.  
     
     
         10 . The method of  claim 10  wherein the catalyst further comprises about 0 to about 0.5 wt. % of at least one Group IA element, based on the weight of the support.  
     
     
         11 . The method of  claim 1  further comprising separating at least a portion of the heavy fraction into a second light fraction and a second heavy fraction and then 
 (i) hydroprocessing the second light fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of at least one selective hydroprocessing catalyst under selective hydroprocessing conditions, and  
 (ii) hydroprocessing the second heavy fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of a hydroprocessing catalyst under non-selective hydroprocessing conditions.  
 
     
     
         12 . A light and heavy hydroprocessed product formed by a process comprising 
 (a) separating a catalytically cracked naphtha into at least a light fraction and a heavy fraction, the heavy fraction having an olefin portion containing C 5  olefins, C 6  olefins, and olefins having a molecular weight greater than C 6 ;    (b) treating the light fraction to remove sulfur at a hydrogen partial pressure of less than about 50 psig H 2  to form a treated light fraction having a sulfur content less than about 150 ppm; and then    (c) treating the heavy fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of a hydroprocessing catalyst under catalytic conversion conditions in order to form a treated heavy fraction having a sulfur content less than about 150 ppm and wherein the hydrotreated heavy fraction contains at least 10% of the C 6 + olefin in the heavy fraction.    
     
     
         13 . The product of  claim 12  further comprising adding to at least one of the treated light fraction and hydrotreated heavy fraction a hydrocarbon containing at least one of light virgin naphtha, reformate, alkylate, isomerate, and butanes.  
     
     
         14 . The product of  claim 12  wherein 
 (i) the catalytically cracked naphtha contains about 20 wt. % to about 40 wt. % olefins;  
 (ii) about 20% to about 30% of the olefins are C 5  olefins;  
 (iii) about 45% to about 65% of the C 5 + olefins are C 5  and C 6  olefins; and  
 (iv) the catalytically cracked naphtha has a boiling point ranging from about 65° F. to about 430° F.  
 
     
     
         15 . The product of  claim 14  wherein the light fraction has a boiling point ranging from about 65° F. to about 165° F., wherein the heavy fraction has a boiling point ranging from about 165° F. to about 430° F., and wherein the heavy fraction contains more than about 50% of the C 7  olefin contained in the naphtha.  
     
     
         16 . The product of  claim 14  wherein the treated light fraction contains less than about 50 ppm sulfur, based on the weight of the light fraction, and wherein the treated light fraction contains more than about 75% of the C 5  olefin contained in the naphtha.  
     
     
         17 . The product of  claim 14  wherein the hydroprocessed heavy fraction contains at least 10% of the catalytically cracked naphtha's olefin portion and wherein about 40% to about 70% of the hydroprocessed heavy fraction's olefins are C 5  and C 6  olefins.  
     
     
         18 . The product of  claim 12  wherein the catalytic conversion conditions include a temperature ranging from about 200° C. to about 400° C., a reaction pressure ranging from about 50 psig to about 1000 psig, a space velocity ranging from about 0.1 to about 10 V/V/Hr, and a hydrogen-containing gas rate ranging from about 500 SCF/B to about 5000 SCF/B.  
     
     
         19 . The product of  claim 18  wherein the hydroprocessing catalyst contains about 0.5 wt. % to about 20 wt. % of at least one Group VIII metal and about 1 wt. % to about 50 wt. % of a Group IV metal on an inorganic support.  
     
     
         20 . The product of  claim 19  wherein the catalyst contains about 1 wt. % to about 10 wt. % M 0 O 3  and about 0.1 wt. % to about 5 wt. % CoO, wherein the support contains at least one of silica and alumina, wherein the catalyst has a metals dispersion by the Oxygen Chemisorption Test ranging from about 800 μmol oxygen/gram of MoO 3 , and wherein the catalytic conversion conditions include selective hydroprocessing conditions.  
     
     
         21 . The product of  claim 20  wherein the catalyst further comprises about 0 to about 0.5 wt. % of at least one Group IA element, based on the weight of the support.  
     
     
         22 . The product of  claim 12  further comprising separating at least a portion of the heavy fraction into a second light fraction and a second heavy fraction and then 
 (i) hydroprocessing the second light fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of at least one hydroprocessing catalyst under selective hydroprocessing conditions; and  
 (ii) hydroprocessing the second heavy fraction in the presence of a hydrogen-containing gas and a catalytically effective amount of a hydroprocessing catalyst under non-selective hydroprocessing conditions.  
 
     
     
         23 . The product of  claim 12  wherein 
 (i) the product contains no more than 13 wt. % olefins, based on the weight of the product;  
 (ii) the product has a percentage of olefins having a carbon number of at least C 5  that are C 5  and C 6  olefins ranging from about 37 to about 84%, and  
 (iii) the product contains less than about 60 ppm sulfur, based on the total weight of the product.  
 
     
     
         24 . A hydrocarbon boiling in the naphtha boiling range comprising C 5  olefins, C 6  olefins, and olefins having more than 6 carbon atoms, wherein 
 (i) the hydrocarbon contains more than about 12 wt. % olefins, based on the weight of the hydrocarbon;    (ii) the hydrocarbon contains an amount of olefins having five or more carbon atoms that are C 5  and C 6  olefins ranging from about 37% to about 84%; and    (iii) the hydrocarbon contains less than about 60 ppm sulfur, based on the weight of the hydrocarbon.    
     
     
         25 . The hydrocarbon of  claim 24  wherein the hydrocarbon contains a lower boiling light portion and a higher boiling heavy portion, wherein the light fraction is present in an amount about 15 wt. % to about 30 wt. % of the hydrocarbon, the balance of the hydrocarbon being substantially the heavy fraction.  
     
     
         26 . The hydrocarbon of  claim 25  further comprising 50 to 70 wt. % of a second hydrocarbon containing at least one of light virgin naphtha, reformate, isomerate, alkylate, and butanes, and wherein the hydrocarbon contains about 2 wt. % to about 12 wt. % olefins, and wherein at least about 25% of the hydrocarbon's olefins are C 5  olefins.