Lead-free gasoline composition and method for production thereof

Abstract

Method of producing lead-free gasoline composition having a sulfur content of 1 ppm or less and an octane number of 89.0 or more, includes: subjecting a cracked naphtha fraction exhibiting a temperature for 5 vol % distillation of 25° C. or higher and for 95 vol % distillation of 210° C. or lower, an olefin content of 5 mass % or more and a diene number of 0.3 g/100 g or less to a desulfurization treatment, and mixing the resultant desulfurized cracked naphtha fraction with another gasoline base material; and a lead-free gasoline composition having an octane number of 89.0 or more, a temperature for 50 vol % distillation of 105° C. or lower, has an olefin content of 10 vol % or more and a total sulfur content of 1 ppm or less, and a percentage of a thiophene type sulfur compound in the total sulfur content of 50% or more.

1 . A method for producing the unleaded gasoline composition having a sulfur content of 1 mass ppm or less and a research octane number of 89.0 or more, comprising a desulfurization step of subjecting a cracked naphtha fraction having a 5 vol % distillation temperature of 25° C. or more, a 95 vol % distillation temperature of 210° C. or less, an olefin content of 5 mass % or more, and a diene value of 0.3 g/100 g or less to a desulfurization treatment, and a blending step of mixing the resulting desulfurized cracked naphtha fraction with another gasoline base materials.  
   
   
       2 . The method for producing the unleaded gasoline composition according to  claim 1 , further comprising a diene-reducing step of reducing the diene content of the raw cracked naphtha fraction by causing the cracked naphtha fraction to come into contact with a diene-reducing catalyst in advance.  
   
   
       3 . The method for producing the unleaded gasoline composition according to  claim 2 , wherein the diene-reducing catalyst comprises at least one metal selected from group 8 elements in the periodic table.  
   
   
       4 . The method for producing the unleaded gasoline composition according to  claim 3 , wherein at least one metal contained in the diene-reducing catalyst is nickel or cobalt.  
   
   
       5 . The method for producing the unleaded gasoline composition according to  claim 1 , wherein the desulfurization treatment comprises causing the cracked naphtha fraction to come in contact with a porous desulfurization agent having a sulfur sorption function in the presence of hydrogen under hydrogen partial pressure of 1 MPa or less.  
   
   
       6 . The method for producing the unleaded gasoline composition according to  claim 5 , wherein the porous desulfurization agent comprises at least one metal selected from copper, zinc, nickel, and iron.  
   
   
       7 . The method for producing the unleaded gasoline composition according to  claim 1 , wherein the blending step comprises mixing 10-90 vol % of the desulfurized cracked naphtha fraction with 90-10 vol % of another gasoline base materials.  
   
   
       8 . The method for producing the unleaded gasoline composition according to  claim 1 , wherein the cracked naphtha fraction is a light cracked naphtha fraction having a 5 vol % distillation temperature of 25-43° C., a 95 vol % distillation temperature of 55-100C., an olefin content of 5 mass % or more, and a diene value of 0.3 g/100 g or less.  
   
   
       9 . The method for producing the unleaded gasoline composition according to  claim 8 , wherein the light cracked naphtha fraction is obtained by subjecting the cracked naphtha fraction to a diene-reducing treatment, followed by fractional distillation, or fractionating the cracked naphtha fraction, followed by a diene-reducing treatment, or simultaneous fractional distillation and diene-reducing treatment of the cracked naphtha fraction.  
   
   
       10 . The method for producing the unleaded gasoline composition according to  claim 9 , further comprising a pretreatment step of subjecting the raw fraction of the cracked naphtha fraction prior to or simultaneously with the fractional distillation for obtaining a light cracked naphtha fraction, or the raw fraction of the cracked naphtha fraction subjected to a diene-reducing treatment to increase the molecular weight of sulfur compounds therein.  
   
   
       11 . The method for producing the unleaded gasoline composition according to  claim 8 , wherein the blending step comprises mixing 10-60 vol % of the light desulfurized cracked naphtha fraction with 90-40 vol % of another gasoline base materials, and the unleaded gasoline composition has a research octane number of 93.0 or more.  
   
   
       12 . An unleaded gasoline composition having a research octane number of 89.0 or more, a 50 vol % distillation temperature of 105° C. or less, an olefin content of 10 vol % or more, a total sulfur content of 1 mass ppm or less, and a proportion of thiophene compounds to the total sulfur compounds of 50 mass % or more, as sulfur.  
   
   
       13 . The unleaded gasoline composition according to  claim 12 , having a research octane number of 93.0 or more.  
   
   
       14 . The unleaded gasoline composition according to  claim 13 , having a proportion of olefins having a boiling point of 35-100° C. to the total olefins of 90.0 vol % or more.  
   
   
       15 . The unleaded gasoline composition according to  claim 13 , having a proportion of total amount of thiophene and 2-methylthiophene to the total sulfur compounds of 50 mass % or more, as sulfur.  
   
   
       16 . The unleaded gasoline composition according to  claim 12 , having a thiol compounds content of 0.1 mass ppm or less, as sulfur.