Method to increase the cetane number of gas oil

Abstract

A method to increase the cetane number of a gas oil product based on a petroleum derived gas oil to a target cetane number Y by adding to the petroleum derived gas oil an amount of a Fischer-Tropsch derived gas oil having a higher cetane number, B, than the petroleum derived gas oil of cetane number, A, wherein the amount of added Fischer-Tropsch derived gas oil is less than the amount which would be added if linear blending is assumed.

1 . A method of increasing the cetane number of a gas oil product based on a petroleum derived gas oil to a target cetane number Y comprising: adding to the petroleum derived gas oil a volume amount of a Fischer-Tropsch derived gas oil having a higher cetane number, B, than the petroleum derived gas oil of cetane number, A, wherein the volume amount of added Fischer-Tropsch derived gas oil is less than the volume amount which would be added if linear blending is assumed.  
     
     
         2 . The method of  claim 1 , wherein the volume fraction of Fischer-Tropsch gas oil is less than x, wherein x is the volume fraction that would be added if linear blending assumptions would have been made according to the following equation:  
           Y=A+x ( B−A ),  
     
     
         3 . The method of claims  1 , wherein a volume fraction x is added as Fischer-Tropsch derived gas oil in order to increase the cetane number to target value Y, wherein Y and x are related according to the following equation:  
         Y=A+(B−A)(−px 2   +qx ),  
       where p and q are constants such that 1.4>q>1.9 and p=q−1 and wherein A is the cetane number of the petroleum derived gas oil and B the cetane number of the Fischer-Tropsch derived gas oil.  
     
     
         4 . The method of  claim 3 , in which x is greater than 0.02 and less than 0.7.  
     
     
         5 . The method of  claim 4 , in which x is less than 0.5.  
     
     
         6 . The method of  claim 1 , of which the cetane number, A, of the petroleum derived gas oil is greater than 40 and less than 70.  
     
     
         7 . The method of claims  1 , of which the cetane number of the petroleum derived gas oil is measured using near infrared spectroscopy.  
     
     
         8 . The method of  claim 2 , in which a volume fraction x is added as Fischer-Tropsch derived gas oil in order to increase the cetane number to target value Y, wherein Y and x are related according to the following equation:  
           Y=A +( B−A )(− px   2   +qx ),  
       where p and q are constants such that 1.4>q>1.9 and p=q-1 and wherein A is the cetane number of the petroleum derived gas oil and B the cetane number of the Fischer-Tropsch derived gas oil.