Crude oil derived and gas-to-liquids diesel fuel blends

Abstract

The invention provides a method for the production of a diesel fuel composition, said method using Gas-to-Liquid (GTL) diesel fuel as a blend component together with at least a crude oil derived diesel fuel, said method producing a diesel fuel composition which, when combusted in an engine, has reduced NOx and soot emissions. The invention further provides a diesel fuel composition and a method of reducing NOx and soot emissions from a Cl engine.

1 . A method for the production of a diesel fuel composition, said method using Gas-to-Liquid (GTL) diesel fuel which has a density at 15 deg C. of below 0.78 kg/l, a sulphur content of less than 1 mg/kg, polyaromatics below 0.1 mass %, and a cetane number above 65, as a blend component together with at least a crude oil derived diesel fuel, which crude oil derived diesel fuel has a density at 15 deg C. below 0.85 kg/l, a sulphur content of less than 10 mg/kg, a polyaromatics content of below 5 mass %, and a cetane number from 51 to 60, said method producing a diesel fuel composition which, when combusted in an engine, has reduced NOx and soot emissions.  
   
   
       2 . A method as claimed in  claim 1 , wherein the reduction of the NOx and soot emissions are reduced in comparison to the crude derived diesel non-linearly to the blending ratio of the GTL diesel in the crude oil derived diesel fuel.  
   
   
       3 . A method as claimed in  claim 1 , wherein the reductions in both NOx and soot emissions for a 1:1 GTL:Crude derived diesel ratio are greater than 70% of the reduction obtained with a 100% GTL diesel fuel.  
   
   
       4 . A method as claimed in  claim 1 , wherein the reductions in both NOx and soot emissions for a 1:4 GTL:Crude derived diesel ratio are greater than 40% of the reduction obtained with a 100% GTL diesel fuel.  
   
   
       5 . A method as claimed in  claim 1 , wherein the GTL to crude oil derived diesel ratio is from 99:1 to 1:99 and the diesel fuel composition produced has a molar H:C ratio of between 1.8:1 and 2.1:1.  
   
   
       6 . A method as claimed in  claim 5 , wherein the molar H:C ratio is from 1.85:1 and 2.05:1.  
   
   
       7 . A method as claimed in  claim 6 , wherein the molar H:C ratio is from 1.9:1 and 2.00:1.  
   
   
       8 . A diesel fuel composition comprising both crude oil derived diesel fuel, which crude oil derived diesel fuel has a density at 15 deg C. below 0.85 kg/l, a sulphur content of less than 10 mg/kg, a polyaromatics content of below 5 mass %, and a cetane number from 51 to 60, and Gas-to-Liquids (GTL) diesel fuel, which GTL diesel has a density at 15 deg C. of below 0.78 kg/l, a sulphur content of less than 1 mg/kg, polyaromatics below 0.1 mass %, and a cetane number above 65, in a volumetric ratio range of from 1:99 to 99:1 and with a molar H:C ratio of between 1.8:1 and 2.1:1.  
   
   
       9 . A diesel fuel composition as claimed in  claim 8 , which diesel fuel composition has a density at 15° C. of from 0.77 kg/l to 0.84 kg/l.  
   
   
       10 . A diesel fuel composition as claimed in  claim 9 , which diesel fuel composition has a density at 15° C. of from about 0.8 kg/l to about 0.82 kg/l.  
   
   
       11 . A diesel fuel composition as claimed in  claim 8 , which diesel fuel composition has a lower heating value of from 42 500 kJ/kg to 43 800 kJ/kg.  
   
   
       12 . A diesel fuel composition as claimed in  claim 11 , which diesel fuel composition has a lower heating value of from 43 100 kJ/kg to 43 600 kJ/kg.  
   
   
       13 . A diesel fuel composition as claimed in  claim 12 , which diesel fuel composition has a lower heating value of from 43 200 kJ/kg to 43 500 kJ/k.  
   
   
       14 . A diesel fuel composition as claimed in  claim 8 , having less than 10 mg/kg sulphur.  
   
   
       15 . A diesel fuel composition as claimed in  claim 8 , having less than 5 mass % polycyclic aromatics.  
   
   
       16 . A method of operating a Cl engine to reduce NOx and soot emissions when compared to use of said engine with crude derived diesel fuel, said method including combusting a diesel fuel composition as claimed in  claim 8  in the engine under said engine's operating conditions, wherein the reductions in both NOx and soot emissions for a 1:1 GTL:Crude derived diesel ratio being combusted in the engine are greater than 70% of the reduction obtained when a 100% GTL diesel fuel is combusted in the engine.  
   
   
       17 . A method as claimed in  claim 16 , wherein the reductions in both NOx and soot emissions for a 4:1 GTL:Crude derived diesel ratio being combusted in the engine are greater than 40% of the reduction obtained when a 100% GTL diesel fuel is combusted in the engine.