Biodegradable diesel fuel

Abstract

This invention relates to diesel fuel having as a component a middle distillate cut having biodegradability properties. More particularly, this invention relates to a diesel fuel including middle distillates produced from a mainly paraffinic synthetic crude which is produced by the reaction of CO and H 2 , typically by the Fischer-Tropsch (FT) process. The middle distillate according to the invention has an aromatics content of less than 9%, as determined by the ASTM D 5186 or IP 391 test method. The paraffinic chains of the middle distillate may be predominantly isoparaffins.

1 . A diesel fuel composition including from 10% to 100% of a synthetic middle distillate cut having less than 9 mass %, as determined according to IP 391 or ASTM D 5186 standards, aromatics content, the synthetic middle distillate cut having less than 8.99 mass % monocyclic aromatics content and less than 0.01 mass % polycyclic aromatic content, wherein the synthetic distillate is derived from a FT primary product and the synthetic middle distillate cut is at least 60% biodegradeable within 28 days when using the Modified Sturm OECD method 301B.  
   
   
       2 . A diesel fuel composition as claimed in  claim 1 , wherein the synthetic middle distillate cut has an isoparaffins to n-paraffins mass ratio of between about 1:1 to about 9:1.  
   
   
       3 . A diesel fuel composition as claimed in  claim 1 , wherein the synthetic middle distillate cut has an isoparaffins to n-paraffins mass ratio is between about 2:1 to about 6:1.  
   
   
       4 . A diesel fuel composition as claimed in  claim 1 , wherein the synthetic middle distillate cut has an isoparaffins to n-paraffins mass ratio is 4:1.  
   
   
       5 . A diesel fuel composition as claimed in  claim 2 , wherein the synthetic middle distillate cut comprises more than 50 mass % isoparaffins, wherein the isoparaffins are predominantly methyl and/or ethyl and/or propyl branched.  
   
   
       6 . A diesel fuel composition as claimed in  claim 2 , wherein the gradient of an isoparaffins to n-paraffins mass ratio profile of the synthetic middle distillate cut increases from about 1:1 for C 8  to 8.54:1 for C 15  and decrease again to about 3:1 for C 18 .  
   
   
       7 . A diesel fuel composition as claimed in  claim 6 , wherein a fraction of the synthetic middle distillate cut in the C 10  to C 18  carbon number range has a higher ratio of isoparaffins to n-paraffins than a C 8  to C 9  fraction of the synthetic middle distillate cut.  
   
   
       8 . A diesel fuel composition as claimed in  claim 7 , wherein the isoparaffins to n-paraffins mass ratio of the C 10  to C 18  fraction is between 1:1 and 9:1.  
   
   
       9 . A diesel fuel composition as claimed in  claim 6 , wherein the isoparaffins to n-paraffins mass ratio is about 8.54:1 for a C 15  fraction of the synthetic middle distillate cut.  
   
   
       10 . A diesel fuel composition as claimed in  claim 6 , wherein a C 19  to C 24  fraction of the middle distillate cut has a mass ratio range of isoparaffins to n-paraffins of between 3.3:1 and 5:1.  
   
   
       11 . A diesel fuel composition as claimed in  claim 10 , wherein the C 19  to C 24  fraction of the middle distillate cut has a mass ratio range of isoparaffins to n-paraffins of between 4:1 and 4.9:1.  
   
   
       12 . A diesel fuel composition as claimed in  claim 6 , wherein the mass ratio of isoparaffins to n-paraffins is adjusted by controlling the blend ratio of hydrocracked to straight run components of the synthetic middle distillate cut.  
   
   
       13 . A diesel fuel composition as claimed in  claim 12 , wherein the isoparaffins to n-paraffins mass ratio of the C 10  to C 18  fraction having 30 mass % straight run component is between 1:1 and 2:5:1.  
   
   
       14 . A diesel fuel composition as claimed in  claim 12 , wherein the isoparaffins to n-paraffins mass ratio of the C 10  to C 18  fraction having 20 mass % straight run component is between 1.5:1 and 3:5:1.  
   
   
       15 . A diesel fuel composition as claimed in  claim 12 , wherein the isoparaffins to n-paraffins mass ratio of the C 10  to C 18  fraction having 10 mass % straight run component is between 2.3:1 and 4.3:1.  
   
   
       16 . A diesel fuel composition as claimed in  claim 12 , wherein the isoparaffins to n-paraffins mass ratio of the C 10  to C 18  fraction having substantially only a hydrocracked component is between 4:1 and 9:1.  
   
   
       17 . A diesel fuel composition as claimed in  claim 5 , wherein at least some of the isoparaffins are di-methyl branched.  
   
   
       18 . A diesel fuel composition as claimed in  claim 5 , wherein at least 30 mass % of the isoparaffins are mono-methyl branched.  
   
   
       19 . A diesel fuel composition as claimed in  claim 18 , wherein at least some of the isoparaffins are ethyl branched.  
   
   
       20 . A diesel fuel composition as claimed in  claim 1 , including from 0 to 90 mass % of at least one other diesel fuel.