Synthetic transportation fuel and method for its production

Abstract

A transportation fuel or blending stock for a transportation fuel which contains substantially no FT oxygenates and no sulfur is provided. An economical method of producing a transportation fuel or blending stock which eliminates oxygenates and which does not cause any significant yield loss is also provided.

1 . A hydrocarbon mixture comprising: 
 an olefin/paraffin mixture having a carbon number range from about C 8  to about C 20+  wherein the olefin/paraffin mixture comprises:    substantially no oxygenates;    between about 1 wt % and 20 wt % olefin wherein at least about 1 wt % of the olefin is mono-olefin;    at least about 5 wt % n-paraffins;    between about 2 and 94 wt % branched paraffins wherein at least about 30% of all branch groups are monomethyl and wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1:1.5.    
     
     
         2 . The hydrocarbon mixture of  claim 1  wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1:1.  
     
     
         3 . The hydrocarbon mixture of  claim 1  wherein the n-paraffins are present in an amount of at least about 10 wt % and wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1.5:1.  
     
     
         4 . The hydrocarbon mixture of  claim 1  wherein the n-paraffins are present in an amount of at least about 10 wt % and wherein the ratio of terminal monomethyl branching to internal monomethyl is at least about 2:1.  
     
     
         5 . The hydrocarbon mixture of  claim 1  wherein the olefin/paraffin mixture is a product of a Fischer-Tropsch reaction.  
     
     
         6 . The synthetic fuel of  claim 5  wherein the Fischer-Tropsch reaction feed syngas comprises 10-65% N 2 .  
     
     
         7 . A process for producing a synthetic fuel comprising the steps of: 
 (a) producing a light Fischer-Tropsch liquid;    (b) dehydrating all or a part of the FT oxygenates in the LFTL while retaining the olefin content in the LFTL;    (c) recovering an organic phase from the product of step (b);    (d) blending the organic phase into a transportation fuel.    
     
     
         8 . The process of  claim 7  further comprising the step of (a 1 ) vaporizing the LFTL before step (b) and after step (a).  
     
     
         9 . The process of  claim 8  wherein the dehydrated product from step (b) is in the gaseous state and step (c) further includes condensing the dehydrated product.  
     
     
         10 . The process of  claim 9  wherein the heat from condensing the dehydrated product is recycled to at least partially vaporize the LFTL in step (a 1 ).  
     
     
         11 . The process of  claim 7  wherein the light Fischer-Tropsch liquid is produced from a feed syngas having 10-65% N 2 .  
     
     
         12 . The process of  claim 11  wherein the feed syngas is produced by autothermal reformation in the presence of air.  
     
     
         13 . A hydrocarbon mixture comprising: 
 a paraffin mixture having a carbon number range from about C 8  to about C 20+  wherein the paraffin mixture comprises: 
 substantially no FT oxygenates;  
 at least about 5 wt % n-paraffins;  
 between about 2 and about 95 w/o branched paraffins wherein at least about 20% of all branch groups are monomethyl and wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1:1.5.  
   
     
     
         14 . The synthetic fuel of  claim 13  wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1:1.  
     
     
         15 . The synthetic fuel of  claim 13  wherein the n-paraffins are present in an amount of at least about 10 wt % and wherein the ratio of terminal monomethyl branching to internal monomethyl branching is at least about 1.5:1.  
     
     
         16 . The synthetic fuel of  claim 13  wherein the n-paraffins are present in an amount of at least about 10 wt % and wherein the ratio of terminal monomethyl branching to internal monomethyl is at least about 2:1.  
     
     
         17 . The synthetic fuel of  claim 13  wherein the base fluid is a product of a Fischer-Tropsch reaction.  
     
     
         18 . The synthetic fuel of  claim 17  wherein the Fischer-Tropsch reaction feed syngas comprises 10-65% N 2 .  
     
     
         19 . A process for producing a synthetic fuel comprising the steps of: 
 (a) producing a light Fischer-Tropsch liquid;    (b) distilling the light Fischer-Tropsch liquid to obtain a C 8 -C 20 +product having C 8 -C 20+  hydrocarbons and FT oxygenates.    (c) dehydrating all or a part of the FT oxygenates in the C 8 -C 20+  product while retaining the olefin content of the C 8 -C 20+  product;    (d) recovering the dehydrated product;    (e) separating the aqueous and organic phases of the dehydrated product; and    (f) blending the organic phase of the dehydrated product into a transportation fuel.    
     
     
         20 . The process of  claim 19  wherein a C 10 -C 20  product is obtained in step (b) and dehydrated in step (c).  
     
     
         21 . The process of  claim 19  further comprising the step of (b 1 ) vaporizing the C 8 -C 20+  product before step (c) and after step (b).  
     
     
         22 . The process of  claim 19  wherein the dehydrated product from step (c) is in the gaseous state and step (d) further includes condensing the dehydrated product.  
     
     
         23 . The process of  claim 23  wherein the heat from condensing the dehydrated product is recycled to at least partially vaporize the C 8 -C 20+  product in step (b 1 ).  
     
     
         24 . The process of  claim 19  wherein the light Fischer-Tropsch liquid is produced from a feed syngas having 10-65% N 2 .  
     
     
         25 . The process of  claim 24  wherein the feed syngas is produced by autothermal reformation in the presence of air.  
     
     
         26 . A synthetic transportation fuel comprising a non-hydroprocessed middle distillate fraction of a crude Fischer-Tropsch synthesis product comprising substantially no FT oxygenates.  
     
     
         27 . The synthetic transportation fuel of  claim 26  wherein the fuel has a cloud point of less than or equal to 5° C.  
     
     
         28 . The synthetic transportation fuel of  claim 27  wherein the fuel contains less than 1 wt % aromatics.  
     
     
         29 . The synthetic transportation fuel of  claim 27  wherein the fuel contain less than or equal to 1 ppm of nitrogen.  
     
     
         30 . A transportation fuel produced by the process of  claim 7 .  
     
     
         31 . A transportation fuel produced by the process of  claim 19 .  
     
     
         32 . A blending stock for a transportation fuel produced by the process of  claim 7 .  
     
     
         33 . A blending stock for a transportation fuel produced by the process of  claim 19 .  
     
     
         34 . A synthetic transportation fuel consisting essentially of olefins and paraffins without presence of hetero-atoms or additives wherein the transportation fuel has a lubricity measured in accordance with ASTM D-6079 of less than or equal to 0.45 mm at 60° C.  
     
     
         35 . A synthetic transportation fuel comprising paraffins and olefins derived from the product of a Fischer-Tropsch synthesis and comprising no hetero-atoms or additives and having total insolubles of less than or equal to 1.5 mg/100 ml measured in accordance with ASTM D-2274.  
     
     
         36 . A synthetic transportation fuel comprising paraffins and olefins derived from the product of a Fischer-Tropsch synthesis and containing no hetero-atoms having a lubricity measured in accordance with ASTM D-6079 of less than or equal to 0.45 mm at 60° C. and a stability of total insolubles of less than or equal to 1.5 mg/100 ml measured in accordance with ASTM D-2274.