Blends of Synthetic Distillate and Biodiesel for Low Nitrogen Oxide Emissions from Diesel Engines

Abstract

This invention shows how to make and use a biodiesel-based fuel in diesel engines without incurring the NO x penalty. Embodiments primarily relate to an optimum range of bulk modulus of compressibility for biodiesel blends, which results in generating “NO x neutral” biodiesel blends or to formulate biodiesel blends with lower NOx emissions than conventional petroleum diesel fuel. These biodiesel blends preferably comprise synthetic paraffinic middle distillate derived from a hydrocarbon synthesis to generate synthetic environmentally-friendly diesel fuels.

1 - 36 . (canceled) 
     
     
         37 . A method of making a synthetic diesel fuel or diesel fuel blendstock characterized by producing low sulfur and NOx emissions when used in compression ignition engines, said method comprising mixing a synthetic liquid distillate and a liquid biofuel at a ratio determined by equation:
     x   b =100( B−B   sd )/( B   b   −B   sd )   
       wherein B represents a desired bulk modulus of compressibility of the synthetic diesel fuel or diesel fuel blendstock at a specific pressure and a specific temperature; B sd  represents a measured bulk modulus of compressibility of the synthetic distillate at the same pressure and temperature settings; B b  represents a measured bulk modulus of compressibility of the liquid biofuel at the same pressure and temperature settings; and x b  represents the calculated volume fraction of the liquid biofuel in the resulting mixture. 
     
     
         38 . The method of  claim 37 , wherein the desired bulk modulus of compressibility B is between about 1300 MPa and about 1600 MPa when measured at 15 MPa and 37° C. 
     
     
         39 . The method of  claim 37 , wherein the liquid biofuel comprises a compound selected from the group consisting of vegetable oils, alkyl esters of vegetable oils, mixtures of alkyl esters of fatty acids, and combinations thereof. 
     
     
         40 . The method of  claim 37 , wherein the liquid biofuel comprises a mixture of alkyl esters of fatty acids. 
     
     
         41 . The method of  claim 37 , wherein the liquid biofuel comprises an alkyl ester of a vegetable oil selected from the group consisting of canola oil, soybean oil, cotton oil, palm oil, sunflower oil, and combinations thereof. 
     
     
         42 . The method of  claim 37 , wherein the liquid biofuel comprises an alkyl ester of a vegetable oil selected from the group consisting of canola oil, soybean oil, and combinations thereof. 
     
     
         43 . The method of  claim 37 , wherein the liquid biofuel comprises a total glycerin content less than 0.24 percent by weight of glycerin. 
     
     
         44 . The method of  claim 37 , wherein the liquid biofuel has a flash point greater than 100° C. 
     
     
         45 . The method of  claim 37 , wherein the liquid biofuel has an alcohol content less than 10 percent by weight. 
     
     
         46 . The method of  claim 37 , wherein the liquid biofuel has a kinematic viscosity at 40° C. between about 1.9 mm 2 /s and about 6 mm 2 /S. 
     
     
         47 . The method of  claim 37 , wherein the synthetic liquid distillate is derived from synthesis gas. 
     
     
         48 . The method of  claim 37 , wherein the synthetic liquid distillate is characterized by a boiling range having a 5% boiling point between about 170° C. and about 210° C. and a 95% boiling point between about 320° C. and about 350° C. 
     
     
         49 . The method of  claim 37 , wherein the synthetic middle distillate is characterized by a sulfur content less than 10 ppm sulfur and by a specific gravity less than about 0.8. 
     
     
         50 . The method of  claim 37 , wherein the synthetic middle distillate is characterized by a Bromine number of less than 0.1 gBr/100 g. 
     
     
         51 . The method of  claim 37 , wherein the synthetic middle distillate is characterized by an aromatics content of less than about 1 percent by weight.