High octane unleaded aviation gasoline

Abstract

An unleaded aviation fuel composition meets the requirements of the ASTM D910 specification. Furthermore, the unleaded aviation fuel compositions of the present invention exhibit reduced bladder delamination, improved materials compatibility such as reduced elastomer swelling and reduced paint staining, and improved engine endurance.

1 . An unleaded aviation fuel composition having a MON of at least 99.6, sulfur content of less than 0.05 wt %, CHN content of at least 98 wt %, less than 2 wt % of oxygen content, an adjusted heat of combustion of at least 43.5 MJ/kg, a vapor pressure in the range of 38 to 49 kPa, comprising a blend comprising:
 from 5 vol. % to 25 vol. % of toluene having a MON of at least 107;   from 0.5 vol. % to 4 vol. % of aniline;   from 30 vol % to 70 vol % of at least one alkylate or alkyate blend having an initial boiling range of from 32° C. to 60° C. and a final boiling range of from 105° C. to 140° C., having T40 of less than 99° C., T50 of less than 100° C., T90 of less than 110° C., the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, 3-20 vol % of C5 isoparaffins, 3-15 vol % of C7 isoparaffins, and 60-90 vol % of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol % of C10+, based on the alkylate or alkylate blend;   from 0.1 vol. % to 10 vol. % of branched alkyl acetate;   at least 8 vol % of isopentane, isobutane, or mixture thereof in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa;   from 2 vol. % to 10 vol. % of mesitylene;   wherein the fuel composition contains less than 1 vol % of C8 aromatics.   
     
     
         2 . An unleaded aviation fuel composition according to  claim 1 , wherein the total content of isopentane, isobutane or mixture thereof in the fuel composition is from 10 vol. % to 20 vol %. 
     
     
         3 . An unleaded aviation fuel composition according to  claim 1  wherein the content of aniline is from 1 vol % to 3 vol %. 
     
     
         4 . An unleaded aviation fuel composition according to  claim 1 , wherein the volume ratio of branched alkyl acetate to aniline is at least 1.5:1. 
     
     
         5 . An unleaded aviation fuel composition according to  claim 1  wherein the volume ratio of isopentane to isobutane is at least 2:1. 
     
     
         6 . An unleaded aviation fuel composition according to  claim 1 , further comprising an aviation fuel additive. 
     
     
         7 . An unleaded aviation fuel composition according to  claim 1 , having a freezing point of less than −58° C. 
     
     
         8 . An unleaded aviation fuel composition of  claim 1 , having a final boiling point of less than 190° C. 
     
     
         9 . An unleaded aviation fuel composition of  claim 1 , wherein the alkylate or alkylate blend have a C10+ content of less than 0.1 vol % based on the alkylate or alkylate blend. 
     
     
         10 . An unleaded aviation fuel composition of  claim 1 , wherein the branched alkyl acetate is t-butyl acetate. 
     
     
         11 . An unleaded aviation fuel composition of  claim 1 , having a final boiling point of at most 180° C. 
     
     
         12 . Use of an unleaded aviation fuel composition having a MON of at least 99.6, sulfur content of less than 0.05 wt %, CHN content of at least 98 wt %, less than 2 wt % of oxygen content, an adjusted heat of combustion of at least 43.5 MJ/kg, a vapor pressure in the range of 38 to 49 kPa, comprising a blend comprising:
 from 5 vol. % to 25 vol. % of toluene having a MON of at least 107;   from 0.5 vol. % to 4 vol. % of aniline;   from 30 vol % to 70 vol % of at least one alkylate or alkyate blend having an initial boiling range of from 32° C. to 60° C. and a final boiling range of from 105° C. to 140° C., having T40 of less than 99° C., T50 of less than 100° C., T90 of less than 110° C., the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, 3-20 vol % of C5 isoparaffins, 3-15 vol % of C7 isoparaffins, and 60-90 vol % of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol % of C10+, based on the alkylate or alkylate blend;   from 0.1 vol. % to 10 vol. % of branched alkyl acetate;   at least 8 vol % of isopentane, isobutane, or mixture thereof in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa;   from 2 vol. % to 10 vol. % of mesitylene;   wherein the fuel composition contains less than 1 vol % of C8 aromatics;   for the purpose of providing one or more of:   (i) improved materials compatibility   (ii) reduced elastomer swelling   (iii) reduced paint staining   (iv) improved engine endurance   (v) reducing bladder delamination.   
     
     
         13 . An unleaded aviation fuel composition of  claim 1 , having a final boiling point of less than 180° C.