Fuel stability additive

Abstract

A fuel additive package is disclosed that prevents degradation of hydrocarbon fuels upon storage and permits extended use of such motor fuels without intake-valve deposit formation in vehicle motors. The additive contains an antioxidant, metal deactivator, corrosion inhibitor, and detergent. The corrosion inhibitor, preferably a carboxylic acid containing a carbon number equal to or less than 18 and the detergent component, preferably a polyisobutylene diamine are selected to avoid antagonistic effects with the antioxidant and metal deactivator components while the antioxidant and metal deactivator components are used in markedly reduced amounts to avoid antagonistic effects resulting in increased intake-valve deposits.

What is claimed is:  
     
         1 . A stability-enhancing additive package for a hydrocarbon-fuel comprising: 
 (a) an antioxidant comprising an aromatic amine and a hindered phenol wherein the aromatic amine is present in the range of 5.5 to 3.0 weight percent and the hindered phenol is present in the range of 2.7 to 1.2 weight percent;    (b) a metal deactivator comprising an alkane diamine present in the range of 1.5 to 0.05 weight percent;    (c) a corrosion inhibitor comprising a carboxylic acid having a carbon number of 18 or less; and a    (d) detergent selected from the group consisting of polyalkylene diamine and polyoxyalkylene diamine.    
     
     
         2 . The additive package of  claim 1  wherein the carboxylic acid is present in an amount ranging from 5.0 to 0.5 weight percent.  
     
     
         3 . The additive package of  claim 1  wherein the detergent is present in an amount ranging from 15 to 70 weight percent.  
     
     
         4 . The additive package of  claim 1  wherein the aromatic amine is N,N′-di-sec-butyl-p-phenylene diamine, the hindered phenol is 2,6-di-t-butyl phenol, the alkane diamine is N,N′-bis-salicylidene-1,2-propane diamine, the carboxylic acid is dodecenyl succinic acid, and the detergent is polyisobutylene diamine.  
     
     
         5 . The additive package of  claim 4  wherein the dodecenyl succinic acid is present in an amount ranging from 5.0 to 0.5 weight percent, and the polyisobutylene diamine is present in an amount ranging from 15 to 70 weight percent.  
     
     
         6 . The additive package of  claim 1  wherein the fuel is motor gasoline.  
     
     
         7 . The additive package of  claim 6  wherein the gasoline contains oxygenates such as ethanol, wherein the oxygen content is in the range of from 0.4 to 5 weight percent of the gasoline.  
     
     
         8 . The additive package of  claim 6  wherein the gasoline contains less than 100 ppmw sulfur.  
     
     
         9 . The additive package of  claim 6  wherein the gasoline contains less than 50 ppmw sulfur.  
     
     
         10 . The additive package of  claim 7  wherein the gasoline contains less than 100 ppmw sulfur.  
     
     
         11 . The additive package of  claim 1  wherein from 0.25 gallon to 1.0 gallon of the additive package is blended with 1000 gallons of fuel.  
     
     
         12 . The stability-enhancing additive package of  claim 1  wherein the package consists essentially of:  
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   N,N′-di-sec-butyl-p- 
                    4.1 wt % 
                 
                     
                   phenylene diamine 
                 
                     
                   2,6-di-t-butyl phenol 
                    1.5 wt % 
                 
                     
                   N,N′-bis-salicylidene-1,2- 
                   0.68 wt % 
                 
                     
                   propane diamine 
                 
                     
                   Dodecenyl succinic acid 
                    3.0 wt % 
                 
                     
                   Polyisobutylene diamine 
                   36.4 wt % 
                 
                     
                   detergent 
                 
                     
                   Xylene 
                   53.7 wt % 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         13 . A stabilized hydrocarbon fuel comprising a hydrocarbon fuel and a stability-inducing additive package, wherein the stability-inducing additive package comprises: 
 (a) from 3.0 to 5.0 weight percent N,N′-di-sec-butyl-p-phenylenediamine;    (b) from 1.2 to 2.7 weight percent 2,6-di-t-butyl phenol;    (c) from 0.5 to 5.0 weight percent dodecenyl succinic acid; and    (d) from 15 to 70 weight percent polyisobutylene diamine.    
     
     
         14 . The stabilized fuel of  claim 11  wherein the fuel is motor gasoline.  
     
     
         15 . The stabilized fuel of  claim 14  wherein the gasoline contains oxygenates such as ethanol, wherein the oxygen content is in the range of from 0.4 to 5 weight percent of the gasoline.  
     
     
         16 . The stabilized fuel of  claim 14  wherein the gasoline contains less than 100 ppmw sulfur.  
     
     
         17 . The stabilized fuel of  claim 14  wherein the gasoline contains less than 50 ppmw sulfur.  
     
     
         18 . The stabilized fuel of  claim 15  wherein the gasoline contains less than 100 ppmw sulfur.  
     
     
         19 . The stabilized hydrocarbon fuel of  claim 13  wherein the stability-inducing additive package consists essentially of:  
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   N,N′-di-sec-butyl-p 
                    4.1 wt % 
                 
                     
                   phenylene diamine 
                 
                     
                   2,6-di-t-butyl phenol 
                    1.5 wt % 
                 
                     
                   N,N′-bis-salicylidene-1,2- 
                   0.68 wt % 
                 
                     
                   propane diamine 
                 
                     
                   Dodecenyl succinic acid 
                    3.0 wt % 
                 
                     
                   Polyisobutylene diamine 
                   36.4 wt % 
                 
                     
                   detergent 
                 
                     
                   Xylene 
                   53.7 wt %