Method and use for the prevention of fuel injector deposits

Abstract

A method of substantially removing, or reducing the occurrence of, injector deposits in a diesel engine operated using a diesel fuel containing a minor amount of a metal-containing species is disclosed. The method includes adding to a diesel fuel the reaction product between a hydrocarbyl-substituted succinic acid or anhydride and hydrazine. The diesel engine is equipped with fuel injectors having a plurality of spray-holes, each spray-hole having an inlet and an outlet, and the fuel injectors have one or more of the following characteristics; (i) spray-holes which are tapered such that the inlet diameter of the spray-holes is greater than the outlet diameter; (ii) spray-holes having an outlet diameter of 0.10 mm or less; (iii) spray-holes where an inner edge of the inlet is rounded; (iv) 6 or more spray-holes; (v) an operating tip temperature in excess of 250° C.

1 . A method of substantially removing, or reducing the occurrence of, injector deposits in a diesel engine operated using a diesel fuel containing a minor amount of a metal-containing species, the method comprising adding to the diesel fuel a reaction product between a hydrocarbyl-substituted succinic acid or anhydride and hydrazine, wherein the diesel engine is equipped with fuel injectors having a plurality of spray-holes, each spray-hole having an inlet and an outlet, and wherein the fuel injectors have one or more of the following characteristics: 
 (i) spray-holes which are tapered such that the inlet diameter of the spray-holes is greater than the outlet diameter;    (ii) spray-holes having an outlet diameter of 0.10 mm or less;    (iii) spray-holes where an inner edge of the inlet is rounded;    (iv) 6 or more spray-holes;    (v) an operating tip temperature in excess of 250° C.    
     
     
         2 . A method according to  claim 1  wherein the fuel injectors have two or more of characteristics (i) to (v).  
     
     
         3 . A method according to  claim 2  wherein the fuel injectors have at least characteristics (i) and (ii).  
     
     
         4 . A method according to  claim 1  wherein at least 25% by weight of the reaction product between the hydrocarbyl-substituted succinic acid or anhydride and hydrazine has a molecular weight which is more than 2 times the average molecular weight of the hydrocarbyl group of the hydrocarbyl-substituted succinic acid or anhydride.  
     
     
         5 . A method according to  claim 1  wherein the hydrocarbyl group of the hydrocarbyl-substituted succinic acid or anhydride comprises a C 8 -C 36  group or a polyisobutylene group with a number average molecular weight of between 400 and 2500.  
     
     
         6 . A method according to  claim 1  wherein the hydrocarbyl-substituted succinic acid or anhydride and hydrazine are reacted in a molar ratio of 2:1-1:4.  
     
     
         7 . A method according to  claim 1  wherein the reaction product between the hydrocarbyl-substituted succinic acid or anhydride and hydrazine is added to the diesel fuel in an amount of between 10 and 500 ppm by weight based on the weight of the fuel.  
     
     
         8 . A method according to  claim 1  wherein the metal-containing species comprises zinc, copper, iron, lead, cerium, a Group I or II metal, platinum or manganese.  
     
     
         9 . A method according to  claim 8  wherein the metal-containing species comprises zinc.  
     
     
         10 . A method according to  claim 1  wherein the metal-containing species comprises a fuel-borne catalyst.  
     
     
         11 . A method according to  claim 1  wherein the amount of metal-containing species in the diesel fuel, expressed in terms of the total weight of metal in the species, is between 0.1 and 50 ppm by weight based on the weight of the diesel fuel.  
     
     
         12 . A process for producing a diesel fuel detergent effective to substantially remove, or reduce the occurrence of, injector deposits in diesel engine, comprising reacting in a solvent, at least one hydrocarbyl-substituted succinic acid or anhydride with hydrazine; refluxing the resulting reaction mixture to complete the reaction; and raising the temperature of the reaction mixture to at least 120° C. under reduced pressure and for at least 30 minutes.