Effective Novel Non-Polymeric and Non-Fouling Additive for Inhibiting High-Temperature Naphthenic Acid Corrosion and Method of Using the Same

Abstract

The present invention relates to inhibition of high temperature naphthenic acid corrosion occurring in hydrocarbon processing units. The invention provides an effective novel non-polymeric and non-fouling additive for inhibiting high-temperature naphthenic acid corrosion, comprising an effective corrosion-inhibiting amount of a second phosphate ester wherein said second phosphate ester is obtained by reacting a first phosphate ester with an oxirane compound selected from the group consisting of butylene oxide, ethylene oxide, propylene oxide or any other oxirane compound or a combination thereof, preferably with butylene oxide, capably yielding said second phosphate ester, having a structure A or B, wherein R 1 and R 2 are each independently selected from the group consisting of moieties having 1 to 20 carbon atoms and R 1 and R 2 may be identical or different, X is H, CH 3 or C 2 H 5 ; and n may vary from 1 to 20, wherein said first phosphate ester is having a structure I or II, wherein R 1 and R 2 are each independently selected from the group consisting of moieties having 1 to 20 carbon atoms and R 1 and R 2 may be identical or different, said first phosphate ester being obtained as a reaction product of reaction of an alcohol with a phosphorous pentaoxide.

1 . An effective novel non-polymeric and non-fouling additive for inhibiting high-temperature naphthenic acid corrosion, comprising an effective corrosion-inhibiting amount of an oxide treated phosphate ester which is obtained by process comprising steps of:
 (a) reacting an alcohol with phosphorus pentoxide resulting in a reaction mixture of mono-, di-, and tri-phosphate esters and other phosphorous compounds predominantly comprising acidic mono- and di-phosphate esters, respectively having structural formulae I and II   
       
         
           
           
               
               
           
         
       
       characterized in that
 (b) the resulted reaction mixture of step (a) is further reacted with an oxirane compound selected from butylene oxide, ethylene oxide, propylene oxide or any other oxirane compound or a combination thereof yielding said oxide treated phosphate ester, predominantly comprising mixture of compounds of structural formulae A and B, 
 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are each independently selected from the group consisting of moieties having 1 to 20 carbon atoms, and R 1  and R 2  may be identical to or different from each other, X is H, CH 3  or C 2 H 5 ; and n may vary from 1 to 20. 
     
     
         2 . An effective additive, as claimed in  claim 1 , wherein said effective additive has acidity varying from about 1 mg KOH/gm to about 20 mg KOH/gm as determined by titration of samples against normal alcoholic KOH. 
     
     
         3 . An effective additive, as claimed in  claim 1 , wherein said effective additive has phosphorus contents varying from about 0.5% to about 9% of said effective additive. 
     
     
         4 . An effective additive, as claimed in  claim 1 , wherein mole ratios of said phosphorus pentoxide and said alcohol are used, such that the mole ratio of said phosphorus pentoxide to said alcohol is 1 mole of said phosphorus pentoxide to 1 to 10 mole of said alcohol and 1 mole of said phosphorus pentoxide to 1 to 7 mole of said alcohol. 
     
     
         5 . An effective additive as claimed in  claim 1 , wherein active dosage of said additive is from 1 to 2000 ppm. 
     
     
         6 . A process of high temperature naphthenic acid corrosion inhibition of metallic surfaces of a hydrocarbon processing unit of a petrochemical plant, used for processing a stream containing naphthenic acid, with said processing units comprising distillation columns, strippers, trays, pump around piping and related equipments, and said process using said oxide treated phosphate ester of  claim 1 , comprising the steps of:
 (a) heating said hydrocarbon containing naphthenic acid to vapourize a portion of said hydrocarbon;   (b) condensing a portion of the hydrocarbon vapors, passing through said hydrocarbon processing unit, to produce a condensed distillate;   (c) adding to said distillate, before said condensed distillate is returned to said hydrocarbon processing unit or collected as a product, from 1 to 2000 ppm of said oxide treated phosphate ester of  claim 1  in corrosion-inhibition-effective-amount, capably forming a reaction mixture;   (d) allowing said reaction mixture to contact said metallic surfaces of said hydrocarbon processing unit to form a protective film on said surfaces whereby each of said surfaces is inhibited against corrosion; and   (e) allowing said condensed distillate to return to said hydrocarbon processing unit, or to be collected as said product.   
     
     
         7 . A process as claimed in  claim 6 , wherein said stream includes crude oil, feedstock, and hydrocarbon stream and/or fractions thereof. 
     
     
         8 - 9 . (canceled) 
     
     
         10 . An effective novel non-polymeric and non-fouling additive for inhibiting high-temperature naphthenic acid corrosion, comprising an effective corrosion-inhibiting amount of an oxide treated phosphate ester which is obtained by process comprising steps of:
 (a) reacting an alcohol with phosphorus pentoxide resulting in a reaction mixture of mono-, di-, and tri-phosphate esters and other phosphorous compounds predominantly comprising acidic mono- and di-phosphate esters, respectively having structural formulae I and II   
       
         
           
           
               
               
           
         
       
       characterized in that
 (b) the resulted reaction mixture of step (a) is further reacted with an oxirane compound selected from butylene oxide, ethylene oxide, propylene oxide or any other oxirane compound or a combination thereof yielding said oxide treated phosphate ester predominantly comprising mixture of compounds of structural formulae A and B, 
 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are each independently selected from the group consisting of moieties having 1 to 20 carbon atoms, and 
       R 1  and R 2  may be identical to or different from each other, 
       X is H, CH 3  or C 2 H 5 ; and 
       n is 1. 
     
     
         11 . An effective additive, as claimed in  claim 10 , wherein butylene oxide treated phosphate ester comprises a mixture of compounds of structural formulae A1 and B1, 
       
         
           
           
               
               
           
         
       
     
     
         12 . A process of high temperature naphthenic acid corrosion inhibition of metallic surfaces of a hydrocarbon processing unit of a petrochemical plant, used for processing a stream containing naphthenic acid, with said processing unit comprising distillation columns, strippers, trays, pump around piping and related equipments, and said process using said oxide treated phosphate ester of  claim 11 , comprising the steps of:
 (a) heating said hydrocarbon containing naphthenic acid to vapourize a portion of said hydrocarbon;   (b) condensing a portion of the hydrocarbon vapors, passing through said hydrocarbon processing unit, to produce a condensed distillate;   (c) adding to said distillate, before said condensed distillate is returned to said hydrocarbon processing unit or collected as a product, from 1 to 2000 ppm of said oxide treated phosphate ester of  claim 11  in corrosion-inhibition-effective-amount, capably forming a reaction mixture;   (d) allowing said reaction mixture to contact said metallic surfaces of said hydrocarbon processing unit to form a protective film on said surfaces whereby each of said surfaces is inhibited against corrosion; and   (e) allowing said condensed distillate to return to said hydrocarbon processing unit, or to be collected as said product.   
     
     
         13 . A process as claimed in  claim 12 , wherein said stream includes crude oil, feedstock, and hydrocarbon stream and/or fractions thereof.