Treatment of hydrocarbons containing acids

Abstract

The invention relates to a method of treating a liquid hydrocarbon (e.g. heavy oil, bitumen, etc.) containing naphthenic acids or other corrosive acids in order to partially or fully convert such acids into non-corrosive compounds. The method comprises adding an alkylating agent to the hydrocarbon, bringing the hydrocarbon into contact with an aqueous liquid containing an alkaline compound and a phase transfer catalyst to form an immiscible two-phase system, maintaining the contact to allow conversion of the naphthenic acids to non-corrosive oil-soluble esters, and separating the aqueous phase from the liquid hydrocarbon. Naphthenic acids are highly corrosive to plant and equipment and the method enables them to be converted to non-corrosive compounds in an economic manner.

1 . A method of treating a liquid hydrocarbon containing acids to reduce corrosive properties thereof, which method comprises bringing the hydrocarbon into contact with an aqueous liquid containing an alkaline compound and a phase transfer catalyst in the presence of an alkylating agent to form a two-phase system, maintaining the contact to allow conversion of the acids to non-corrosive oil-soluble esters, and separating the aqueous phase from the liquid hydrocarbon. 
   
   
       2 . The method of  claim 1 , wherein the hydrocarbon is naturally occurring and said acids are naphthenic acids. 
   
   
       3 . The method of  claim 2 , wherein said hydrocarbon is selected from the group consisting of bitumen, heavy oil, whole crude, topped crude and distillates thereof. 
   
   
       4 . The method of  claim 1 , wherein the phase transfer catalyst has the formula:
   [XR 1 R 2 R 3 R 4 ]Y   wherein: X is N or P (and most preferably N);
 Y is Cl, Br, I or OH; and 
 R 1 , R 2 , R 3  and R 4  may be the same or different and each represents an alkyl group having a carbon number in the range of 1 to 20. 
   
   
   
       5 . The method of  claim 1 , wherein the phase transfer catalyst is a tetraalkylammonium compound. 
   
   
       6 . The method of  claim 1 , wherein the catalyst is selected from the group consisting of tetrabutylammonium bromide and tributylhexadecaylammonium bromide. 
   
   
       7 . The method of  claim 1 , wherein the alkylating agent is an alkyl halide. 
   
   
       8 . The method of  claim 1 , wherein the alkylating agent is an alcohol other than methanol. 
   
   
       9 . The method of  claim 1 , wherein said hydrocarbon is maintained at a temperature of 0 to 120° C. during said contact. 
   
   
       10 . The method of  claim 1 , wherein said hydrocarbon is maintained at a temperature of 40 to 90° C. during said contact. 
   
   
       11 . The method of  claim 1 , wherein said contact is maintained under atmospheric pressure. 
   
   
       12 . The method of  claim 1 , wherein said contact is maintained for a period of time in a range of 10 to 240 minutes. 
   
   
       13 . The method of  claim 1 , wherein said contact is maintained for a period of time in a range of 30 to 120 minutes. 
   
   
       14 . The method of  claim 1 , wherein the hydrocarbon and aqueous liquid are agitated during said contact. 
   
   
       15 . The method of  claim 1 , wherein the alkaline compound is selected from the group consisting of NaOH, KOH, Ca(OH) 2 , ammonium hydroxide and mixtures thereof. 
   
   
       16 . The method of  claim 1 , wherein the alkaline compound is used at a concentration up to 1.0 M. 
   
   
       17 . The method of  claim 1 , wherein the alkaline compound is used at a concentration in a range of 0.001 to 1.0 M. 
   
   
       18 . The method of  claim 1 , wherein the catalyst is used in an amount in a range of 0.05 to 10 wt. % of the aqueous phase. 
   
   
       19 . The method of  claim 1 , wherein a molar ratio of the alkylating agent to the acids is 1-10:1. 
   
   
       20 . The method of  claim 1 , wherein said alkaline liquid is used in an amount of 1 to 20 volume % of the total amount of said hydrocarbon and aqueous liquid.