Process for reducing the acidity of oil

Abstract

An improved process is disclosed for removing trace acidic compounds from liquid hydrocarbons. Traces of acidic compounds, including carboxylic acids, H 2 S, naphthenic acids, et al., are present in most hydrocarbon streams. The presence of these acidic compounds is considered deleterious to accepted product specifications. The trace acidic compounds which interfere are removed via injection of a dilute aqueous alkaline solution into the hydrocarbon stream and passage of this stream through a coalescing bed.

1 . A process for de-acidifying crude oil and/or crude oil distillate, said process comprising: 
 (a) contacting crude oil and/or crude oil distillate with a Group IIA metal hydroxide in the presence of water, wherein water is present in a concentration of 0.01 to 100 wt % of the crude oil and/or crude oil distillate; and    (b) introducing a demulsifier to the mixture of crude oil and/or crude oil distillate, Group IIA metal hydroxide and water, in an amount effective to cause the mixture to separate into an oil-rich phase, an aqueous phase and an interface layer disposed between the oil-rich phase and aqueous phase.    
     
     
         2 . A process as claimed in  claim 1 , wherein step a) is carried out by adding the Group IIA metal hydroxide to the oil, such that a water-in-oil type emulsion is produced.  
     
     
         3 . A process as claimed in  claim 1 , wherein the Group IIA metal hydroxide is at least one hydroxide selected from the group consisting of barium hydroxide, magnesium hydroxide, and calcium hydroxide.  
     
     
         4 . A process as claimed in  claim 1 , wherein the concentration of water employed in step a) is between 0.01 and 30 wt % of the oil.  
     
     
         5 . A process as claimed in  claim 1  which further comprises adding a phase transfer agent to the reaction mixture formed in step a).  
     
     
         6 . A process as claimed in  claim 5 , wherein the phase transfer agent is selected from the group consisting of cetyltrimethyl ammonium bromide (CTAB), didodecyltrimethyl ammonium bromide, tetrabutyl ammonium bromide (TBAB) and tetrapentyl ammonium bromide.  
     
     
         7 . A process as claimed in  claim 1 , which further comprises adding an emulsifier to the reaction mixture formed in step a).  
     
     
         8 . A process as claimed in  claim 7 , wherein the emulsifier is selected from the group consisting of sorbitan monooleate, sorbitan monostearate, sorbitan trioleate, sorbitan monopalmitate, sorbitan tristearate, non-ionic block co-polymers, polyoxyethylene stearyl alcohols, polyoxyethylene cocoa amines, fatty amine ethoxylates, polyoxyethylene oleyl alcohols, polyoxyethylene stearyl alcohols, polyoxyethylene cetyl alcohols, fatty acid polyglycol esters, glyceryl stearate, glyceryl oleate, propylene glycol stearate, polyoxyethylene oleates, polyoxyethylene stearates, diethylene glycol stearate, and fatty acid polyamine condensates.  
     
     
         9 . A process as claimed in  claim 1  which further comprises adding a mutual solvent to the reaction mixture formed in step a).  
     
     
         10 . A process as claimed in  claim 9 , wherein the mutual solvent is a glycol ether.  
     
     
         11 . A process as claimed in  claim 1 , wherein the demulsifier comprises at least one surfactant selected from the group consisting of: 
 (a) polyamine salts;    (b) multifunctional polyethers;    (c) polyethers; and    (d) p-alkylphenol-formaldehyde resins and ethylene oxide and/or propylene oxide derivatives thereof.    
     
     
         12 . A process as claimed in  claim 11 , wherein said at least one surfactant is dissolved in a solvent selected from the group consisting of monoethylene glycol (MEG), tetraethylene glycol (TEG), butylethylene glycol (BGE), butyldiethylene glycol (BDGE), water, xylene and toluene.  
     
     
         13 . A process as claimed in  claim 1 , wherein the demulsifier is prepared by reacting I) an addition product of a phenol and formaldehyde or acetaldehyde, with II) a block polymer containing nitrogen.  
     
     
         14 . A process as claimed in  claim 1 , wherein the concentration of demulsifier employed in step b) is 0.01 to 5 wt % of oil.  
     
     
         15 . A process as claimed in  claim 1 , which further comprises the step of 
 c) recovering the oil-rich phase formed in step b) from the aqueous phase and interface layer.    
     
     
         16 . A process as claimed in  claim 15 , which further comprises 
 d) recovering the aqueous phase formed in step b),    e) purifying this aqueous phase, and    f) recycling purified water obtained from this aqueous phase to step a).    
     
     
         17 . A process as claimed in  claim 16 , which further comprises 
 g) removing the interface layer formed in step b) and separating this layer into a water layer, an oil layer and a solid layer.    
     
     
         18 . A process as claimed in  claim 17 , wherein the oil layer formed in step g) is recovered.  
     
     
         19 . A process as claimed in  claim 17 , wherein at least part of the water layer formed in step g) is recycled to step a).