Method for reducing corrosive ions in aromatic compound extraction solvent

Abstract

In order to suppress corrosion of an extractor caused by corrosive ions contained in an aromatic compound extraction solvent of a circulation system, a method for reducing corrosive ions in an aromatic compound extraction solvent is provided, by which the corrosive ions in the aromatic compound extraction solvent are conveniently and efficiently reduced. A method for reducing corrosive ions in an aromatic compound extraction solvent in a circulation system where the aromatic compound extraction solvent circulates, the corrosive ions being at least one kind selected from the group consisting of chloride ions, sulfate ions, and sulfite ions, the method comprising: a step of forming a non-volatile salt by adding a corrosive ion scavenger to react the corrosive ions with the corrosive ion scavenger, and a step of removing the salt resulting from concentrating the solvent comprising the salt.

1 . A method for reducing corrosive ions in an aromatic compound extraction solvent in a circulation system where the aromatic compound extraction solvent circulates,
 the corrosive ions being at least one kind selected from the group consisting of chloride ions, sulfate ions, and sulfite ions,   the method comprising:   a step of forming a non-volatile salt by adding a corrosive ion scavenger to react the corrosive ions with the corrosive ion scavenger, and   a step of removing the salt resulting from concentrating the solvent comprising the salt.   
     
     
         2 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the aromatic compound extraction solvent is one or more selected from the group consisting of sulfolane, diethylene glycol, triethylene glycol, tetraethylene glycol, N-methylpyrrolidone, dimethyl sulfoxide, morpholine, N-formylmorpholine, methyl carbamate, diglycolamine, furfural, and phenol. 
     
     
         3 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the corrosive ion scavenger is a quaternary ammonium compound represented by general formula (1) below: 
       
         
           
           
               
               
           
         
       
       wherein R 1  to R 3  are each independently a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 10. 
     
     
         4 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein one or more selected from the group consisting of ammonia and neutralizing amines are also used in the circulation system. 
     
     
         5 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the concentration is performed in a regenerator for the aromatic compound extraction solvent. 
     
     
         6 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the corrosive ion scavenger is added in a frequency and a concentration determined based on a corrosive ion concentration in the aromatic compound extraction solvent in circulation. 
     
     
         7 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 6 , wherein the corrosive ion scavenger is added so as to be 0.5 to 2 molar equivalents relative to the corrosive ion concentration. 
     
     
         8 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the corrosive ion scavenger is added in a frequency and a concentration determined based on a metal ion concentration in the aromatic compound extraction solvent in circulation. 
     
     
         9 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 8 , wherein the metal ion is an iron ion. 
     
     
         10 . The method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 , wherein the aromatic compound contains one or more selected from the group consisting of benzene, toluene, and xylene. 
     
     
         11 . A method for extracting an aromatic compound, using the method for reducing corrosive ions in an aromatic compound extraction solvent according to  claim 1 .