| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an ether carboxylic acid (salt) in high quality and yield by separating and recovering a rare-earth element used as a catalyst in high efficiency from a reaction liquid. SOLUTION: The method for producing an ether carboxylic acid (salt) comprises a reaction step to react an organic compound having hydroxyl group with an unsaturated organic compound and/or an epoxy compound having carboxy group in an aqueous medium in the presence of a catalyst containing a rare-earth element and a catalyst recovery step to separate and recover the rare-earth element from the reaction liquid of the former step in the form of a rare-earth metal carbonate. In the catalyst recovery step, the reaction liquid obtained by the reaction step is diluted, the diluted liquid is mixed with an alkaline carbonate to crystallize the carbonate of the rare-earth element and the crystallized product is separated from the system. The process is carried out by setting the organic acid concentration of the diluted liquid to 10-60 wt.% and/or the pH of the liquid to 5-11.5. |
