Apparatus and method for recovering acetic acid and catalyst in process for preparation of 2,6-naphthalenedicarboxylic acid
An apparatus and a method for effectively recovering acetic acid and catalyst from a mother liquor discharged from a series of processes including an oxidation process, a crystallization process and a solid-liquid separation process, in a continuous process for preparing naphthalenedicarboxylic acid by oxidizing dimethylnaphthalene in the presence of an oxygen-containing gas and an acetic acid solvent, using a catalyst system comprising a transition metal such as cobalt or manganese, and a bromine-based compound, are provided.
1. An apparatus for recovering acetic acid together with catalyst from a mother liquor discharged from a process for preparation of 2,6naphthalenedicarboxylic a acid, containing acetic acid, catalyst and o the apparatus compnsing:
a mother liquor receptacle having said mother liquor therein and including an inlet for receiving the mother liquor or sodium hydroxide, an outlet for acetic acid, and an outlet for catalyst and organic materials;
a heating means for heating the mother liquor receptacle;
an acetic acid outlet mounted on an upper part of the mother liquor receptacle for discharging acetic acid to be vaporized after the received mother liquor is heated by the heating means:
a sodium hydroxide inlet to precipitate catalyst and organic materials from the residue remaining after the discharge of acetic acid;
an outlet for catalyst and organic materials mounted on a lower part of the mother liquor receptacle for discharging the precipitated catalyst and organic materials;
a downstream membrane filter connected to and mounted on a lower part of the outlet for catalyst and organic materials for separating the catalyst from the organic materials; and
an agitator for agitating the inside of the mother liquor receptacle.
2. The apparatus of claim 1 , wherein the heating means is a jacket including an inlet for steam attached around the external wall of the mother liquor receptacle, and an outlet for condensed water.
3. The apparatus of claim 1 , wherein the apparatus has a shape of cone or truncated cone.
4. The apparatus of claim 1 , wherein the downstream membrane filter has a degree of vacuum of 50 to 150 mmHg, a total filter area of 0.3 to 0.7 m 2 , and membrane pore size of 20 to 80 μm.