Process to produce an enrichment feed
A process is provided for producing an enriched carboxylic acid compositions produced by contacting composition comprising a carboxylic acid with an enrichment feed in an enrichment zone to form an enriched carboxylic acid composition. This invention also relates to a process and the resulting compositions for removing catalyst from a carboxylic acid composition to produce a post catalyst removal composition.
1. A process to produce and recycle an enrichment feed, said process comprising:
(a) subjecting a catalyst rich liquor produced in a terephthalic acid production process to a cooling and/or concentration zone to form a concentrated mother liquor stream; wherein said catalyst rich liquor comprises at least one solvent, at least one catalyst; wherein said catalyst was previously utilized in the oxidation of paraxylene;
(b) subjecting at least a portion of said concentrated mother liquor stream and an extraction solvent to an extraction zone to form a catalyst depleted stream;
(c) subjecting—the balance of said concentrated mother liquor stream not sent to said extraction zone and a wash stream in a SLS zone to form a wet cake stream; wherein said wash stream is any stream suitable for removing a portion of said catalyst from solids isolated in said SLS zone to produce said wet cake stream;
(d) subjecting at least a portion of said wet cake stream and optionally said catalyst depleted stream to a mix zone to form said enrichment feed; wherein said enrichment feed comprises at least one compound selected from the group consisting of isophthalic acid, phthalic acid, benzene-tricarboxylic acid isomers, hydroxybenzoic acid isomers, hydroxymethylbenzoic acid isomers, dicarboxybiphenyl isomers, dicarboxystilbene isomers, tricarboxybiphenyl isomers, tricarboxybenzophenone isomers, dicarboxybenzophenone isomers, dicarboxybenzil isomers, form-acet-hydroxybenzoic acid isomers, acet-hydroxymethylbenzoic acid isomers and phthaldehyde isomers; and
(e) recycling at least a portion of said enrichment feed to any point in a TPA production process after a primary oxidation zone and before the isolation of a dried TPA product.
2. The process according to claim 1 wherein said concentrated mother liquor stream has a solid content ranging from 10% by weight to 45% by weight.
3. The process according to claim 1 wherein said concentrated mother liquor stream has a solid content ranging from 10% by weight to 30% by weight.
4. The process according to claim 1 wherein said extraction zone comprises at least one extractor operated at a temperature of 30° C. to 70° C.
5. The process according to claim 2 wherein said extraction zone comprises at least one extractor operated at a temperature of 30° C. to 70° C.
6. The process according to claim 1 wherein said extraction zone comprises at least one extractor; wherein the solvent ratio for said extractor is 1 to 4 parts by weight solvent per part extractor feed.
7. The process according to claim 1 wherein said extraction zone comprises at least one extractor; wherein the space velocities for the combined feed to said extractor range from 1 to about 3 hr −1 .
8. The process according to claim 1 wherein said extraction solvent comprises at least one solvent selected from the group consisting of N-propyl acetate (n-PA), isopropyl acetate, isobutyl acetate, sec-butyl acetate, ethyl acetate, and n-butyl acetate.
9. The process according to claim 1 wherein said extraction solvent comprises at least one solvent selected from the group consisting of N-propyl acetate and isopropyl acetate.