Phenol recovery of bisphenol-A mother liquor purge using purification train in the phenol production unit
Systems and methods for recovering phenol have been disclosed. The methods of recovering phenol includes concurrently processing, in a phenol recovery unit, a crude phenol stream from a phenol production unit, and a bisphenol-A purge stream from a bisphenol-A production unit to produce a first product stream comprising 60 to 95 wt. % phenol. The phenol recovery unit comprises a crude phenol distillation column and a bisphenol-A-phenol distillation column. The processing includes distilling a bottom stream from the crude phenol distillation column in the bisphenol-A-phenol distillation column.
1 . A method of recovering phenol, the method comprising:
concurrently processing, in a phenol recovery system, (i) a crude phenol stream comprising phenol and phenol tar and (ii) a bisphenol-A purge stream comprising phenol and bisphenol-A tar;
wherein the phenol recovery system comprises a crude phenol distillation column and a bisphenol-A-phenol distillation column and the processing comprises:
distilling the crude phenol stream in the crude phenol distillation column to form a top stream comprising 85 to 99 wt. % phenol and a bottom stream, and
distilling the bottom stream in the bisphenol-A-phenol distillation column.
2 . The method of claim 1 , wherein the bottom stream comprises 2 to 15 wt. % phenol, and 85 to 98 wt. % combined phenol tar and bisphenol-A tar.
3 . The method of claim 2 , wherein the distilling of the bottom stream produces a bisphenol-A-phenol distillation column bottom stream comprising primarily phenol tar and bisphenol-A tar, collectively.
4 . The method of claim 3 , further comprising:
subjecting the bisphenol-A-phenol distillation column bottom stream to reaction conditions sufficient to crack the phenol tar and/or the bisphenol-A tar to produce additional phenol and α-methylstyrene.
5 . The method of claim 4 , wherein the reaction conditions for the subjecting step comprise a reaction temperature of 100 to 250° C. and a reaction pressure of 0.2 to 1.5 bar.
6 . The method of claim 4 , wherein the subjecting step comprises:
contacting the bisphenol-A-phenol distillation column bottom stream with sulfonic acid.
7 . The method of claim 1 , wherein the phenol tar comprises acetophenone, dimethylbenzylalcohol, o-cumylphenol, p-cumylphenol, alphamethylstyrene dimers, phenol, or combinations thereof.
8 . The method of claim 1 , wherein the bisphenol-A tar comprises p,p-bisphenol-A, o,p-bisphenol-A, isopropenyl phenol, Chroman, BPX, isopropenyl phenol dimers, spirobiindane bisphenol, or combinations thereof.
9 . The method of claim 1 , wherein:
the processing comprises combining the crude phenol stream and the bisphenol-A purge stream to form a feed stream;
the bottom stream comprises phenol, combined phenol tar and bisphenol-A tar; and
distilling of the bottom stream in the bisphenol-A phenol distillation column further produces an intermediate phenol stream comprising phenol.
10 . The method of claim 9 , wherein the processing further comprises:
distilling the intermediate phenol stream in the crude phenol distillation column to produce additional phenol in the top stream.
11 . The method of claim 9 , wherein the processing further comprises:
treating the top stream in a hydro-extraction unit to produce a first product stream and a recycle stream comprising 0.5 to 2 wt. % phenol.
12 . The method of claim 1 , wherein:
the bottom stream comprises phenol, phenol tar, and bisphenol-A tar; and
the processing comprises distilling the bisphenol-A purge stream and the bottom stream in the bisphenol-A-phenol distillation column to form a bisphenol-A-phenol distillation column bottom stream, and an intermediate phenol stream comprising phenol.
13 . The method of claim 12 , wherein the processing further comprises:
combining at least a portion of the intermediate phenol stream with the crude phenol stream to form a combined stream comprising at least the portion of the intermediate phenol stream and the crude phenol stream; and
distilling the combined stream comprising at least the portion of the intermediate phenol stream and the crude phenol stream in the crude phenol distillation column.
14 . The method of claim 12 , wherein the processing further comprises:
combining at least a portion of the second intermediate phenol stream with the top stream to form a combined stream comprising primarily phenol; and
processing the combined stream comprising primarily phenol in a hydro-extraction unit to form a first product stream and a recycle stream comprising 0.5 to 2 wt. % phenol.
15 . The method of claim 12 , wherein the hydro-extraction unit is operated at an extraction temperature of 100 to 250° C. and an extraction pressure of 0.4 to 2 bar.
16 . The method of claim 12 , wherein the crude phenol distillation column is operated at an overhead temperature range of 120 to 150° C., a reboiler range of 180 to 220° C., and an operating pressure of 0.1 to 0.5 bar.
17 . The method of claim 12 , wherein the bisphenol-A-phenol distillation column is operated at an overhead temperature range of 80 to 120° C., a reboiler range of 150 to 200° C., and an operating pressure of 0.1 to 0.7 bar.
18 . The method of claim 1 , wherein the crude phenol stream is produced by separating an effluent of a cumene based phenol production process.
19 . The method of claim 1 , wherein the bisphenol-A purge stream includes a bisphenol-A dry mother liquor purge stream generated by crystallization of bisphenol-A from an effluent of a bisphenol-A synthesis reactor.