BPA process improvement
View Patent ↗The present disclosure enables phenol recovery, purification and recycle in a simple, economic manner from waste streams from, for example, a phenol/acetone production process, e.g., a phenol/acetone plant or an upstream cumene hydroperoxide cleavage process step, and BPA production step, for use in the reaction with acetone to produce BPA. The disclosure therefore reduces the overall consumption of phenol in the production of BPA.
1. A process for recovering phenol from a waste stream comprising water and phenol from a BPA production process, comprising the steps of:
(A) contacting a first aqueous waste stream comprising water and phenol from a BPA production process and a crude phenol/acetone product stream comprising phenol, acetone, cumene, and alpha methyl styrene (AMS), produced by cleavage of cumene hydroperoxide in a phenol/acetone production process,
(B) contacting the combined stream from step (A) with a second aqueous waste stream containing alkali metal salts, produced in a phenol/acetone production process,
(C) separating the combined stream from step B to form an immiscible hydrocarbyl stream containing at least a majority of said phenol from said first aqueous waste stream and an immiscible second aqueous waste stream comprising less than 5 wt % of phenol; and
(D) recovering substantially all the phenol from a portion of said immiscible second aqueous waste stream by extraction, distillation, absorption, or a combination thereof, to produce an aqueous stream substantially free of phenol from the phenol/acetone production process.
2. The process of claim 1 , further comprising recycling at least a portion of said immiscible second waste stream from step (C) to combine with the first waste stream in step (A) before contacting the crude phenol/acetone product stream.
3. The process of claim 1 , wherein said second aqueous waste stream comprises 0.5 wt % to 5 wt % phenol, 1 wt % to 20 wt % alkali metal salt, and at least 70 wt % water.
4. The process of claim 1 , wherein said first waste stream comprises volatile sulfur compounds and said first waste stream is subjected to stripping prior to step (A).
5. The process of claim 1 , wherein said first waste stream comprises at least 5 wt % phenol based on the total weight of said first waste stream.
6. The process of claim 1 , wherein the process for producing BPA comprising the steps of:
(A) reacting acetone with a stoichiometric excess of phenol in the presence of an acidic catalyst, possibly in the presence of a cocatalyst or promoter either homogeneously fed or heterogeneously bound to an acidic catalyst, to form a reaction product stream comprising crude BPA product, unreacted phenol, possibly unreacted acetone, possibly cocatalyst or promoter, water of condensation, and other reaction byproducts;
(B) distilling in single or multistage the reaction product stream from step (A) to distill off a first stream comprising water, a portion of unreacted phenol, possibly unreacted acetone, possibly cocatalyst or promoter or derivatives thereof if present in step (A), and other reaction byproducts, which constitutes the BPA waste stream, and a second stream having a portion of unreacted phenol; while sending downstream to a BPA purification step, the purification step comprising one or more solid-liquid separation and wash steps, the resulting concentrated BPA phenolic feed stream consisting essentially of phenol in which the BPA and byproducts have been concentrated;
(C) producing purified BPA by crystallization of the concentrated BPA phenolic feed stream of step (B); and
(D) separating the purified BPA crystals of step (C) by solid-liquid separation and washing same in one or multiple stages with a wash stream which may include at least a portion of the second stream, or spent wash or mother liquor from one or more subsequent crystallization, solid-liquid separation, and wash steps, to produce a washed BPA-phenol adduct, a spent wash stream and a mother liquor stream; and
(E) heating and removing phenol from the washed purified BPA-phenol adduct from the final stage of crystallization and solid-liquid separation to produce a purified BPA melt stream where the removed phenol is recycled in whole or in part, to steps (A) or (C).
7. The process of claim 6 , wherein step (A) is conducted in the presence of added promoter selected from the group consisting of methyl mercaptan, ethyl mercaptan, 2,2-bis(methylthio)propane, and mercaptocarboxylic acid.
8. The process of claim 1 , wherein the upstream phenol/acetone production process comprises of a first process step to form cumene hydroperoxide by oxidation of cumene, a second process step to form phenol and acetone by cleavage of cumene hydroperoxide in the presence of an acid catalyst, a third process step to neutralize the effluent from the cleavage step, and a fourth process step to separate and purify the neutralized cleavage effluent to form purified phenol and acetone product streams.