Purification of bisphenol-A
First Claim
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1. A process for simultaneously and continuously purifying the bisphenol-A crystals and the aqueous liquid of a water/BPA crystals slurry, said process comprising the steps of:
- (a) forming an aqueous-crystal stream from a water/BPA crystals slurry, said aqueous-crystal stream having a flow which is substantially downward and continuous;
(b) contacting said aqueous-crystal stream with a stream comprising an organic solvent in a region of intersecting paths, the stream of organic solvent having a flow in a direction substantially upward and counter-current to the flow of said aqueous crystal stream, said organic solvent being immiscible in water, lighter than water and a good solvent medium for impurities within said aqueous liquid and bisphenol-A crystals;
(c) mixing the aqueous-crystal stream and the organic solvent stream passing through the region of contact in the center of said region of contact;
(d) forming a lower aqueous-crystal phase below the the region of contact and an upper organic solvent phase above the region of contact;
(e) recovering purified bisphenol-A crystals and purified aqueous liquid from said lower aqueous-crystal phase;
(f) removing organic solvent with extracted impurities from said upper organic solvent phase;
said process being performed at a temperature below the melting point of said bisphenol-A crystals.
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Abstract
An efficient method of purifying bisphenol-A is presented whereby solvent washing of the bisphenol-A crystals and extraction of impurities, bisphenol-A and phenol from the aqueous liquid of a water/bisphenol-A crystal slurry is accomplished simultaneously and in a continuous operation. The method involves contacting the water/bisphenol-A crystals with an organic washing solvent in a continuous, multi-stage, countercurrent extraction column.
20 Citations
7 Claims
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1. A process for simultaneously and continuously purifying the bisphenol-A crystals and the aqueous liquid of a water/BPA crystals slurry, said process comprising the steps of:
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(a) forming an aqueous-crystal stream from a water/BPA crystals slurry, said aqueous-crystal stream having a flow which is substantially downward and continuous; (b) contacting said aqueous-crystal stream with a stream comprising an organic solvent in a region of intersecting paths, the stream of organic solvent having a flow in a direction substantially upward and counter-current to the flow of said aqueous crystal stream, said organic solvent being immiscible in water, lighter than water and a good solvent medium for impurities within said aqueous liquid and bisphenol-A crystals; (c) mixing the aqueous-crystal stream and the organic solvent stream passing through the region of contact in the center of said region of contact; (d) forming a lower aqueous-crystal phase below the the region of contact and an upper organic solvent phase above the region of contact; (e) recovering purified bisphenol-A crystals and purified aqueous liquid from said lower aqueous-crystal phase; (f) removing organic solvent with extracted impurities from said upper organic solvent phase; said process being performed at a temperature below the melting point of said bisphenol-A crystals.
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2. A process for simultaneously and continuously purifying the bisphenol-A crystals and the aqueous liquid of a water/BPA crystals slurry, said process comprising the steps of:
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(a) forming an aqueous-crystal stream from a water/BPA crystals slurry, said aqueous-crystal stream having a flow which is substantially downward and continuous; (b) contacting said aqueous-crystal stream with a stream comprising an organic solvent in a region of intersecting flow paths, the stream of organic solvent having a flow in a direction substantially upward and counter-current to the flow of said aqueous-crystal stream, said organic solvent being immiscible in water, lighter than water and a good solvent medium for impurities within said aqueous liquid and bisphenol-A crystals; (c) mixing the aqueous-crystal stream and the organic solvent stream passing through the region of contact in multiple isolated portions of said region of contact; (d) forming two small intermediate phases between each isolated mixing portion, the intermediate phase pairs comprising an aqueous crystal phase and an organic solvent phase; (e) forming a lower aqueous-crystal phase below said region of contact and an upper organic phase above said region of contact; (f) recovering purified bisphenol-A crystals and purified aqueous liquid from said lower aqueous crystal phase, and (g) removing organic solvent with extracted impurities from said upper organic solvent phase, said process being performed at a temperature below the melting point of said bisphenol-A crystals. - View Dependent Claims (3, 4, 5, 6, 7)
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Specification