Methods for purifying p,p-bisphenol-A
First Claim
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1. A method for purifying p,p-bisphenol A, said method comprising:
- distilling a feedstream comprising p,p-bisphenol A in a distillation column at a pressure less than or equal to 20 millibars;
producing a light fraction, an intermediate fraction, and a heavy fraction from the distillation column;
feeding the heavy fraction to a second reactor and isomerizing impurities in the heavy fraction to produce additional p,p-bisphenol A;
feeding a portion of the light fraction to a first reactor and purging a remaining portion of the light fraction in a third reactor, wherein feeding the portion to the first reactor converts impurities in the light fraction to produce additional p,p-bisphenol A, and wherein feeding the remaining portion to the third reactor removes impurities from the remaining portion; and
recovering the intermediate fraction as a side draw of the distillation column, wherein the p,p-bisphenol A in the intermediate fraction contains less impurities than the p,p-bisphenol A in the feedstream.
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Abstract
Methods for purifying a p,p-bisphenol A generally include distilling a feed stream comprising p,p-BPA in a distillation column at a pressure less than or equal to 20 millibars. The distillation column separates the bisphenol feed stream to produce a light fraction, an intermediate fraction and a heavy fraction. The intermediate fraction comprising the purified bisphenol contains lesser impurities that the p,p-BPA in the feed stream. In one embodiment, the intermediate stream is recovered using a side-draw. The side-draw is located between a first zone and a third zone in the distillation column.
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Citations
20 Claims
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1. A method for purifying p,p-bisphenol A, said method comprising:
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distilling a feedstream comprising p,p-bisphenol A in a distillation column at a pressure less than or equal to 20 millibars; producing a light fraction, an intermediate fraction, and a heavy fraction from the distillation column; feeding the heavy fraction to a second reactor and isomerizing impurities in the heavy fraction to produce additional p,p-bisphenol A; feeding a portion of the light fraction to a first reactor and purging a remaining portion of the light fraction in a third reactor, wherein feeding the portion to the first reactor converts impurities in the light fraction to produce additional p,p-bisphenol A, and wherein feeding the remaining portion to the third reactor removes impurities from the remaining portion; and recovering the intermediate fraction as a side draw of the distillation column, wherein the p,p-bisphenol A in the intermediate fraction contains less impurities than the p,p-bisphenol A in the feedstream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for purifying a feedstream comprising p,p-bisphenol A, comprising:
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flowing the feedstream comprising p,p-bisphenol A into a distillation column, wherein the distillation column comprises a first zone, a third zone, and a second zone intermediate the first and third zones;
wherein flowing the feedstream comprises introducing the feedstream into the second zone;distilling the feedstream into three fractions, wherein a light fraction is produced from the first zone, an intermediate fraction is produced from the second zone and a heavy fraction is produced from the third zone, wherein the intermediate fraction is withdrawn from the distillation column as a side draw and comprises p,p-bisphenol A at a purity greater than 90% and at a purity greater than the p,p-bisphenol A in the feedstream. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification