Process for the production of bisphenol A.
First Claim
1. A process of producing bisphenol A, comprising the steps of:
- liquefying a crystalline adduct of bisphenol A and phenol to obtain a liquefied adduct containing bisphenol A and phenol;
feeding said liquefied adduct to an evaporating zone and forming said liquefied adduct into a downwardly flowing liquid film while maintaining said evaporating zone at a temperature of 160-185°
C. and a pressure of 15-60 Torr to vaporize and remove phenol from said liquefied adduct and thereby obtain a first product containing bisphenol A and 1-5% by weight of phenol;
introducing said first product into a first stripping zone and forming said first product into a downwardly flowing liquid film while feeding a stripping gas to said first stripping zone, wherein said liquid film of said first product is brought into counter-current contact with said stripping gas at a temperature of 170-185°
C. and a pressure of not higher than 15 Torr to strip phenol and to obtain a second product;
introducing said second product into a second stripping zone and forming said second product into a downwardly flowing liquid film while feeding steam to said second stripping zone, wherein said liquid film of said second product is brought into counter-current contact with said steam at a temperature of 170°
-185°
C. and a pressure of not higher than 15 Torr to strip phenol and thereby obtain a bisphenol A product and phenol-entraining steam; and
feeding said phenol-entraining steam to said first stripping zone as said stripping gas.
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Accused Products
Abstract
High quality bisphenol A is produced from a neutral crystalline adduct of bisphenol A and phenol by fusing the adduct in an atmosphere having a maximum oxygen content of 0.005% by volume, followed by evaporation of liberated phenol. The crystalline adduct may be mixed with an aliphatic carboxylic acid before the fusion to reduce the coloring of the product. When an acidic crystalline adduct is used, the use of a strong alkali salt of an aliphatic carboxylic acid is suitably used. Interior surfaces of the apparatuses for carrying out the fusion and evaporation are desirably washed with an organic solvent to remove oxygen therefrom. The evaporation of phenol is suitably performed by two stage steam stripping wherein a used stripping gas obtained in the second stage is employed as a stripping gas in the first stage while steam is used as the stripping gas in the second stage.
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Citations
8 Claims
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1. A process of producing bisphenol A, comprising the steps of:
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liquefying a crystalline adduct of bisphenol A and phenol to obtain a liquefied adduct containing bisphenol A and phenol; feeding said liquefied adduct to an evaporating zone and forming said liquefied adduct into a downwardly flowing liquid film while maintaining said evaporating zone at a temperature of 160-185°
C. and a pressure of 15-60 Torr to vaporize and remove phenol from said liquefied adduct and thereby obtain a first product containing bisphenol A and 1-5% by weight of phenol;introducing said first product into a first stripping zone and forming said first product into a downwardly flowing liquid film while feeding a stripping gas to said first stripping zone, wherein said liquid film of said first product is brought into counter-current contact with said stripping gas at a temperature of 170-185°
C. and a pressure of not higher than 15 Torr to strip phenol and to obtain a second product;introducing said second product into a second stripping zone and forming said second product into a downwardly flowing liquid film while feeding steam to said second stripping zone, wherein said liquid film of said second product is brought into counter-current contact with said steam at a temperature of 170°
-185°
C. and a pressure of not higher than 15 Torr to strip phenol and thereby obtain a bisphenol A product and phenol-entraining steam; andfeeding said phenol-entraining steam to said first stripping zone as said stripping gas. - View Dependent Claims (2, 3)
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4. A process of producing bisphenol A, comprising the steps of:
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liquefying a crystalline adduct of bisphenol A and phenol, which has an APHA color of not greater than 15 and which shows a pH of 4.9-5.5 when dissolved in an aqueous methanol solution having a pH of 5, to obtain a liquefied adduct containing bisphenol A and phenol; feeding said liquefied adduct to an evaporating zone and forming said liquefied adduct into a downwardly flowing liquid film while maintaining said evaporating zone at a temperature of 160°
-185°
C. and a pressure of 15-60 Torr and in an atmosphere having an oxygen concentration of 0.005% by volume or less to vaporize and remove phenol from said liquefied adduct and thereby obtain a first product containing bisphenol A and 1-5% by weight of phenol;introducing said first product into a first stripping zone and forming said first product into a downwardly flowing liquid film while feeding a stripping gas to said first stripping zone, wherein said liquid film of said first product is brought into counter-current contact with said stripping gas at a temperature of 170-185°
C. and a pressure of not higher than 15 Torr to strip phenol and to obtain a second product;introducing said second product into a second stripping zone and forming said second product into a downwardly flowing liquid film while feeding steam to said second stripping zone, wherein said liquid film of said second product is brought into counter-current contact with said steam at a temperature of 170-°
185°
C. and a pressure of not higher than 15 Torr to strip phenol and thereby obtain a bisphenol A product and phenol-entraining steam; andfeeding said phenol-entraining steam to said first stripping zone as said stripping gas. - View Dependent Claims (5, 6, 7, 8)
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Specification