Process for production of a carboxylic acid/diol mixture suitable for use in polyester production
First Claim
1. A process for producing a carboxylic acid/diol mixture, said process comprising adding a decolorized carboxylic acid solution comprising a carboxylic acid and water in an esterification reactor zone and adding a diol to said decolorized carboxylic acid solution in said esterification zone;
- wherein said diol is added to remove at least 5% by weight of said water vaporization from said decolorized carboxylic acid solution to form said carboxylic acid/diol mixture.
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Abstract
In this invention, a process is provided by which a carboxylic acid/diol mixture suitable as starting material for a polyester production is obtained from a decolorized carboxylic acid solution without isolation of a substantially dry carboxylic acid solid. More specifically, in this invention, a process is provided by which a terephthalic acid/ethylene glycol mixture suitable as starting material for a polyester production is obtained from a decolorized terephthalic acid solution without isolation of a substantially dry terephthalic acid solid.
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Citations
22 Claims
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1. A process for producing a carboxylic acid/diol mixture, said process comprising adding a decolorized carboxylic acid solution comprising a carboxylic acid and water in an esterification reactor zone and adding a diol to said decolorized carboxylic acid solution in said esterification zone;
- wherein said diol is added to remove at least 5% by weight of said water vaporization from said decolorized carboxylic acid solution to form said carboxylic acid/diol mixture.
- View Dependent Claims (2, 5)
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3. A process for producing a carboxylic acid/diol mixture, said process comprising the following steps:
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(a) mixing a crude carboxylic acid powder with water in a mixing zone to form a crude carboxylic acid solution;
wherein said carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and mixtures thereof;(b) decolorizing said crude carboxylic acid solution in a reactor zone to produce a decolorized carboxylic acid solution; (c) optionally, flashing said decolorized carboxylic acid solution in a flashing zone to remove a portion of the water from said decolorized carboxylic acid solution; and (d) adding said decolorized carboxylic acid solution comprising a carboxylic acid and water in an esterification reactor zone and adding a diol to said decolorized carboxylic acid solution in said esterification zone;
wherein said diol is added to remove at least 5% by weight of the said water by vaporization from said decolorized carboxylic acid solution to form said carboxylic acid/diol mixture. - View Dependent Claims (4)
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6. A process for producing a terephthalic acid/diol mixture, said process comprising the following steps:
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(a) mixing a crude terephthalic acid powder with water in a mixing zone to form a crude terephthalic acid solution; (b) decolorizing said crude terephthalic acid solution in a reactor zone to form a decolorized terephthalic acid solution; (c) optionally, flashing said decolorized terephthalic acid solution in a flashing zone to remove a portion of the water from said decolorized terephthalic acid solution; and (d) adding a diol to said decolorized terephthalic acid solution comprising terephthalic acid and water in an esterification reactor zone;
wherein said diol is added to remove at least 5% of said water by vaporization from said decolorized terephthalic acid solution to form said terephthalic acid/diol mixture; and
wherein said terephthalic acid and diol subsequently reacts in said esterification zone to form a hydroxy alkyl ester stream. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A process for producing a terephthalic acid/ethylene glycol mixture, said process comprising the following steps:
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(a) mixing a crude terephthalic acid powder with water in a mixing zone to form a crude terephthalic acid solution wherein said mixing zone is operated at a temperature greater than about 230°
C., wherein the pressure in said mixing zone is in a range of about 900 psia to about 1400 psia;
wherein the concentration of said crude terephthalic acid in said crude terephthalic acid solution is in a range of about 15% to about 35% by weight;
wherein the color of said crude terephthalic acid powder is less than about 7 measured by b*;
wherein the total concentration of p-toluic and 4-carboxybenzaldehyde in said crude terephthalic acid powder is less than about 900 ppm by weight;(b) decolorizing said crude terephthalic acid solution with hydrogen in a reactor zone in the presence of a catalyst to form a decolorized terephthalic acid solution;
wherein said catalyst comprises a group VIII metal or combination thereof;
wherein said hydrogen is introduced into said reactor zone at a flow rate of about 1.5 times the molar ratio necessary to convert 4-carboxybenzaldehyde to p-toluic acid in said crude terephthalic acid solution;
wherein said reacting occurs at a temperature greater than about 230°
C., wherein said reacting occurs at a pressure between about 900 psia to about 1400 psia;(c) optionally, flashing said decolorized terephthalic acid solution in a flashing zone to remove a portion of water from said decolorized terephthalic acid solution wherein said flashing zone comprises at least one flash vessel operated at a pressure in the range of about 75 psia to about 1400 psia; and
wherein said vessel is operated at a temperature in a range greater than about 150°
C.; and(d) adding a diol to said decolorized terephthalic acid solution comprising terephthalic acid and water in an esterification reactor zone;
wherein said diol is added to remove at least 5% by weight of water by vaporization to form said terephthalic acid/ethylene glycol mixture; and
wherein said carboxylic acid and diol subsequently reacts to form a hydroxy alkyl ester stream;
wherein said diol is ethylene glycol at a temperature in a range of about 150°
C. to about 300°
C.
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Specification