System and method for producing 1,4-cyclohexanedimethanol and 1,4- cyclohexanedicarboxylic acid from terephthalic acid
AssigneeClearWaterBay CHDM Technology Limited
InventorsKetan D. Samant, Drow Lionel O'Young, Yik Chung Chan
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Abstract
This invention relates to the continuous production of 1,4-cyclohexane dimethanol (CHDM) and optionally and additionally of 1,4-cyclohexane dicarboxylic acid (CHDA) directly using terephthalic acid (TPA) as the raw material. More specifically, this invention relates to a method and system for continuous production of CHDM and CHDA that features direct use of TPA as feedstock, promotes efficient use of solvent and energy, and provides products with the desired high trans isomer content, by exploiting unexpected features of the thermodynamic phase behavior and the reaction mechanisms.
Claims54
A method for continuous production of CHDM by direct hydrogenation TPA, comprising the steps of:
- preparing a solution of TPA feed using recycled solvent and CHDA product solution recirculation such that TPA is completely dissolved at a desired reaction temperature;
- contacting the TPA solution with hydrogen in a first hydrogenation stage in presence of a suitable catalyst in one or more GLS reactors at temperature and pressure conditions such that the TPA is converted into CHDA via hydrogenation of the aromatic ring to produce the CHDA product solution;
- recirculating a part of the CHDA product solution from the first hydrogenation stage back to the step of preparation of the TPA solution;
- contacting the remaining CHDA product solution from the first hydrogenation stage with hydrogen in a second hydrogenation stage in presence of a suitable catalyst in one or more GLS reactors at temperature and pressure conditions such that the CHDA is converted into CHDM via hydrogenation of the —COOH side-chains to —CH2OH side chains to produce a CHDM product;
- and
- separating the CHDM product from the solvent by distillation and recycling a part of the solvent back to the step of preparation of TPA solution.
A method for continuous production of CHDA and CHDM by direct hydrogenation of TPA, comprising the steps of:
- preparing a solution of TPA feed using recycled solvent and CHDA product solution recirculation such that TPA is completely dissolved at a desired reaction temperature;
- contacting the TPA solution with hydrogen in a first hydrogenation stage in presence of suitable catalyst in one or more GLS reactors at temperature and pressure conditions such that the TPA is converted into CHDA via hydrogenation of the aromatic ring to produce the CHDA product solution;
- recirculating a part of the CHDA product solution from the first hydrogenation stage back to the step of preparation of the TPA solution;
- separating trans CHDA, by crystallization and subsequent solid-liquid separation, from the remaining part of the CHDA product solution from the first hydrogenation stage;
- contacting cis CHDA rich mother liquor from the crystallization and subsequent solid-liquid separation with hydrogen in a second hydrogenation stage in presence of suitable catalyst in GLS reactors at temperature and pressure conditions such that the CHDA is converted into CHDM via hydrogenation of the —COOH side-chains to —CH2OH side chains to produce a CHDM product;
- and
- separating the CHDM product from the solvent by distillation and recycling a part of the solvent back to the step of preparation of TPA solution,
- wherein the trans CHDA or trans CHDA rich solids product is separated by crystallization from the product of the first hydrogenation reactor and the cis CHDA rich mother liquor is hydrogenated in the second hydrogenation reactor without affecting the trans content of the CHDM produced in the reactor.
Dependencies are inferred from the claim text.