Method for preparation of 1, 4-cyclohexanedimethanol
This invention relates to a method for preparing 1,4-cyclohexanedimethanol (CHDM), more specifically to a method for preparing 1,4-cyclohexanedimethanol having a high rate of trans isomers without an isomerization reaction step, wherein two-step hydrogenation reactions and a purification step are conducted using terephthalic acid as starting material.
1 . A method for preparing 1,4-cyclohexanedimethanol (CHDM) comprising:
a step 1 wherein a reaction solution comprising terephthalic acid, a first hydrogenation catalyst, and water is supplied to a first reactor equipped with a stirrer, and a hydrogenation reaction is conducted to prepare 1,4-cyclohexane dicarboxylic acid (CHDA) comprising cis isomers and trans isomers; and
a step 2 wherein a reaction solution comprising a reaction product of the step 1, a second hydrogenation catalyst, and water is supplied to a second reactor equipped with a stirrer, and a hydrogenation reaction is conducted to prepare 1, 4-cyclohexanedimethanol (CHDM) comprising cis isomers and trans isomers, and
a step of removing the first hydrogenation catalyst included in the reaction product of the step 1, before conducting the step 2,
wherein the terephthalic acid is included in an amount of 12 to 22 wt %, based on a total amount of terephthalic acid and water, and
wherein the reaction product of step 1 comprises 1,4-cyclohexane dicarboxylic acid and water, and the 1,4-cyclohexane dicarboxylic acid is included in a content of 10 to 23 wt %, based on a total amount of 1,4-cyclohexane dicarboxylic acid and water, and
wherein a surface area per unit volume of hydrogen gas is maintained in a range of 15 m 2 /m 3 to 500 m 2 /m 3 during the hydrogenation reaction of the step 1 and the hydrogenation reaction of the step 2.
2 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the hydrogenation reaction of the step 1 is conducted at a temperature of 230 to 300° C.
3 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein in the step 1, hydrogen gas is supplied at a pressure of 50 to 220 bar.
4 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the first hydrogenation catalyst comprises one or more metals selected from the group consisting of palladium(Pd), rhodium(Rh), ruthenium(Ru), and platinum(Pt).
5 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the 1,4-cyclohexane dicarboxylic acid comprises 60 wt % or more of trans isomers.
6 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the hydrogenation reaction of the step 2 is conducted at a temperature of 230 to 300° C.
7 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein in the step 2, hydrogen gas is supplied at a pressure of 50 to 220 bar.
8 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the second hydrogenation catalyst comprises one or more metals selected from the group consisting of palladium(Pd), rhodium(Rh), and ruthenium(Ru), and
one or more metals selected from the group consisting of tin(Sn), iron(Fe), rhenium(Re), and gallium(Ga).
9 . The method for preparing 1,4-cyclohexanedimethanol according to claim 8 , wherein the second hydrogenation catalyst comprises ruthenium(Ru) and tin(Sn).
10 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , wherein the 1,4-cyclohexanedimethanol obtained in the step 2 comprises 63 wt % or more of trans isomers.
11 . The method for preparing 1,4-cyclohexanedimethanol according to claim 1 , further comprising a step 3 of removing water and by-products in a reaction product of the step 2 to recover purified 1,4-cyclohexanedimethanol.
12 . The method of claim 1 , wherein
in the step 1, the hydrogenation reaction of the step 1 is conducted at a temperature of 230 to 300° C. and hydrogen gas is supplied at a pressure of 50 to 220 bar,
the first hydrogenation catalyst comprises one or more metals selected from the group consisting of palladium(Pd), rhodium(Rh), ruthenium(Ru), and platinum(Pt),
in the step 2, the hydrogenation reaction of the step 2 is conducted at a temperature of 230 to 300° C. and hydrogen gas is supplied at a pressure of 50 to 220 bar,
the second hydrogenation catalyst comprises one or more metals selected from the group consisting of palladium(Pd), rhodium(Rh), and ruthenium(Ru), and one or more metals selected from the group consisting of tin(Sn), iron(Fe), rhenium(Re), and gallium(Ga),
the reaction product of the step 1 and the reaction product of the step 2 each are generated without performing an isomerization reaction,
a ratio of trans isomers in the CHDA of the reaction product of the step 1 is 60 wt % of more of trans isomers among the CHDA,
a ratio of trans isomers in the CHDM of the reaction product of the step 2 is 63 wt % of more of trans isomers among the CHDM.
13 . The method of claim 12 , further comprising:
a step of removing the second hydrogenation catalyst from a reaction solution comprising the reaction product of the step 2.
14 . The method of claim 13 , wherein
the surface area per unit volume of hydrogen gas is maintained in a range of 200 m 2 /m 3 to 500 m 2 /m 3 during the hydrogenation reaction of the step 1 and the hydrogenation reaction of the step 2.
15 . The method of claim 12 , wherein
the ratio of trans isomers in the CHDA of the reaction product of the step 1 is higher than a ratio of trans isomers in the terephthalic acid in the reaction solution of the step 1, and
the ratio of trans isomers in the CHDA of the reaction product of the step 1 is less than the ratio of trans isomers in the CHDM of the reaction product of the step 2.