Claims
- 1. A process for producing terephthalic acid with a high purity, where terephthalic acid is produced by oxidizing p-tolualdehyde with molecular oxygen in the presence of a heavy metal catalyst and a bromine compound in water as a solvent, characterized by conducting the oxidation at 180.degree.-280.degree. C., using manganese and/or cerium as the heavy metal catalyst, maintaining the bromine concentration in the reaction system during the reaction in a range of 0.5-12% by weight on the basis of the reaction solution in terms of bromine ions, and maintaining the amount of mineral acid in the reaction system during the reaction at a ratio of g-equivalents of hydrogen ions of the mineral acid to sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions (H.sup.+ /H.sup.+ +2Mn.sup.++ or H.sup.+ /H.sup.+ +3Ce.sup.+++) of 1-85%, and at a ratio of sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions to g-equivalents of bromine ions (H.sup.+ +2Mn.sup.++ /Br.sup.- or H.sup.+ +3Ce.sup.+++ /Br.sup.-) of 0.5-5.
- 2. A process according to claim 1, characterized in that the bromine compound is manganese bromide, cerium bromide or hydrogen bromide.
- 3. A process according to claim 1, characterized in that the bromine concentration is maintained in the reaction system during the reaction in a range of 0.5-6% by weight on the basis of the reaction solution in terms of bromine ions.
- 4. A process according to claim 3, characterized in that the bromine concentration is maintained in the reaction system during the reaction in a range of 1-4% by weight on the basis of the reaction solution in terms of bromine ions.
- 5. A process according to claim 1, characterized in that the mineral acid is maintained in the reaction system at a ratio of g-equivalents of the hydrogen ions to sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions (H.sup.+ /H.sup.+ +2Mn.sup.++ or H.sup.+ /H.sup.+ +3Ce.sup.+++) of 5-75% and at a ratio of sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions to g-equivalents of the bromine ions (H.sup.+ +2Mn.sup.++ /Br.sup.- or H.sup.+ +3Ce.sup.+++ /Br.sup.-) of 0.75-4.
- 6. A process according to claim 1, characterized in that the mineral acid is hydrogen bromide or sulfuric acid.
- 7. A process according to claim 1, characterized in that the oxidation is carried out at 210.degree.-260.degree. C.
- 8. A process according to claim 1, characterized in that the oxidation is carried out under a pressure of 10-50 kg/cm.sup.2 gauge.
- 9. A process according to claim 1, characterized in that the oxidation is carried out with air.
- 10. A process according to claim 1, characterized in that the water as the solvent is used in an amount of at least twice the weight of p-tolualdehyde.
- 11. A process according to claim 1, characterized in that the water as the solvent is used in an amount of 3-6 times the weight of p-tolualdehyde.
- 12. A process according to claim 1, characterized in that the oxidation is carried out batchwise, semicontinuously or continuously.
- 13. A process for preparing terephthalic acid having a high purity, where terephthalic acid is produced by oxidizing p-tolualdehyde with air in the presence of a heavy metal catalyst and a bromine compound in water as a solvent, characterized by conducting the oxidation under a pressure of 10-50 kg/cm.sup.2 gauge and at 180.degree.-280.degree. C. by using manganese and/or cerium as the heavy metal catalyst, maintaining the bromine concentration in the reaction system during the reaction in a range of 0.5-12% by weight on the basis of the reaction solution in terms of bromine ions, and maintaining an amount of mineral acid in the reaction system during the reaction to maintain a ratio of g-equivalents of hydrogen ions of the mineral acid to sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions (H.sup.+ /H.sup.+ +2Mn.sup.++ or H.sup.+ /H.sup.+ +3Ce.sup.+++) of 1-85%, and at a ratio of sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions of g-equivalents of bromine ions (H.sup.+ +2Mn.sup.++ /Br.sup.- or H.sup.+ +3Ce.sup.+++ /Br.sup.-) of 0.5-5.
- 14. The process of claim 1 in which the terephthalic acid with a high purity is colorless and can be reacted directly, without a prior purification step, with a glycol to obtain a polyester.
- 15. The process of claim 13 in which the terephthalic acid having a high purity is colorless and can be reacted directly, without a prior purification step, with a glycol to obtain a polyester.
Priority Claims (1)
Number |
Date |
Country |
Kind |
52-146935 |
Dec 1977 |
JPX |
|
Parent Case Info
This is a continuation, of application Ser. No. 967,091, filed Dec. 6, 1978 now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
2907792 |
McIntyre |
Oct 1959 |
|
3012038 |
O'Neill et al. |
Dec 1961 |
|
3944601 |
Kuhlmann |
Mar 1976 |
|
Continuations (1)
|
Number |
Date |
Country |
Parent |
967091 |
Dec 1978 |
|