Claims
- 1. A process for purifying crude terephthalic acid containing up to 10,000 ppm of 4-carboxybenzaldehyde wherein 4-carboxybenzaldehyde content is reduced to a level of less than 100 parts per million in a standard laboratory test wherein said process comprises hydrogenating said crude acid in liquid phase at a temperature of from about 100.degree. C. to about 300.degree. C. and a pressure of from about 200 to about 1500 psi with hydrogen in the presence of water and of a catalyst composition which comprises crystallites of catalytically active palladium upon the surface of a porous activated carbon support material having a surface area of at least 600 m.sup.2 /g wherein said crystallites are predominantly less than 35 .ANG. in longitudinal measurement, and wherein said catalyst composition is prepared by contacting said support with an aqueous solution of a nitritopalladate salt.
- 2. The process of claim 1 wherein said nitritopalladate salt is prepared by reacting stoichiometric quantities of a nitrite salt with a palladium halide selected from the group consisting of palladium chloride, palladium bromide and palladium iodide.
- 3. The process of claim 2 wherein said nitrite salt is sodium nitrite.
- 4. The process of claim 1 wherein said support material is selected from the group consisting of plant origin carbon, animal origin carbon, and mineral origin carbon.
- 5. The process of claim 4 wherein said plant origin carbon is coconut charcoal.
- 6. The process of claim 1 wherein said temperature is 250.degree. C., and pressure of hydrogen is 200 psi.
Parent Case Info
This is a division of application Ser. No. 316,337, filed Oct. 29, 1981, now U.S. Pat. No. 4,421,676.
US Referenced Citations (10)
Divisions (1)
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Number |
Date |
Country |
Parent |
316337 |
Oct 1981 |
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