Palladium-rhodium catalyst for purification of crude terephthalic acid
AssigneeStandard Oil Company (Indiana)
InventorsImre Puskas, David E. James
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Abstract
A process for producing a purified terephthalic acid which comprises reacting in a liquid phase a mixture of hydrogen and crude terephthalic acid, a palladium/rhodium catalyst on a porous carbonaceous support wherein the catalyst compound is prepared by adsorbing palladium on the support from a complex salt formed in the presence of an amine and acetic acid, followed by deposition of rhodium from a solution of sodium hexanitritorhodate.
Claims22
A method of making a catalyst used for purification of terephthalic acid containing up to 10,000 ppm of 4-carboxybenzaldehyde in a standard laboratory test wherein 4-carboxybenzaldehyde content is decreased to less than 100 parts per million and p-toluic acid content increase is minimized wherein catalytically active palladium crystallites and rhodium crystallites are adsorbed on a porous activated carbon support material having a surface area of at least 600 m.sup.2 /g which comprises contacting said support with (a) an aqueous solution of an amine and a palladium salt in the presence of an organic carboxylic acid wherein concentration of said amine is sufficient to solubilize said palladium salt and mole ratio of said acid to said amine is at least 0.75 and with (b) an aqueous solution of a rhodium salt and an alkali metal nitrite wherein penetration of said palladium and rhodium crystallites into said porous support is within the range of from about 70 to 150 micrometers of the surface of said support.
The method of caim 1 wherein said support material is selected from the group consisting of plant origin carbon, animal origin carbon, and mineral origin carbon.
A catalyst composition for purification of terephthalic acid which comprises crystallites of palladium and rhodium adsorbed on a porous activated carbon support material, said support material having a surface area of at least 600 m.sup.2 /g wherein said catalyst composition is prepared by contacting said support with (a) an aqueous solution of an amine and a palladium salt in the presence of an organic carboxylic acid wherein concentration of said amine is sufficient to solubilize said palladium salt and mole ratio of said acid to said amine is at least 0.75 and with (b) an aqueous solution of a rhodium compound and an alkali metal nitrite wherein penetration of said palladium and rhodium crystallites into said porous support is within the range of from about 70 to 150 micrometers of the surface of said support.
Dependencies are inferred from the claim text.