Catalyst and process for purification of crude terephthalic acid
AssigneeAmoco Corporation
InventorsImre Puskas, Steven A. Cerefice
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Abstract
A catalyst, a process for preparing said catalyst, and a process for producing purified terephthalic acid, wherein 4-carboxybenzaldehyde is reduced to very low levels, wherein said catalyst is prepared by contacting a solution of a suitable palladium salt in an organic solvent with a suitable activated carbon support, wherein said palladium salt is reduced to palladium metal crystallites by said activated carbon support. Purified terephthalic acid is prepared by hydrogenating crude terephthalic acid in the presence of said catalyst.
Claims9
A process for purifying crude terephthalic acid containing up to 10,000 ppm of 4-carboxybenzaldehyde wherein said 4-carboxybenzaldehyde is selectively hydrogenated and reduced to a level of less than 100 parts per million in a standard laboratory test wherein said process comprises hydrogenating said crude acid at a suitable temperature and pressure with hydrogen in the presence of a catalyst composition which comprises crystallites of catalytically-active palladium upon the surface of a porous activated carbonaceous support material consisting essentially of activated carbon granules having a surface area of at least 600 m.sup.2 /g, said crystallites being predominantly less than 35 .ANG. in longitudinal measurement, wherein said catalyst composition is prepared by contacting said activated support in the absence of hydrogen with a non-aqueous solution of a palladium salt in an organic solvent which is inert to said support material, wherein said palladium salt is reduced to palladium metal crystallites by said activated support.
Dependencies are inferred from the claim text.