Process for the hydrogenation of maleic acid to 1,4-butanediol

A process for the production of tetrahydrofuran and 1,4-butanediol comprising catalytically hydrogenating a hydrogenatable precursor in contact with a hydrogen-containing gas and a hydrogenation catalyst comprising palladium, silver and rhenium on a carbon support to produce a product comprising a major portion of 1,4-butanediol wherein the hydrogenation catalyst is prepared by the steps of

• (i) impregnating the carbon support with a source of palladium, silver and rhenium in one or more impregnation steps comprising contacting the carbon support with a source of palladium, silver and rhenium, said palladium, silver and rhenium being in at least one solution;
• (ii) drying the impregnated carbon support to remove solvent after each impregnation step;
• and
• (iii) heating the impregnated carbon support at a temperature of about 100.degree. C. to about 350.degree. C. under reducing conditions.