Process for the production of butanediol by liquid phase hydrogenation

Process for the production of butanediol comprising selective catalytic hydrogenation of gammabutyrolactone, succinic anhydride esters or mixtures of gamma butyrolactone and succinic anhydride esters in at least two successive catalytic steps at a pressure ranging between 60 and 100 bars and temperature ranging between 160 and 250° C., and wherein a liquid phase is present at the entrance of the first stage.