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Abstract

A hydrogenation process is described for the production of a hydroxylic compound selected from alcohols and diols by hydrogenation of a corresponding unsaturated organic compound selected from esters, diesters and lactones which involves use of two hydrogenation zones (11, 36), each containing a charge of a hydrogenation catalyst (12, 37). In a first phase of operation one of the hydrogenation zones (36 or 11) is in standby condition and a stream of hot hydrogen-containing gas is passed therethrough. Meanwhile a vaporous feed stream comprising a hydrogen-containing gas and the unsaturated organic compound to be hydrogenated, e.g. dimethyl 1,4-cyclohexanedicarboxylate, is fed to the active zone (11 or 36). This feed stream can include the gas stream from the first mentioned hydrogenation zone (36 or 11). In a second phase of operation the roles of the reactors (11, 36) are switched so that the zone (36 or 11) previously in reactivation condition becomes the active zone whilst the zone that was formerly active (11 or 36) goes into reactivation condition and its partially deactivated catalyst charge is reactivated by the hot hydrogen-containing gas stream.

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First Claim