Abstract: Butane-1,4-diol, gamma-butyrolactone or tetrahydrofuran are prepared by vapor phase hydrogenation of a C4-dicarboxylic acid derivative. A maleic anhydride containing vapor stream is contacted in an absorption zone with a first high boiling solvent. A waste gas stream is passed to a scrubbing zone containing a second, higher boiling solvent. The waste gas is purged and the first and second solvents are recovered and recycled. Maleic anhydride is obtained from the absorption zone and converted to a maleic acid diester, which is stripped from the first solvent with hydrogen. The desired products are obtained by hydrogenation.

Abstract: A process is described for the production of a hydroxylic compound selected from alcohols and diols by hydrogenation of a corresponding hydrogenatable material selected from monoesters of carboxylic acids, monoesters of dicarboxylic acids, diesters of dicarboxylic acids, lactones, and mixtures of two or more thereof which comprises:(a) providing a hydrogenation zone containing a charge of a granular heterogeneous ester hydrogenation catalyst;(b) supplying to the hydrogenation zone a vaporous feed stream containing hydrogen and a hydrogenatable material selected from monoesters of carboxylic acids, monoesters of dicarboxylic acids, diesters of dicarboxylic acids, lactones, and mixtures of two or more thereof, at an inlet temperature which is above the dew point of the mixture;(c) maintaining the hydrogenation zone under temperature and pressure conditions which are conducive to effecting hydrogenation of esters;(d) recovering from the hydrogenation zone a two phase product stream containing a hydroxylic compou