| abstract |
Butane-1,4-diol, gamma-butyrolactone or tetrahydrofuran are prepared by vapour phase hydrogenation of a C4-dicarboxylic acid derivative. A maleic anhydride containing vapour 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. |