Process for the preparation of butanediol, butyrolactone and tetrahydrofuran

A process is described for the production of at least one of butane-1,4-diol, gamma -butyrolactone and tetrahydrofuran by hydrogenation in the vapour phase of a C4 dicarboxylic acid derivative selected from maleic anhydride and di-(C1 to C4 alkyl) esters of a C1 to C4 dicarboxylic acid. In this process a vaporous stream containing maleic anhydride vapour, water vapour, and carbon oxides is contacted in an absorption zone with a first high boiling organic solvent having a boiling point at atmospheric pressure which is at least about 30 DEG C higher than that of maleic anhydride. From the absorption zone there is recovered a waste gas stream containing a minor amount of said first high boiling organic solvent which is contacted in a scrubbing zone with a second high boiling organic solvent having a boiling point at atmospheric pressure which is at least 30 DEG C higher than that of the first high boiling organic solvent. The washed waste gas from the scrubbing zone is purged. The resulting solution of the first high boiling organic solvent in the second high boiling organic solvent is treated for recovery of first high boiling solvent for recycle to the absorption zone, while the resulting residual second high boiling solvent is recycled to the scrubbing zone. Maleic anhydride in the solution from the absorption zone is converted, if necessary, to a di-(C1 to C4 alkyl) ester of maleic acid or fumaric acid. The solution of the C4 dicarboxylic derivative in the first high boiling solvent is contacted with a gaseous stream containing hydrogen thereby to strip said C4 dicarboxylic acid derivative therefrom and to form a vaporous stream comprising hydrogen and said C4 dicarboxylic acid derivative which is converted by hydrogenation to butane-1,4-diol, gamma -butyrolactone and/or tetrahydrofuran.