Process for the preparation of butane-1,4-diol, γ-butyrolactone and tetrahydrofuran

A process for the production of at least one C4 compound selected from butane-1,4diol, γ-butyrolactone and tetrahydrofuran, which includes the step of hydrogenation in the vapour phase of maleic anhydride in the presence of a heterogeneous hydrogenation catalyst, which process comprises:

• (a) contacting a vaporous stream containing maleic anhydride vapour, water vapour, and carbon oxides in an absorption zone with a high boiling ester as solvent thereby to form a solution of maleic anhydride in the high boiling organic solvent, said high boiling ester having a boiling point at atmospheric pressure which is at least about 30° C. higher than that of maleic anhydride and being selected from di-(C1 to C4 alkyl) esters of alkyl dicarboxylic acids containing up to 13 carbon atoms, mono- and di-(C10 to C18 alkyl) esters of maleic acid, fumaric acid, succinic acid, and mixtures thereof, (C1 to C4 alkyl) esters of maphthalenemonocarboxylic acids, tri-(C1 to C4 alkyl) esters of aromatic tricarboxylic acids, and di-(C1 to C4 alkyl) esters of isophthalic acid;
• (b) recovering from the absorption zone a waste gas stream;
• (c) contacting the solution of maleic anhydride in the high boiling ester with a gaseous stream containing hydrogen thereby to strip maleic anhydride therefrom and to form a vaporous stream comprising hydrogen and maleic anhydride;
• (d) contacting material of the vaporous stream of step (c) in a hydrogenation zone under hydrogenation conditions with of a heterogeneous hydrogenation catalyst thereby to convert maleic anhydride by hydrogenation to at least one C4 compound selected from butane-1,4diol, γ-butyrolactone and tetrahydrofuran;
• and
• (e) recovering from the hydrogenation zone a product stream containing said at least one C4 compound.