| abstract |
A process is described for the production of at least one C4 compound selected from butane-1,4-diol, η-butyrolactone and tetrahydrofuran, which includes the step of hydrogenation in the vapour phase of a di-(C1 to C4 alkyl) maleate in the presence of a particulate ester 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 organic solvent having a boiling point at atmospheric pressure which is at least about 30 °C higher than that of the di-(C1 to C4 alkyl) maleate thereby to form a solution of maleic anhydride in the high boiling organic solvent; (b) recovering from the absorption zone a waste gas stream; (c) reacting maleic anhydride in the solution of maleic anhydride of step (a) under esterification conditions in an esterification zone with a C1 to C4 alkanol to form the corresponding di-(C1 to C4 alkyl) maleate; (d) recovering from the esterfication zone a solution of the di-(C1 to C4 alkyl) maleate in the high boiling solvent; (e) contacting the solution of the di-(C1 to C4 alkyl) maleate in the high boiling solvent with a gaseous stream containing hydrogen thereby to strip di-(C1 to C4 alkyl) maleate therefrom and to form a vaporous stream comprising hydrogen and di-(C1 to C4 alkyl) maleate; (f) contacting material of the vaporous stream of step (e) in a hydrogenation zone under ester hydrogenation conditions in the presence of a heterogeneous ester hydrogenation catalyst thereby to convert di-(C1 to C4 alkyl) maleate to at least one C4 compound selected from butane-1,4-diol, η-butyrolactone and tetrahydrofuran; and (g) recovering from the hydrogenenation zone a product stream containing said at least one C4 compound. |