Patent ID: 6239292
Filing Date: 2001-05-29
Classification: C07C,C07D

Abstract:
A process for the production of at least one C.sub.4 compound selected from butane-1,4-diol, .gamma.-butyrolactone and tetrahydrofuran, which includes the step of hydrogenation in the vapour phase of a di-(C.sub.1 to C.sub.4 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 ester as solvent thereby to form a solution of maleic anhydride in the high boiling ester, said high boiling ester having a boiling point at atmospheric pressure which is at least about 30.degree. C. higher than that of the di-(C.sub.1 to C.sub.4 alkyl) maleate and being selected from di-(C.sub.1 to C.sub.4 alkyl) esters of alkyl dicarboxylic acids containing up to 13 carbon atoms, mono- and di-(C.sub.10 to C.sub.18 alkyl) esters of maleic acid, fumaric acid, succinic acid, and mixtures thereof, (C.sub.1 to C.sub.4 alkyl) esters of naphthalenemonocarboxylic acids, tri-(C.sub.1 to C.sub.4 alkyl) esters of aromatic tricarboxylic acids, and di-(C.sub.1 to C.sub.4 alkyl) esters of isophthalic acid;(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 C.sub.1 to C.sub.4 alkanol to form the corresponding di-(C.sub.1 to C.sub.4 alkyl) maleate;(d) recovering from the esterification zone a solution of the di-(C.sub.1 to C.sub.4 alkyl) maleate in the high boiling ester;(e) contacting the solution of the di-(C.sub.1 to C.sub.4 alkyl) maleate in the high boiling ester with a gaseous stream containing hydrogen thereby to strip di-(C.sub.1 to C.sub.4 alkyl) maleate therefrom and to form a vaporous stream comprising hydrogen and di-(C.sub.1 to C.sub.4 alkyl) maleate;(f) contacting material of the vaporous stream of step (e) in a hydrogenation zone under ester hydrogenation conditions with a heterogeneous ester hydrogenation catalyst thereby to convert di-(C.sub.1 to C.sub.4 alkyl) maleate by hydrogenation to at least one C.sub.4 compound selected from butane-1,4-diol, .gamma.-butyrolactone and tetrahydrofuran; and(g) recovering from the hydrogenation zone a product stream containing said at least one C.sub.4 compound.