Patent ID: 6274743
Filing Date: 2001-08-14
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 C.sub.4 dicarboxylic acid derivative in the presence of a heterogeneous hydrogenation catalyst, said C.sub.4 dicarboxylic acid derivative being selected from maleic anhydride and di-(C.sub.1 to C.sub.4 alkyl) esters of a C.sub.1 to C.sub.4 dicarboxylic acid, which process comprises:(a) contacting a vaporous stream containing maleic anhydride vapour, water vapour, and carbon oxides in an absorption zone with a first high boiling solvent having a boiling point at atmospheric pressure which is at least about 30.degree. C. higher than that of maleic anhydride thereby to form a solution of maleic anhydride in the first high boiling solvent;(b) recovering from the absorption zone a waste gas stream containing a minor amount of said first high boiling solvent;(c) contacting the waste gas stream of step (b) in a scrubbing zone with a second high boiling solvent having a boiling point at atmospheric pressure which is at least 30.degree. C. higher than that of the first high boiling solvent, thereby to form a solution of the first high boiling solvent in the second high boiling solvent and to yield a washed waste gas;(d) recovering first high boiling solvent from the solution of step (c) for recycle to step (a);(e) recycling residual second high boiling solvent from step(d) to step (c);(f) purging washed waste gas of step (c);(g) converting maleic anhydride in said solution of step (a), if necessary, to said C.sub.4 dicarboxylic derivative;(h) contacting the solution of said C.sub.4 dicarboxylic acid derivative in the first high boiling solvent with a gaseous stream containing hydrogen thereby to strip said C.sub.4 dicarboxylic acid derivative therefrom and to form a vaporous stream comprising hydrogen and said C.sub.4 dicarboxylic acid derivative;(i) contacting material of the vaporous stream of step (h) in a hydrogenation zone under hydrogenation conditions with a heterogeneous hydrogenation catalyst thereby to convert said C.sub.4 dicarboxylic acid derivative to at least one C.sub.4 compound selected from butane-1,4-diol, .gamma.-butyrolactone and tetrahydrofuran; and(j) recovering from the hydrogenation zone a product stream containing said at least one C.sub.4 compound.