| 摘要 |
The invention relates to a method for producing optionally alkyl substituted 1,4 butane diol by the two-stage catalytic hydrogenation of C4 dicarboxylic acids and/or their derivatives in the gaseous phase. Said method comprises the following steps: (a) introduction of a gaseous stream of a C4 dicarboxylic acid or a derivative thereof at between 200 and 300 °C and between 2 and 60 bar into a first reactor and a catalytic gaseous phase hydrogenation to form a product containing gamma-butyrolactone that is optionally alkyl-substituted; (b) separation of succinic anhydride from the product obtained in step (a), preferably to achieve a residual content of < approx. 0.3 to 0.2 wt. %, (c) introduction of the product stream obtained in step (b) into a second reactor at a temperature of between 150 °C and 240 °C and pressure of between 15 and 100 bar and a catalytic gaseous phase hydrogenation to obtain optionally alkyl-substituted 1,4-butane diol; (d) separation of the desired product from the intermediate products, by-products and optionally the non-converted educt; (e) optional return of the non- converted intermediate products to one or both hydrogenation stages, whereby a respective catalyst containing = 95 wt. %, preferably 5 to 95 wt. % and in particular 10 to 80 wt. % CuO and = 5 wt. %, preferably 5 to 95 wt. % and in particular 20 to 90 wt. % of an oxidic support, is used in both hydrogenation stages and in the second reactor a higher pressure prevails than in the first reactor.
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