Patent ID: 7442810

Claim:
A process for variably preparing mixtures of optionally alkyl-substituted butanediol (BDO), butyrolacetone (GBL) and tetrahydrofuran (THF) by two-stage hydrogenation in the gas phase of C 4 dicarboxylic acids and/or derivatives thereof, which comprises a) hydrogenating in a gas phase a gas stream of C 4 dicarboxylic acids and/or derivatives thereof over a catalyst at a pressure of from 2 to 100 bar and a temperature of from 200° C. to 300° C. in a first reactor in the presence of a noble metal-free catalyst in the form of shaped catalyst bodies having a volume of less than 20 mm 3 , said catalyst from 5 to 95% by weight of oxide of copper and from 5 to 95% by weight of an oxide having acidic sites, to give a stream containing alkyl-substituted GBL and THF, b) removing any succinic anhydride (SA) formed by partial condensation, c) converting the products remaining predominantly in the gas phase in the partial condensation, THF, water and GBL, under the same pressure or under a pressure reduced by the pressure drops in the hydrogenation circuit and at a temperature of from 150 to 240° C., in a second reactor over a noble metal-free catalyst which ≦95% by weight of CuO and from 5 to 95% by weight of one or more oxides selected from the group of ZnO, Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , CeO 2 , MgO, CaO, SrO, BaO, La 2 O 3 and Mn 2 O 3 to give a stream comprising a mixture of BDO, GBL and THF, d) removing the hydrogen from the products and recycling it into the hydrogenation, e) separating by distillation the products, THF, BDO, GBL and water, recycling a GBL-rich stream into the second reactor or discharging it, and working up BDO, THF and GBL by distillation, and setting the ratio of the products, THF, GBL and BDO, relative to one another within the range from 10 to 100% by weight of THF, from 0 to 90% by weight of GBL and from 0 to 90% by weight of BDO only by varying the temperatures in the two hydrogenation reactors and also the GBL recycle stream.