Abstract: An oxidic composition which is suitable as a catalyst precursor comprises

Abstract: The iron-containing catalyst suitable for use as a catalyst contains a) iron or a mixture containing iron and an iron-based compound. The iron has an average crystallite size ranging from 1-35 nm measured by X-ray diffraction.

Abstract: The present invention relates to a process for the gas-phase hydrogenation of C4-dicarboxylic acids and/or their derivatives over a catalyst based on copper oxide to give substituted or unsubstituted &ggr;-butyrolactone and/or tetrahydrofuran, which comprises, which a first reaction zone in which the C4-dicarboxylic acid and/or its derivatives is/are reacted to give a mixture comprising a substituted or unsubstituted &ggr;-butyrolactone as main product and a subsequent second reaction zone in which the substituted or unsubstituted &ggr;-butyrolactone present in the mixture from the first hydrogenation step is reacted at a temperature lower than the temperature in the first hydrogenation step to give substituted or unsubstituted tetrahydrofuran.

Abstract: The present invention provides a process for preparing 2-cyclopentenones of the general formula: where R1 to R4 are each hydrogen atoms or are alkyl or alkenyl radicals having from 1 to 12 carbon atoms, cycloalkyl or cycloalkenyl radicals having from 5 to 7 carbon atoms, aralkylene or aryl radicals, by converting hexenedioic acids and/or their esters of the general formulae where R1 to R4 are each as defined above and R5 and R6 are each hydrogen atoms or are alkyl radicals having from 1 to 12 carbon atoms, cycloalkyl radicals having 5 or 6 carbon atoms, aralkyl or aryl radicals, at temperatures of from 150 to 450° C., over solid, oxidic catalysts, wherein the catalysts on an oxidic support material comprise from 0.01 to 5% by weight of at least one alkali metal oxide.

Abstract: A process is provided for reducing the content of a monounsaturated aliphatic amine (III) in a mixture (IV) containing an aminonitrile (I) or a diamine (II), or mixtures thereof, and the amine (III), wherein a) the mixture (IV) is reacted with an anionic nucleophile (V),  which contains a nucleophilic atom selected from the group comprising oxygen, nitrogen and sulfur,  which is capable of taking up an H+ ion to form an acid with a pKa ranging from 7 to 11, measured in water at 25° C., and  which has a relative nucleophilicity, measured in methyl perchlorate/methanol at 25° C.,  ranging from 3.4 to 4.7 when oxygen is the nucleophilic atom,  ranging from 4.5 to 5.8 when nitrogen is the nucleophilic atom, and  ranging from 5.5 to 6.8 when sulfur is the nucleophilic atom,  in an amount ranging from 0.

Abstract: A process for continuously preparing 2-pyrrolidone by reacting gamma-butyrolactone with ammonia in the liquid phase in the presence of water, wherein the reaction is carried out at a temperature of from 275 to 300° C. and an absolute pressure of from 140 to 180 bar.

Abstract: The continuous process for preparing a polyamide by reacting at least one aminonitrile with water comprises: (1) reacting at least one aminonitrile with water in the presence of an organic liquid diluent at from 90 to 400° C. and from 0.1 to 35×106 Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture, (2) further reacting the reaction mixture at from 150 to 400° C.

Abstract: Polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of these polymers are prepared by polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer, which is in the form of shaped catalyst bodies or catalyst particles having a volume of the individual shape of the body or particle of at least 0.05 mm3, preferably at least 0.

Abstract: A catalyst for the hydrogenation of C4-dicarboxylic acids and/or derivatives thereof, preferably maleic anhydride, in the gas phase comprises

Abstract: In a process for preparing pyrrolidone, which may be N-substituted, substrates selected from among C4-dicarboxylic acids and their derivatives are hydrogenated in the gas phase under anhydrous conditions with or without addition of ammonia or primary amines and using a Cr-free catalyst which comprises from 5 to 95% by weight of CuO, preferably from 30 to 70% by weight of CuO, and from 5 to 95% by weight of Al2O3, preferably from 30 to 70% by weight of Al2O3, and from 0 to 60% by weight, preferably from 5 to 40% by weight, of ZnO.

Abstract: In a process for the preparation of alcohols by catalytic hydrogenation of carbonyl compounds, the catalyst used is 0.01 to 50% by weight of rhenium and 0 to 20% by weight, in each case based on the total weight of the catalyst, of at least one further metal chosen from Zn, Cu, Ag, Au, Ni, Fe, Cr, V on oxidatively pretreated activated carbon as support.

Abstract: A process for preparing toluene derivatives of the formula I 1

Abstract: The present invention provides a process for preparing 2-cyclopentenones of the general formula: 1

Abstract: The continuous process for preparing a polyamide by reacting at least one aminonitrile with water comprises:

Abstract: Unsubstituted or alkyl-substituted THF is obtained by catalytic hydrogenation in the gas phase of C4-dicarboxylic acids and/or their derivatives using a catalyst comprising <80% by weight, preferably <70% by weight, in particular from 10 to 65% by weight, of CuO and >20% by weight, preferably >30% by weight, in particular from 35 to 90% by weight, of an oxidic support having acid centers, at a hot spot temperature of from 240 to 310° C., preferably from 240 to 280° C., and a WHSV over the catalyst of from 0.01 to 1.0, preferably from 0.02 to 1, in particular from 0.05 to 0.5, kg of starting material/l of catalyst x hour.

Abstract: A process for the single-stage preparation of polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton by polymerization of tetrahydrofuran over a heterogeneous acid catalyst in the presence of at least one telogen and/or comonomer selected from the group consisting of alpha,omega-diols, water, polytetrahydrofuran having a molecular weight of from 200 to 700 dalton and cyclic ethers comprises a) separating off the catalyst and/or downstream products of the catalyst suspended and/or dissolved in the output from the polymerization, b) fractionating the resulting catalyst-free output from the polymerization in at least one distillation step to give a distillation residue comprising the polymerization product and at least one tetrahydrofuran fraction and returning at least part of the tetrahydrofuran fraction to the polymerization and c) separating low molecular weight polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of

Abstract: C4-dicarboxylic acids or derivatives thereof are hydrogenated in the gas phase in a fluidized-bed reactor. It is possible to use catalyst compositions known per se.

Abstract: Unsubstituted or alkyl-substituted THF is obtained by catalytic hydrogenation in the gas phase of C4-dicarboxylic acids and/or their derivatives using a catalyst comprising <80% by weight, preferably <70% by weight, in particular from 10 to 65% by weight, of CuO and >20% by weight, preferably >30% by weight, in particular from 35 to 90% by weight, of an oxidic support having acid centers, at a hot spot temperature of from 240 to 310° C., preferably from 240 to 280° C., and a WHSV over the catalyst of from 0.01 to 1.0, preferably from 0.02 to 1, in particular from 0.05 to 0.5, kg of starting material/l of catalyst×hour.

Abstract: The present invention relates to a process for the gas-phase hydrogenation of C4-dicarboxylic acids and/or their derivatives over a catalyst based on copper oxide to give substituted or unsubstituted &ggr;-butyrolactone and/or tetrahydrofuran, which comprises, which a first reaction zone in which the C4-dicarboxylic acid and/or its derivatives is/are reacted to give a mixture comprising a substituted or unsubstituted &ggr;-butyrolactone as main product and a subsequent second reaction zone in which the substituted or unsubstituted &ggr;-butyrolactone present in the mixture from the first hydrogenation step is reacted at a temperature lower than the temperature in the first hydrogenation step to give substituted or unsubstituted tetrahydrofuran.

Abstract: A hydrogenation catalyst which is suitable, in particular, for the hydrogenation of maleic anhydride and its derivatives to THF or its derivatives comprises copper oxide and at least one further metal or compound thereof, preferably an oxide, selected from the group consisting of Al, Si, Zn, La, Ce, the elements of groups IIIA to VIIIA and the elements of groups IA and IIA and having a pore volume of ≧ 0.01 ml/g for pore diameters of >50 nm and a ratio of the pore volume of macropores having a diameter of >50 nm to the total pore volume for pores having a diameter of >4 nm of >10%.