Abstract: The present invention relates to a process for separating off solvents from solvent-comprising hydrogenation outputs from a catalytic hydrogenation process, which comprise at least one water-soluble hydrogenation product having at least one alcohol, lactone, ether, lactam or amino group in a solvent which is immiscible or not completely miscible with water and has a boiling point below 100° C., wherein water is added to the hydrogenation output, the solvent-comprising phase is separated off and recirculated to the hydrogenation.

Abstract: Processes for decreasing fumaric acid deposits in preparing maleic anhydride by heterogeneously catalyzed oxidation of a hydrocarbon with molecular oxygen. Maleic anhydride is absorbed from the crude mixture in an absorbent in an absorption column and desorbed in a desorption column, the entirety or portion of absorbent depleted in maleic anhydride, for controlled precipitation of fumaric acid, being cooled and/or concentrated by evaporating a portion of absorbent such that the difference between the concentration of fumaric acid in the recycle stream at the outlet of the desorption column under existing conditions and the equilibrium concentration of fumaric acid according to the solubility curve after cooling and/or evaporation of a portion of absorbent is ?250 ppm by weight, and the fumaric acid precipitated as a solid is removed completely or partly from the absorbent recycling system and the fumaric acid-depleted absorbent is recycled completely or partly to the absorption column.

Abstract: What is described is a process for obtaining maleic anhydride by distillation from a solution of maleic anhydride in a high-boiling absorbent which has been obtained by gas phase oxidation of a hydrocarbon and at least partial absorption of the oxidation products into the absorbent, by i) introducing the solution into the side of a feed column with a rectifying section disposed above the feed point and a stripping section disposed below the feed point, ii) providing an upper combining column which communicates with the upper end of the rectifying section and a lower combining column which communicates with the lower end of the stripping section, iii) providing a draw column which communicates with the upper combining column and the lower combining column, iv) drawing maleic anhydride off as a side draw from the draw column, and drawing off compounds having a lower boiling point than maleic anhydride at the top of the upper combining column and the high-boiling absorbent at the bottom of the lower combining c

Abstract: The invention relates to a method of controlling a hydrogenation of a starting material in a hydrogenation reactor, in which the amount of hydrogen reacted in the hydrogenation is firstly determined, the ratio of the amount of hydrogen reacted to the amount of starting material fed in is then derived, this ratio is compared with a prescribed value and, finally, at least one process parameter is altered if the ratio of the amount of hydrogen reacted to the amount of starting material fed in deviates by a prescribed amount from the prescribed value.

Abstract: The present invention relates to a process for preparing tetrahydrofuran by absorption of C4-dicarboxylic acids and/or derivatives thereof from a crude product mixture into an organic solvent or water as absorption medium, removal of the absorption medium, catalytic hydrogenation of the resulting C4-dicarboxylic acids and/or derivatives thereof and distillation of the water-comprising crude tetrahydrofuran in at least one distillation column, wherein THF-comprising waste streams from the distillation are catalytically hydrogenated with complete or partial recirculation to the process.

Abstract: A process for decreasing fumaric acid deposits in the preparation of maleic anhydride by heterogeneously catalyzed oxidation of a hydrocarbon with molecular oxygen, in which the maleic anhydride is absorbed from the crude product mixture in an absorbent in an absorption column and desorbed again in a desorption column, the entirety or a portion of the absorbent depleted in maleic anhydride, for controlled precipitation of fumaric acid, being cooled and/or concentrated by evaporating a portion of the absorbent to such an extent that the difference between the concentration of fumaric acid in the recycle stream at the outlet of the desorption column under the conditions existing there and the equilibrium concentration of fumaric acid according to the solubility curve after the cooling and/or evaporation of a portion of the absorbent is greater than or equal to 250 ppm by weight, and the fumaric acid precipitated as a solid is removed completely or partly from the absorbent recycling system and the fumaric acid-

Abstract: The invention relates to a catalyst provided in the form of an extrudate, which contains 5 to 85% by weight of copper oxide and comprises, in the active material and as binders, the same oxidic carrier material. The invention also relates to the use of the catalyst for hydrogenating carbonyl compounds.

Abstract: What is described is a process for obtaining maleic anhydride by distillation from a solution of maleic anhydride in a high-boiling absorbent which has been obtained by gas phase oxidation of a hydrocarbon and at least partial absorption of the oxidation products into the absorbent, by i) introducing the solution into the side of a feed column with a rectifying section disposed above the feed point and a stripping section disposed below the feed point, ii) providing an upper combining column which communicates with the upper end of the rectifying section and a lower combining column which communicates with the lower end of the stripping section, iii) providing a draw column which communicates with the upper combining column and the lower combining column, iv) drawing maleic anhydride off as a side draw from the draw column, and drawing off compounds having a lower boiling point than maleic anhydride at the top of the upper combining column and the high-boiling absorbent at the bottom of the lower combining c

Abstract: The present invention relates to a process for separating off solvents from solvent-comprising hydrogenation outputs from a catalytic hydrogenation process, which comprise at least one water-soluble hydrogenation product having at least one alcohol, lactone, ether, lactam or amino group in a solvent which is immiscible or not completely miscible with water and has a boiling point below 100° C., wherein water is added to the hydrogenation output, the solvent-comprising phase is separated off and recirculated to the hydrogenation.

Abstract: The present invention provides a process for distillatively purifying tetrahydrofuran in the presence of a polar solvent.

Abstract: The present invention provides a process for preventing fumaric acid deposits in the preparation of maleic anhydride, comprising the following steps: a) absorption of a C4-dicarboxylic acid or of a derivative from a crude product mixture into an organic solvent or water as an absorbent, b) removal of the C4-dicarboxylic acid or of a derivative from the absorbent, the absorbent thus recovered being catalytically hydrogenated fully or partly and recycled fully or partly into the absorption stage (a).

Abstract: Catalyst in the form of an extrudate which comprises from 5 to 85% by weight of copper oxide and in which the same oxidic support material is present in the active composition and as binder, and the use of the catalyst for the hydrogenation of carbonyl compounds.

Abstract: A process for variably preparing mixtures of optionally alkyl-substituted BDO, GBL and THF by two-stage hydrogenation in the gas phase of C4 dicarboxylic acids and/or derivatives thereof, which comprises a) hydrogenating in a gas phase a gas stream of C4 dicarboxylic acids and/or derivatives thereof over a particular catalyst at a particular pressure and temperature to give a stream mainly containing of optionally alkyl-substituted GBL and THF, b) removing any succinct anhydride, c) converting the products remaining predominantly in the gas phase in the partial condensation, THF, water and GBL 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) distillatively separating the products, THF, BDO, GBL and water, if appropriate recycling a GBL-rich stream or if appropriate discharging it, and working up BDO, THF and GBL distillatively, and setting the ratio of the products, THF, GBL and BDO, relative to one another wi

Abstract: The invention relates to a process for separating off maleic anhydride from a gas stream comprising maleic anhydride, in which a) the gas stream comprising maleic anhydride is brought into contact with a liquid absorbent phase comprising at least one high-boiling inert absorption medium for maleic anhydride and b) maleic anhydride is separated off from the resulting liquid absorbate phase by stripping with a hydrogen-comprising gas as stripping medium in a column, wherein the stripping medium is fed in at two points on the column which are at least one theoretical plate apart.

Abstract: The invention relates to a method of controlling a hydrogenation of a starting material in a hydrogenation reactor, in which the amount of hydrogen reacted in the hydrogenation is firstly determined, the ratio of the amount of hydrogen reacted to the amount of starting material fed in is then derived, this ratio is compared with a prescribed value and, finally, at least one process parameter is altered if the ratio of the amount of hydrogen reacted to the amount of starting material fed in deviates by a prescribed amount from the prescribed value.

Abstract: Crude water-containing tetrahydrofuran is purified by passing the crude tetrahydrofuran through three distillation columns, withdrawing water from the bottom of the first column, recycling water-containing tetrahydrofuran from the top of the second column into the first column, passing a sidestream of the first column into the second column, recycling the bottom product of the third column into the first column, and withdrawing a distillate at the top of the first column. Additionally, a sidestream of the second column is passed into the third column and the purified tetrahydrofuran is recovered as the top product of the third column.

Abstract: Catalyst in the form of an extrudate which comprises from 5 to 85% by weight of copper oxide and in which the same oxidic support material is present in the active composition and as binder, and the use of the catalyst for the hydrogenation of carbonyl compounds.

Abstract: The present invention provides a process for distillatively purifying tetrahydrofuran in the presence of a polar solvent.

Abstract: Optionally alkyl-substituted 1,4-butanediol is prepared from C4-dicarboxylic acids and/or of derivatives thereof by: a) a gas stream of the C4-dicarboxylic acid or the derivative thereof in a first reactor in the gas phase to obtain a product which contains mainly optionally alkyl-substituted ?-butyro-lactone; b) removing succinic anhydride from the product of step a); c) catalytically hydrogenating the product of step b) in a second reactor in the gas phase to obtain optionally alkyl-substituted 1,4-butanediol; d) removing the desired product from intermediates, by-products and any unconverted reactants; and e) optionally recycling unconverted intermediates into one or both hydrogenation stages. The catalysts employed in each of the hydrogenation stages comprise ?95% by weight of CuO, and ?5% by weight of an oxidic support, and the second reactor has a higher pressure than the first reactor.

Abstract: The present invention provides a process for variably preparing mixtures of optionally alkyl-substituted BDO, GBL and THF by two-stage hydrogenation in the gas phase of C4 dicarboxylic acids and/or derivatives thereof, which comprises a) in a first step in the gas phase, hydrogenating a gas stream of C4 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.