Abstract: A continuous process for isolating butenes from a C4 fraction comprising butanes, butenes and other C3-C5-hydrocarbons by extractive distillation using a selective solvent (LM), comprising a first process stage I in a scrubbing zone (E) and a second process stage II in a degassing zone (A), wherein the liquid or a substream of the liquid is taken off from the degassing zone (A) at a theoretical plate located one or more theoretical plates below the feed point for the bottom stream (LM/C4H8) from the scrubbing zone (E), heated and/or vaporized by indirect heat exchange with the hot bottom stream (LM) from the degassing zone (A) and returned to the degassing zone (A) at the same theoretical plate or above this, with the theoretical plate from which the liquid or substream of liquid is taken off being selected so that the total energy requirement in the process stages I and II is minimized, is proposed.

Abstract: The invention relates to a method for obtaining raw-1,3-butadiene by extractive distillation with a selective solvent from a C4-fraction, containing C4-acetylenes as secondary components, in a partition column (TK) with a bottom evaporator (V1) inside of which a partition (T) is arranged in longitudinal direction of the column while forming a first partial area (A), a second partial area (B) and a lower shared column area (C), and to which an extractive wash column (K) is connected upstream therefrom. The invention is characterized in that the supply of energy into the partition column (TK) via the bottom evaporator (V1) is controlled in such a manner that a bottom flow (17) is drawn out from the partition column (TK), this bottom flow containing solvent loaded with C4-acetylenes whose proportion of 1,3-butadiene is limited in order to tender the loss of 1,3-butadiene economically acceptable.

Abstract: Sudstituted the abstract with a new abstract as follows: The invention relates to a continuous process for separation a mixture of hydrocarbons which has beenobtained by extractive distillation of C4 fraction useing a selective solvent and the hydrocarbons from the fraction C4 which are more readily soluble in the selective solvent than are the butanes and the butenes. The mixture is fed into a first distillation column in which it is separated into a steam which is taken off at the top and comprises 1,3-butadiene, propyne, possibly further low boilers and possibly water and a bottom stream comprising 1,3-butadiene, 1,2-butadiene, acetylenes and possibly further high boilers, with the proportion of 1,3-butadiene in the bottom stream from the distillatin column being regulated in such a way that it is at least sufficiently high to dilute the acetylenes to outside the range in which there is a risk of spontaneous decomposition.

Abstract: A process for recovering crude 1,3-butadiene from a C4 fraction by extractive distillation using a selective solvent in a dividing wall column (TK) in which a dividing wall (T) is arranged in the longitudinal direction of the column to form a first subregion (A), a second subregion (B) and a lower common column region (C) and which is preceded by an extractive scrubbing column (K), wherein the operation of the dividing wall column (TK) is set by regulation of the energy input into the dividing wall column (TK) via a bottom vaporizer (V) and setting of the number of the theoretical plates in the lower common column region (C) so that a bottom stream (17) consisting of purified solvent is obtained from the dividing wall column (TK), is proposed.

Abstract: A process for fractionating a crude C4 fraction comprising butanes, butenes, 1,3-butadiene and small amounts of other hydrocarbons including C4-acetylenes, by extractive distillation using a selective solvent, wherein the crude C4 fraction (1) is fed into the middle region of a first extractive distillation column (K I) and the selective solvent (2) is fed into the column at a point above that at which the crude C4 fraction (1) is introduced and a gaseous side stream (3) which comprises the C4-acetylenes together with predominantly the selective solvent and in which the concentration of the C4-acetylenes is below the spontaneous decomposition limit is taken off from the first extractive distillation column (K I) at a point below the feed point for the crude C4 fraction (1) and an overhead stream (5) comprising the components which are less soluble than the C4-acetylenes in the selective solvent is taken off from the top of the first extractive distillation column, is proposed.

Abstract: The invention relates to a continuous process for separating a mixture of hydrocarbons which has been obtained by extractive distillation of a C4 fraction (C4) using a selective solvent (LM) and comprises the hydrocarbons from the C4 fraction (C4) which are more readily soluble in the selective solvent (LM) than are the butanes and the butenes. The mixture is fed into a first distillation column (K I) in which it is separated into a stream (K I-K) which is taken off at the top and comprises 1,3-butadiene, propyne, possibly further low boilers and possibly water and a bottom stream (K I-S) comprising 1,3-butadiene, 1,2-butadiene, acetylenes and possibly further high boilers, with the proportion of 1,3-butadiene in the bottom stream (K I-S) from the distillation column (K I) being regulated in such a way that it is at least sufficiently high to dilute the acetylenes to outside the range in which there is a risk of spontaneous decomposition.

Abstract: A process for fractionating a starting mixture of two or more components by extractive distillation using a selective solvent in a dividing wall column aligned in the longitudinal direction of the column and extending to the upper end of the column and dividing the column interior into a first region, a second region, and a lower combined column region. The starting mixture is fed into the first region, a first top stream is taken off from the first region, and a second top stream is taken off from the second region, each stream having a prescribed specification. The selective solvent is introduced in the upper part of the first region and/or in the upper part of the second region, and solvent flow into the first region and/or solvent flow into the second region are set so that each of the prescribed specifications for the top streams are met.

Abstract: A continuous process for isolating butenes from a C4 fraction comprising butanes, butenes and other C3-C5-hydrocarbons by extractive distillation using a selective solvent (LM), comprising a first process stage I in a scrubbing zone (E) and a second process stage II in a degassing zone (A), wherein the liquid or a substream of the liquid is taken off from the degassing zone (A) at a theoretical plate located one or more theoretical plates below the feed point for the bottom stream (LM/C4H8) from the scrubbing zone (E), heated and/or vaporized by indirect heat exchange with the hot bottom stream (LM) from the degassing zone (A) and returned to the degassing zone (A) at the same theoretical plate or above this, with the theoretical plate from which the liquid or substream of liquid is taken off being selected so that the total energy requirement in the process stages I and II is minimized, is proposed.

Abstract: A process for isolating acrylic acid forward during catalytic gas phase oxidation of propene, which entails separating acrylic acid from the gas phase oxidation reaction using an absorbent containing biphenyl, diphenyl ether or dimethyl phthalate; and extracting acrylic acid from acid water of the gas phase reaction with a solvent containing biphenyl, diphenyl ether or dimethyl phthalate.

Abstract: Aqueous glyoxylic acid solutions, essentially free of other acids, are recovered from aqueous solutions which still contain other acids, by a method in which the aqueous solution is mixed with an organic nitrogen compound at as high as 50.degree. C., the phases are separated, and the glyoxylic acid is extracted from the organic phase with water, at a higher temperature.

Abstract: Aqueous solutions of glyoxal which contain acids are purified by treatment with a solution which contains from 20 to 60% by weight of a tertiary amine and from 80 to 40% by weight of an alcohol which is not infinitely miscible with water, the treatment being carried out by mixing the two solutions during a residence time of less than 5 minutes.