摘要:
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.
摘要:
In a process for the continuous fractional distillation of mixtures comprising tetrahydrofuran, γ-butyrolactone and/or 1,4-butanediol to give at least three fractions, the fractionation is carried out in an assembly of distillation columns comprising at least one dividing wall column or at least one assembly of thermally coupled conventional distillation columns.
摘要:
In a process for purifying an organic solvent for the absorption of maleic anhydride from a gaseous mixture, in which the maleic anhydride is separated off from the solvent, a substream is taken from the solvent stream, this substream is distilled and returned to the solvent circuit, the proposed improvement comprises separating off a low-boiling fraction and a high-boiling fraction from the fraction consisting essentially of purified solvent and feeding the fraction consisting essentially of purified solvent back into the solvent stream.
摘要:
In a process for preparing 1,4-butanediol, tetrahydrofuran and &ggr;-butyrolactone by oxidation of butane to give a product stream comprising maleic anhydride, absorption of maleic anhydride from the product stream using a high-boiling alcohol to give a liquid absorption product comprising monoesters and diesters of maleic acid and also high-boiling alcohol, after-esterification of the liquid absorption product and subsequent hydrogenation of the after-esterified product in the liquid phase, the high-boiling alcohol is a polyhydric alcohol having a boiling point at atmospheric pressure of above 233° C. and the after-esterified product has an acid number of less than 30 mg KOH/g and a water content of less than 1% by weight.
摘要:
A process for preparing 1,4-butanediol and, if desired, &ggr;-butyrolactone and THF by oxidizing butane or benzene to form a product stream including maleic anhydride, absorbing maleic anhydride from the product stream with a high-boiling inert solvent in an absorption stage to give a liquid absorption product, esterifying the liquid absorption product with a C1-C5 esterifying alcohol in an esterification stage to form an esterification product comprising the corresponding diester and high-boiling inert solvent, then hydrogenating the esterification product to give a hydrogenation product which comprises the products of value, 1,4-butanediol and, if desired, &ggr;-butyrolactone and tetrahydrofuran and the esterifying alcohol and which is separated by distillation into the products of value and the esterifying alcohol, and recycling the esterifying alcohol to the esterification zone, which comprises separating the esterification product into the diester and the inert solvent by distillation under reduced pressure prior to the hydrogenation, recycling the inert solvent to the absorption stage, and hydrogenating the diester in the liquid phase over a fixed-bed catalyst.
摘要:
In a process for carrying out an exothermal reaction, selected from the addition reaction of organomagnesium halide compounds to carbonyl compounds and the ensuing hydrolysis of the addition product, a considerable fraction of the heat liberated during the reaction is removed by evaporation of the solvent.
摘要:
Apparatus and processes for continuous distillative separation of a mixture comprising one or more alkanolamine(s) are described. The separation is performed in one or more dividing wall column(s) and the alkanolamine or the alkanolamines is/are withdrawn as a side draw stream or side draw streams (side fraction(s)).
摘要:
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 column. The maleic anhydride obtained as a side draw has a low content of acrylic acid and acetic acid.
摘要:
A process is described for continuously hydrogenating unsaturated compounds, in which particles of a first hydrogenation catalyst are suspended in a liquid phase in which an unsaturated compound is dissolved, the liquid phase, in the presence of a hydrogenous gas at a first partial hydrogen pressure and at a first temperature, is conducted through a packed bubble column reactor in cocurrent counter to the direction of gravity, the effluent from the bubble column reactor is sent to a gas-liquid separation, the liquid phase is sent to a crossfiltration to obtain a retentate and a filtrate, the retentate is recycled into the bubble column reactor and the filtrate, in the presence of a hydrogenous gas at a second partial hydrogen pressure and at a second temperature, is passed over a bed of a second hydrogenation catalyst, wherein the second partial hydrogen pressure is at least 10 bar higher than the first partial hydrogen pressure.
摘要:
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).