Abstract: Apparatus for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a stream containing hydrocarbons having at least 4 carbon atoms per molecule, which includes a reactor with reaction tubes into which a solid-state catalyst over which the exothermic reaction of the stream with an oxygen-comprising gas stream takes place is introduced and one or more pumps and heat exchangers located outside the reactor and through which a heat transfer medium formed by a salt melt flows through the intermediate space in the reactor between the reaction tubes and takes up the heat of reaction, with the temperature of the melt being in the range from 350 to 480° C. The reaction tubes are made of a heat-resistant alloy steel which includes at least 0.5% by weight of chromium or at least 0.25% by weight of molybdenum or both.

Abstract: A process is provided for recovering components from a low boiler mixture which is obtained in the distillation of hydrogenation effluents from the preparation of polymethylols, by multistage distillation of the low boiler mixture having a tertiary amine, water, methanol, a polymethylol, a methylolalkanal, an alcohol and an alkanal with a methylene group in the alpha position to the carbonyl group. A first distillation stage involves separating the low boiler mixture into a higher-boiling, predominantly water-rich fraction and into a lower-boiling aqueous organic fraction having the tertiary amine. A second distillation stage involves separating the aqueous organic fraction from the first distillation stage into a predominantly amine-containing fraction and a further amine-depleted fraction. The tertiary amine is trimethylamine or triethylamine and the bottom temperature in the second distillation stage is at least 110° C.

Abstract: The present invention relates to a process for distilling an aqueous polymethylol mixture which comprises a polymethylol of the formula (I) (HOCH2)2—C—R2??(I) in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, a tertiary amine, water and the adduct of tertiary amine and formic acid (amine formate), which comprises performing the distillation in a distillation column which is connected at the bottom to an evaporator, the bottom temperature being above the evaporation temperature of the monoester of formic acid and polymethylol (polymethylol formate) which forms during distillation. The present invention further relates to a composition comprising polymethylol and 1 to 10 000 ppm by weight of polymethylol formate, and to the use thereof.

Abstract: The present invention relates to a process for preparing neopentyl glycol (NPG) by continuously hydrogenating hydroxypivalaldehyde (HPA) with hydrogen, in the liquid phase, in the presence of a hydrogenation catalyst, in a hydrogenation reactor (5), by combining an HPA-comprising stream (1) with an NPG-comprising stream (2) to give a hydrogenation feed (4) and introducing the hydrogenation feed (4) into the hydrogenation reactor (5) and additionally supplying at least one pH regulator (3) selected from the group consisting of tertiary amine, an inorganic base, an inorganic acid and an organic acid to the HPA-comprising stream (1) or the NPG-comprising stream (2) or the hydrogenation feed (4), in order to establish a pH of 7.0 to 9.

Abstract: The present invention relates to a process for purifying crude polymethylol which comprises polymethylol of the formula (I) (HOCH2)2—C—R2??(I) in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, and also hydroxy acid of the formula (IV) in which each R is independently as defined above, which comprises performing the purification in a distillation column, the bottom of the distillation column being connected to an evaporator with a short residence time. The present invention further relates to a composition comprising polymethylol and 1 to 10 000 ppm by weight of an ester of polymethylol and of a hydroxy acid and to the use thereof.

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: A process for distilling an aqueous NPG mixture comprising NPG, a tertiary amine, water and the adduct of tertiary amine and formic acid (amine formate), said distillation being performed in a distillation column, which comprises drawing off a gaseous stream in the upper region of the column and feeding it to two condensers connected in series, the first condenser being operated in such a way that a portion of the gaseous stream is condensed in the first condenser and the second condenser being operated in such a way that the uncondensed portion of the gaseous stream is essentially fully condensed in the second condenser, the condensed stream from the first condenser being recycled fully or partly as reflux into the column.

Abstract: The present invention relates to a process for preparing hydroxypivalaldehyde (HPA), which comprises in a first stage reacting isobutyraldehyde with formaldehyde in the presence of a tertiary amine and in a second stage introducing the reaction output obtained from the first stage into a stripping column. The present application further relates to a process for preparing neopentyl glycol (NPG) by hydrogenating the hydroxypivalaldehyde prepared in accordance with the invention and the further conversion of the NPG thus obtained to polyester resins, unsaturated polyester resins, lubricants or plasticizers.

Abstract: The present invention relates to a process for distilling an aqueous polymethylol mixture which comprises a polymethylol of the formula (I) (HOCH2)2—C—R2??(I) in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, a tertiary amine, water and the adduct of tertiary amine and formic acid (amine formate), which comprises performing the distillation in a distillation column which is connected at the bottom to an evaporator, the bottom temperature being above the evaporation temperature of the monoester of formic acid and polymethylol (polymethylol formate) which forms during distillation. The present invention further relates to a composition comprising polymethylol and 1 to 10 000 ppm by weight of polymethylol formate, and to the use thereof.

Abstract: The present invention relates to a process for purifying crude polymethylol which comprises polymethylol of the formula (I) (HOCH2)2—C—R2 ??(I) in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, and also hydroxy acid of the formula (IV) in which each R is independently as defined above, which comprises performing the purification in a distillation column, the bottom of the distillation column being connected to an evaporator with a short residence time. The present invention further relates to a composition comprising polymethylol and 1 to 10 000 ppm by weight of an ester of polymethylol and of a hydroxy acid and to the use thereof.

Abstract: The present invention relates to a process for preparing neopentyl glycol (NPG) by continuously hydrogenating hydroxypivalaldehyde (HPA) with hydrogen, in the liquid phase, in the presence of a hydrogenation catalyst, in a hydrogenation reactor (5), by combining an HPA-comprising stream (1) with an NPG-comprising stream (2) to give a hydrogenation feed (4) and introducing the hydrogenation feed (4) into the hydrogenation reactor (5) and additionally supplying at least one pH regulator (3) selected from the group consisting of tertiary amine, an inorganic base, an inorganic acid and an organic acid to the HPA-comprising stream (1) or the NPG-comprising stream (2) or the hydrogenation feed (4), in order to establish a pH of 7.0 to 9.

Abstract: The present invention relates to a process for recovering components from a low boiler mixture which is obtained in the distillation of hydrogenation effluents from the preparation of polymethylols, by multistage distillation of the low boiler mixture comprising a tertiary amine, water, methanol, polymethylol of the formula (I) methylolalkanal of the formula (II) alcohol of the formula (III) and an alkanal with a methylene group in the ? position to the carbonyl group, and in which each R is independently a further methylol group or an alkyl group having 1 to 22 carbon atoms or an aryl or aralkyl group having 6 to 22 carbon atoms, a first distillation stage involving separating the low boiler mixture into a higher-boiling, predominantly water-rich fraction and into a lower-boiling aqueous organic fraction comprising the tertiary amine, and the second distillation stage involving separating the aqueous organic fraction from the first distillation stage into a predominantly amine-containing fract

Abstract: An apparatus for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a feed stream comprising hydrocarbons having at least 4 carbon atoms per molecule, which comprises a reactor having a bundle of reaction tubes into which a solid-state catalyst over which the exothermic reaction of the feed stream with an oxygen-comprising gas stream takes place has been introduced and also one or more. pumps and one or more heat exchangers which are located outside the reactor and through which a heat transfer medium formed by a salt melt flows through the intermediate space in the reactor between the reaction tubes and takes up the heat of reaction, with the temperature of the salt melt being in the range from 350 to 480° C., wherein the reaction tubes are made of a heat-resistant alloy steel which comprises either at least 0.5% by weight of chromium or at least 0.25% by weight of molybdenum or at least 0.5% by weight of chromium and at least 0.25% by weight of molybdenum, is proposed.

Abstract: The preparation of hydroxypivalaldehyde is effected by aldolizing isobutyraldehyde with formaldehyde and subsequently working up the resulting reaction effluent by distillation, wherein the reaction effluent is fed to a distillation column which is operated at a top pressure in the range from 0.5 to 1.5 bar and in which a two-stage condensation is provided in the top region, in which the vapors are first conducted into a partial condenser operated at a temperature in the range from 50 to 80° C., whose condensate is recycled at least partly into the distillation column, and in which the vapors uncondensed in the partial condenser are fed to a downstream condenser operated at a temperature in the range from ?40 to +30° C., whose condensate is at least partly discharged.

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 preparation of hydroxypivalaldehyde is effected by aldolizing isobutyraldehyde with formaldehyde and subsequently working up the resulting reaction effluent by distillation, wherein the reaction effluent is fed to a distillation column which is operated at a top pressure in the range from 0.5 to 1.5 bar and in which a two-stage condensation is provided in the top region, in which the vapors are first conducted into a partial condenser operated at a temperature in the range from 50 to 80° C., whose condensate is recycled at least partly into the distillation column, and in which the vapors uncondensed in the partial condenser are fed to a downstream condenser operated at a temperature in the range from ?40 to +30° C., whose condensate is at least partly discharged.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises compressing 1,4-butynediol to from 50 to 1500 bar, depressurizing it, waiting for phase separation to occur after depressurization and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.

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

Abstract: The present invention relates to processes for making 1,4-butanediol, 1,4-butenediol, or a mixture thereof by processing 1,4-butynediol in a dynamic mixing apparatus in an inert gas atmosphere at from 25 to 150° C. at a shear rate in the radial gap between rotor and stator of the mixing apparatus of more than 100 000 sec?1; phase separating the processed 1,4-butynediol at a temperature of from 25 to 150° C.; removing a bottom phase to obtain purified 1,4-butynediol; and reacting the purified 1,4-butynediol with hydrogen in the presence of a catalyst.

Abstract: The present invention relates to a process for purifying 1,4-butynediol, which comprises compressing 1,4-butynediol to from 50 to 1500 bar, depressurizing it, waiting for phase separation to occur after depressurization and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.