Abstract: A process for purifying a crude ester containing dimethyl terephthalate, includes flash distilling a mixture including para-xylene and methyl para-toluate, and separating the crude ester into fractions. By separating the crude ester with a distillation column containing structured packing and using a lower bottom temperature, product yield is increased, and the process is made more economical.

Abstract: Neopentyl glycol hydroxypivalate (NGH) is isolated from a mixture containing NGH, lower- and higher-boiling products and inorganic salts and purified in a two-stage process, whereinin a first separation stage, the inorganic salts and part of the higher-boiling products are separated off in a wiped-film evaporator and a vapor stream consisting of NGH, lower- and higher-boiling products is discharged and fed to a heat exchanger and condensed therein,and, in a second separation stage, the resulting condensate is distilled in a rectification column from which NGH is taken off in a side stream and condensed. Further discharges of the rectification column containing lower-boiling products or higher-boiling products are separately taken off. The higher-boiling products which comprise residual NGH are partly or completely recycled to the lower region of the rectification column.

Abstract: A process for preparing high-purity cyclopropyl methyl ketone from compositions which contain cyclopropyl methyl ketone, 4,5-dihydro-2-methylfuran, addition products of 4,5-dihydro-2-methylfuran by a continuous rectification process in which at least a portion of the composition to be purified is introduced into a rectification apparatus via a side feed located above the bottom portion of the apparatus.

Abstract: A process and apparatus are provided for recovering diluent, unreacted monomer, and unreacted comonomer from a polymerization reactor effluent. The comonomer has a boiling point higher than the boiling point of the monomer and the diluent has a boiling point between the boiling points of the monomer and comonomer. The process and apparatus employ at least one flash tank, a first fractionation stage including a first column and operating at a first fractionation pressure, and a second fraction stage including a second column and operating at a higher second fractionation pressure. Comonomer is withdrawn from the first column as a fractionation product, and overhead vapor containing diluent and monomer is substantially condensed to yield a substantially condensed overhead stream. Liquid and vapor from the stream are separated in an accumulator.

Abstract: 5-Formylvaleric esters are prepared in a yield of not less than 90% by distillation of a formylvaleric ester mixture of 5-formylvaleric ester and either 3- or 4-formylvaleric ester or a mixture of 3- and 4-formylvaleric esters, where the ester radicals of the respective formylvaleric esters are identical, wherein the 3- or 4-formylvaleric ester or a mixture thereof is separated from the 5-formylvaleric ester in a distillation column at a pressure in the range from 2 to 100 mbar and a temperature of not above 150.degree. C. (measured as the temperature at the bottom of the column) and the esters used are the corresponding methyl or ethyl esters, where the purity of the 5-formylvaleric ester is not less than 98% and, as impurity, 4-formylvaleric ester is present in an amount of not more than 100 ppm.

Abstract: Propylene oxide obtained by an epoxidation process which uses methanol as a solvent may be effectively treated to remove acetaldehyde by subjecting the crude epoxidation reaction product to fractional distillation. The methanol solvent is utilized during such distillation to lower the relative volatility of the acetaldehyde impurity, thereby making it possible to obtain a bottoms fraction containing substantially all the acetaldehyde. Purified propylene oxide having a reduced acetaldehyde concentration is removed as an overhead stream. Water may also be effectively separated from the propylene oxide using this procedure.

Abstract: In a process for the purification by distillation of chlorinated aromatic hydrocarbons originating from the chlorination of aromatic hydrocarbons in the presence of FeCl.sub.3, the crude reaction product is first partially degassed and then directly subjected to distillation in the presence of said FeCl.sub.3.

Abstract: A process for recovering processing liquids such as gas-treating liquids wherein a feed mixture containing the processing liquid and components or impurities that are more volatile and less volatile than the processing liquid is initially heated in a first heating zone to a temperature sufficient to volatilize at least one of the more volatile components and a portion of the processing liquid, the temperature being maintained below the decomposition temperature of the processing liquid to produce a vapor stream containing the less volatile component and the vaporized portion of the processing liquid and a residuum containing the processing liquid, a reduced concentration of the more volatile components and the less volatile components, the vapor stream being separated from the residuum in a first separation zone, a portion of the residuum being passed through a second heating zone at a temperature below the decomposition temperature of the processing liquid to produce a first heated recycle stream, the heated

Abstract: Butanol and dibutyl ether are separated from a mixture containing water, dibutyl ether and n-butanol, 2-butanol and/or isobutanol by a process in whicha) the mixture is introduced into a first distillation column, essentially butanol is separated off at the bottom of this distillation column and the mixture taken off at the top of the distillation columnb) is introduced into a second distillation column and essentially dibutyl ether is separated off at the bottom of this second distillation column and the mixture formed at the top of the second distillation column is removed,c) the second distillation column being operated at a higher pressure than the first distillation column and at least one of the two mixtures taken off via the top of the distillation columns being subjected to phase separation, only the organic phase separated off being fed to the second distillation column in the case of phase separation downstream of the first distillation column, and separation into an aqueous and an organic phase als

Abstract: A process for removing tetrahydroazepine from aminocapronitrile or hexamethylenediamine by sequential distillation in which the overhead from the second distillation is combined with a fresh, incoming mixture of tetrahydroazepine and aminocapronitrile or hexamethylenediamine.

Abstract: An extractive distillation agent used for the distillation of propylene oxide contaminated with water, acetone, acetaldehyde and methanol and consisting essentially of ethylene glycol monomethyl ether is fed to an extractive distillation column within about 2 to about 15 stages from the top of the tower to obtain an overhead distillate fraction consisting of essentially anhydrous propylene oxide contaminated with reduced quantities of acetone, acetaldehyde and methanol, and a heavier bottoms distillation fraction containing substantially all of the ethylene glycol monomethyl ether, water and acetone and some of the methanol introduced into the distillation column.

Abstract: A process for the separation of a mixture of a titanium tetrahalide, a reaction diluent of an intermediate boiling point and at least one of a titanium alkoxide, ester or complex thereof without the aid of a distinct separation solvent by subjecting the mixture to a first distillation step to separate the titanium tetrahalide as the lights component and subjecting the heavies product to a second distillation step to recover a portion of the reaction diluent as the lights component.

Abstract: A method for purifying acetic acid containing at least one component selected from the group consisting of unsaturated compounds and carbonyl compounds as an impurity involves the step of purifying the acetic acid with a distillation column having at least 30 plates by operating the distillation column at a pressure ranging from 40 to 760 mmHg and a reflux ratio of at least 4, and yields a high-quality acetic acid which rates high in the potassium permanganate test without needing of the addition of any chemical to the acetic acid to be purified and a large amount of energy, and is economical.

Abstract: A process for the separation of dimethyl ether and chloromethane in mixturesA process for the separation of dimethyl ether and chloromethane in mixtures by two distillation steps. In the first step, the mixture is subjected to an extractive distillation with water, aqueous salt solutions or organic liquids as extractant, the top product being chloromethane. In the second step, the dimethyl ether is separated from the extractant.

Abstract: A process is provided for the isolation of (meth)acrylic acid from a mixture containing (meth)acrylic acid as the main component and lower aldehydes as secondary components by rectification in a rectification column having a stripping section and a rectification section, wherein the starting mixture containing the (meth)acrylic acid to be isolated by rectification is not fed directly to the rectification column but is first passed into a heated dwell vessel which is connected to the vapor side of the rectification section of the rectification column and in which the starting mixture is kept at the boil and, instead of the starting mixture as such, the bottom liquid of the dwell vessel is fed to the rectification column.

Abstract: A process for the preparation and fractionation of a mixture of dimethyl ether and chloromethane by extractive distillation with water as extractant. The mixture is prepared by reacting methanol with hydrogen chloride. It is then subjected to an extractive distillation with water as extractant, resulting in chloromethane as top product. In the next step, the dimethyl ether is removed by distillation and, in another step, the extraction water is separated from the methanol which is still present.

Abstract: An aqueous solution of free hydroxylamine is prepared by a process in which the solution obtained by treating a hydroxylammonium salt with a base is separated into an aqueous hydroxylamine solution and a salt fraction by treatment with water or steam at .ltoreq.80.degree.0 C. The novel process can be carried out in a simple and gentle manner and on a large industrial scale. Owing to the low thermal load, the low concentration of hydroxylamine and the short residence time in the process, the risk of decomposition is minimized.

Abstract: The disclosure relates to separating 1,1,1-trifluoroethane (HFC-143a from fluorocarbon impurities by using extractive distillation with an extractive agent comprising an alcohol. Examples of suitable extractive agents comprise at least one member from the group of methanol, butanol, ethanol, propanol, their isomers and cyclic compounds thereof, among others.

Abstract: A process for preparing bisphenol A which has a purity of at least 99.95 wt. % of p,p-bisphenol A (BPA). Thermally stable and colour-stable BPA purified in accordance with the invention produces improved thermal and colour stability and improved optical transparency in polymers such as e.g. polycarbonates prepared therefrom.

Abstract: The present invention provides a method for separating dichlorodifluoromethane from difluoromethane. More specifically, a process is provided for separating dichlorodifluoromethane and difluoromethane using azeotropic distillation.

Abstract: In the purification of an aqueous acetone-contaminated propylene oxide feedstock in an extractive distillation column in the presence of an oxyalkylene glycol extractive distillation agent under distillation conditions selected to promote the formation and maintenance of an acetone buffer in the distillation column, a higher boiling (heavier) distillation fraction containing substantially all of the oxyalkylene glycols, water, and acetone introduced into the extractive distillation column is continuously withdrawn and the higher boiling (heavier) distillation fraction is partially vaporized in a first reboiler; the remaining liquid being partially vaporized in a second reboiler and the vapors being recycled to the extractive distillation column.

Abstract: A process for removing trioxane from a liquid mixture containing trioxane, water and formaldehyde, which includes distilling the liquid mixture in a first distillation stage at a low pressure, distilling the resulting distillate in a second distillation stage at a higher pressure and taking off trioxane as bottom product.

Abstract: A process for the recovery of a carbonylation product from a liquid reaction composition of an iridium-catalysed carbonylation reaction of a carbonylatable reactant includes subjecting the composition to a vaporization with or without the addition of heat to produce a vapor-fraction and a liquid fraction, the vapor fraction includes carbonylation product and the liquid fraction has a water concentration of at least 0.5% by weight to stabilise the iridium catalyst.

Abstract: An improved urea recovery process is presented. In the improved process, multiple vacuum rated surface condensers used to condense water vapor evolved during urea vacuum evaporation/concentration are replaced by a direct contact cooler/absorber to obtain substantial capital and utility cost savings. Improved heat exchange efficiency of the present process significantly reduces cooling water usage in comparison to the surface condensers.

Abstract: Amine mixtures generated during the production of diaminotoluene by hydrogenating dinitrated aromatic compounds are treated to separate high boiling materials from the desired amine products. In this process, any water of reaction and any solvent are first removed from the diaminotoluene isomer mixture (TDA mixture). The low-boiling TDA isomers are then separated using a TDA isomer distillation column. In the process of the present invention, the bottom phase remaining after the initial distillation contains a mixture of m-TDA and high-boiling materials. This bottom phase is separated and concentrated until the high-boiling material content is from approximately 25 to 60 wt. %. This concentrated bottom phase is then mixed with o-TDA in a ratio of 1:1 to 1:5 and a m-/o-TDA mixture is removed by distillation. The m-/o-TDA mixture thus recovered is then returned to the TDA isomer distillation column.

Abstract: A process for the separation of hydrogen fluoride (HF) and of difluoromethane (F32) by fractional distillation and/or condensation, in at least one stage, including in at least one stage obtaining a stream whose HF and F32 contents correspond.

Abstract: Impure 2,6-diisopropylphenol (DIP) is purified by use of a distillation process in which a single distillation column is used. The process comprises: (a) subjecting the impure DIP to a first continuous distillation in the column in an inert environment to distill off lower boiling components and produce first column bottoms enriched in DIP; (b) collecting, cooling and storing the first column bottoms while continuously maintaining them in an inert environment; (c) discontinuing the first continuous distillation; (d) subjecting the first column bottoms to a second continuous distillation in an inert environment in the same column to produce a second overhead distillate composed of purified DIP. The process avoids the formation in the distilling mixtures of dose boiling impurities due to seepage of air through standard pipe flanges and fittings and consequent oxidation reactions which occur under the conditions needed for batch distillations conducted in typical industrial distillation facilities.

Abstract: A process for preparing essentially pure 3-chlorophthalic anhydride from a mixture in which 3-chlorophthalic anhydride is present in addition to 4,5-dichlorophthalic anhydride, which involves first distilling off a mixture of 3-chlorophthalic anhydride and 4,5-dichlorophthalic anhydride, so that the obtained bottoms is essentially free of 4,5-dichlorophthalic anhydride, and then by distillation of the obtained bottoms, recovering 3-chlorophthalic anhydride in a second distillation step. The starting mixture is preferably prepared without solvent in a melt by incomplete chlorination of phthalic anhydride using FeCl.sub.3 as a catalyst.

Abstract: An extractive distillation process using a high boiling polyol such as glycerol is employed for separating high purity catechol, 3-methylcatechol and 4-methylcatechol from a high boiling, pitch-like dihydric phenol fraction. Fractional distillation first separates an impure overhead mixture of the catechol and 3-methylcatechol and an impure 4-methylcatechol bottoms. The impure overhead is extractively distilled to remove impurities and then extractively distilled again to separate the catechol and 3-methylcatechol. This produces a pure overhead of 3-methylcatechol and a bottoms of catechol and polyol which is distilled to recover the catechol and recycle the polyol. The impure 4-methylcatechol is distilled to remove residual material and then extractively distilled to remove impurities. The resulting mixture of 4-methylcatechol and polyol is distilled to recover the pure 4-methylcatechol and to recycle the polyol.

Abstract: Disclosed is an improved process for the preparation of tocotrienol/tocopherol blend concentrates from vegetable oil distillates which are enriched in tocotrienols. Tocotrienol/tocopherol blend concentrates are obtained containing 20-80% tocotrienols/tocopherols by weight, with an overall recovery of tocotrienols/tocopherols of 72% to 97%. The process is comprised first of an esterification reaction where the more volatile alcohols are converted to their less volatile fatty acid esters, followed by a series of distillation steps where components boiling higher and lower than the tocotrienols/tocopherols are separated from tocotrienols/tocopherols and other like boiling substances. Advantages of the process are that tocotrienol/tocopherol blend concentrates are produced efficiently and economically in a minimum number of steps without the use of solvents and with a relatively small capital investment.

Abstract: A tertiary butyl hydroperoxide reaction product is distilled to provide a tertiary butyl alcohol distillation fraction containing tertiary butyl alcohol and a heavier fraction containing unreacted tertiary butyl hydroperoxide, and reaction by-products boiling below tertiary butyl alcohol, the tertiary butyl alcohol fraction is charged to a vacuum distillation column for separation into a vaporized overhead tertiary butyl alcohol fraction that is cooled to obtain a liquefaction product containing a minor amount of vaporized tertiary butyl alcohol and a major amount of a liquified tertiary butyl alcohol, andthe tertiary butyl alcohol vapors are dissolved in water to form an aqueous solution of tertiary butyl alcohol from which the tertiary butyl alcohol is recovered.

Abstract: In a solvent recovery plant including a recovery or distillation tower from which solvent product is recovered overhead, an isothermal separator, preferably a cyclone, is used to separate liquid phase contaminant (i.e. oil in a lubricating oil extraction process) in overhead product and to feed the separated liquid to the recovery tower as reflux. In addition, a portion of the feed to the tower can be branched off and mixed with the overhead product to bring its temperature down to close to the dew point of the solvent vapor. In this way, flooding of the uppermost tower trays and distillation of oil overhead can be overcome.

Abstract: The invention relates to a process for separating 1,1-difluoroethane from its mixtures with hydrogen fluoride, in which the mixture is subjected to a distillation in a column operating at a pressure of less than 10 bar.

Abstract: A process for treating an aqueous solution mainly containing nitric acid and hydrofluoric acid. The process involves distilling to provide an aqueous solution concentrated in nitric acid and hydrofluoric acid for the separation thereof, then separating by distillation.

Abstract: A method for separating boric acid from a liquid, especially liquid waste obtained from a nuclear power plant. In the method, the waste solution containing the boric acid is contacted with steam in a reactor so that the boric acid evaporates from the liquid and passes into the steam vapor phase. Consequently, the radioactive wastes which are not evaporated with the steam remain in the waste water while the boric acid is removed from the waste water when it passes into the vapor or steam phase. The boric acid can then be separated and recovered from the steam by means of a distillation and fractionating column or a wash column. By removing the boric acid from the liquid waste, it is possible to obtain concentrated radioactive waste having a reduced volume due to the absence of boric acid in the waste.

Abstract: A method for the separation and purification in a single pass of a heat or oxygen-sensitive liquid feed, such as a plant derived liquid feed mixture of fatty acids, tocopherol compounds and sterols, into a low boiling point purified fraction of Vitamin E tocopherol compounds and a high boiling point concentrate fraction of triglycerides, which method can be maintained in the presence of an inert gas to provide reduced degradation and increased purity of the Vitamin E fraction.

Abstract: A distillation process and apparatus for recovering high purity aromatic products from a mixed aromatic hydrocarbon feedstock containing benzene, toluene and xylene by use of distillation towers integrated by heat exchange whereby substantial savings in operating costs and apparatus costs are realized. The distillation apparatus includes a benzene distillation tower and heat exchanger, a first toluene distillation tower and external heater, a second toluene distillation tower and heat exchanger and a xylene distillation tower and external heater, whereby the benzene distillation tower and heat exchanger are operably connected to the first toluene distillation tower and external heater and the second toluene distillation tower and heat exchanger are operably connected to the xylene distillation tower and external heater.

Abstract: In the multistage distillation of a methyl tertiary butyl ether reaction product comprising methyl tertiary butyl ether, tertiary butyl alcohol, methanol, isobutylene and water, the methyl tertiary butyl ether reaction product is separated in a primary methyl tertiary butyl ether distillation column into a lower boiling methyl tertiary butyl ether fraction and a higher boiling aqueous tertiary butyl alcohol fraction; the lower boiling aqueous tertiary butyl alcohol fraction is separated in a tertiary butyl alcohol distillation column into a vaporized overhead tertiary butyl alcohol fraction and a higher boiling water fraction; cooling water is charged to the reflux condenser for the tertiary butyl alcohol distillation column to liquify the vaporized, overhead tertiary butyl alcohol fraction and to convert the cooling water to wet steam, and the wet steam is independently charged to the reboiler for the primary methyl tertiary butyl ether distillation zone to supply the heat necessary for the distillation to b

Abstract: A process for producing 5-vinyl-2-norbornene which comprises the steps of subjecting a liquid raw material in which tetrahydroindene/dicyclopentadiene ratio (by weight) falls within the range of from 5/100 to 80/100 to a thermal decomposition in liquid phase in the presence of an aromatic hydrocarbon solvent having a boiling point of from 250.degree. C. to 300.degree. C. at a reaction temperature of not lower than 200.degree. C. and lower than 240.degree. C.

Abstract: An improved process for azeotropic distillation of chloral to anhydrous chloral containing as little as 0.1% water. An azeotropic mixture is used which contains chloral in at least a 1.4:1 ratio with the concentration (% of weight) of a azeotropic agent (preferably ethylene dichloride). The feed stream may contain other components, but will contain at least 60% chloral and less than 40% water. Preferably, the feed stream is substantially free of components other than choral and water. Water is removed from the overhead product of the azeotropic and EDC separation distillations periodically or continuously throughout the process. The azeotropic agent is preferably separated from the anhydrous chloral product. This separation may be performed in the azeotropic distillation column or in a separate distillation column.

Abstract: A process for making and purifying dipropylene glycol tert-butyl ethers (DPTB). DPTB is made by reacting dipropylene glycol with isobutylene in the presence of an acidic catalyst. Extractive distillation of the product mixture using a glycol extracting agent, preferably dipropylene glycol, allows removal of di-tert-butyl ether impurities as an overhead product. The DPTB product is then distilled to separate it from the glycol extracting agent. High-purity DPTB, substantially free of diethers and exceptionally useful as a solvent, is obtained from the process.

Abstract: A process is provided whereby phenol is separated from 1-phenyl ethanol, acetophenone or mixtures by extractive distillation with sulfolane as extractive distillation agent which decreases phenol volatility relative to 1-phenyl ethanol and acetophenone.

Abstract: For the regeneration of a liquid desiccant, a stripping agent is used which is liquid at ambient temperature and pressure, and forms a heteroazeotrope with water, along with the following steps: (a) distillation of the water-laden liquid desiccant to form vapor and partially regenerated liquid desiccant; (b) reboil partially regenerated liquid desiccant; (c) stripping of partially regenerated liquid desiccant during (a) and (b), using vaporized stripping agent; (d) a condensing of vapor the exiting the distillation, the condensation producing two liquid phases, one mainly water and the other mainly stripping agent; (e) heating the stripping agent-rich liquid phase exiting step (d) to generate a vapor phase which is richer in water than said liquid phase and a water-depleted liquid phase; and (f) returning the vaporized liquid phase exiting step (e) to step (c).

Abstract: A distillation method for the purification of crude propylene oxide containing contaminating quantities of water and methanol by partially purifying the crude propylene oxide in a plural stage distillation zone to provide a vaporized overhead distillate propylene oxide fraction containing a minor contaminating amount of vaporized water, andpassing the propylene oxide vapor fraction through a drying chamber containing a porous hygroscopic solid absorbent to selectively absorb water vapor onto the absorbent,and liquefying and recovering the thus-dehydrated purified propylene oxide.

Abstract: A novel process for the recovery of tocopherols and sterols from natural, especially vegetable, sources. This process is especially a process for the separation of tocopherols and sterols from deodorizer sludges by distillation of these deodorizer sludges, in that prior to the distillation the sterols present in the deodorizer sludge are esterified with the fatty acids which are also present, the resulting mixture is distilled to obtain residual fatty acids and subsequently to obtain tocopherols, whereby the sterol esters formed in the esterification remain in the residue of this distillation, and then the tocopherols are isolated from the distillate and the sterols, after cleavage of their esters, are isolated from the distillation residue.

Abstract: An apparatus for extracting, concentrating, and separating biochemical compounds from plant or animal biological substances. It has a heating vessel for the substance to be treated, and is connected at its lower part to an evaporation circuit. The evaporation circuit is connected to the upper part of the heating vessel and, by a valve, to the bottom of a distillation column. A condenser is connected to a vacuum source and, by a valve to the top of the distillation column. A decanter is connected by a valve to the condenser and then successively to a first tank for recovering essential oil, a second tank for recovering aromatic water, and to the vacuum source. A dual discharge circuit has its first circuit connected by two valves to a third tank for receiving light aromatic compounds and to a fourth tank for receiving regenerated solvents.

Abstract: The present invention provides a method for separating boric acid from a liquid, especially liquid waste obtained from a nuclear power plant. In the process, the waste solution containing the boric acid is contacted with steam in a reactor so that the boric acid evaporates from the liquid and passes into the steam vapor phase. Consequently, the radioactive wastes which are not evaporated with the steam remain in the waste water while the boric acid is removed from the waste water when it passes into the vapor or steam phase. The boric acid can then be separated and recovered from the steam by means of a distillation and fractionating column or a wash column. By removing the boric acid from the liquid waste, it is possible to obtain concentrated radioactive waste having a reduced volume due to the absence of boric acid in the waste.

Abstract: Propylene oxide adducts of oxyethylene glycols are used as extractive distillation agents in an extractive distillation column in the distillation of propylene oxide contaminated with water, acetone and methanol to obtain an overhead propylene oxide distillate fraction contaminated with reduced quantities of water, acetone and methanol, and a heavier bottoms distillation fraction containing substantially all of the extractive distillation agent, and acetone and some of the methanol and water introduced into the distillation column.

Abstract: A procedure for the recovery of phenol from its mixtures containing cumene and alpha-methylstyrene, is based on the extractive distillation of the mixtures with acetophenone.

Abstract: An extractive distillation agent comprising a mixture of polyoxypropylene glycols is fed to an extractive distillation column used for the distillation of propylene oxide contaminated with water, acetone and methanol to obtain an overhead distillate anhydrous propylene oxide fraction contaminated with reduced quantities of methanol and a heavier bottoms distillation fraction containing the polyoxypropylene glycols, water and acetone and some of the methanol introduced into the distillation column.