Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boils and high boils is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b). which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).

Abstract: In the purification of an easily polymerizable compound such as (meth)acrylic acid by the use of a purification column adapted to withdraw a liquid from the middle portion of the column, a novel liquid withdrawing tray adapted to prevent the compound from polymerization effectively and permit the purification to be stably performed for a long time, a purification column using this tray, and a method for purifications using this purification column are provided. The liquid withdrawing tray for the purification column is composed of a liquid receiving plate and a liquid withdrawing tube for withdrawing the liquid from the liquid receiving plate.

Abstract: A process for recovering carboxylic acids from an aqueous mixture such as a fermentation broth using a solvent containing at least one olefin without the need for first removing the spent microorganism cells is provided. A co-solvent which increases the partition coefficient of the solvent relative to the carboxylic acid may optionally be included.

Abstract: In a centrifugal evaporator for evaporating a mixture of liquids having different volabilities and specific gravities, the mixture being contained in a test tube 14 pivotally mounted on a rotatable support arm 12 in a sealable vacuum chamber 16, the support arm is rotated up to a speed of the order of 2000 rpm before evaporation of the more volatile component occurs, and only then is the chamber progressively evacuated. The motor is preferably a three-phase induction motor connected to the electric supply in a frequency convertor.

Abstract: Process for purifying acrylic acid in order to remove the polymer-type impurities in those places in the distillation columns in which they have a tendency to accumulate, and more particularly a process directed towards removing the polymeric impurities which are formed during a step for removing the aldehyde impurities from acrylic acid, according to which step the medium containing the acrylic acid to be purified is distilled by adding to this medium at least one amino compound of hydrazine type and by flushing away, at the foot of the distillation column, the heavy compounds formed by the said hydrazine-type amino compound(s) with the impurities. According to the invention, the acrylic acid to be purified is also distilled in the presence of at least one compound from the class of nonionic surface agents and of at least one polymerization inhibitor. Polysaccharide ethers and acetates, in particular ethers derived from cellulose or starch, may be mentioned as nonionic surface agents.

Abstract: A process for distillative separation of pure (meth)acrylic acid from mixtures which include comprise (meth)acrylic acid and dimers and oligomers of (meth)acrylic acid and are essentially free from aldehydes and from components whose boiling point is lower than that of (meth)acrylic acid, using a distillation apparatus which has a thin-film evaporator, a condenser and a connection which contains a baffle device and links the thin-film evaporator and the condenser.

Abstract: A process for the continuous recovery of (meth)acrylic acid from the reaction gases of a catalytic gas-phase oxidation by (I) absorption in a high-boiling solvent, (II) isolation of the (meth)acrylic acid from the mixture with the solvent and, if required, further purification of the (meth)acrylic acid isolated, (III) purification of the solvent and (IV) recycling of the purified solvent to absorption stage (I) is proposed, the temperature in each process stage not exceeding 155° C., in particular 140° C., preferably 120° C.

Abstract: In a process for the purification of (meth)acrylic acid and/or its ester using a distillation unit containing a distillation column, a multitubular reboiler and a pipe connecting these elements, an oxygen containing gas is supplied from a least one point in regions between the distillation column and an inlet of the multitubular reboiler and/or in regions between the inlet and an inlet side tube sheet of the multitubular reboiler. This process can effectively prevent the formation of polymerization products and can stably purify (meth)acrylic acid and/or its ester over a long time.

Abstract: The geometric isomers of olefins and olefinic compounds are separated by means of liquid chromatography using a stationary phase comprising an organosilane with a pendant aliphatic functional group such as C18 and a mobile phase which includes an additive comprising alkanes and alkenes.

Abstract: A method for starting up a distilling column destined to handle an easily polymerizing compound-containing solution characterized by supplying at the start of the operation of the distilling column a polymerization inhibitor to the bottom liquid of the distilling column having a temperature of not higher than 80° C. Further, by supplying a reflux liquid through the top of the distilling column or the middle stage of the column prior to the start of the temperature elevation of the distilling column, thereby preventing the polymerization of the easily polymerizing compound more effectively.

Abstract: A process for the continuous recovery of (meth) acrylic acid from the reaction gases of a catalytic gas-phase oxidation by (I) absorption in a high-boiling solvent, (II) isolation of the (meth)acrylic acid from the mixture with the solvent and, if required, further purification of the (meth)acrylic acid isolated, (III) purification of the solvent and (IV) recycling of the purified solvent to absorption stage (I) is proposed, the temperature in each process stage not exceeding 155° C., in particular 140° C., preferably 120° C.

Abstract: A process for distillative separation of pure (meth)acrylic acid from mixtures which comprise (meth)acrylic acid and dimers and oligomers of (meth)acrylic acid and are essentially free from aldehydes and from components whose boiling point is lower than that of (meth)acrylic acid, using a distillation apparatus which has a thin-film evaporator, a condenser and a connection which contains a baffle device and links the thin-film evaporator and the condenser.

Abstract: This invention resides in providing a method for the prevention of possible polymerization of the easily polymerizable substance during the purification thereof by a column provided with (a) at least one tray directly fixed to a support ring with a bolt and a nut and/or (b) at least one tray fixed to a support ring with a vertical clamp or a distillation column provided in the lower part thereof with a splash collision plate.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-4.5 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution and a method for purifying acrylic acid, comprising a step for purifying the acrylic acid-containing organic liquid obtained by the step mentioned above. By this invention, a product of acrylic acid containing a low boiling substance at a low concentration can be produced.

Abstract: In a method for distilling (meth)acrylic acid and/or (meth)acrylic ester, the method has the step of uniformly distributing a supply liquid in a distillation tower over an entirety of a horizontal cross sectional area in the distillation tower. A distillation apparatus for distilling (meth)acrylic acid and/or (meth)acrylic ester in a distillation tower has a supply element for supplying the supply liquid into the distillation tower. The supply element is formed with at least two supply ports through which the liquid is supplied into the distillation tower.

Abstract: A method of producing highly purified acrylic acid in a high yield is provided. A method of producing acrylic acid including the steps of an oxidation step, an absorption step, a distillation step, a crystallization step, and a dimer decomposition step.

Abstract: The method consists in extracting acrylic acid by countercurrent filtration washing of reaction gases by at least a hydrophobic absorbing heavy solvent, then recuperating the purified acrylic acid from the solution obtained at the end of this extracting step. As hydrophobic absorbing heavy solvent at least a hydrophobic aromatic compound is used having: a boiling point under atmospheric pressure between 260° C. and 380° C.; a crystallisation temperature less than 35° C. and a viscosity less than 10 mPa·s in a range of temperature between 30-80° C.

Abstract: A method for producing (meth) acrylic acid of high purity by repressing formation of a polymer possibly generated during the course of production is disclosed. The production is accomplished by returning the waste liquid generated at the step of the addition of aldehyde treating agents (d) to the step of the absorption (b) and/or the step of separation (c).

Abstract: There is described a process for the production of a substantially anhydrous salt of an organic acid which comprises reacting a basic compound of a metal with the appropriate organic acid, removing a substantial proportion of water present so as to produce the salt or its hydrate as a liquid phase and then dissolving the liquid phase in a non-aqueous solvent.

Abstract: (Meth)acrylic acid is recovered continuously from the reaction gas containing (meth)acrylic acid, low boilers, medium boilers and high boilers and originating from a catalytic gas-phase oxidation by

Abstract: The present invention provides an industrially easy and economical method for purification of acrylic acid which enables to efficiently eliminate impurities from a crude acrylic acid containing aldehydes as the impurities while the formation of acrylic acid polymer is inhibited.

Abstract: The present invention provides an apparatus for producing (meth)acrylic acid and a process for producing (meth)acrylic acid with this apparatus wherein the apparatus enables to produce (meth)acrylic acid stably for a long period of time by effectively inhibiting the polymerization of (meth)acrylic acid in its production process (for example, in a reboiler). At least a part of the apparatus is made of a nickel-chromium-iron alloy with a molybdenum content of 3 to 20 mass %, but not including 3 mass %, or with a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %.

Abstract: A method for recovering acrylic acid from high boiling impurities containing acrylic acid dimer, acrylic acid and maleic acid at high efficiency with stability which includes the steps of (1) introducing said high boiling impurities containing acrylic acid dimer, acrylic acid and maleic acid into an acrylic acid recovery column, distilling acrylic acid from the column top and recovering the same, (2) introducing bottom liquid A from said acrylic acid recovery column into a pyrolyzing tank to decompose the acrylic acid dimer in the bottom liquid A, and (3) recirculating at least a part of bottom liquid B from said pyrolyzing tank into the acrylic acid recovery column.

Abstract: In a process for the separation by rectification of (meth)acrylic acid from a mixture containing (meth)acrylic acid and an inert hydrophobic organic liquid having a boiling point higher than that of (meth)acrylic acid as main constituents and also lower aldehydes as secondary constituents, a primary amine and/or a salt thereof are added.

Abstract: A distillation column is arranged so that a liquid hole which allows liquid containing a polymerizable organic compound to flow from on a tray supporting member downward is formed in a part of the tray supporting member, for example, a support ring, so that substantial retention of the liquid on the tray supporting member is avoided. Therefore, the liquid, such as crude acrylic acid, is allowed to smoothly flow down from on surfaces of a tray and the tray supporting member, thereby causing no substantial retention of the liquid. As a result, polymerization which tends to occur when the liquid is retained on the surfaces of the tray and the tray supporting member thereby being heated is effectively prevented, and the polymerizable organic compound is efficiently purified.

Abstract: Crude (meth)acrylic acid is purified by a process in which a primary amine compound and an organic sulfonic acid are added to the crude (meth)acrylic acid and the latter is then worked up by distillation.

Abstract: A process for inhibiting free-radical polymerization of an alpha,beta-unsaturated (&agr;,&bgr;-unsaturated) carboxylic acid, and for providing desired grade &agr;,&bgr;-unsaturated carboxylic acid for use following storage and transport is described herein. In particular, bulk storage and shipment such as with overseas transport is described. The process comprises combining the &agr;,&bgr;-unsaturated carboxylic acid with a phenolic inhibitor and a coinhibitor to form an inhibited mixture, storing the inhibited mixture, transporting the inhibited mixture, and removing the coinhibitor to provide the desired grade &agr;,&bgr;-unsaturated carboxylic acid for use. In preferred embodiments, the &agr;,&bgr;-unsaturated carboxylic acid is acrylic acid, the phenolic inhibitor is p-methoxyphenol, the coinhibitor is manganese cation, and removal of the coinhibitor is carried out using an ion exchange resin.

Abstract: Disclosed is a method for recovering acrylic acid from process or waste water streams in which the stream is vaporized and contacted with a liquid high boiling solvent for acrylic acid, thereby absorbing acrylic acid into the solvent. Mixed trialkylphosphine oxides are a preferred solvent. Acrylic acid is stripped from the solvent with heat and, optionally, stripping gas. It may be separated from any accompanying materials to produce acrylic acid of high purity.

Abstract: The present invention concerns a method for producing acrylic acid which involves subjecting an acrylic acid-containing aqueous solution obtained by catalytic vapor phase oxidation of propylene and/or acrolein to evaporation whereby an acrylic acid-containing vapor is obtained; and subjecting the acrylic acid-containing vapor to azeotropic dehydration. The present invention offers a number of advantages including a reduce amount of polymer that may adhere to the surface of an azeotropic dehydration column, a low-blowing separation column or an in a high-boiling separation column in a plant for producing acrylic acid. Consequently, the production plant can be operated for a long time without stopping operations.

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: An improved process for the preparation of 3-pentenoic acid by reaction of butadiene with carbon monoxide and water in the presence of a rhodium-containing catalyst and an iodide promoter where carbon monoxide stripping is employed to separate and recover the 3-pentenoic acid product.

Abstract: An improved method which enables stable and effective recovery of acrylic acid over a prolonged period is provided, said method comprising contacting an acrylic acid-containing gas obtained upon gas-phase catalytic oxidation of propylene and/or acrolein, with water, whereby collecting the acrylic acid in form of an aqueous solution, introducing said aqueous solution into an azeotropic separation column and distilling it in the presence of an azeotropic solvent to isolate and recover the acrylic acid, in which polymerization of the acrylic acid in the azeotropic separation column is prevented. Said method is characterized by using as the azeotropic solvent either a mixed solvent composed of solvent A (eg., ethyl acrylate, methyl methacrylate, etc.) and solvent B (eg., toluene, heptane, etc.) (first embodiment) or the solvent A alone (second embodiment).

Abstract: Broadly, the present invention is directed to a process for the removal of sulfur from an acrylate stream. In particular, disclosed is a process for the recovery and reuse of an acid catalyst employed primarily in the reaction to form acrylic esters. Reaction end components which include the acid catalyst employed in the reaction process, are directed to an extractor for contact with water. Upon contact with water, a phase separation occurs between the acid catalyst/water mixture and other organic matter. The organic matter is sent forward for product purification while the acid/water mixture is recycled to the reaction process.The present invention employs the use of an extractor to aid in the separation of the acid catalyst from the reaction by-products. This removal of acid results in fewer organic sulfur components to be emitted from the reaction process and hence is a more environmentally friendly process.

Abstract: 1,4-Dibenzothiazine-comprising crude acrylic acid is purified by crystallization by raising its diacrylic acid content to at least 1% by weight prior to the crystallization step.

Abstract: The invention is directed toward preparation of (meth)acrylic acid, comprising condensation of a gas comprising (meth)acrylic acid, absorption with water, and extraction with an aqueous solution forming a miscibility gap.

Abstract: Compounds having the active site of natural lipoxins, but a longer tissue half-life are disclosed. In particular, 15-epi-lipoxins and their use in ameliorating undesired cell proliferation, which characterizes diseases such as cancer, are also disclosed.

Abstract: A process for inhibiting free-radical polymerization of an alpha,beta-unsaturated (.alpha.,.beta.-unsaturated) carboxylic acid, and for providing desired grade .alpha.,.beta.-unsaturated carboxylic acid for use following storage and transport is described herein. In particular, bulk storage and shipment such as with overseas transport is described. The process comprises combining the .alpha.,.beta.-unsaturated carboxylic acid with a phenolic inhibitor and a coinhibitor to form an inhibited mixture, storing the inhibited mixture, transporting the inhibited mixture, and removing the coinhibitor to provide the desired grade .alpha.,.beta.-unsaturated carboxylic acid for use. In preferred embodiments, the .alpha.,.beta.-unsaturated carboxylic acid is acrylic acid, the phenolic inhibitor is .rho.-methoxyphenol, the coinhibitor is manganese cation, and removal of the coinhibitor is carried out using an ion exchange resin.

Abstract: The use of organic, polymeric, anionic water-soluble flocculants for the phase separation of an organic-aqueous system which essentially comprises monomeric acrylates, diacrylates, (poly)ester acrylates or (poly)ether acrylates and unreacted residues of the carboxylic anhydrides, carboxylic acids or alcohols used for preparing the acrylates.

Abstract: An improved process for producing n-butyl acrylate in high yield and high purity substantially free of acrylic acid, incorporates one or more of the following new process components in an acid-catalyzed esterification process for producing n-butyl acrylate:1. A hydrolytic recovery component, wherein heavy end adducts produced during the acid-catalyzed esterification are hydrolyzed, recovered, and recycled as valuable reactants from a hydrolytic recovery unit (HRU);2. A cracking reactor component, preferably used with the HRU, wherein additional valuable reactants are recovered and recycled after treatment in the cracking reactor; and3. A new distillative component, wherein a crude n-butyl acrylate stream is efficiently distilled in an aqueous mode through an acrylic acid separation column, thereby providing n-butyl acrylate substantially free of acrylic acid and in high yield.The first two components also are applicable to acid-catalyzed processes producing C.sub.1 to C.sub.4 alkyl acrylates.

Abstract: A process for preparing refined acrylic esters, the process including steps of distilling an acrylic ester containing stream in the presence of hydroquinone or substituted hydroquinone, at a concentration in the range of 200 to 5000 ppmw, wherein the distillation is carried out in the presence of 0.001 to 1.0 % v, on the vapor phase, of oxygen.

Abstract: A process for the separation by rectification of (meth)acrylic acid from a mixture containing (meth)acrylic acid and an inert hydrophobic organic liquid having a boiling point higher than that of (meth)acrylic acid as main constituents and also lower aldehydes as secondary constituents, a primary amine and/or a salt thereof are added.

Abstract: A process for producing refined methacrylic acid comprising the steps of oxidizing methacrolein and the like catalytically in a vapor phase to form a methacrylic acid-containing gas, cooling and condensing the gas to an aqueous methacrylic acid solution, adding to the solution an organic solvent that forms two liquid phases with water to carry out an extraction operation and thereby to obtain an extract, bringing the extract into contact with water to mix them together, separating the mixture into an organic phase and a water phase, and distilling the organic phase. According to this process, highly refined methacrylic acid containing little dibasic acids such as maleic acid and citraconic acid can be obtained economically and without increasing wastes that are unrecoverable to the process.

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: An improved process for producing n-butyl acrylate in high yield and high purity substantially free of acrylic acid, incorporates one or more of the following new process components in an acid-catalyzed esterification process for producing n-butyl acrylate:1. A hydrolytic recovery component, wherein heavy end adducts produced during the acid-catalyzed esterification are hydrolyzed, recovered, and recycled as valuable reactants from a hydrolytic recovery unit (HRU);2. A cracking reactor component, preferably used with the HRU, wherein additional valuable reactants are recovered and recycled after treatment in the cracking reactor; and3. A new distillative component, wherein a crude n-butyl acrylate stream is efficiently distilled in an aqueous mode through an acrylic acid separation column, thereby providing n-butyl acrylate substantially free of acrylic acid and in high yield.The first two components also are applicable to acid-catalyzed processes producing C.sub.1 to C.sub.4 alkyl acrylates.

Abstract: The present invention provides a process for producing (meth)acrylic acid by gas-phase catalytic oxidation, which comprises cooling and condensing a (meth)acrylic acid-containing reaction product gas to obtain a crude aqueous (meth)acrylic acid solution; cooling the aqueous solution to deposit the impurities contained in the aqueous solution, as solid matter; separating the solid matter; and then extracting and separating (meth)acrylic acid from the purified aqueous (meth)acrylic acid solution obtained. Unlike the conventional processes in which (meth)acrylic acid is extracted and separated from a crude aqueous (meth)acrylic acid solution, the present process can avoid various troubles caused by the impurities contained in the crude aqueous (meth)acrylic acid solution, for example, generation of scum and the like, and therefore can produce (meth)acrylic acid at a higher purity than in the conventional processes.

Abstract: A process for inhibiting polymerization of a vinyl compound comprising using (A) one or both of N-nitrosophenylhydroxylamine and a salt thereof in combination with (B) a salt of copper or in combination with (B') a metal salt of a dialkyldithiocarbamic acid and (C) at least one selected from the group consisting of inorganic acids, salts of inorganic acids, and water.In accordance with the above process, stable continuous operation of a process for producing a vinyl compound, particularly acrylic acid or methacrylic acid, such as a distillation process of the vinyl compound, for a long time is enabled by effectively suppressing polymerization of the vinyl compound in the process or by effectively suppressing polymerization of the vinyl compound in the process while corrosion of the apparatus for the production is prevented.

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: Acrylic acid or methacrylic acid is purified by(a) subjecting a mixture comprising the acrylic acid or methacrylic acid to a sharply defined separation process essentially in the absence of an organic solvent, with the composition of the phase in which the acrylic acid or methacrylic acid accumulates remaining essentially constant when the composition of the other phases participating in the mass transfer changes, then taking off this phase and(b) subjecting at least a part of the remaining phase from stage(a) to a less sharply defined separation process and(c) feeding one of the phases formed in stage (b) to the sharply defined separation process in stage (a).In addition, the invention provides a process for preparing acrylic acid or methacrylic acid which includes the abovementioned purification process.

Abstract: The present invention provides an improved process for production of acrylic acid by subjecting propylene and/or acrolein to catalytic gas-phase oxidation with a molecular oxygen-containing gas. In the process, the mixed gas obtained by the catalytic gas-phase oxidation is contacted with an aqueous collecting agent containing acrylic acid, acetic acid and a poorly-soluble-in-water solvent, to form an aqueous acrylic acid solution; and the aqueous acrylic acid solution is subjected to azeotropic distillation in the presence of a poorly-soluble-in-water solvent to remove by-products and obtain high-purity acrylic acid.

Abstract: A process for the separation of (meth)acrylic acid from the reaction gas mixture formed in the catalytic gas phase oxidation by countercurrent absorption using a high-boiling inert hydrophobic organic liquid, in which the reaction gas mixture is passed through an absorption column countercurrently to the descending high-boiling inert hydrophobic organic liquid and (meth)acrylic acid is subsequently fractionally separated from the liquid effluent leaving the absorption column and containing (meth)acrylic acid, wherein a rectifying process is superimposed on the absorption process occurring naturally in the absorption column by removing a quantity of energy from the absorption column which exceeds its natural energy loss resulting from contact with the ambient atmosphere.