Abstract: A process for decreasing the concentration of phenothiazine from a solution of acrylic acid by contacting the acrylic acid solution with a hydrophobic clay, such as an organophilic clay; or by protonating the phenothiazine, oxidizing the phenothiazine, and contacting the protonated, oxidized phenothiazine with a hydrophilic clay, such as an acid-activated smectite clay or sodium bentonite clay to sorb (absorb and/or adsorb) the phenothiazine into or onto the clay. Once sorbed onto the smectite clay, the phenothiazine easily can be removed, together with the clay, from the solution of acrylic acid, e.g., by filtration.

Abstract: Processes are provided for producing a pure grade of acrylic acid having residual aldehyde levels under 10 parts per million. The processes apply selected groups of amines sequentially and, preferably, continuously in selectively reducing, for example, acrolein and furfural, and may be advantageously conducted in the presence of maleic acid and maleic anhydride impurities.

Abstract: A continuous process for producing a pure grade of acrylic acid having residual aldehyde levels under 10 parts per million. The process applies two groups of amines sequentially and continuously in selectively reducing acrolein and furfural and may be advantageously conducted in the presence of maleic acid and maleic anhydride impurities.

Abstract: To recover these noble products consisting of acrylic acid monomer, acrylic ester monomers and alcohols, a thermal cracking is performed in the absence of catalyst on a mixture of heavy distillation residues originating, on the one hand, from the manufacture of acrylic acid and, on the other hand, from the manufacture of the esters, the light fraction originating from the dissociation reactions is continuously vaporized during the cracking operation and this light fraction is distilled in order to recover, after condensation, the required products.

Abstract: The invention comprises a method of dispersing foulants, residues, gums, precipitates, polymeric tars and other highly oxidized carbonaceous tars which can be formed in the process of manufacture and recovery of acrylic acid. The method comprises adding to the liquid or gaseous phases passing through, or stored in acrylic acid process equipment, an effective antifouling amount of a dispersant which is stable in the environment within an acrylic acid process and is compatible with the equipment used for the manufacture of acrylic acid.

Abstract: Acrylic acid obtained by catalytic oxidation of propylene, extracted by countercurrent washing of the reaction gases which at least one hydrophobic heavy solvent in an extraction column (C1) is purified.

Abstract: The invention provides a continuous process for producing a pure grade of acrylic acid having residual aldehyde levels under 10 parts per million. The process applies two groups of amines sequentially and continuously in selectively reducing acrolein and furfural and may be advantageously conducted in the presence of maleic acid and maleic anhydride impurities.

Abstract: This invention embodies a process for releasing acidic organic compounds in high yield and good purity from aqueous solutions of their salts which comprises converting the salts by carbon dioxide to their corresponding free acidic organic compounds and metal hydrogen carbonates, removing the acidic organic compounds from the mixture by extraction with an essentially water-insoluble organic solvent, and re-extracting the organic phase with carbon dioxide containing water. Using this process, the acidic organic compounds are completely released from their corresponding salts, i.e., the organic solution is free of salt. The acidic organic compounds released by the claimed process are organic compounds which contain acidic protons which can be replaced by metals. Some examples are carboxylic acids, sulfonic acids, phosphonic acids, phenols, naphthols, and aliphatic alcohols.

Abstract: A process for the preparation of an .alpha.,.beta.-unsaturated C.sub.3 -C.sub.6 carboxylic acid of greater than 98% purity, which combines fractional distillation and melt crystallization procedures.

Abstract: The present invention relates to a process for the treatment of waste gas discharged from a cyclohexane oxidation reactor used in the manufacture of adipic acid, said waste gas containing mainly nitrogen, oxygen, carbon monoxide, carbon dioxide, acetic acid, and up to 10% by weight cyclohexane, as well as other gases or vapors, by (a) scrubbing the waste gas from the cyclohexane oxidation reactor with acetic acid in a first absorption step to reduce the amount of cyclohexane to a residual content of less than about 1% by weight, (b) scrubbing the waste gas from the first absorption step with water in a second absorption step to reduce the amount of acetic acid to a residual content of less than about 1% by weight, and (c) subjecting the scrubbed waste gas from the second absorption step to an oxidation step to oxidize carbon monoxide and other oxidizable components of the waste gas to carbon dioxide and water.

Abstract: A method of purifying acrylic acid by fractional crystallization is provided. The method includes the steps of subjecting an acrylic acid containing mixture to a dynamic crystallization stage to recover purified acrylic acid, leaving a residue containing acrylic acid; subjecting the residue to a static crystallization stage to recover an acrylic acid enriched fraction; and recycling the acrylic acid enriched fraction to the dynamic crystallization stage for recovery of purified acrylic acid.

Abstract: In a process for purifying crude (meth)acrylic acid, the crude (meth)acrylic acid is worked up by distillation after addition of an organic carboxylic acid hydrazide and, if desired, an organic sulfonic acid.

Abstract: The removal of water from aqueous acrylic acid solutions is carried out by removing 10 to 90 wt. % of the water by pervaporation. Subsequent work-up of the acrylic acid by distillation is thereby made easier.

Abstract: A process for the separation of acrylic acid from the reaction gases from the catalytic oxidation of propylene and/or acrolein by countercurrent absorption using a mixture of from 70 to 75 wt % of diphenyl ether and from 25 to 30 wt % of diphenyl plus from 0.1 to 25 wt % of o-dimethyl phthalate, based on said mixture.

Abstract: A method of reducing the levels of impurities in aqueous monomer solutions is provided. Subjecting aqueous monomer solutions to ultraviolet radiation for from about 2 minutes to about 5 hours, reduces the level of impurities, especially carbonyl-compounds.

Abstract: This invention provides an improved method for recovering an organic acid as a salt from various process streams by addition of a crystallizing base to a concentrated solution of neutralized organic acid. The addition of such a base causes crystallization of the salt. This process provides more efficient recovery of organic acid salt from a fermentation process stream than traditional recrystallization and it may be used essentially as a one step purification process. The improved method is particularly applicable to the recovery of trisodium or tripotassium citrate from process streams produced in the fermentation and recovery of citric acid, with the addition of a crystallizing base such as sodium hydroxide, potassium hydroxide or ammonia.

Abstract: A process for producing acrylic acid is described, which process comprising providing a mixed gas of acrylic acid and by-products produced by catalytic gas phase oxidation of propylene and/or acrolein, contacting the mixed gas with water to obtain an aqueous solution, and adding an azeotrope solvent to the aqueous solution for distillation to obtain a mixture of the by-products, water and the azeotrope solvent from a tower top and acrylic acid from a tower bottom. Highly pure acrylic acid is obtained by using, as the azeotrope solvent, a mixed solvent of solvent A selected from diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl-tert-butyl ketone, n-propyl acetate and mixtures thereof and solvent B selected from toluene, heptane, methyl cyclohexane and mixtures thereof.

Abstract: Preparation of 3-pentenoic acid by the reaction of 3-pentenoylchloride, water and butadiene. 3-chloro-1-butene and 1-chloro-2-butene are also formed. Preferably the 3-pentenoylchloride is formed by the reaction of chlorobutene with carbon monoxide using a palladium catalyst.

Abstract: A process for the catalytic gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor with contacting tubes, at elevated temperature on catalytically active oxides with a conversion of acrolein for a single pass of .gtoreq.95%, wherein the reaction temperature in the flow direction along the contacting tubes in a first reaction zone before the starting reaction gases containing the reactants enter the contacting tubes is from 260.degree. to 300.degree. C. until an acrolein conversion of from 20 to 40% is reached, and the reaction temperature is subsequently reduced by a total of from 5.degree. to 40.degree. C., abruptly or successively in steps or continuously along the contacting tubes until a methacrolein conversion of .gtoreq.95% has been reached, with the proviso that the reaction temperature in this secondary reaction zone is not lower than 240.degree. C.

Abstract: Processes are disclosed for producing lactic acid, esters of lactic acid, acrylic acid, and esters of acrylic acid, primarily from fermentable carbohydrate materials. An overall process for producing esters of acrylic acid comprises: a) fermenting carbohydrate material with a lactic-acid-forming organism in the presence of NH.sub.3 to produce ammonium lactate; b) combining the ammonium lactate with an alcohol; c) combining the ammonium lactate and alcohol with an effective catalyzing amount of gaseous CO.sub.2 to catalytically esterify the ammonium lactate and alcohol into a lactic acid ester containing solution; d) recovering purified lactic acid ester; and e) vaporizing the lactic acid ester and passing it through a solid catalyst bed comprised of an effective catalyzing amount of crystalline hydrated and partially calcined calcium sulfate to catalytically convert lactic acid ester into an acrylic acid ester. Step "d" would be useful in a process for making low-cost, purified lactic acid.

Abstract: In the production of methacrylic acid by the vapor phase catalytic oxidation of isobutylene, t-butanol, methacrolein isobutyl aldehyde or isobutyric acid, or mixture thereof, the reaction product gas is condensed by contact with an aqueous phase containing methacrylic acid and acetic acid thereby forming an aqueous solution of methacrylic acid and a gas phase containing methacrolein and methacrylic acid. The aqueous solution of methacrylic acid is extracted with a saturated hydrocarbon solvent containing from 6-9 carbon atoms. The methacrylic acid is extracted into the solvent phase and an aqueous phase containing acetic acid is also formed. Methacrolein is recovered from the gas containing methacrolein and methacrylic acid by contacting the gas with an aqueous phase containing methacrylic acid and acetic acid. An aqueous phase containing methacrylic acid, acetic acid and methacrolein is formed in the methacrolein recovery step.

Abstract: The present invention provides a method of reducing the levels of protoanemonin present in aqueous monomer solutions by adding an effective amount of one or more para-phenylenediamines having the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same or different radical selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, phenyl or methoxyphenyl with the proviso that at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is hydrogen; R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are the same or different radical selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, methoxy or ethoxy with the proviso that at least one of R.sub.5, R.sub.6, R.sub.7 and R.sub.8 is hydrogen; and salts thereof.

Abstract: A process is provided for the purification of methacrylic acid. The process can easily remove dibasic acids and aldehydes containing in trace amounts as impurities. According to the process, crude methacrylic acid obtained as an aqueous solution by vapor-phase catalytic oxidation of isobutylene, tertiary butanol, methacrolein or isobutyl aldehyde is treated with at least one compound selected from the group consisting of m-aminophenol, m-phenylenediamine, 2,4-diaminotoluene and 2,4-diamino-diphenylamine, followed by distillation, optionally, in the presence of a p-phenylene diamine.

Abstract: A process for the isolation of a carboxylic acid of the general formula (I)R.sup.1 --COOH (I),in which R.sup.1 denotes hydrogen, methyl, ethyl, or vinyl, from a dilute aqueous solution thereof by extraction with a secondary amide of the general formula (II) ##STR1## in which R.sup.1 has the meanings stated, and R.sup.2 and R.sup.3 are independently of each other C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.4 -C.sub.20 -cycloalkylalkyl, aryl, C.sub.7 -C.sub.20 -aralkyl, or R.sup.2 and R.sup.3 together form a 1,4- or 1,5-alkylene group which may be mono- to penta-substituted by C.sub.1 -C.sub.4 -alkyl, wherein the losses of secondary amide (II) are compensated by the addition of the corresponding amine of the general formula (III) ##STR2## in which R.sup.2 and R.sup.3 have the meanings stated above.

Abstract: Acrylic acid cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. Acrylic acid can be readily separated from water by extractive distillation. Effective agents are dimethylsulfoxide, sulfolane, dimethylformamide or dimethylacetamide.

Abstract: Black acid or the sulfuric acid residue obtained in the manufacture of ethyl acrylate by reaction of ethylene and acrylic acid in the presence of sulfuric acid is heated and distilled in the presence of a solvent for recovery of acrylic acid and ethyl acrylate.

Abstract: Methacrylic acid can be prepared with advantage by gas phase oxidation of methacrolein or isobutyraldehyde over Mo- and P-containing catalysts at from 250.degree. to 400.degree. C. with cooling of the hot reaction gas to below 100.degree. C., absorption of the methacrylic acid in a water-operated absorption column, at below 100.degree. C. and partial recycling into the oxidation reactor after admixture of methacrolein or isobutyraldehyde and oxygen by feeding a quantity of methacrolein or isobutyraldehyde equal to the quantity of methacrolein or isobutyraldehyde consumed in the reaction in liquid form together with a polymerization inhibitor into the reactor gas in the lower two-thirds of the absorber column and upstream of the feed point for the fresh methacrolein or isobutyraldehyde or down-stream of the absorption column splitting off the reactor off-gas a side stream which is washed in a wash column operated with water at <10.degree. C.

Abstract: A process for producing cis-2-methyl-2-butenoic acid, which process is preferably based on technical 2-methyl-2-butene nitrile and leads to pure products preferably without costly rectification. The technical nitrile is hydrolyzed by concentrated sulfuric acid at temperatures of up to 130.degree. C. and, following dilution of the sulfuric acid to about 50%, at temperatures of up to 130.degree. C. It is treated by distilling and fractional crystallization.

Abstract: A process for producing acrylic ester by the catalytic esterification of a crude liquid stream of enriched acrylic acid recovered by the partial condensation of the reaction gas effluent from the catalytic oxidation of propylene and/or acrolein. The partial condensation allows a significant proportion of volatile aldehydes and water to pass through the first recovery stage to a second stage for conventional recovery, along with uncondensed acrylic acid vapors and the remainder of the uncondensed reaction gases.

Abstract: In order to recover methacrolein and/or methacrylic acid by quenching a reaction product gas obtained by catalytic oxidation of isobutylene or the like, the reaction product gas is charged into a quench column through a double-wall pipe and is then brought into contact with a condensate as a cooling medium. Deposition of terephthalic acid and the like inside the column is prevented by controlling the temperature of a bottom in the quench column and that of an overhead gas of a quench column unit. An aromatic carboxylic acid, aromatic aldehyde, metal powder is added to an aqueous solution of methacrylic acid, which contains terephthalic acid and the like, so that the terephthalic acid and the like are caused to precipitate for their removal.

Abstract: A novel process for the preparation of E-2-propyl-2-pentenoic acid and its physiologically compatible salts is described, in which di-n-propyl-ketone-cyanohydrin is used as the starting compound. The compound is either(a) dehydrated with thionyl chloride and the acid nitrile formed is subsequently saponified with a stoichiometric excess of potassium hydroxide, or(b) is initially converted into 2-hydroxy-2-propyl-pentanoic acid and the latter is subsequently dehydrated in the presence of a less than stoichiometric quantity of a tertiary amine at a temperature of at least 200.degree. C.The free acid is optionally converted into the salt form, preferably using the corresponding salts of carbon dioxide in an aqueous acetone solution.

Abstract: A method of isolating and recovering methacrylic acid from a methacrylic acid-containing reaction product gas resulting from the vapor-phase catalytic oxidation of isobutylene, tertiary butanol or isobutyraldehyde, which comprises introducing the reaction product gas comprising methacrylic acid and various by-products including high boiling substances at a high temperature of 250.degree. to 300.degree. C. into a cooling zone, rapidly cooling the gas therein to a temperature of not more than 100.degree. C. to condense methacrylic acid and thus isolate methacrylic acid, while also converting the high boiling substances to fumes, thereafter introducing the cooled gas containing said fumes into a venturi scrubber, contacting it therein with an aqueous medium to remove said fumes, finally introducing the treated gas into a methacrylic acid-absorbing zone and absorbing methacrylic acid by absorption into an aqueous medium.

Abstract: The invention relates to a process for the preparation of pure cis- or trans-crotonic acid from a mixture of the two isomers by melt crystallization. To prepare trans-crotonic acid, an isomer mixture I containing at least 40% by weight of trans-crotonic acid is used as the starting material. On the other hand, if cis-crotonic acid is to be prepared, an isomer mixture II containing at least 80% by weight of cis-crotonic acid is used as the starting material. The particular isomer mixture is melted and then left to cool, trans-crotonic acid being allowed to crystrallize out of mixture I to a residual content of at least 35% by weight, and cis-crotonic acid being allowed to crystallize out of mixture II to a residual content of at least 75% by weight.

Abstract: Disclosed herein is a process for bringing methacrylic acid, which has been obtained by the catalytic oxidation of compound having 4 carbon atoms, into contact with a basic anion-exchange resin so as to remove byproduced dibasic acids and the like from the methacrylic acid and to purify the same.

Abstract: Acrolein and acrylic acid are produced by vapor-phase catalytic oxidation of propylene in a multi-tubular, fixed-bed reaction vessel with the use of a composite oxide catalyst represented by the formula Mo.sub.a Bi.sub.b Fe.sub.c A.sub.d B.sub.e C.sub.f D.sub.g Si.sub.h O.sub.x, wherein A, B, C, and D represent components selectable from respective groups of elements, and the subscripts a through h and x are specific numbers of atoms of respective elements and groups of elements. This catalyst is adapted and packed in each reaction tube in a manner such that its activity is controlled to increase from the inlet toward the outlet of the tube.

Abstract: Aldehydes are removed from .alpha.,.beta.-olefinically unsaturated monocarboxylic acids of 3 or 4 carbon atoms by adding hydrazine derivatives and distilling the unsaturated monocarboxylic acids if the hydrazine derivatives used are aminoguanidine and/or aminoguanidine salts in amounts of from 1 to 3 moles per mole of aldehyde.

Abstract: The process relates to the removal of copper contaminants from crude polyacetylenes containing up to 30 wt. % copper impurity by contacting a melt of the polyacetylene with aqueous hydrogen chloride to form an oil phase and an aqueous acid phase, separating said phases, treating the separated oil phase with from about 1 to about 10 volumes of water until subsequent oil and water phases are formed, agitating the separated oil phase while cooling to form a particulate product and drying said particles to recover purified polyacetylene.

Abstract: A process for separation of methacrylic acid from methacrylic acid-isobutyric acid mixtures involving the selective crystallization and removal of the methacrylic acid from said mixtures is decribed.

Abstract: Preparation of sorbic acid from precursors by contact with acid catalysts is improved by utilizing crystallization to separate sorbic acid during the preparation.

Abstract: A process is disclosed for separation of propionic acid and methacrylic acid and esterification of methacrylic acid with an aliphatic alcohol of from 1 to 4 carbon atoms in presence of a suitable catalyst wherein separation and esterification is obtained with minimal polymerization of methacrylic acid.

Abstract: The invention relates to a process for the extraction of carboxylic acids from aqueous solutions with a carboxylic acid content below 8% by weight. A mixture of an aliphatic amine with a total carbon number of at least 10 and a phenol or naphthol is used as extracting agent. The molar ratio of phenol:amine or alkylated phenol:amine or naphthol:amine is in the range from 0.1:1 to around 1.1:1.

Abstract: A process for forming a purified solute from an aqueous solution is provided whereby a mixture of an extractant, a hydrate former and the aqueous solution is first formed. The hydrate former forms a hydrate with water while the solute does not form a hydrate. The extractant takes up the solute from the aqueous solution. The mixture is subjected to a temperature and pressure sufficient to form the solid hydrate of the hydrate former, an aqueous solution of the solute and a portion comprising the extractant containing the solute. The solute is recovered from the portion comprising the extractant and the solute.

Abstract: The distillative separation of methacrylic acid from isobutyric acid is significantly improved by the introduction into the distillation system of a third component selected from the group consisting of methyl methacrylate, methyl isobutyrate and dimethylformamide.

Abstract: In extracting a solute from an aqueous solution using a mixer-settler extractor and an organic extractant comprising a mixture of a tertiary amine and an organic diluent, the extractor is operated while the liquid phase inside the mixer thereof is kept in a state of solvent dispersion. Thus, the mixer-settler extractor can be operated efficiently.

Abstract: A 1,2-unsaturated carboxylic acid or its ester such as acrylic or methacrylic acid or its alkyl ester is purified to remove aldehyde impurities contained therein by treating the acid or its ester with a mercapto containing compound in the presence of an acid catalyst.

Abstract: Production of acrylic acid by oxidation of acrolein with gas containing oxygen in the gas phase at elevated temperature in the presence of a catalyst which, in addition to oxygen, consists essentially of (a) molybdenum, (b) tungsten, (c) vanadium and (d) iron and/or copper. The atomic ratio of molybdenum:tungsten:iron and/or copper is 1 to 20:0.01 to 10:1 and the atomic ratio of vanadium:molybdenum is 0.2 to 6:6. Acrylic acid is an important starting material for the production of high polymers.

Abstract: A process for separation of methacrylic acid from a methacrylic acid-containing, gaseous reaction mixture obtained by subjecting methacrolein or a compound which can afford methacrolein under reaction conditions and molecular oxygen to gas phase reaction in the presence of a catalyst for oxidation under the coexistence of an inert gas for dilution which comprises (a) cooling the gaseous reaction mixture from a reactor wherein the gas phase reaction has been effected to separate into condensable components including methacrylic acid, acetic acid and water vapor as a condensed liquor and non-condensable components including methacrolein as a non-condensed gaseous mixture, (b) eliminating contaminating methacrolein from the condensed liquor and (c) contacting the resulting condensed liquor with an organic solvent to extract methacrylic acid, followed by separation into an organic solvent solution including methacrylic acid and an aqueous solution as waste water, characterized in that (1) the inert gas for diluti

Abstract: A method for isolating a vinyl salt compound in solid form from an aqueous solution thereof by spray drying such an aqueous salt solution.

Abstract: In the recovery and purification of methacrylic acid or its esters produced by the vapor phase catalytic oxydehydrogenation of isobutyric acid or its esters the problem of downstream plugging is avoided by the inclusion of a small amount of surfactant in the gaseous effluent at or near the point of its condensation.

Abstract: Process is disclosed for treating the reaction product of propionic acid and formaldehyde to recover methacrylic acid from an aqueous effluent wherein said effluent contains methacrylic acid, unreacted formaldehyde, unreacted propionic acid, water and by-products.