Abstract: A process is proposed for preparing (meth)acrolein and/or (meth)acrylic acid by partially oxidizing C3 and/or C4 precursor compounds in the gas phase in the presence of a heterogeneous particulate catalyst, in a reactor having two or more thermoplates (1) arranged vertically and parallel to each other while in each case leaving a gap (2), the heterogeneous particulate catalyst being installed in the gaps (2) and the gaseous reaction mixture being passed through the gaps (2), which comprises monitoring, controlling and/or regulating the process by selecting as a monitoring, control and/or regulation parameter one or more temperatures which are measured in one or more gaps (2), at one or more measurement points which are distributed over the height of each gap (2).

Abstract: Clogging of a distillation column by polymerization caused by a change of the production rate of (meth)acrylic acid, is prevented to carry out a stabilized operation over a long period. A process for producing (meth)acrylic acid, which includes a purification step wherein a (meth)acrylic acid-containing material to be purified is supplied to and distilled by a distillation column, wherein during a cut operation in which the production rate of (meth)acrylic acid is reduced by ?% relative to the production rate of (meth)acrylic acid during the ordinary operation, the liquid/gas flow rate in the distillation column is adjusted to be at least (100??/2)% of the liquid/gas flow rate during the ordinary operation.

Abstract: A method for producing acrylic acid by using an acrylic acid-containing solution of high concentration without azeotropic distillation is provided. This method of producing acrylic acid comprises introducing an acrylic acid-containing gas obtained by catalytic gas phase oxidation reaction into an absorption column and supplying the acrylic acid-containing solution to crystallization step thereby separating the solution into acrylic acid and residual mother liquid, and distilling at least part of the residual mother liquid and circulating the distillate obtained by the distillation to the absorption column.

Abstract: In a process for preparing water-absorbent resins based on acrylic acid, crude acrylic acid is firstly isolated from the reaction gases from the catalytic gas-phase oxidation of propane, propylene and/or acrolein. This is treated with an aldehyde scavenger and pure acrylic acid is separated by distillation from the treated crude acrylic acid, and this pure acrylic acid can be subjected directly to a free-radical polymerization.

Abstract: A process for producing a (meth)acrylic acid compound, which comprises distilling acrylic acid, methacrylic acid (these will hereinafter generally be referred to as “(meth)acrylic acid”) or an ester thereof (these will hereinafter generally be referred to as “a (meth)acrylic acid compound”) in a distillation column to obtain a purified (meth)acrylic acid compound, characterized in that in the course of operation of the distillation column including suspension and resumption of the operation, the distillation column is washed with water and, thereafter, inside washing with an organic solvent and/or azeotropic distillation in the presence of the organic solvent is conducted. In some cases, washing with alkaline water may be added prior to the washing with water. Washing of the distillation column for separating and purifying a crude (meth)acrylic acid compound, can be carried out easily.

Abstract: A process prepares an aqueous alkali metal acrylate solution by distillatively removing acrylic acid from a mixture as vapors and taking up the vapors immediately from the gas phase into an aqueous alkali solution.

Abstract: (Meth)acrylic monomers are separated by a thermal separation process by ascending at least one ascending gaseous stream in a separating column containing a sequence of mass transfer trays and a liquid stream that contains dissolved polymerization inhibitor which descends in the separating column, and in at least one of the streams being (meth)acrylic monomers; and spraying the inner surface of the separating column with the descending liquid stream that contains the dissolved polymerization inhibitor, and the separating column having internals, certain areas of which are shadow regions of the sprayed descending liquid stream; and which shadow regions are equipped by covering means which prevent contact of the shadow regions with (meth)acrylic monomers and consequently undesired polymerization of monomer.

Abstract: A method for producing acrylic acid from an acrylic acid-containing solution of high concentration without performing azeotropic distillation is provided. This method of producing acrylic acid comprises steps of absorbing acrylic acid-containing gas, distilling the acrylic acid-containing solution without using an azeotropic solvent thereby obtaining crude acrylic acid as a column bottom stream and/or a column side stream, and supplying the crude acrylic acid to a crystallizing step and melt crystallizing the crude acrylic acid thereby obtaining purified acrylic acid.

Abstract: There is provided a process for purifying (meth)acrylic acid by efficiently removing transition metal components from crude (meth)acrylic acid containing the transition metal components as impurities. When the crude (meth)acrylic acid containing the transition metal components as impurities is contacted with the cation exchange resin to remove the transition metal components therefrom, water is previously added to the crude (meth)acrylic acid prior to contacting the crude (meth)acrylic acid with the cation exchange resin. In the preferred embodiment of the present invention, the transition metal component is manganese.

Abstract: The invention relates to a method for the production of a purified melt of a monomer melt obtained by condensation, absorption or extraction in a crystallizer, wherein the inlet to the crystallizer is subjected to a mechanical solid/liquid separation operation.

Abstract: A process for the high yield production of high purity glacial methacrylic acid (“HPMAA”) with minimization of decomposition of hydroxy isobutyric acid (HIBA). The HPMAA is substantially pure, specifically 99% pure or greater with a water content of 0.05% or less. This improved process involves the steps of providing a crude MAA stream which was formed by hydrolyzing acetone cyanohydrin and, therefore, includes HIBA which is an intermediate product of the hydrolysis reaction, and purifying that crude methacrylic acid stream in a series of successive distillation steps.

Abstract: Inhibitor blends that include both nitrosophenols and nitrosoanilines, optionally in combination with air or oxygen, reduce the premature polymerization of ethylenically unsaturated monomers. unsaturated monomers.

Abstract: A process for preparing and/or working up mixtures by (meth)acrylic acid and/or (meth)acrylic ester in the presence of at least one polymerization inhibitor and at least one oxygenous gas, which comprises metering in at least part of the oxygenous gas at an exit rate of at least 50 mm/s.

Abstract: In a process for the purification of a crude acrylic acid melt, the crude acrylic acid melt is converted, under the action of low temperatures, into a crude acrylic acid suspension consisting of acrylic acid crystals and residual melt, and the acrylic acid crystals of the crude acrylic acid suspension are freed from remaining residual melt in a wash column, the production of the acrylic acid crystals of the crude acrylic acid suspension being carried out in the presence of water, the wash column being a wash column with forced transport of the acrylic acid crystals and the wash liquid used being the melt of acrylic acid crystals purified in the wash column.

Abstract: A method is disclosed which produces acrylic acid in a high yield as maintaining the conditions for purifying acrylic acid in constant ranges and preventing the acrylic acid from polymerization. By using single a single reactor, propylene concentration adjusting in the range of 7–15 vol. % and water concentration adjusting in the range of 0–10 vol. % are introduced thereinto thereby obtaining an acrylic acid-containing gas. Then the gas is introduced to an acrylic acid absorption column to adjust water concentration in the range of 1–45 wt. %, thereby preventing from polymerization.

Abstract: A process for the fractional condensation of a hot gas mixture which as well as acrylic acid contains at least one further condensable component in a column in the presence of at least one stabilizer comprises metering in at least a portion of the at least one stabilizer as a melt.

Abstract: A process for the continuous recovery of (meth)acrylic acid from the reaction gas of a catalytic gas-phase oxidation comprising the following process stages is proposed: I quenching of the reaction gas by evaporative cooling using a high-boiling solvent, II separation of the (meth)acrylic acid from the quenched reaction gas by absorption into the high-boiling solvent, III separation of the solvent laden with (meth)acrylic acid by rectification into a first part-stream IIIA), which contains predominantly (meth)acrylic acid, and into a second part-stream IIIB) which contains predominantly the solvent, IV recycling of the stream IIIB) to process stage II and V distillative production of (meth)acrylic acid from stream IIIA), all liquid residual streams obtained in process stage V being recycled to process stage I.

Abstract: There is provided a method for storing (meth)acrylic acid or (meth)acrylic esters in a storage tank for receiving or discharging the (meth)acrylic acid or (meth)acrylic esters, which is capable of storing the (meth)acrylic acid or (meth)acrylic esters for a long period of time. According to the method of the present invention, upon storing the (meth)acrylic acid or (meth)acrylic esters in the storage tank for receiving or discharging the (meth)acrylic acid or (meth)acrylic esters, a concentration of suspended particulate matters contained in a gas phase portion of the storage tank is controlled to not more than 0.01 mg/m3.

Abstract: A multimetal oxide material contains the elements Mo, V and Te and/or Sb and at least one of the elements Nb, Ti, W, Ta and Ce and promoters and has a specific X-ray diffraction pattern. Moreover, such a multimetal oxide material is used as a catalyst for heterogeneously catalyzed gas-phase partial oxidations of hydrocarbons.

Abstract: The object of this invention to provide an improved arrangement that enables to prevent adhesion of polymer on or around the inner wall of a purification apparatus directly equipped on the outer wall thereof with an attachment such as a support by suppressing local temperature lowering inside the apparatus due to the existence of the attachment. The present invention provides a purification apparatus comprising an attachment directly mounted on an outer wall of the apparatus; and a covering material made of a low heat conductive material which partly or entirely covers the outer wall of the apparatus, and which partly or entirely covers the attachment.

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. The method for purification of acrylic acid includes the step of distilling a crude acrylic acid which is charged with an aldehyde treatment chemical, wherein the concentration ratio of furfural to acrolein by weight in the crude acrylic acid is adjusted so as to satisfy the following equation: (furfural concentration by weight)/(acrolein concentration by weight)?100.

Abstract: The present invention provides a process for producing purified (meth)acrylic acid by subjecting crude (meth)acrylic acid containing maleic acids and aldehydes as impurities to distillation, the said process comprising, prior to the distillation, the following steps: (A) adding hydrazines to the crude (meth)acrylic acid at a temperature of not less than a melting point of acrylic acid and not more than 50° C. to react the maleic acids with the hydrazines; (B) heat-treating the reaction solution obtained in the above step (A) at a temperature of 60 to 90° C. to convert the reaction product into a substance soluble in the reaction solution; and (C) adding hydrazines to the thus heat-treated reaction solution obtained in the above step (B) at a temperature of not less than the melting point of acrylic acid and not more than 50° C. to react the aldehydes with the hydrazines, thereby producing a substance soluble in the reaction solution.

Abstract: In an acrylic acid production process which comprises the step of producing acrylic acid by catalytic vapor-phase oxidation of propane, propylene, and/or acrolein; and purifying the acrylic acid produced in the step of producing with distillation in the presence of the polymerization inhibitor for preventing polymerization of the acrylic acid, a viscosity at 20° C. of the bottoms which comprises the polymerization inhibitor, discharged in the step of purifying, is adjusted to 2 Pa·s (2,000 cP) or less and the polymerization inhibitor is extracted using an aqueous medium. According to the method, in an acrylic acid production process, an extraction operation for recovery of the polymerization inhibitor can be continuously conducted in a stable manner.

Abstract: In an apparatus capable of distilling and refining an easily polymerizable substance, piping is performed so that when a strainer in action is switched to a backup strainer, the strainer can be switched after removing air in the backup strainer to replace air in the backup strainer with a discharge liquid of a pump. According to the apparatus, switching the strainers installed on an upstream side of the pump for extracting a liquid of a vacuum distillation column, which distills and refines the easily polymerizable substance, can be performed with no trouble during operation of the distillation column. When the apparatus includes a device for measuring a differential pressure between an upstream side and a downstream side of the strainer in action, two or more strainers installed in parallel can be switched at proper times and the easily polymerizable substance can be produced efficiently.

Abstract: A process for preparing a multimetal oxide material which contains the elements Mo, V and Te and/or Sb and at least one of the elements Nb, Ti, W, Ta and Ce and if desired promoters and has a specific X-ray diffraction pattern, in which process the last process step comprises washing with acidic liquids. In addition, a multimetal oxide material obtainable in such a way is used as a catalyst for heterogeneously catalyzed gas-phase partial oxidations and/or ammoxidation of hydrocarbons.

Abstract: The invention concerns a method of purifying a (meth) acrylic monomer selected among (meth) acrylic acids and their esters, by distillation in the presence of at least a polymerisation inhibitor requiring input of oxygen and/or an inhibitor having better efficacy in the presence of oxygen for stabilizing the liquid phase. The invention is characterized in that the distillation is performed in the presence of a NO2 gas, with an oxygen/organic vapor (p/p) ratio ranging between 0.02 and 3%, and with a NO2 condensed organic vapor (p/p) ratio ranging between 0.01 and 50 ppm.

Abstract: In the purification and distillation step of acrylic acid (including (meth)acrylic acid), stable continuous operation for a long period is enabled by inhibiting the undesirable polymerization reaction of acrylic acid thereby to prevent the device from a trouble such as clogging.

Abstract: An apparatus and a process for purification of an acrylic acid family.

Abstract: To provide: a process in which a coarse gel itself is made not to form in the case of applying the aqueous solution polymerization; and a process in which the polymerization is mildly controlled and the production is stably carried out in the case of applying the reversed-phase suspension polymerization or static polymerization, in a production of a water-absorbent resin.

Abstract: A method for effectively preventing polymerization of acrylic acid during an azeotropic dehydration distillation in an acrylic acid manufacturing process and thus enabling stable operation of the azeotropic dehydration column over an extended period of time. The acrylic acid is separated in an azeotropic dehydration column from an acrylic acid aqueous solution fed therein, and the method includes withdrawing from the bottom of the azeotropie dehydration column a bottom effluent containing 50% or more of glyoxal (including the hydrates thereof) contained in the acrylic acid aqueous solution fed into the azeotropic dehydration column.

Abstract: A process for the catalytic gas-phase oxidation of propene to acrylic acid, in which the reaction gas starting mixture is oxidized, with a high propene loading, in a first reaction stage, over a first fixed-bed catalyst which is housed in two successive reaction zones A, B, the reaction zone B being kept at a higher temperature than the reaction zone A, and the acrolein-containing product gas mixture of the first reaction stage is then oxidized in a second reaction stage, with a high acrolein loading, over a second fixed-bed catalyst which is housed in two successive reaction zones C, D, the reaction zone D being kept at a higher temperature than the reaction zone C.

Abstract: The gas reaction mixture (1), formed of propylene, if the case arises, of ultimate oxidation products, of acrylic acid, of acrolein, of steam, of acetic acid and of heavy products, is sent to the bottom of an absorption column (C1) fed countercurrentwise at the top with a heavy hydrophobic absorption solvent. The gas flow (7), formed of propylene and of ultimate oxidation products, of major amounts of water and acetic acid, and of acrolein, is obtained at the top of (C1) and a flow (4), formed of acrylic acid, of the heavy solvent, of heavy products and of minor amounts of acetic acid and of water, is obtained at the bottom of (C1).

Abstract: There is provided a method for handling high-viscosity substances discharged from a production process of acrylic acid or esters thereof by gas-phase catalytic oxidation, which method is improved such that upon transporting the high-viscosity substances in a molten state to a storage tank through a pipeline, the retention or clogging of the high-viscosity substances in the pipeline can be effectively prevented without adding a solvent thereto, resulting in smooth transportation thereof through the pipeline.

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 the production of (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: An object of the present invention is to provide a method for efficiently removing a metal from wastewater formed by subjecting the liquid waste to wet combustion treatment or wet oxidation treatment, said liquid waste resulting from an acrylic acid production process. Provided is a method for removing a metal from wastewater formed by subjecting at least a part of liquid waste to wet combustion treatment or wet oxidation treatment, said liquid waste resulting from an acrylic acid production process involving the steps of forming acrylic acid through catalytic vapor phase oxidation of at least one of propane, propylene, and acrolein, and purifying the acrylic acid through distillation, wherein the method comprises the steps of: (a) removing a solid content from the wastewater; (b) removing carbonate ions and carbonate salts from the treated liquid obtained by the step (a); and (c) removing a metal from the treated liquid from the step (b).

Abstract: The present invention provides a process for producing a water-absorbent resin of which the residual monomer content and the extractable content are low. The process for producing a water-absorbent resin comprises the step of polymerizing at least one monomer component including acrylic acid and/or its salt as major components to produce a water-absorbent resin that is a neutralized salt, and this process is characterized in that the acrylic acid is a product obtained by catalytic gas phase oxidation of propylene and/or propane and has a protoanemonin content of not more than 10 ppm, and in that the resultant water-absorbent resin has a neutralization ratio of not less than 50 mol %.

Abstract: Acrylic acid or methacrylic acid is purified by crystallization to obtain crystals and a mother liquor, by a process in which the crystals are washed with a wash liquid containing the acid and having a temperature from 15 to 40° C. Furthermore, a process for the preparation of acrylic acid or methacrylic acid comprises the abovementioned purification process.

Abstract: A method for the decomposition of a Michael type adduct, characterized by causing a Michael type adduct to react in the presence of an N-oxyl compound thereby decomposing the Michael type adduct into acrylic acid and/or the acrylic ester and/or the alcohol and a method for the production of acrylic acid and/or the acrylic ester, characterized by comprising a step of recovering a Michael type adduct formed in the process for the production of acrylic acid or acrylic ester and a step of decomposing the recovered Michael type adduct by the method of decomposition mentioned above. This invention, therefore, allows promotion of efficient utilization of the raw materials.

Abstract: Provided are a packed column arranged so as to be capable of effectively preventing polymerization of a polymerizable compound such as a (meth)acrylic acid in treating the compound, and a method for treating a polymerizable compound using the packed column. The packed column, which is provided with a packing support plate and is filled with a packing on the packing support plate, is arranged so as to include a packing layer (B) having a greater percentage of voids than that of a packing layer (A), between the packing support plate and the packing layer (A).

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 0.2-7.0 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 including a low boiling substance in the range of 0.7-7.5 wt % based on the weight of bottom liquid of absorption column.

Abstract: An object of this invention is to provide a method for producing acrylic acid that enables to suppress adverse influence of byproducts during distillation and to accomplish long-term continuous operation of the acrylic acid production apparatus. This invention is directed to a method for producing (meth)acrylic acid comprising the step of isolating (meth)acrylic acid from a liquid containing (meth)acrylic acid by distillation wherein the liquid contains glyoxal (including its hydrate) in a concentration of 0.1 mass % or less.

Abstract: A process for inhibiting a polymerization of an easily polymerizable compound purification system is disclosed. According to the present invention, the polymerization of the easily polymerizable compound such as (meth)acrylic acid and (meth)acrylate flowed into a vacuum section can be inhibited by contacting a liquid containing a polymerization inhibitor with the compound directly in the vacuum section. When the vacuum section includes a gas and liquid contact chamber (usually a condenser), the liquid containing a polymerization inhibitor may be supplied to the chamber. When the vacuum section includes a liquid ejector and/or a nash pump as a vacuuming device, the liquid containing a polymerization inhibitor may be circulated by the liquid ejector and/or the nash pump for reducing a pressure of a purifying section. Examples of easily polymerizable compounds are (meth)acrylic acid and (meth)acrylates.

Abstract: (Meth)acrylic acid is purified by crystallization by a process in which the (meth)acrylic acid is purified by a combination of at least two different dynamic crystallization processes, in particular a suspension crystallization and a layer crystallization.

Abstract: A process is provided herein for the high yield production of high purity glacial methacrylic acid (“HPMAA”) that is substantially pure, specifically 99% pure or greater, with water content of 0.05% or less and low levels of other impurities, including HIBA, acrylic acid, MOMPA, methacrolein and others. This improved process comprises providing a crude MAA stream and purifying the crude methacrylic acid stream in a series of successive distillation steps involving two distillation columns. The inventive process is capable producing high purity methacrylic acid product that is especially suitable for the production of specialty MAA polymers.

Abstract: In the stopping and starting operations of a distillation column used for producing (meth)acrylic acids according to the present invention, upon stopping the operation of the distillation column, the heating of a reboiler attached thereto is interrupted and then the reboiler is rapidly cooled; and/or upon starting the operation of the distillation column for production of the (meth)acrylic acids, an inner wall surface of the distillation column is heated to a temperature higher than a condensation temperature of the (meth)acrylic acids and the operation of the distillation column is started under the heated condition. According to the present invention, it is possible to early and safely stop the operation of the distillation column while preventing the occurrence of polymerization within the distillation column, and stably perform an operation for distillation of acrylic monomers for a long period of time.

Abstract: A method for removing impurities from an aqueous mixture or purified aqueous by extracting the aqueous mixture or purified aqueous mixture with an extraction solvent in an extraction zone to form an extract stream and the raffinate stream; and optionally separating the extract stream and a solvent rich stream in a separation zone to form a high boiling point organic impurities stream and a recovered extraction solvent stream

Abstract: A method for producing acrylic acid by using an acrylic acid-containing solution of high concentration without azeotropic distillation is provided. This method of producing acrylic acid comprises introducing an acrylic acid-containing gas obtained by catalytic gas phase oxidation reaction into an absorption column and supplying the acrylic acid-containing solution to crystallization step thereby separating the solution into acrylic acid and residual mother liquid, and distilling at least part of the residual mother liquid and circulating the distillate obtained by the distillation to the absorption column.

Abstract: A method for producing acrylic acid from an acrylic acid-containing solution of high concentration without performing azeotropic distillation is provided. This method of producing acrylic acid comprises steps of absorbing acrylic acid-containing gas, distilling the acrylic acid-containing solution without using an azeotropic solvent thereby obtaining crude acrylic acid as a column bottom stream and/or a column side stream, and supplying the crude acrylic acid to a crystallizing step and melt crystallizing the crude acrylic acid thereby obtaining purified acrylic acid.

Abstract: A method for removing impurities from a mother liquor comprising a carboxylic acid, a metal catalyst, impurities by (a) evaporating the mother liquor comprising a carboxylic acid, a metal catalyst, impurities and a solvent in a first evaporator zone to produce a vapor stream and a concentrated mother liquor stream;(b) evaporating the concentrated mother liquor stream in a second evaporator zone to form a solvent rich stream and a super concentrated mother liquor stream; (c) mixing in a mixing zone a water-solvent solution and optionally an extraction solvent with the super concentrated mother liquor stream to form an aqueous mixture;(d) optionally separating organic impurities from the aqueous mixture in a solid-liquid separation zone to form a purified aqueous mixture; and (e) extracting the aqueous mixture or purified aqueous mixture with an extraction solvent in an extraction zone to form an extract stream and the raffinate stream.

Abstract: The object of the present invention is to provide a method to suppress changes the concentration of (meth)acrylic acid in the bottom solution discharged from the absorption column, and to enable stable operation for separating and purifying (meth)acrylic acid in the subsequent steps onward. The above-mentioned object can be achieved by way of changing the water amount contained in the gas exhausted from the top portion of the absorption column.