Abstract: A process for isolating pure butyl acrylate from crude butyl acrylate, which is carried out in a dividing wall column having separation-active internals and a vaporizer, and in which: a dividing wall is arranged in a longitudinal direction of the column to form an upper joint column region, a lower joint column region, an inflow section having a side feed point and an offtake section having a side offtake point; a ratio of an amount of liquid at an upper end of the dividing wall going to an enrichment section and a stripping section of the column is set in the range from 1:0.2 to 1:5; and a ratio of an amount of vapor streams at a lower end of the dividing wall going to the stripping section and the enrichment section of the column is set in a range from 1:0.5 to 1:2.0.

Abstract: The present invention relates to the use of at least two phenol derivatives jointly with at least one ancillary polymerization inhibitor which is different from these two phenol derivatives and particularly is selected from phenol derivatives, amine derivatives, thiazine derivatives, nitroso compounds, N-oxyl derivatives, metal salts, quinone derivatives, and mixtures thereof, to inhibit the polymerization of ethylenically unsaturated monomers comprising at least one heteroatom, it being also possible for a dispersant to be incorporated. The present invention also relates to a corresponding polymerization-inhibiting composition and to the corresponding process for preparing ethylenically unsaturated monomers comprising at least one heteroatom, and particularly acrylic monomers.

Abstract: Provided are integrated processes for the conversion of beta propiolactone to acrylic acid. Systems for the production of acrylic acid are also provided.

Abstract: The invention relates to a method for producing alkyl (meth)acrylate comprising a linear or branched alkyl chain comprising 4 to 10 carbon atoms, by direct esterification of (meth)acrylic acid with a linear or branched alcohol comprising 4 to 10 carbon atoms in the presence of a catalyst, leading to formation of a reaction mixture comprising the desired ester, unreacted acid and alcohol, light by-products, and heavy by-products. The mixture undergoes purification treatment by separation means to obtain purified alkyl (meth)acrylate. The purification treatment comprises a step of membrane separation dehydration applied to at least one of the following: the stream subjected to the final distillation leading to the recovery of the purified (meth)acrylic ester, the aqueous stream originating from the settling out of the reaction mixture, or the stream resulting from the distillation of the light by-products present in the reaction mixture.

Abstract: The present invention relates to a method for continuous recovery of (meth)acrylic acid and an apparatus used for the recovery method. The recovery method according to the present invention enables stable recovery of (meth)acrylic acid and the operation of a continuous process, while securing a high (meth)acrylic acid recovery rate through a solvent recovery process.

Abstract: The present invention relates to a method for continuous recovery of (meth)acrylic acid and an apparatus used for the recovery method. The recovery method according to the present invention enables stable recovery of (meth)acrylic acid and the operation of a continuous process, while securing a high (meth)acrylic acid recovery rate through the acetic acid separation process.

Abstract: The invention relates to a process for preparing concentrated solutions of polymerization inhibitor, that can be used for the production, purification and storage of monomer compositions. This process comprises a step in which at least one polymerization inhibitor in the molten state is mixed with a solvent.

Abstract: The invention is directed to an improvement in operation of wash columns, and more in particular to an apparatus for separating solid particles from a slurry and to a process for separating solid particles from a mother liquor slurry. The apparatus of the invention comprises a wash column (1), which comprises a melting circuit (8,10,11,21), wherein means (22,23) are present to introduce a compound or composition to said wash column between a wash front (6b) formed in said wash column in operation and a product outlet and/or in the melting circuit.

Abstract: The present invention relates to a method of recovering (meth)acrylic acid and an apparatus used for the recovery method. The recovery method according to the present invention discharges each (meth)acrylic acid aqueous solution of different concentrations at a (meth)acrylic acid absorption tower, and uses an extraction solvent of a specific ratio in the step of extracting (meth)acrylic acid, thus enabling the operation of a continuous process of recovering (meth)acrylic acid that can secure a high (meth)acrylic acid recovery rate, and can simultaneously significantly reduce purification energy cost.

Abstract: The invention relates to the production of (meth)acrylic acid, and to implementation of a step of condensing water contained in a recycled gas effluent and/or in the air feed in a (meth)acrylic acid production process, which further includes a process for purifying a reaction mixture comprising (meth)acrylic acid without using azeotropic solvent and based on the use of two distillation columns.

Abstract: Disclosed is a method of preparing acrylic acid from glycerol, including: (a) preparing products including allyl alcohol from reactants including glycerol and carboxylic acid; (b) adding a heterogeneous catalyst and a basic solution to the product including allyl alcohol and then performing oxidation, thus preparing a mixture composed of 3-hydroxypropionic acid and acrylic acid; (c) dehydrating 3-hydroxypropionic acid of the mixture composed of 3-hydroxypropionic acid and acrylic acid, thus producing acrylic acid.

Abstract: A process for obtaining acrylic acid, comprising (a) providing a liquid stream S7 comprising acetic acid and acrylic acid, where the molar ratio of acetic acid to acrylic acid in stream S7 is greater than 1:1, (b-1) crystallizing a portion of the acetic acid present in stream S7 to obtain solid crystallized acetic acid in its mother liquor, (b-2) separating the mother liquor from the acetic acid crystallized in (b-1) to obtain the solid crystallized acetic acid and a liquid stream S8 comprising acrylic acid and acetic acid, (c) separating stream S8 into at least one stream S10 depleted of acrylic acid compared to S8 and a stream S11 enriched in acrylic acid compared to S8.

Abstract: An aim of the present invention is to produce, from glycerol, a bioresourced acrylic acid, that is to say an acrylic acid essentially based on a carbon source of natural origin, meeting all the quality criteria of monomers customarily used as starting material in processes for polymerization of acrylic acid and of its esters, via an economical process. The process according to the invention comprises a final stage of extraction of acrylic acid by fractional crystallization applied to one of the effluents resulting from the acrylic acid purification chain, the location of this final stage possibly depending on the initial feedstock treated, the nature and the source of the glycerol used in the process, purity specifications to be achieved for the final acrylic acid, or finally economic criteria.

Abstract: A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.

Abstract: The invention relates to a process for reclaiming methacrylic acid from a high-boiler phase in a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid comprising the following steps a) Providing a high-boiler phase from a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid b) Providing an aqueous phase, preferably organically loaded, from a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid c) Mixing of components a) and b) optionally followed by filtration or centrifugation d) Adding an extraction media to the mixture from c) e) Subjecting the multiple-phase mixture from d) to at least one mixer-settler extraction process f) Recycling the organic phase from the last mixer-settler process back into the C4-process

Abstract: Improvement in separating lower carboxylic acids from aqueous streams via liquid-liquid extraction with pressurized liquefied propylene and/or propane, wherein carboxylic acid is transferred from the aqueous phase into the liquid solvent phase (extract). The extracted carboxylic acids are recovered as a liquid concentrate by evaporating off the propylene and/or propane solvent from the extract at mild temperatures.

Abstract: An aqueous solution comprising acrylic acid and the conjugate base thereof in a total amount of at least 10% by weight, based on the weight of the aqueous solution, and propionic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, benzoic acid and the conjugate base thereof, maleic anhydride, maleic acid and the conjugate bases thereof, phthalic anhydride, phthalic acid and the conjugate bases thereof, acrolein, benzaldehyde, 2-furaldehyde, and at least 20 mol % of at least one alkali metal cation; process for preparing this solution; and the use of this solution for preparation of polymer by free-radical polymerization.

Abstract: A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.

Abstract: A process for producing (meth)acrylic acid comprising the step of repeating a crystallization operation “n” times to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein: the each crystallization operation comprises a crystallizing step and a melting step; a polymerization inhibitor is not added to a (meth)acrylic acid melt obtained in the melting step of the first to n?1th crystallization operation(s) and a (meth)acrylic acid solution subjected to the crystallizing step of the second to nth crystallization operation(s); and a concentration of a polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the first crystallization operation is adjusted so that a concentration of the polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the nth crystallization operation is 2 ppm by mass or higher.

Abstract: A thermal separation process between a gas ascending in a separating column and a liquid descending in the separating column, which comprise (meth)acrylic monomers, wherein the separating column comprises a sequence of crossflow mass transfer trays, the crossflow mass transfer trays of which have passage orifices for the ascending gas in crossflow direction both in front of and beyond a downcomer for the descending liquid, and such crossflow mass transfer trays and one such crossflow mass transfer tray in a sequence of crossflow mass transfer trays present in a separating column.

Abstract: The invention relates to a method for producing a product mixture (2) by means of the technical hydroformylation of a hydrocarbon stream (1) that contains isobutene, and for separating the product mixture (2) that is obtained, as well as to a device for the claimed method and to the use of a claimed device. The problem addressed thereby is that of providing a method and an associated device that allow the amount of high-boiling substances in the product mixture (2) to be kept as low as possible and thus the yield of the reaction to be increased. The problem is solved by the use of a nano-filtration device (M) for separating the catalyst from the product mixture (2), said device having especially high permeability to 3-methylbutanoic acid.

Abstract: There are provided a dividing wall distillation column for producing high-purity acrylic acid, and a fractional distillation method using the same. The dividing wall distillation column includes a condenser, a reboiler and a main column having a dividing wall. Here, the main column is divided into a column-top zone, an upper feed zone, an upper outflow zone, a lower feed zone, a lower outflow zone and a column-bottom zone. Accordingly, since one distillation column can be used to realize the same effect as that obtained from the use of two distillation columns, the dividing wall distillation column can have an effect of reducing the costs of equipment to produce high-purity acrylic acid, as well as an energy-reducing effect, compared to a conventional process system.

Abstract: In one embodiment, the present invention is directed to a process for producing an acrylate product. The process comprises the step of reacting, optionally in a reaction zone, a reaction mixture comprising an alkanoic acid and an alkylenating agent under conditions effective to form a crude acrylate product. The crude acrylate product comprises acrylate product and acetic acid. The process further comprises the step of reacting, in a separation zone, at least a portion of the acrylate product and at least a portion of the acetic acid to form an intermediate acrylate product. The intermediate acrylate product comprises a Michael addition by-product, e.g., 3-acetoxypropionic acid and/or 3-acetoxypropanoic acid. The process further comprises the step of separating at least a portion of the intermediate acrylate product to form a by-product stream and a purified acrylate product stream.

Abstract: There are provided a dividing wall distillation column for producing high-purity acrylic acid, and a fractional distillation method using the same. The dividing wall distillation column includes a condenser, a reboiler and a main column having a dividing wall. Here, the main column is divided into a column-top zone, an upper feed zone, an upper outflow zone, a lower feed zone, a lower outflow zone and a column-bottom zone. Also, a crude acrylic acid raw material (F) flows in a middle inflow plate NR1 in which the upper feed zone and the lower teed zone come in contact with each other, a low boiling point component (I)) flows out from the column-top zone, a high boiling point component (B) flows out from the column-bottom zone, and a middle boiling point component (S) flows out through a middle outflow plate NR2 in which the upper outflow zone and the lower outflow zone come in contact with each other. In this case, the middle boiling point component is acrylic acid. Accordingly.

Abstract: Provided is a crystallization method by which a highly-pure methacrylic acid crystal can be produced with high productivity. The method for purifying methacrylic acid according to the present disclosure involves using crude methacrylic acid having a maleic acid concentration of 2000 ppm by mass or less and an acrylic acid concentration of 2000 ppm by mass or less and setting the slurry temperature to ?10 to 10° C. in order to crystallize methacrylic acid. A suspension-type jacket-cooling-system crystallization vessel is used as the crystallization apparatus, and an absolute value of the difference between a crystallization temperature and a temperature of a cooling medium in the jacket is preferably 15° C. or less.

Abstract: In one aspect, a process for the preparation of a superabsorbent polymer is described herein. In some embodiments, the process comprises (I) preparing acrylic acid, wherein the process comprises (a1) provision of a fluid F1 having a composition comprising from about 5 to about 20 wt. % of hydroxypropionic acid, salts thereof, or mixtures thereof; from about 0.1 to about 5 wt. % of inorganic salts; from about 0.1 to about 30 wt. % of organic compounds which differ from hydroxypropionic acid; from 0 to about 50 wt. % of solids; and from about 20 to about 90 wt. % of water; (a2) dehydration of said hydroxypropionic acid to give a fluid F2 containing acrylic acid; and (a3) purification of said fluid F2 to give a purified acrylic acid phase comprising acrylic acid having a purity of at least 70 wt. %; and (II) polymerizing the acrylic acid of (I) to form a superabsorbent polymer.

Abstract: A process for producing an acrylate product. The process comprises the step of providing a crude product stream comprising the acrylate product and an alkylenating agent. The process further comprises the step of separating at least a portion of the crude product stream to form an alkylenating agent stream and an intermediate product stream. The alkylenating agent stream comprises at least 1 wt % alkylenating agent and the intermediate product stream comprises acrylate product. The separating is performed in at least one column at an operating pressure ranging from 40 kPa to 80 kPa.

Abstract: A crystallization device and a crystallization process are provided for obtaining (meth)acrylic acid with higher purity without causing leakage of a crude solution by preventing complete clogging in a crystallization tube from occurring. The device for crystallizing (meth)acrylic acid includes a crude (meth)acrylic acid solution supply part, a crystallization tube, a heat medium supply tube, a heat medium discharge tube, a storage part of a crude (meth)acrylic acid solution passed through the crystallization tube, a tube for circulating and supplying the crude (meth)acrylic acid solution to the supply part from the storage part, and a pump for circulating and supplying the crude (meth)acrylic acid solution to the supply part from the storage part, and also includes a pressure meter in the circulate-supply tube.

Abstract: PROBLEM An object of the present invention is to provide a crystallization unit capable of producing a purified acrylic acid having high purity efficiently. SOLUTION The present invention provides a crystallization unit to separate an acrylic acid-containing solution into a mother liquid and a purified acrylic acid, wherein the crystallization unit comprises a crystallizer having an exit to take out the mother liquid and the purified acrylic acid alternately; a supply line to supply the acrylic acid-containing solution to the crystallizer; and a recovery line to recover the mother liquid and the purified acrylic acid alternately from the crystallizer which is connected to the exit, and wherein the recovery line is equipped with an opening and closing unit consisting of a ball valve or a gate valve.

Abstract: A process for transporting a liquid monomer phase which has been withdrawn from a storage vessel and comprises methacrylic monomers to an extent of ?90% by weight, in a tank truck or in a tanker ship, in which the liquid monomer phase is subjected to a separating operation on the route from the storage vessel into the tank of a tank truck or of a tanker ship in order to separate polymer of the monomer present in dissolved form in the liquid monomer phase.

Abstract: In one embodiment, the invention is to a catalyst composition comprising vanadium and titanium. The catalyst composition has a surface area of at least 22.6 m2/g and a plurality of pores, and the plurality of pores have a pore diameter of less than 11.9 nm.

Abstract: Improvement in separating lower carboxylic acids from aqueous streams via liquid-liquid extraction with pressurized liquefied propylene and/or propane, wherein carboxylic acid is transferred from the aqueous phase into the liquid solvent phase (extract). The extracted carboxylic acids are recovered as a liquid concentrate by evaporating off the propylene and/or propane solvent from the extract at mild temperatures.

Abstract: The invention relates to a process for reclaiming methacrylic acid from a high-boiler phase in a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid comprising the following steps a) Providing a high-boiler phase from a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid b) Providing an aqueous phase, preferably organically loaded, from a heterogeneously catalysed gas phase oxidation of a C4-compound to methacrylic acid c) Mixing of components a) and b) optionally followed by filtration or centrifugation d) Adding an extraction media to the mixture from c) e) Subjecting the multiple-phase mixture from d) to at least one mixer-settler extraction process f) Recycling the organic phase from the last mixer-settler process back into the C4-process.

Abstract: The present invention relates to a process for preparing methacrylic acid based on the hydrolysis of methacrylic esters.

Abstract: The present invention provides a method for reducing accumulation of solid materials when manufacturing a (meth)acrylic acid ester having low biacetyl content (less than 2 ppm) by adding an aromatic diamine under conditions which provide sufficient residence time and thorough mixing to react up to 100% by weight of the biacetyl in the crude (meth)acrylic acid ester stream, prior to separation and purification. A feedback method is also provided for reducing solids accumulation in the separation and purification equipment of such processes by measuring the biacetyl content and adjusting the aromatic diamine addition rate so that excess aromatic diamine can be minimized. A third embodiment provides a method for reversing an accumulation of solid materials during such processes, while still producing a (meth)acrylic acid ester having low biacetyl content (less than 2 ppm), by reducing or ceasing the addition rate of aromatic diamine for a period of time.

Abstract: The invention relates to a process for preparation of methacrylic acid, comprising process steps a) providing a crude methacrylic acid-comprising aqueous solution comprising at least one impurity at least partially dissolved therein; b) precipitation of at least a part of the at least one impurity from the crude methacrylic acid-comprising aqueous solution to form at least one solid impurity and a mother liquor; c) separation of at least a part of the at least one solid impurity from the mother liquor to obtain a purified methacrylic acid-comprising aqueous solution and a solid impurity; d) separation of methacrylic acid from the purified methacrylic acid-comprising aqueous solution.

Abstract: In one embodiment, the invention is to a catalyst composition comprising vanadium and titanium. The catalyst composition further comprises ethylene glycol and citric acid. Preferably, the catalyst composition is substantially free of oxalic acid and lactic acid.

Abstract: The present invention relates to a method and apparatus for continuous recovery of (meth)acrylic acid, and more specifically to a method of continuous recovery of (meth)acrylic acid, including: conducting gas phase oxidation of at least one compound selected from the group consisting of propane, propylene, butane, i-butylene, t-butylene, and (meth)acrolein in the presence of a catalyst to obtain a mixed gas containing (meth)acrylic acid; quenching the (meth)acrylic acid-containing mixed gas to remove high boiling point by-products in the (meth)acrylic acid-containing mixed gas; contacting the high boiling point by-product-free (meth)acrylic acid-containing mixed gas with water or an aqueous solution to obtain an aqueous solution containing (meth)acrylic acid; and purifying the aqueous solution containing (meth)acrylic acid to obtain (meth)acrylic acid.

Abstract: PROBLEM There is provided a melting method of (meth)acrylic acid crystal which is capable of providing a higher quality of (meth)acrylic acid without carrying out an additional purification treatment to (meth)acrylic acid obtained by a crystallization operation accompanied by melting of (meth)acrylic acid. In addition, there is provided a simple method for adjusting a content of polymerization inhibitor in a product (meth)acrylic acid. SOLUTION In the crystallization method melting (meth)acrylic acid crystal while wetting with the crystalline molten liquid, a polymerization inhibitor is added to a molten liquid melted after initiation of melting, and all of crystal is melted while circulating and feeding the molten liquid containing said polymerization inhibitor to the crystal.

Abstract: The objective of the present invention is to provide a process for production of (meth)acrylic acid with improved production efficiency by efficiently shifting from heating procedure to cooling procedure for a crystallizer. A process for production of (meth)acrylic acid according to the present invention is characterized in comprising the steps of crystallizing (meth)acrylic acid from a crude (meth)acrylic acid solution by using a batch type crystallizer, and melting the obtained (meth)acrylic acid crystal to obtain a (meth)acrylic acid melted liquid; wherein preliminary cooling of the crystallizer for the next crystallization step is started during transferring the (meth)acrylic acid melted liquid from the crystallizer.

Abstract: A process for producing (meth)acrylic acid of the present invention comprises the steps in the following order: a crystallization step of supplying a cooling medium cooled by a heat source device to a crystallizer to obtain a (meth)acrylic acid crystal from a crude (meth)acrylic acid solution; an adjustment step of returning the cooling medium discharged from the crystallizer to the crystallizer without cooling; a sweating step of supplying a heating medium to the crystallizer to partially melt the (meth)acrylic acid crystal, thereby obtaining a melted liquid, and discharging the melted liquid from the crystallizer; and a melting step of supplying the heating medium to the crystallizer to melt the (meth)acrylic acid crystal, thereby obtaining purified (meth)acrylic acid. According to the present invention, purified (meth)acrylic acid with high purity can be obtained.

Abstract: A process for producing (meth)acrylic acid comprising the step of repeating a crystallization operation “n” times to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein: the each crystallization operation comprises a crystallizing step and a melting step; a polymerization inhibitor is not added to a (meth)acrylic acid melt obtained in the melting step of the first to n?1th crystallization operation(s) and a (meth)acrylic acid solution subjected to the crystallizing step of the second to nth crystallization operation(s); and a concentration of a polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the first crystallization operation is adjusted so that a concentration of the polymerization inhibitor in a (meth)acrylic acid solution subjected to the crystallizing step of the nth crystallization operation is 2 ppm by mass or higher.

Abstract: A process for producing (meth)acrylic acid, comprising the step of repeating a crystallization operation “n” times (providing “n” is an integer 2 or more) to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein a (meth)acrylic acid solution is crystallized and the crystallized (meth)acrylic acid is melted to obtain a (meth)acrylic acid melt in the crystallization operation; wherein a constant amount Ak of the (meth)acrylic acid solution is subjected to the kth crystallization operation (providing “k” is an integer 1 to n?1), and the (meth)acrylic acid melt obtained by the kth crystallization operation is utilized as the (meth)acrylic acid solution for the k+1th crystallization operation without being discharged from a crystallizer or is transferred from the crystallizer to a k+1th storage tank for storing the (meth)acrylic acid solution to be used in the k+1th crystallization operation depending on the stored amount of the k+1th storage tank.

Abstract: In one embodiment, the invention is to a process for producing an acrylate product. The process comprises the step of providing a crude product stream comprising the acrylate product, an alkylenating agent, and water. The process further comprises the step of contacting at least a portion of the crude product stream or a derivative thereof with an extraction agent mixture to form an extract stream and a raffinate stream. The extract stream comprises acrylate product and extraction agent. The raffinate stream comprises alkylenating agent and water. Preferably, the extraction agent mixture comprises at least two extraction agents.

Abstract: In one embodiment, the invention is to a process for producing an acrylate product. The process comprises the step of providing a crude product stream comprising the acrylate product and an alkylenating agent. The process further comprises the step of separating at least a portion of the crude product stream to form an alkylenating agent stream and an intermediate product stream. The alkylenating agent stream comprises at least 1 wt % alkylenating agent and the intermediate product stream comprises acrylate product.

Abstract: A method of extracting (meth)acrylic acid from an aqueous reaction medium into an organic phase in contact therewith is described. The aqueous reaction medium is formed from at least one base catalyst and at least one dicarboxylic acid selected from maleic, fumaric, malic, itaconic, citraconic, mesaconic, and citramalic acid or mixtures thereof in aqueous solution and contains the base catalysed decarboxylation products of the base catalysed reaction. The method includes either the addition of at least one of the said dicarboxylic acids and/or a pre-cursor thereof to the aqueous reaction medium to enhance the solvent extraction of the (meth)acrylic acid into the organic solvent or maintaining the level of base catalyst to dicarboxylic acid and/or pre-cursor at a sub-stoichiometric level during the extraction process. The method extends to a process of producing (meth)acrylic acid, its esters and polymers and copolymers thereof.

Abstract: A method for efficiently producing (meth)acrylic acid by crystallization using a plurality of crystallizers to purify (meth)acrylic acid and a refrigerator for supplying both of a cooling medium and a heating medium, while the refrigerator is stably operated for supplying media having a proper temperature and the temperature of the crystallizers is maintained.

Abstract: In one embodiment, the invention is to a process for producing an acrylate product. The process comprises the step of providing a crude product stream comprising the acrylate product and an alkylenating agent. The process further comprises the step of separating at least a portion of the crude product stream into an intermediate acrylate product stream and an alkylenating stream. The process further comprises separating at least a portion of the intermediate acrylate product stream by azeotropic distillation in the presences of an entrainer to form a stream containing acrylate product and a stream containing entrainer.

Abstract: A production process for the manufacture of ethylenically unsaturated acids or esters thereof is described. The process includes the steps of reaction of an alkanoic acid, or ester of an alkanoic acid, of the formula R3—CH2—COOR4 where R3 and R4 are each independently hydrogen or an alkyl group, in the presence of a catalyst system to produce an ethylenically unsaturated acid or ester product. The process is characterised in that the acid or ester product is subsequently contacted with a dienophile to thereby remove discolouration therefrom. An ethylenically unsaturated acid or ester crude product purification process is also described.

Abstract: A process for producing (meth)acrylic acid comprising the steps of: supplying a cooling medium to a crystallizer (1) from a heat source device (4A), thereby crystallizing (meth)acrylic acid from a crude (meth)acrylic acid solution; discharging the cooling medium from the crystallizer (1) and returning the cooling medium to the heat source device (4A); supplying a heating medium to the crystallizer (1) from a heat source device (4B), thereby melting the (meth)acrylic acid; and discharging the heating medium from the crystallizer (1) and returning the heating medium to the heat source device (4B); wherein temperature of the cooling medium returned to the heat source device (4A) is maintained constant by utilizing a first buffer tank (5); and temperature of the heating medium returned to the heat source device (4B) is maintained constant by utilizing a second buffer tank (6).