Abstract: A method for preparing a purified styrene composition with a styrene yield of at least 80%. The method comprises providing a crude composition containing styrene, and subjecting the crude composition to at least one crystallization step. The at least one crystallization step comprises at least one static crystallization stage and at least one dynamic crystallization stage.

Abstract: A method for preparing a purified styrene composition with a styrene yield of at least 80%. The method comprises providing a crude composition containing styrene, and subjecting the crude composition to at least one crystallization step. The at least one crystallization step comprises at least one static crystallization stage and at least one dynamic crystallization stage.

Abstract: A method for preparing a purified styrene composition is provided. The method includes providing a crude composition and subjecting the crude composition to at least one crystallization step. The crude composition contains 70% by weight or more styrene based on the total weight of the crude composition. The at least one crystallization step comprises at least one of a static crystallization stage and a dynamic crystallization stage. The crude composition contains at least one impurity selected from the group consisting of: color inducing species, oxygenates, sulfur species, alpha-methylstyrene, and mixtures thereof.

Abstract: A method for preparing a purified styrene composition with a styrene yield of at least 80%. The method comprises providing a crude composition containing styrene, and subjecting the crude composition to at least one crystallization step. The at least one crystallization step comprises at least one static crystallization stage and at least one dynamic crystallization stage.

Abstract: A method for preparing a purified styrene composition includes providing a crude hydrocarbon composition containing styrene, subjecting the crude hydrocarbon composition to a distillation in a divided-wall column to produce an overhead hydrocarbon stream, a bottom hydrocarbon stream and a side hydrocarbon stream and subjecting the side hydrocarbon stream to at least one crystallization step to obtain a purified styrene composition.

Abstract: A method for preparing a purified styrene composition with a styrene yield of at least 80%. The method comprises providing a crude composition containing styrene, and subjecting the crude composition to at least one crystallization step. The at least one crystallization step comprises at least one static crystallization stage and at least one dynamic crystallization stage.

Abstract: A method for preparing a purified styrene composition is provided. The method includes providing a crude composition and subjecting the crude composition to at least one crystallization step. The crude composition contains 70% by weight or more styrene based on the total weight of the crude composition. The at least one crystallization step comprises at least one of a static crystallization stage and a dynamic crystallization stage. The crude composition contains at least one impurity selected from the group consisting of: color inducing species, oxygenates, sulfur species, alpha-methylstyrene, and mixtures thereof.

Abstract: A plant for preparing a purified isomeric methylene diphenyl diisocyanate monomer from a mixture of different isomeric monomers is disclosed herein. The plant can comprise a distillation apparatus, which comprises: a) a distillation column including a structured packing, b) a source for a mixture of different isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) an overhead vapor condenser, e) optionally, an overhead vacuum system and f) a flow-controlled reflux system. The overhead vapor condenser comprises a shell and tube arrangement and is embodied so as to directly subcool the condensate to less than 47° C. The flow-controlled reflux system comprises a heater, which is embodied so as to reheat a partial stream of the condensate formed in the overhead vapor condenser up to 190° C.

Abstract: A plant for preparing a purified isomeric methylene diphenyl diisocyanate monomer from a mixture of different isomeric monomers is disclosed herein. The plant can comprise a distillation apparatus, which comprises: a) a distillation column including a structured packing, b) a source for a mixture of different isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) an overhead vapor condenser, e) optionally, an overhead vacuum system and f) a flow-controlled reflux system. The overhead vapor condenser comprises a shell and tube arrangement and is embodied so as to directly subcool the condensate to less than 47° C. The flow-controlled reflux system comprises a heater, which is embodied so as to reheat a partial stream of the condensate formed in the overhead vapor condenser up to 190° C.

Abstract: A process for the separation of a substance from a liquid feed mixture and for the purification of the substance by fractional layer crystallization, wherein the liquid feed mixture comprises the substance to be separated and purified in a concentration of less than 50% by weight, which comprises the subsequent steps in the given order: (a) feeding the liquid feed mixture into a crystallization zone, in which at least one surface is provided, so that at least a part of the surface contacts the liquid feed mixture, (b) cooling the at least one surface of the crystallization zone to a temperature below the equilibrium freezing temperature of the liquid feed mixture so that a crystal layer enriched in the substance to be separated and purified is deposited on the at least one cooled surface, whereby a mother liquid having a lower concentration of the substance to be separated and purified than the liquid feed mixture is formed from the liquid feed mixture, (c) removing at least a portion of the mother liquid fro

Abstract: A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aldehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

Abstract: A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aidehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a falling film crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: The present invention relates to a method for purifying a crude benzoic acid (32) containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (54), which comprises a divided wall column (10).

Abstract: The invention relates to a process for purification of a stream containing a cyclic ester of an alpha-hydroxycarboxylic acid of formula (I), wherein each R independently represents hydrogen or an aliphatic hydrocarbon having 1 to 6 carbon atoms comprising the steps of: (a) separating the cyclic ester-containing stream into one or more cyclic ester-containing vapor fractions and one or more cyclic ester-containing liquid fractions; (b) condensing a cyclic ester-containing vaporized fraction as obtained in step (a) to obtain a cyclic ester-containing condensate; (c) subjecting at least part of the cyclic ester-containing condensate as obtained in step (b) to melt crystallization to obtain a purified cyclic ester-containing stream and a residue stream; and (d) recovering the purified cyclic ester-containing stream as obtained in step (c). The invention further relates to an apparatus suitable for carrying out the present process.

Abstract: A process for the separation of a substance from a liquid feed mixture and for the purification of the substance by fractional layer crystallization, wherein the liquid feed mixture comprises the substance to be separated and purified in a concentration of less than 50% by weight, which comprises the subsequent steps in the given order: (a) feeding the liquid feed mixture into a crystallization zone, in which at least one surface is provided, so that at least a part of the surface contacts the liquid feed mixture, (b) cooling the at least one surface of the crystallization zone to a temperature below the equilibrium freezing temperature of the liquid feed mixture so that a crystal layer enriched in the substance to be separated and purified is deposited on the at least one cooled surface, whereby a mother liquid having a lower concentration of the substance to be separated and purified than the liquid feed mixture is formed from the liquid feed mixture, (c) removing at least a portion of the mother liquid fro

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a suspension crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: Disclosed is a method to prepare a polylactic acid comprising the steps of performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, and purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of crystallization by desublimation from the gas phase, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is then polymerized by feeding it back into the ring opening polymerization.

Abstract: The present invention relates to a method for purifying a crude benzoic acid (32) containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (54), which comprises a divided wall column (10).

Abstract: The invention relates to a process for purification of a stream containing a cyclic ester of an alpha-hydroxycarboxylic acid of formula (I), wherein each R independently represents hydrogen or an aliphatic hydrocarbon having 1 to 6 carbon atoms comprising the steps of: (a) separating the cyclic ester-containing stream into one or more cyclic ester-containing vapour fractions and one or more cyclic ester-containing liquid fractions; (b) condensing a cyclic ester-containing vaporized fraction as obtained in step (a) to obtain a cyclic ester-containing condensate; (c) subjecting at least part of the cyclic ester-containing condensate as obtained in step (b) to melt crystallization to obtain a purified cyclic ester-containing stream and a residue stream; and (d) recovering the purified cyclic ester-containing stream as obtained in step (c). The invention further relates to an apparatus suitable for carrying out the present process.