摘要:
A process is described for continuously preparing alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid and alkanols having from 1 to 5 carbon atoms in homogeneous, liquid, solvent-free phase at elevated temperature and in the presence of an acidic esterification catalyst, in which the (meth)acrylic acid, the alkanol and the acidic esterification catalyst are fed to a reaction zone (5, 6), a reaction mixture (21) is discharged from the reaction zone (5, 6), and is introduced into a rectification unit I and separated by addition of water into a top stream (23), comprising the alkyl ester of (meth)acrylic acid, and a bottom stream (22), and a substream of the bottom stream (22) from the rectification unit I is fed to a residue dissociation unit IV, which comprises a dissociating boiler (61), and is separated therein into a top stream (29), which is recycled into the rectification unit I and a bottom stream (40), which is removed from the system, wherein the residue dissociation unit IV, as well as the dissociating boiler (61), further comprises a rectification column (62), the water content of the liquid obtained at the bottommost stage thereof being less than 0.1% by weight.
摘要:
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.
摘要:
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.
摘要:
Crude (meth)acrylic acid is purified by a process in which a primary amine compound and an organic sulfonic acid are added to the crude (meth)acrylic acid and the latter is then worked up by distillation.
摘要:
A process for preparing pure (meth)acrylic acid or a (meth)acrylate starting from a crude (meth)acrylic acid, which comprises the following stages: A: treating the crude (meth)acrylic acid with at least one compound which is able to remove aldehydes, to give an aldehyde-free crude (meth)acrylic acid; B: subjecting the aldehyde-free crude (meth)acrylic acid to imprecise distillation, to give a low-boiling fraction comprising (meth)acrylic acid and acetic acid and a high-boiling fraction comprising (meth)acrylic acid and high boilers; C: isolating a pure (meth)acrylic acid from the high-boiling fraction and, if desired, D: esterifying the low-boiling fraction comprising (meth)acrylic acid and acetic acid that is obtained in stage B by means of one or more alkanols, to give an esterification mixture comprising one or more (meth)acrylates, one or more acetic esters, and one or more alkanols.
摘要:
A process for the catalytic gas-phase oxidation of propene or isobutene to acrolein or methacrolein in a tubular fixed bed reactor or catalytically active oxides with a .gtoreq.90% conversion of the initial olefin on a single passage, wherein the temperature of the gases containing the reactants in the direction of flow along the tubes from their entrance until the conversion of the initial olefin is from 30 to 70% is from 360.degree. to 420.degree. C. and is then adjusted to from 360.degree. to 300.degree. C. until the conversion of the initial olefin is from 80 to 90% and is thereafter maintained at from 330.degree. to 390.degree. C. until the gases emerge from the tubes, is described.
摘要:
A process for preparing (meth)acrylic acid, in which a saturated hydrocarbon precursor compound is conducted through a catalyst charge which consists of two spatially successive catalyst beds I, II in the flow direction of the reaction mixture, each of which contains different catalysts and has different reaction-selectivity behavior.
摘要:
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.
摘要:
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.
摘要:
A thermal separating process for removing a stream containing enriched (meth)acrylic monomers from a mixture containing (meth)acrylic monomers, in which the liquid phases retained in the separating space at high temperature and high (meth)acrylic monomer content are minimized.